when the pus formation is only suspected, and has not yet broken out at the
coronet or elsewhere, then the first indication in treatment is the use
of warm poultices or of hot baths. Their application is in most cases
productive of pointing at the coronet.
Directly this appears it is a wise plan to thin the wall down with the rasp
immediately below the swelling. To some extent it relieves the pressure of
the inflammatory products within, and at the same time paves the way for
operative measures which may be necessary later on.
With the breaking of the abscess and the discharging of its contents, we
may in some measure ascertain the condition we have to deal with. The probe
is used, and the abscess cavity explored. The size of the wound, its depth
below the upper margin of the wall, the structures involved, and other
information, may be thus obtained.
At first, however, the nature of the wound, and the character of the
discharges, must largely guide us as to the treatment we adopt. In many
cases, even where the abscess cavity is far below the upper margin of the
wall, and is presumably in an unfit position to drain and heal, a a regular
application of an astringent and antiseptic dressing is sufficient to bring
about resolution. If, however, the discharge from the wound continues to be
liquid, and the wound itself at one spot refuses to heal, it may be judged
that a portion of necrotic tissue is situated under the wall, and affecting
the laminæ, the cartilage, or ligament, as the case may be. If this is so,
then operative measures must be determined on (see Removal of the Wall, p.
349).
_Blisters_.--Instead of the poultice and hot baths, the pointing of the
abscess and the casting off of the slough may be brought about by the
application of a sharp cantharides blister. We have, in fact, seen many
cases where this treatment was adopted prior to the formation of a fistula,
and also in cases where one or more fistulous openings already existed,
where repeated blisters to the coronet have alone been sufficient to effect
a cure.
We are bound to admit, however, that the treatments of poulticing and
blistering are only expectant--we might almost say empirical. At any rate,
we admit to ourselves that what we have advised and carried out is not in
itself curative, but only a means of assisting Nature to satisfactorily
work her own ends. Empirical or not, however, we believe that in every
case of quittor it is wise in practice to at first adopt some such simple
measure, for in nearly every instance where operative measures are
practised, the patient must be laid aside for at least several weeks,
whereas in this way he may be kept at work and a cure effected at the same
time.
_The Actual Cautery_.--Largely of the same empirical nature, yet doing
something a little more calculated to destroy necrotic tissue and bring
about its sloughing is the use of the cautery, both actual and potential.
The actual cautery may be beneficially employed for the relief of sub-horny
quittor in at least two ways.
In the first place, it is often used--a blunt 'point-firing' iron being the
instrument--instead of the knife as a means of evacuating the contents of
the coronary abscess. Those who use it for this purpose are able to say
this in its favour: it brings about the opening of the abscess without the
unsightly hæmorrhage attending the use of the knife, and at the same time
just as effectually empties it. The opening made is not nearly so likely
to close prematurely--that is, before a proper course of treatment of the
wound has been carried out--and so leave necrotic tissue at its bottom. The
intense tissue reaction it sets up is productive of a large slough, cast
off by highly active inflammatory phenomena, which means that the remaining
wound is one in which no dead tissue is left, and which is more amenable to
treatment.
We have also seen the actual cautery used in sub-horny quittor, where that
disease has reached a chronic fistulous stage, as a means of cauterizing
the whole length of the lining of each fistulous passage.
At the present day this method is regarded as barbarous, and savouring
too largely of the methods and practice of the old empirics. There is no
denying the fact, however, that it is at times followed by a speedy and
complete cure of what has for months been an intractable and apparently
incurable quittor; and, honestly speaking, we ourselves can see nothing
very greatly against the operation in certain cases save its appearance. In
that it is certainly rough, and is not calculated to favourably impress the
more critical of our clientele. With the animal chloroformed, however, much
of what can really be urged against it disappears, and on farms and other
places where a skilled and competent dressing of an operation wound cannot
be looked for, it is sometimes wise to advise this method of treatment in
preference to more advanced methods of operating. So far as we can judge,
the after-effects are very little worse than those following other
operative measures, more especially when a suitable case has been chosen.
This method of treatment is particularly applicable to cases of chronic
sub-horny quittor in the more posterior parts of the foot. Here, if one or
more fistulas exist, their openings are probed and the direction of the
sinuses determined. In all probability they are burrowing down along-side
the wall to the sole, where, for want of outlet, they are invading the
substance of the plantar cushion or the plantar aponeurosis.
Should this preliminary probing demonstrate that neither of the fistulas
run dangerously near the joint, then the operation may be decided on.
The animal is cast and chloroformed, the foot firmly fixed, and the horn of
the quarter rasped away quite thin. The sole of the same side is also pared
with the knife until the horn of both the quarter and the sole yields
easily to pressure of the thumb. All that is then needed is three or four
long, round, and pointed irons (about 1/4 to 3/8 inch in diameter) heated
to redness. These are inserted into the fistulas, and the false mucous coat
of these passages thus destroyed. When the iron, on being directed into the
fistulous opening at the coronet, is found to travel alongside the wall,
and to easily reach the sole, it should be made to go further still. The
sole is penetrated, and a dependent opening thus made for the escape of the
discharge that afterwards accumulates.
What happens now, of course, is that an intense and acute inflammation
is set up along the whole track of the fistula, in which position the
inflammatory changes were heretofore chronic. The whole lining of the
fistula, and with it, we hope, all necrotic tissue, is cast as a slough,
leaving nothing but healthy tissue behind. This, with a suitable dressing,
heals and gives no further trouble.
The after-treatment consists in the application of hot poultices. These
tend to greatly ease the pain, and at the same time to facilitate the
removal of the slough. The poulticing should be continued, therefore, until
the sloughing comes about, which happens, as a rule, at about the fifth or
seventh day.
Immediately the slough is cast off, the poultices may be discontinued and
dressing of the wound carried out. This consists of injections of solutions
of zinc chloride 1 in 200, perchloride of mercury 1 in 1,000, carbolic acid
1 in 20, of Villate's solution, or of such other antiseptic as the surgeon
may think fit. The dependent orifice at the sole should be kept open for as
long as possible, being occasionally trimmed round with the drawing-knife,
and scooped out with a sharp-edged director.
Directly a healthy and pink-looking granulation is observed along the
track of the iron, and the discharge therefrom takes on a thick and yellow
appearance, the strength of the antiseptic solutions should be gradually
diminished. This point, in fact, is of great importance in treating all
wounds of the foot. There is a great temptation, on account of the known
excessive liability of the parts to septic infection, to use an antiseptic
solution unduly strong. What must be remembered is that used _too_ strong
they themselves give rise to dead tissue, or to impermeable layers
consisting of compounds of the discharges with themselves, and so create
substances that prove a source of irritation and subsequent trouble.
_The Potential Cautery_.--This is employed in the treatment of sub-horny
quittor, either in the solid form (in sticks, in lumps, or in the powder),
or in the liquid form, when it is injected with a quittor syringe.
In the former method such drugs as perchloride of mercury in the lump, or
nitrate of silver, chloride of zinc, and caustic potash or soda in the
stick, are introduced into each of the sinuses present. This is done by
means of a director or a probe.
A better method, however, when the dressing lends itself to the purpose, is
to use it in the form of a powder, wrapped in the form of small cubes
in extremely thin paper, such, for instance, as is used for rolling
cigarettes. It is then conveniently inserted into each fistula. Introduced
in this more finely divided form the drug is, perhaps, a little more active
in bringing about the desired result.
This method of 'plugging,' although practised by many, we cannot recommend
in preference to the use of the hot iron or of liquid injections. Our
reasons are these: the action of the drug is a protracted one. Almost
immediately after its introduction into the fistula there is formed about
it an almost impermeable layer of a metallic albuminate, which effectively
prevents further rapid action of the caustic. In addition to thus
preventing further action of the dressing, this combination of the tissue
albumin with the metal of the salt, together with much necrotic tissue that
it has caused, is extremely hard to remove from the healthy tissues. This
we explain by pointing out that the action of the caustic, prolonged as
it is, sets up a tissue reaction which partakes largely of the type of a
chronic rather than an acute inflammation. With a chronic inflammation
there is sooner a tendency to the production of fibrous tissue (and thus
the firmer attachment of the necrosed portions) rather than an active
phagocytosis and the casting-off of a slough. Again, careful though we may
be with the probe, it is extremely difficult to be certain that we have
discovered the whole extent of any fistula. An equal difficulty, therefore,
exists in being certain that we have placed the caustic in the position
in which it is most wanted--namely, at the furthermost end of the fistula
where the necrotic tissue is to be found.
When a caustic is used at all, it is far better to employ it in the liquid
form, when either of the drugs we have just mentioned may again be used. In
the first place, the liquid is far more likely to be brought into contact
with the diseased structures than is the solid salt. Also, its action may
be regulated by altering the strength of the solution, and the liability to
form impermeable albuminates thus diminished.
Probably the best solution for use in this way is the old-fashioned
Villate's solution (see p. 199).
This liquid should be injected at least every day, and, in a bad case,
even two or three times daily. Practical hints to be borne in mind when
attempting to cure quittor by means of injections are these:
If the fistulas are numerous, the fluid should be injected into their
various orifices.
In order to force the fluid to the bottom of each diseased track, it is
necessary, when injecting one opening, to firmly close all others.
Several injections should be made at each time of injection. In other
words, we must not be content with just forcing fluid in. It must be forced
in, and again forced out by a further syringeful. The fistulous tracks
must, in fact, be washed in the liquid.
The effect of the injection during the first eight or ten days is to render
suppuration more abundant and whiter. After two weeks of the treatment
sloughing of the inside of the sinuses occurs, and healing of the wound
commences. Signs that this is occurring are--slight hæmorrhage at the end
of each injection, and a gradually increasing difficulty in forcing in the
fluid.
_The Making of Counter-openings to the Fistulas_.--Although Villate's
solution or any other caustic used in the manner we have described
often effects a cure, many practitioners insist on the fact that a
counter-opening to the fistula must also be made.
The probe is used and the direction and depth of the fistula ascertained.
Through the wall is then made an opening at exactly opposite the lowest
point found by the probe, or through the sole if the probe should there
lead us. This opening is best made with a sharp-pointed iron, and may
afterwards be kept large enough by an occasional trimming with the knife.
Many of the older authors, and with them writers of the present day,
declare that unless this is done the ordinary injection is likely to fail
in a great many instances where it would otherwise have been successful.
Where a counter-opening is thus made it is found that it very readily
closes with granulation tissue, and the purpose for which it was made
defeated. This may be avoided by the use of a seton. In preference to the
seton, however, we ourselves would advise that the opening be kept free by
the occasional use of a sharp-edged director or a fine scalpel.
An interesting modification of the practice of making a counter-opening is
that related by Veterinary-Captain S.M. Smith.[A] In point of severity it
runs a middle course between the making of a simple counter-opening and
the removal of a wedge-shaped portion of the coronary band and the wall, a
method which we shall later describe.
[Footnote A: _Veterinary Record_, vol ii., p. 157.]
To perform this operation, the animal is cast and chloroformed. The foot is
fixed and the parts thoroughly cleansed. The horn of the wall is then sawed
through in a direct line from the coronary margin to the solar edge, the
saw-line running exactly over the seat of the sinus.
A strong scalpel is now introduced at the coronary opening, with its
cutting-edge outwards, and is gradually passed down the opening made by the
saw. In this way the sinus is completely destroyed, and from end to end
converted into an open wound. The parts are then washed in a perchloride of
mercury solution, covered with a mixture of powdered iodoform and boracic
acid, over which a pledget of carbolized tow is placed, and then a bandage
over the whole. This dressing should be left on three or four days, after
which the injury should be treated as an ordinary wound. In conclusion,
the author says: 'I can safely recommend this line of treatment to any
practitioner having an obstinate case under treatment.'
_Removal of the Wall and Excision of the Necrotic Tissue_.--This we
may term the radical operation for sub-horny quittor, for it is often
productive of a successful issue when all other means have failed. No
matter in what position the sinus is, whether at the extreme anterior
portion of the coronet, or whether in the region of the heels, it is to be
thoroughly opened up. To do this, the fistula is carefully explored with
the probe and a knowledge of its exact dimensions arrived at. This is
carefully noted, and the horn of the wall for some little distance around
it then rasped down quite thin. Immediately over the sinus, and for a short
distance on either side of it, the horn is stripped away to the sensitive
structures. The cavity of the fistula is then opened up with a scalpel, and
every particle of diseased tissue removed with this instrument and a pair
of forceps. After-dressing consists simply in the application of suitable
antiseptics.
_When the Complication of Necrosed Tendon or Ligament exists_.--We may take
it as an axiom that wherever this exists, whether it is in the extensor
pedis, in the lateral ligaments of the joint, or in portions of the
flexors, all diseased structures should, where possible, be removed. This
is done either with a scalpel or with a curette.
When septic matter has gained the sheath of the perforans, and the
formation of pus therein is indicated by inflammatory swellings in the
hollow of the heel, it is sometimes advisable to lay the sheath open for 1
to 2 inches along the course of the tendons. This, if a fistula is present,
may be best done with a blunt-pointed bistoury, or with a cannulated
director and a scalpel. With the pus thus given exit, and an antiseptic
dressing regularly applied, the case sometimes ends in rapid resolution.
More often than not, however, it is found that the pus has been liberated
too late, and that it has gravitated in the sheath to the extent of
affecting the plantar aponeurosis. Or it may be, of course, that it was in
the plantar aponeurosis the disease commenced. Whichever may have been the
case, we have in the hollow of the heel one or more fistulous openings, or
an opening we have made ourselves, leading down to a necrosed portion of
the terminal expansion of the perforans.
In such cases we ourselves have derived benefit from a regular flushing
of the sinuses with a 1 in 2,000 solution of perchloride of mercury,
introduced by means of a glass syringe, followed later by flushing in the
same manner with a 1 in 40 solution of carbolic acid, the hollow of the
heel meanwhile being kept clean with an antiseptic pad and bandage, or by
liberal applications of an antiseptic powder.
The septic materials are in this way destroyed, and the wound heals without
further complication. We must admit, however, that the cure of the lesion
is generally at the expense of slight lameness, due, in all probability,
to inflammatory tissue adhesions between the flexor perforans and the
perforatus, and to a partial destruction of the synovial membrane of the
sheath.
If, in spite of the antiseptic irrigations, the fistula persists, then
nothing remains but to resort to excision of the aponeurosis, as described
on p. 222.
_When Necrosis of the Lateral Cartilage is present_.--In this case we may
at first try the ordinary treatments of poulticing; and blistering, of
antiseptic caustic injections, and of plugging. In some cases a cure is
effected. Should these fail, however, and we intend to see the finish of
our case, then operative measures must be determined on. This means cutting
down upon the diseased cartilage, and either removing the necrosed portion,
or excising the cartilage in its entirety.
The latter method is seldom practised in this country. As it is the most
radical of the two, however, we shall describe it here first.
_Extirpation of the Lateral Cartilage_.--The operation of extirpating the
lateral cartilage is by no means a new one, being introduced, according to
Zundel, by the senior Lafosse in 1754. It consisted in removing a portion
of the wall by grooving and stripping it, and of excising the exposed
cartilage by means of a sage-knife.
As to what portion of, and how much of the horn of, the quarter should
first be removed, and as to what particular direction each groove should
take, opinion among the older writers varied considerably. This we know
now is not an important matter, and it is sufficient to say that the first
preliminary is a thinning down of the horn of the quarter with the rasp
over the position occupied by the cartilage. At the present time there are
two or three modifications of the operation as originally introduced.
In all, however, the preliminary steps are the same. We shall therefore
describe them collectively, as applying correctly to either of the three
methods of operating we are about to show.
_Preparation of the Subject and Preliminary Steps in the Operation_.--On
the day previous to the operation the horn of the wall immediately over the
cartilage must be so thinned with a rasp as to yield readily to pressure
of the thumb in any position. It should be so thin as to only just avoid
wounding the sensitive structures below.
The whole of the foot must then be thoroughly cleansed, and rendered as
nearly aseptic as possible. The use of warm water, soap, and a stiff brush
is the readiest means of removing the surface dirt. Afterwards the foot
should be soaked for some time in a reliable antiseptic solution, a 1 in
1,000 solution of perchloride of mercury being the most suitable. When
removed from the solution the foot must be packed round with wool or
tow impregnated with corrosive sublimate, and then bandaged, the whole
afterwards wrapped in a thick cloth, or protected with a boot.
On the following day the animal is brought out and cast, and the foot
desired to be operated on firmly secured, after the manner described on p.
81. The bandages and sublimate pads are then removed, and the skin of
the coronet over the seat of operation shaved of hair. An Esmarch rubber
bandage is next run up the limb, and the tourniquet applied, thus rendering
the operation a nearly bloodless one.
This done, the animal is chloroformed, and an antiseptic douche played over
the foot.
So far, the steps in the operation are common to all methods. There are
now, however, three slightly differing modes of extirpating the cartilage,
which modes vary simply according to the structures severed by the knife.
_First Method_.--This is the oldest method of the three, and consists in
making (1) a horizontal incision through the sensitive laminæ along the
lower border of the cartilage, and (2) a vertical incision through the skin
of the coronet, the coronary cushion, and a portion of the sensitive laminæ
(see Fig. 139).
The flaps (Fig. 139, _a, a_) are now held back by tenaculæ, and the whole
of the cartilage, or only the necrosed portion, carefully excised by means
of right- and left-handed sage-knives. Fistulous openings in either of the
flaps _a, a_ must now be carefully curetted and dressed, and the flaps
allowed to fall into position. They are then sutured with carbolized gut,
and the wound finally dressed as to be described later (p. 357).
[Illustration: FIG. 139.--EXCISION OF THE LATERAL CARTILAGE (OLD METHOD).
The wall covering the lateral cartilage first thinned and stripped off; the
two flaps (_a, a_) of skin and the coronary cushion made by the vertical
incision turned back. _a_, The operation flaps; _b_, the exposed cartilage;
_c_, the sensitive laminæ; _d_, the coronary cushion.]
_Second Method (after Holler and Frick_[A]).--These operators deem it wise
to leave untouched the skin of the coronet and the coronary cushion. They
therefore make their first incision along the lower border of the coronary
cushion (see Fig. 140), afterwards exposing the lower half of the cartilage
by removing a half-moon-shaped portion of the thinned horn and underlying
sensitive laminæ (see Fig. 140, _b_).
[Footnote A: Two cases of quittor successfully treated by this method are
reported by R. Paine, M.R.C.V.S., in the _Journal of Comparative Pathology
and Therapeutics_, vol. xv., p. 81.]
[Illustration: FIG. 140.--EXCISION OF THE LATERAL CARTILAGE. (AFTER MOLLER
AND FRICK.) _a_, The thinned horny wall covering the coronary cushion; _b_,
the lateral cartilage exposed by stripping off the thinned wall; _c_, the
sensitive laminæ.]
This done, the external face of the cartilage is separated from the skin
of the coronet. To do this a double sage-knife is run flatwise between the
coronary cushion and the cartilage, with the convex surface of the blade
towards the skin. The knife is then passed backwards and forwards until the
necessary separation is accomplished. During these movements of the knife
a finger of the unoccupied hand should follow the knife, and guard the
coronary cushion against injury.
Following this, the inner surface of the cartilage must be also separated
from the structures lying beneath it. To this end a sage-knife (right- or
left-handed, according as to whether the anterior or posterior portion of
the cartilage is to be first removed) is again passed into the incision.
With the cutting-edge of the knife forward, it is gradually reached round
and under the hindermost end of the cartilage, and theposterior half of
the cartilage separated from underlying structures, and at the same time
excised by one clean cut forwards. Using the second sage-knife in a similar
manner, the cutting-edge this time backwards, it is reached in front of the
cartilage, whose anterior half is then excised by a careful cut backwards.
Any small portions of cartilage remaining after this are sought for with
the finger, and carefully removed by means of a scalpel and a tenaculum.
The fistulous opening or openings in the skin of the coronet should now be
thoroughly curetted, and the whole of the wound dressed as to be described
later.
In removing the anterior half of the cartilage it is highly important to
remember the close contiguity to it of the synovial membrane of the
pedal articulation. This projects as a small sac between the antero- and
postero-lateral ligaments of the joint. Risks of injury to it may be
diminished by having the foot secured with a line, and pulled forward by an
assistant while the cut is being made.
_Third Method (after Bayer)_.--This operator recommends that, after
stripping a half-moon-shaped piece of horn from the seat of operation,
instead of raising the skin of the coronet and the attached coronary
cushion in two flaps (as Fig. 139, a, a), that the cartilage be exposed
by raising up one flap only (Fig. 141, a), consisting of a portion of
the sensitive laminæ, the coronary cushion, and the skin and underlying
structures of the coronet.
With the horse cast and the preliminary steps over, the thinned horn of
the quarter is incised in a semicircular fashion, and the half-moon-shaped
piece thus separated from its surroundings stripped off. At about 1/4 inch
from the incision in the horn, a second incision of similar shape is made
through the sensitive structures, which incision is also carried up into
the skin and structures of the coronet. This incision severs, from bottom
to the top, (1) the sensitive laminæ covering a portion of the pedal bone
and a portion of the lateral cartilage, (2) the coronary cushion, and (3)
the skin of the coronet and such structures as lie between it and the
cartilage.
[Illustration: FIG. 141.--EXCISION OF THE LATERAL CARTILAGE. (AFTER
BAYER.) The horny wall is stripped off over the seat of operation. _a_,
Semicircular flap of sensitive laminæ, coronary cushion, and skin; _b_, the
lateral cartilage; _c_, the sensitive laminæ; _d_, the coronary cushion.]
That this incision of the sensitive structures should be kept at 1/4 inch
from the one in the horn has a reason. It is that when this flap is again
placed into position (as later it will have to be) we have round its
circumference a rim of soft structures into which to place the sutures. And
in this connection it is well to advise the operator that the thinness of
the keratogenous membrane (the laminal portion of it) should warn him that
the portion of it to be turned up--namely, that forming the tip of the
flap--should be _scraped_ away quite close to the os pedis. Unless this is
done, there will not be a sufficient thickness left to afterwards bring
into position and suture.
The half-moon-shaped piece of tissue incised is now carefully dissected
away from the external face of the cartilage, until it may be turned up as
a flap (see Fig. 141, _a_), and held from off the cartilage by a tenaculum.
The exposed cartilage is now carefully removed by the aid of a sage-knife
and a stout pair of forceps, the same precaution of holding the foot well
forward being again taken in order to avoid wounding of the articular
capsule.
At this stage in the operation considerable care is required. The operator
must remember that close beneath him, and more particularly in front, is
the pedal articulation. It is better, therefore, to excise the cartilage
piecemeal, and to do it carefully, than to attempt, at the risk of injury
to the joint, to make the operation 'showy.'
During removal of the cartilage, the terminal branches of the digital
arteries are wounded, as also are the veins of the coronary plexus. Should
either of these stand out with extra prominence from the others, it should
be picked up with a pair of forceps, and ligatured with either carbolized
gut or silk.
Attention should then be given to the flap of skin and coronary cushion.
Wherever a sinus has existed in it, it is to be carefully scraped, and all
dead portions of tissue removed. This done, the flap is allowed to fall
into position, and is there carefully sutured, not only at the skin of the
coronet, but along the whole circumference of the incision.
_Dressing of the Wound and After-Treatment_.--The whole secret of the
success of this operation is in afterwards maintaining a strict asepsis
of the wound. Unless there is reasonable room for belief that this may be
done, the operation had far better not be advised, for if the wound is
afterwards suffered to get into a suppurating and dirty condition, the last
stage of the case may be worse than the first Synovitis and arthritis, with
certain anchylosis of the joint, and a probable loss of our patient, is
almost bound to follow.
We cannot, therefore, too strongly insist upon the advice that the whole of
the preliminary antisepticising of the foot that we have described, and the
after maintaining of asepsis that we are now about to relate, _must_ be
methodically and thoroughly carried out. It is of even _more_ importance
than little details in the operation itself.
In the first and second methods of operating, directly the actual operation
is over, the surface of the wound and both surfaces of the skin-flaps
should first be thoroughly douched with a 1 in 1,000 solution of
perchloride of mercury. Bayer prefers a 1 in 5 solution of iodoform in
ether.
Next, either iodoform or chinosol in the powder should be dusted over the
whole surface, including again both inner and outer faces of the reverted
skin-flaps. This done the flaps are allowed to fall into position and
sutured there with carbolized silk or gut.
Another liberal application of an antiseptic dressing follows this.
Iodoform, iodoform and boracic acid, or chinosol, is freely dusted over
the wound and for some distance around it. Bayer, however, again prefers a
dressing of the wound, and especially the moistening of the line of sutures
with the 1 in 5 solution of iodoform in ether.
Over the wound is then placed a protective layer of gauze, impregnated
either with boric acid, with a mercuric salt, or with iodoform.
Finally, numerous small and lightly-rolled balls of dry carbolized tow
are packed regularly over the whole of the operation wound, and the foot
bandaged.
Practical points to be remembered in this after-dressing are: (1) The
balls[A] of tow should be numerous enough to exercise pressure upon the
sutured flap when the foot is finally bandaged. (2) The bandage should
be run on from the coronet downwards, in order to insure pressure being
exerted in the exact position over the sutured flap. (3) Bandages should
be used in abundance, commencing always from the coronet, and carefully
applied so as to exert an even and uniform pressure. (4) The bandages
should be of clean, unused linen.
[Footnote A: Bayer recommends that the tow be rolled into cylindrical
tampons, each long enough to cross the wound. These are placed on the wound
in alternate horizontal and vertical layers, so that when rolled round by a
bandage they are pressed into an even and compact pad.]
Once the bandages are adjusted, the hobbles may be removed, and the
tourniquet loosened. Directly the tourniquet is removed there is a steady
oozing of blood through the bandages, no matter how many we have put on.
This should occasion no alarm, as experience has taught that the careful
attention to antiseptic measures observed throughout the operation has the
effect of maintaining the lowermost dressings, those next to the wound, in
a state of asepsis. The bandaged foot should now be wrapped in a piece of
thick clean cloth or placed in a boot.
If our antiseptic precautions have been thorough, the dressings and
bandages so adjusted may be allowed to remain without disturbance for from
eight to fourteen days. In this, however, the veterinary surgeon must be
largely guided by the symptoms of his patient. If, at the end of the
first three or four days, the animal maintains a vigorous appetite, if he
commences to place a little weight on the foot, and if the thermometer
gives no indication of a rise beyond the one or two degrees of ordinary
surgical fever, then the surgeon may know that things are proceeding
satisfactorily. Pawing movements with the foot, inability to place weight
upon it, loss of appetite, an increase in the number of respirations, and
a serious rise of temperature, denote the opposite state of affairs. The
wound is in all probability suppurating. The bandages and dressings should
therefore be removed, and the wound either redressed and bandaged, or
treated as an ordinary open wound.
Ordinarily, however, if the operation has been properly performed, healing
takes place by first intention, and the wound when the bandages are removed
at the end of the first or second week appears clean and _dry_.
Having assured ourselves that such is the case, we dress the foot in
exactly the same manner as before, save that so many bandages are not put
on. A similar dressing is repeated weekly until such time as the wound
shows sufficient growth of horn--quite a thin pellicle--to act as a
protective. It may then be left undressed, except for some simple hoof
dressing and a bandage.
Complete healing of the wound takes from about four to eight weeks, at the
end of which time the animal can be again gradually put into work. The
labour, however, should be light, and quite three or four months should be
allowed to elapse before any attempt is made to put him to heavy work.
Should the second method of operating have been the one adopted, then there
is one slight difference in the after-dressing that needs attention calling
to it. In this case we have more or less of a _hidden_ cavity left to deal
with rather than the broad and _open_ wound left in either of the other
methods. This cavity, left by the extirpation of the cartilage, must be
thoroughly dressed with iodoform or chinosol, or with Bayer's iodoform
in ether. The packing with carbolized tow and the bandaging may then be
proceeded with as before.
In conclusion, we may say that the operation is one of some delicacy, and
needs a good surgeon for its successful performance. Furthermore, no one of
the antiseptic precautions we have advised can be omitted. It is, perhaps,
these two considerations (and in justice to the English surgeon we should
say most probably the latter of them) that have prevented this operation
from being generally adopted.
That it is successful there is no gainsaying. Professor Bayer, of the
Vienna School, with whose name is associated the last of the three methods
of operating we have described, is enthusiastic in praise of the operation,
and says: 'The favourable results that I have got by this operation have
caused me wholly to abandon the medicinal treatment, and to prefer in all
cases the surgical operation as being the best means to the end.'
_Partial Excision of the Lateral Cartilage_.--Discarding the somewhat
elaborate methods we have just described, there are English operators who
removed the necrosed portion only of the cartilage, and do so in what
appears at first sight a comparatively rough-and-ready manner.
The apparent roughness is that they do not concern themselves with
conserving the coronary cushion, and hesitate but little in cutting
portions of it bodily away. One would imagine that in this case the quarter
of the side operated on would be always more or less bare of horn. Such,
however, is not the case.
To perform this operation the animal is again cast and chloroformed. Some
operators, however, use the stocks and dispense with the anæsthetic. The
foot is first well cleaned with soap and water and a stiff brush, and the
hair of the coronet over the seat of operation shaved. Again, too, the horn
of the affected quarter is rasped until it yields easily to pressure of the
thumb, and the whole of the foot washed in an antiseptic solution.
A probe is now inserted into the opening at the coronet, and the direction
of the fistula noted, after which the foot is firmly secured, and an
Esmarch bandage and tourniquet applied to the limb.
This done, a triangular or wedge-shaped portion of skin, coronary cushion,
and thinned horn is removed with a strong sage-knife or scalpel.
The base of the wedge-shaped portion removed contains the opening of the
fistula, and the apex of the wedge should reach to the bottom of the sinus
(see Fig. 142).
After the horn is removed and the fistula followed up, it is sometimes
found that what we at first thought was its end, it may now be continued in
an altogether different direction.
It is again followed up with the probe, and the horn and sensitive
structures excised until we are quite certain we have reached its furthest
extent.
Attention should next be paid to the cartilage. Wherever spots of necrosis
are found, as indicated by the pea-green colour of the affected parts, they
must be _carefully_ excised. Care should be taken in so doing to carry the
line of excision some little distance around the visibly affected parts.
This is done that we may be quite certain nothing at all remains calculated
to give rise to further trouble.
It goes without saying that, in addition to the necrosed cartilage, all
other diseased and necrotic tissues should also be removed. The os pedis is
occasionally found necrotic just where the cartilage joins it, or it may be
that a small portion of the sensitive laminæ, by reason of its _liver-red_
or even gray coloration, gives evidence of death of the part.
The former must be well curetted, and the latter cleaned carefully with a
scalpel and forceps.
[Illustration: FIG. 142.--PARTIAL EXCISION OF THE LATERAL CARTILAGE BY
REMOVING A PORTION OF THE CORONARY CUSHION. The dotted lines show the
outline of the wedge-shaped portion of structures to be removed, including
skin, coronary cushion, horn, and sensitive laminæ. _a_, The opening of the
fistula.]
The operation finished, the foot is again douched in an antiseptic
solution, the wound mopped dry with carbolized tow, dressed with either of
the dressings described on page 358, and finally bandaged. The dressing
should be changed every three days only, unless in the meanwhile pawing
movements and other symptoms of distress indicate their removal.
The length of coronary cushion removed in this operation is from 1/4 to 1/2
inch (we ourselves, however, have seen it more), and yet its loss seems to
occasion no serious after-trouble beyond a slight deformity of the parts
beneath. The sensitive structures become sufficiently covered with horn,
and the animal in nearly every case is returned to work, while in a great
many instances he may also trot perfectly sound.
Simple though the operation may appear, and apparently rough in its method,
it is nevertheless successful in effecting a cure in cases where blisters,
plugging, injections, and other means have failed.
Mr. W. Dacre, M.R.C.V.S.,[A] after reading an article on the operation
before the members of the Lancashire Veterinary Medical Association, says:
'My observations have not been based on a single case, and having had nine
of them, and all of them successful, I felt it to be my duty to bring this
subject before the Society.'
[Footnote A: _Veterinary Record_, vol. v., p. 407.]
Mr. T.W. Thompson, M.R.C.V.S.,[A] says: 'In a great number of cases I have
removed a 1/2 inch of the coronary band.... I have performed the operation
a great number of times, and have never seen a foot that has been damaged
by it.'
[Footnote A: _Ibid_.]
Professor Macqueen[A] says: 'I do not spare the coronary band or sensitive
laminæ when I find those parts diseased. I do not unnecessarily damage
those structures. At the same time, I am confident that excision of a piece
of the coronary band or removal of a few sensitive laminæ has not the
untoward consequences so much dreaded in former days.'
[Footnote A: _Ibid_., p. 714.]
Mr. John Davidson, M.E.C.V.S.,[A] says: 'The treatment described, if
carefully carried out and details attended to, will be found a success in
dealing with the majority of cases of quittor. If I may be permitted to say
so, without being considered boastful, I have yet to see the first case
that has resisted the treatment.'
[Footnote A: _Ibid_., vol. xiv., p. 769.]
Should our case of quittor be complicated by caries of the bone, this must,
where possible, be scraped or curetted until the whole of the diseased
portion is removed, and a healthy surface is left. After-dressing must then
be carried out as in other cases.
The treatment of ossified cartilage will be found under treatment of
side-bones, and the methods of dealing with penetrated articulation and
purulent arthritis are treated of in Chapter XII.
_Surgical Shoeing in Quittor_.--In the case of simple or cutaneous quittor,
no alteration in the shoeing is necessary.
When the condition becomes sub-horny, however, and particularly when it is
situated in the region of the quarters, ease is afforded to the diseased
parts by removing the bearing of the shoe in that position.
Should there be no dependent opening at the sole, then the best shoe for
the purpose is an ordinary bar shoe (Fig. 68), with the bearing eased under
the affected quarter.
If, however, there is a dependent orifice, or one is expected, then it will
be necessary either to leave the animal unshod or to provide him with
a shoe that admits of dressing the lesion. In the latter case the most
suitable shoe will be found to be either a three-quarter shoe (Fig. 102)
or a three-quarter bar shoe (Fig. 103). Many operators, however, keep the
animal unshod. We must say ourselves that we consider a shoe useful after
either of the operations for removal of the cartilage, if only to assist in
maintaining the bandages and dressings in position.
In this case a very useful shoe will be the three-quarter bar shoe. With a
little manipulation the bandages are easily run under the bar portion of
the shoe, and a few of their turns every now and again wrapped round the
bar in order to keep the whole firmly in position.
In connection with tendinous quittor, when septic matter has gained the
sheath of the flexor tendons, there is, for a long time after healing of
the fistula, a marked tendency for the animal to go on his toe. To a large
extent we judge this to be due to slight adhesions between the two tendons
brought about by the growth of inflammatory fibrous tissue. In such cases
benefit is sometimes derived from the application of a shoe with an
extended toe-piece (see Figs. 84 and 108).
C. OSSIFICATION OF THE LATERAL CARTILAGES, OR SIDE-BONES.
_Definition_.--An abnormal condition of the lateral cartilages, in which
the substance of the cartilage becomes gradually removed and bone formed in
its place.
[Illustration: FIG. 143.--OSSIFIED LATERAL CARTILAGES (SIDE-BONES).]
_Symptoms and Diagnosis_.--Side-bones are nearly always met with in heavy
draught animals, and are rarely seen in the feet of nags. They are,
moreover, nearly always confined to the fore-feet. In the ordinary way
little need be said concerning their characteristics, and the way in which
they may be detected. Neither need any concern be ordinarily manifested
with regard to the effect they may have on the animal's gait and future
usefulness. Seeing, however, that side-bone constitutes one of the
recognised hereditary diseases, and that at the various agricultural and
horse shows its existence or otherwise in a certain animal is a matter of
great importance, some little attention must be given to these two points.
With a side-bone anywhere approaching full development, diagnosis is easy.
The thumb is pressed into the coronet over the seat of the cartilage, when,
in place of the elasticity we should normally meet with, we have the solid
resistance offered by bone. In some instances diagnosis is even easier
still. We refer to those cases in which the side-bone stands above the
level of the coronet with such prominence as to be readily _seen_ and
recognised without manipulation, and where its growth has caused distinct
enlargement and bulging of the wall of the affected quarter. It seems that
in such cases the bone-forming process does not end with simply depositing
bone in place of the removed cartilage, but that, after that is
accomplished, the bone still continues to be produced, as in the case of an
exostosis elsewhere.
Although diagnosis in cases such as these is easy, it becomes a very
different matter when we are called upon to give an opinion in cases where
ossification of the cartilage is only just commencing. Whether the result
of our examination is to decide the sale or purchase of an animal, to
determine his fitness or otherwise to enter the show-ring, or to merely
advise a client as to whether or no a side-bone is in course of formation,
our position is equally difficult, and in either case our examination must
be searching.
Perhaps the best advice we can give is to say that the whole of the
cartilage must be manipulated both with the foot _on_ and _off_ the ground.
What the reason may be we do not pretend to say, but it is a well-known
fact that in many instances the cartilage, with the foot bearing weight,
is so rigid as to at once convey the impression that ossification has
commenced or is even far advanced. And yet that same cartilage, with the
foot removed from the ground, is as pleasantly yielding to pressure of the
thumb as the most exacting of us could wish for. In any case, then, where
doubt exists, the foot should be lifted to the knee, and the cartilage
carefully examined with the foot in that position. If, then, at any spot
above the normal contour of the os pedis we meet with hardness or rigidity,
we are to look upon that foot with suspicion. Nevertheless, providing our
conscience is sufficiently elastic, the animal may be passed _sound_ so far
as the _existence_ of a side-bone is concerned. We know, however, that with
commencing rigidity we may ere long expect one, and if our opinion is asked
with regard to that particular, it must be admitted that with rigidity of
the cartilage once commenced it is usually not long afterwards before a
fully-developed side-bone makes its appearance.
As is only to be expected, the first noticeable hardening of the cartilage
is to be found near the normal bone. We may thus look for it more
particularly in the lower portions of the cartilage. We think we may say,
too, that in the vast majority of cases the ossification of the cartilage
commences in its anterior half. It is thus brought about that often we
are called upon to examine and report on the condition when we have
_anteriorly_ a side-bone in course of formation, and _posteriorly_ a
perfectly normal cartilage. It is to the latter half of the cartilage that
dealers and others mainly, if not wholly, devote their attention. A horse
with the cartilage in this transition state will therefore pass muster, and
a nice little point of ethics has again to be decided by the veterinary
surgeon before giving his signature to a certificate of examination of an
animal in this condition.
With regard to alteration in gait, we may say at once that side-bones in
heavy animals are not often the cause of lameness. In fact, where the foot
is well developed, when neither the foot as a whole nor the phalangeal
bones give evidence of disease, and where the pasterns are fairly oblique
and well formed, this alteration of the cartilages may be looked upon as of
no serious import at all. Neither is the side-bone due to blows or other
injuries likely to be productive of lameness--that is, always supposing, of
course, that the foot in other respects is of good shape. If lameness is
met with at all, then it is where we have a foot that is in other respects
unsound, with badly contracted heels and upright 'stumpy' hoof, or where
side-bones have occurred in a young animal, and have already reached a
large size before the horse is put to labour. In this latter case, the
added effects of concussion and the evil influences of shoeing are
sufficient to turn the scale. Directly the animal, previously sound, is
asked to work, lameness is the result.
It follows, therefore, that side-bone in the feet of young animals is of
far more serious import than when occurring in older horses. In a nag
animal they constitute a positive unsoundness, and lameness in this case is
more often than not an accompanying symptom.
_Causes_.--To commence with, we may remark that, although met with
sometimes in very early life, side-bones are seldom, if ever, congenital,
and that more often than not they may be looked for in animals of three
years old, or older, seldom earlier. They appear, in fact, only when the
animal is shod and commences work.
This at once suggests two of the principal factors in their
causation--namely, concussion and loss of normal function. Directly the
horse is put to work he has for a great part of his time to travel upon
roadways--either macadamized roads or town sets--where everything is
calculated to bring concussion about. In addition to that he has the
lateral cartilage itself thrown largely out of action by shoeing. We
explained in Chapter III. (p. 66) that the chief function of the cartilage
was to take concussion received by the plantar cushion and direct the
greater part of it outwards and backwards. Now, with the animal shod, the
plantar cushion does not itself, as normally it should, receive concussion.
By the shoeing the frog is lifted from the ground, and the plantar cushion,
together with the cartilage, taken largely out of active work. In other
words, the normal outward and inward movements of the cartilage are
enormously reduced.
It is fair, we think, to take it that the mere fact of the lateral
cartilage persisting _as_ cartilage is due in large measure to its constant
movement. Directly, therefore, it is placed in a state of comparative
idleness, then it commences to ossify, more particularly if there should at
the same time be a tendency to a low type of inflammation of the parts.
Does this latter exist? We may safely say that it does. It is in this way:
The secondary effect of loss of ground-pressure upon the frog and plantar
cushion is to bring about contraction of the heels. With this we get
compression of the parts within, with a certain amount of irritation and
the exact low type of inflammatory phenomena calculated to assist in the
bone-forming process.
The fact that concussion acts as a cause explains in great measure how it
is that side-bones are more frequent in cart animals than in nags, and also
why they should be more common in the fore-feet than in the hind. Taking,
in both animals, a rough calculation as to the weight of body carried
by feet of a certain size, we notice at once that the cart animal has
proportionately more weight to carry than has the nag. Concussion to the
foot is therefore greater. The greater part of the body-weight is borne by
the fore-limbs. Concussion is therefore greater to the fore-feet than to
the hind.
This, however, does not explain altogether the comparative immunity of the
nag animal from this defect. He, too, must also be subject to the effects
of concussion, especially when his higher and faster action is taken into
account. To our minds there is only one explanation to be offered here. We
point at once to the years of constant and judicious breeding of the nag.
Compare that with the relatively few minutes that have been devoted to a
more careful selection of the cart animal, and we at once see a possible
explanation. That the explanation holds some amount of truth is borne out
by the fact that, since a greater attention has been paid to the selection
of our cart animals, side-bone has grown a great deal less common.
Is side-bone hereditary? We can best answer that by saying that, some
several years ago, the Council of the Royal College of Veterinary Surgeons,
at the request of the Royal Commission on Horse Breeding, drew up a list of
those diseases 'which by heredity rendered stallions so affected unfit as
breeding sires,' and that in that list was included side-bone.
Side-bones, therefore, are hereditary. We think, however, the statement
needs qualifying. It is in this way: side-bones occur only at a certain,
usually well-defined, time after birth, and we might say are _never_
congenital. They occur only after the animal has been put to work, and are
more or less plainly due to mechanical causes--namely, the ill effects of
shoeing and concussion. The cause of their appearance, in short, is more
plainly extrinsic than intrinsic, and side-bone in the horse is, as
Professor McCall puts it, about as much due to heredity as is corn on the
human foot.
Between these two opinions--that they are plainly hereditary, and that they
just as plainly are not--it is well to strike a middle course. They are, we
will say, hereditary in this way: So long as a cart animal is bred, to put
it vulgarly, 'top-heavy' (that is, with a body out of reasonable proportion
to the feet that have it to support), so long will the foot be subjected to
a greater concussion, and so long will side-bones in such animals commence
to make their appearance at about middle life.
In addition to the causes we have now mentioned, side-bones are often
the result of other diseases of the foot. They thus occur as a sequel to
sub-horny quittor, to suppurating corn, to complicated quarter sand-crack,
or to the inflammation of the parts occasioned by a prick. They also arise
in many instances from the effect of a prick or injury to the coronet.
Among the latter we may mention treads from other animals, and treads
inflicted by the animal himself with the calkin of an opposite shoe, or the
repeated injury occasioned by the shafts being carelessly allowed to drop
on to the foot. In severe cases of laminitis, too, the cartilages are
nearly always affected. In this instance the inflammatory phenomena in the
os pedis no doubt give rise to an abnormal activity of bone-forming cells.
The cartilage is invaded, and the side-bone formed (see Fig. 118).
_Treatment_.--In the ordinary way the 'treatment' of side-bone is a thing
but rarely mentioned. The explanation lies, of course, in the fact that
side-bones are so rarely the cause of lameness. When lameness does occur
with a side-bone, and we have reason to believe that the said side-bone
is the cause of the lameness, it is well before talking of treatment to
question ourselves thus: 'In what way does the side-bone cause lameness?'
The now generally-accepted answer to that query is the explanation put
forward several years ago by Colonel Fred Smith--namely, that the pain, and
therefore the lameness, was due to the compression of the sensitive laminæ
between the ossified and enlarged cartilage and the non-yielding and often
contracted wall of the quarters. That, in fact, constitutes the basis upon
which Smith's operation for side-bone (that of grooving the wall of the
quarters) is founded.
Before describing the operation, however, we may say that we are now able
to understand that older operators who claimed success for other methods of
treatment, were to a very great extent justified in so doing.
For instance, take the combined treatments of firing and blistering, and
the use of a bar shoe. Here the beneficial action of the cautery and the
blister may be largely problematical. The bar shoe, however, would be
almost certain to give good results. Frog-pressure with the ground would be
again restored, and the contraction of the heels removed. Pinching of the
sensitive structures would be diminished, and the lameness cured.
Take, again, the treatment of 'unsoling.' It was barbarous, we know
barbarous, because unnecessary and easily avoidable. It was practised,
however, certainly very little more than two decades ago, and practised by
men of standing in the profession. Without dragging the case to light again
by mentioning the names of those concerned, we may mention that not
many years ago a highly respected member of the profession was, at the
instigation of the Royal Society for the Prevention of Cruelty to Animals,
prosecuted for practising unsoling for the relief of side-bone. Practically
only one other member of the profession was able to come forward and defend
the operation on the score of its utility. We see now, however, that--as
does Smith's operation--unsoling does permit of the greater expansion of
the heels. The contraction is done away with, the pressure on the sensitive
laminæ again diminished, and the lameness relieved.
Not that we are attempting to defend the operation--far from it. We simply
mention it as interesting, and quote this and the use of the bar shoe (with
both of which methods older operators have claimed success) merely as
evidence that the operation of Smith is based on a logical foundation.
When treatment is decided on, therefore, we may first advise blistering and
the use of a bar shoe. After that, should the lameness continue, and should
we still judge the side-bone to be the cause of it, the operation may be
advised.
As we have said before, the operation consists in so grooving the wall as
to allow of the quarters widening sufficiently to relieve pressure on
the parts within. In one or two previous portions of this work we have
considered operations involving this procedure. Before detailing the
operation here, therefore, we will first describe the instruments
necessary, and the most satisfactory methods of incising the horn.
To begin with, it must be remembered that all methods of hoof section have
for their object the after-expansion of the horny box, and that this can
only be brought about by making each groove complete from coronary margin
to solar edge of the wall, and carrying it, throughout its length, _deep
enough to reach the commencement of the sensitive structures_.
To this end, therefore, the operator must bear in mind the comparative
thickness of the various parts of the wall, and must, in particular,
remember the relative thinness of that portion of horn forming the outer
boundary of the cutigeral groove, and accommodating the coronary cushion.
For the making of the incisions there is the special saw devised for this
operation by Colonel F. Smith, A.V.D., and which we illustrate in Fig. 144.
With this the wall is sawn through _until the depth arrived at is equal to
what is indicated by a previous examination of the thickness of the crust
as viewed from the solar surface_. Here Colonel Smith says: 'I strongly
advise everyone to use a metal gauge (a thin piece of material) to
introduce into the incision made by the saw, and run it up and down to
ascertain whether the wall is properly divided throughout. The depth to
which this should be done we know from the previous measurements of our
gauge on the crust.'
[Illustration: FIG. 144.--SMITH'S SIDE-BONE SAW (EARLY PATTERN).]
Should the saw be of a pattern in which the set of its teeth makes only a
narrow incision,[A] it should, while operating, be kept well oiled, and
should be withdrawn every few seconds in order that the horn-dust lying in
its teeth may be examined. If this is getting slightly blood-stained,
we know, of course, that the sensitive structures are reached, and the
incision has been carried far enough. In so judging the depth of the
incision, however, care must be taken to see that the top of the coronary
cushion is not injured with the saw, for if this is done the blood
trickling into the depth of the incision will tinge the horn-dust, and give
the false impression that the incision is sufficiently deep.
[Footnote A: That is Smith's older pattern. The newer pattern (Fig. 145)
has the teeth so set as to make an incision wide enough to be looked into.
In this case the depth arrived at is to be judged by the appearance of the
bottom of the incision.]
If the operator has had no previous experience of the use of the saw in
this operation, he must also be careful to avoid placing too great a
pressure on the teeth of its lower third. This is done by keeping the hand
too greatly depressed. Again, this leads to wounding of the sensitive
structures (this time at the lower end of the incision), and again the
operator is confused by the blood thus allowed to run into the groove.
The only portion of horn difficult to operate on is that immediately under
the coronet. This is best severed with a succession of downward movements,
and is easier performed with Smith's later pattern of side-bone saw (Fig.
145) in which the set of the foremost teeth is reversed.
[Illustration: FIG. 145.--SMITH'S SIDE-BONE SAW (IMPROVED PATTERN).]
In making these grooves we must say that we think the use of the special
saw may be dispensed with, and the incisions just as easily, or, at any
rate, just as successfully, made with the knife. Those who select to use
this instrument should choose a narrow-topped and sharp searcher, or a
modern shaped drawing-knife of suitable size, such as those depicted in
Fig. 46, _a_ and _b_, and they will find their work much easier if
they will make the first steps in the incisions with an ordinary flat
firing-iron. By the use of the latter instrument the grooves are made
conveniently open along their tops, and room left for nicely finishing the
more delicate manner of removing with the knife the softer horn near the
sensitive structures.
Those whose leaning is towards the use of special instruments, but who, at
the same time, do not care to use the saw, will find their wants supplied
in the hoof plane (Smith's), Fig. 146, or the hoof chisel (Hodder's), Fig.
147. With the hoof plane the groove in the wall is made by a succession of
downward scraping movements, while with the chisel the cut in the wall is
made either from below upwards, or from above downwards, according as
the foot is held forward or backward--whichever, in fact, comes most
convenient.
[Illustration: FIG. 146.--HOOF PLANE (SMITH'S).]
When using the knife or the hoof plane it is not often that the sensitive
structures are injured. In all cases, however, no matter what the
instrument used, the metal gauge should be employed when the sensitive
structures have been touched, and the operation obscured by blood.
[Illustration: FIG. 147.--HOOF CHISEL (HODDER'S).]
Our instruments at hand, the operation may be proceeded with. The first
step is to ascertain the extent of the side-bone, and to determine the
position of the incisions. To do this the coronet is felt with the thumb,
and the anterior extremity of the side-bone noted. This is marked on the
horn with a piece of chalk, and a vertical line dropped from this position
to the inferior margin of the wall (Fig. 148,1). The line crosses the horn
fibres obliquely, and is purposely made in that direction in order that its
inferior end may be far enough back to avoid the last nail-hole. Should the
side-bone reach very far forwards, it may be wise to cause this line to
slant from before backwards (see dotted line _a_, Fig. 148). Unless this is
done, it is found that in some feet so much of the wall is isolated at the
bottom that insufficient is left to nail the shoe to.
The next line to be made is the rear one. Its correct position is
ascertained by first noting the junction off the wall with the bar (see
groove 2, Fig. 149); and its inferior end must be just anterior to the
inflexion of the wall. This is done that we may avoid cutting the bar. The
position of the lower end of the rear line thus ascertained, it is run
upwards with the chalk in the direction of the horn fibres.
[Illustration: FIG. 148.--DIAGRAM ILLUSTRATING THE POSITION OF THE GROOVES
IN THE WALL IN COLONEL SMITH'S OPERATION FOR SIDE-BONE. 1,2, and 3, mark
the grooves in the order in which they are made; the dotted line _a_ marks
the position taken by the anterior line when the side-bone, is one reaching
far forward, while the dotted lines _b_ and _c_ mark the position of the
additional grooves to be made if thought necessary.]
The third line is made in such a position as to divide into two equal
portions the wall between lines 1 and 2. Here, however, some operators
prefer to make two, or even three, lines, adding those as at _b_ and
_c_, Fig. 148; and Smith himself says that a multiplicity of lines is an
advantage rather than not.
In any case, having once determined the position of the lines, they should
be plainly marked out with chalk, and then viewed from a distance with
the foot on the ground, in order to judge of their regularity. If we are
satisfied with them, we then lightly mark them with the saw, with the hot
iron, or with the knife, whichever instrument we may be intending to use.
Unless the details are methodically carried out as here described, it is
probable that more of the foot will be isolated than is necessary, and that
as a consequence very little is left to which to nail the shoe.
[Illustration: FIG. 149.--DIAGRAM ILLUSTRATING THE POSITION OF THE GROOVES
MADE IN THE HOOF IN COLONEL SMITH'S OPERATION FOR SIDE-BONES. 1, 2, and 3,
show the grooves in the wall in the order in which they are made; 4 shows
the groove made at the junction of the sole with the wall.]
The incisions are then made with the saw or the knife, with the foot
held in a convenient position by an assistant. That usually found most
comfortable for the first incision is with the foot held forwards and
placed on an assistant's thigh in the position adopted for 'clenching up'
when shoeing, while that for the rear incision is with the animal's knee
flexed, and the foot held well up to the elbow. In this, however, each
operator will suit himself.
Should the preliminary steps in making the incisions be performed with the
iron, it will be easiest done with the foot on the ground.
When the incisions through the wall are complete, our attention must be
given to the sole. A drawing-knife is here used, and a further incision
made over the white line so as to destroy the union of the sole with the
wall between incisions 1 and 2, and so completely isolate the portions of
wall included within the four grooves (see groove 4, Fig. 149). When this
is done it should be found that the portions of the isolated wall spring
readily to pressure of the thumb.
The inferior or wearing margin of the isolated wall must now be so trimmed
that it takes no bearing on the ground when the opposite limb is held up by
an assistant and full weight placed upon the foot.
For a day or two after the operation lameness is intense. This is to be
treated with hot poultices or hot baths, and and soon disappears. Three to
four days later a bar shoe is nailed on (taking care that the bearing of
the quarters is still eased), and the hot poultices still continued. Four
days later still walking exercise may be commenced, to be followed
shortly afterwards by trotting. At about the twelfth day some animals may
conveniently be put to work, while in other cases a fortnight, or even a
month, must elapse before this can be done. When put to work early, it is
wise to fill in the fissures made in the wall with hard soap, with wax, or
with a suitable hoof dressing, in order that irritation of the sensitive
structures with outside matter may be prevented.
This operation is soon followed by remarkable changes in the shape of the
foot. At about the third week the coronet shows signs of bulging, and the
upper part of the wall operated on is often so protruding as to render the
foot wider here than at the ground surface. This is a sign that the case is
doing well.
Should no improvement be noticed at the end of three weeks or a month, or
should the grooves become filled from the bottom (which they do remarkably
fast), then the incisions must be deepened, the exercise reduced, and the
fomentations or poulticing repeated. So treated, many cases of side-bone
lameness will be relieved, if not entirely cured, and, should the worst
happen, and no alteration in the lameness is noticeable, no harm will have
been done to the foot. In this connection, the originator of the treatment
says: 'I may assure those induced to doubt either their diagnosis or the
value of hoof section that no harm is done to the foot, even should the
operation be of no value. It may do much good; it cannot do harm. The
operation will never succeed until the inherent timidity of sawing or
cutting into the wall is overcome. The _incisions must be deep, and of the
same depth from the coronet to the ground_.'[A]
[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol.
iii., p. 313.]
It is well to remark here that the operation of hoof section cannot be
expected to succeed in every case. The last man in the world to claim that
for it would be its originator. Failure to relieve the lameness may be
accounted for in a variety of ways. First, of course, will come errors in
diagnosis. No one of us is infallible, and the lameness we have judged as
resulting from side-bone may arise from another cause. There are, too,
complications to be reckoned with, the existence or absence of which cannot
always be definitely ascertained. Such are: Ringbone, especially that form
of ringbone known as 'low'; bony deposits on the pedal bone, either on its
laminal or plantar surface, or even changes in the navicular bursa.
CHAPTER XI
DISEASES OF THE BONES
A. PERIOSTITIS AND OSTITIS.
We head this section, Periostitis _and_ Ostitis, for the reason that in
actual practice it is rare for one of these affections to occur without the
other. The periosteum and the bone are so intimately connected that it is
difficult to conceive of disease of the one failing to communicate itself
in some degree to the other. Pathologically, however, and for purposes of
description, it is more convenient to describe separately the abnormal
changes occurring in these two tissues.
With the main phenomena of inflammation occurring elsewhere we presume
our readers are aware. Briefly we may put it, that under the action of an
irritant, either actual injury, chemical action, or septic infection,
the healthy tissues around react in order to effect repair of the parts
destroyed. Also that this reaction involves the distribution of a greater
blood-supply to the part, with an abundant migration of leucocytes, and
the outpouring of an inflammatory exudate, together with symptoms of heat,
pain, redness, and swelling of the affected area. And that in chronic
inflammations, owing to persistence of the cause, the process of repair
thus instituted does not stop at mere restoration of lost tissue, but
continues to the extent of forming an abnormal quantity of such tissue as
normally exists in the parts implicated.
The process of inflammation in bone is essentially the same. It takes place
along the course of the bloodvessels, and is only modified in its attendant
phenomena by the structure of the parts involved. Swelling, for instance,
cannot take place in the centre of compact bone tissue. Otherwise, other
changes occur exactly as in inflammations of other structures.
When the causal irritant has been excessively severe and the migration of
leucocytes abundant, actual formation of pus may occur, the bony tissue
being broken down and mingled with it, and an abscess cavity formed. In
milder cases, affected and necrotic tissue is removed by a process of
phagocytosis, and new tissue (this time osseous) formed in its place.
In the periosteum we may take it roughly that inflammation runs a course
similar to that occurring in soft tissues elsewhere. There is but one
exception, and that, as we shall mention shortly, is connected with its
deeper layer.
As we know, the periosteum consists of two layers, an outer fibrous and
an inner yellow elastic, and is extremely vascular. Numerous bloodvessels
ramify in it, and, with their attendant nerves, break up to enter the
numberless canals of the Haversian system. This extreme vascularity, of
course, favours abundant exudation. The exudate, however, is, as it were,
shut in by the dense fibrous layer of the membrane, and the result is that
in periostitis it collects between the membrane and the bone, causing
swelling and raising of the membrane, and giving rise to excruciating pain
from pressure upon the nerves.
Should the periostitis be complicated by the formation of pus, then the
vessels entering and supplying the bone are, in the suppurative area,
destroyed. With their destruction it may happen that we get also death of
a portion of the osseous tissue. This, however, when the suppuration is
abundant, cannot commonly occur, as the bloodvessels within the bone--those
of the medulla--commence to supply blood to the affected part. In cases of
trouble with the bones of the foot, these last few remarks have a special
significance. Here we have three bones whose medullary cavity is extremely
small--almost nil, in fact--which explains in some measure how easy it is
when suppuration exists to get necrosis and exfoliation of, say, portions
of the os pedis. Necrosis and sloughing of the periosteum itself may also
happen, but as the extreme vascularity of the membrane is a fairly strong
safeguard against that it is of only rare occurrence.
In connection with the deep layer of the periosteum, and forming part of
it, are found numerous bone-forming cells (_osteoblasts_). These, under
ordinary conditions, are relatively quiescent. Under the slightest
irritation or stimulation, however, their bone-forming functions are
stirred into abnormal activity, thus explaining how easy it is (especially
with bones so open to receive slight injuries as are those of the foot) to
get ossific deposits, the starting-point of which we are quite unable to
account for.
With this brief introduction we will now describe such pathological changes
as occur in the separate structures, and which we are likely to encounter
in the various diseases of the foot. While so doing, we shall draw
attention to such diseases as we have previously described in which the
pathological conditions we are considering may be met with.
1. PERIOSTITIS.
This we shall consider under _(a)_ Simple Acute Periostitis, _(b)_
Suppurative Periostitis, _(c)_ Osteoplastic Periostitis.
_(a) Simple Acute Periostitis_.--This is the periostitis that follows on
the infliction of a slight injury to the membrane--an injury without an
actual wound and free from infective material. It is one, therefore, which
we always judge as existing in those cases where we have distinct evidence
or history of injury, but in which the injury has not been severe enough to
lead to fracture or to the infliction of an actual wound.
Such cases may be those of lamenesses persisting after violent blows upon
the foot--cases where the animal has been kicking against the stable
fittings, or where the foot has been partially passed over by the wheel of
a waggon. It may be, too, that in a case of 'nail-bound' a great deal of
the pain and lameness is due to a simple periostitis caused by pressure of
the bulged inner-layer of horn upon the sensitive structures.
Simple acute periostitis may also occur in cases where an actual wound is
in existence, but where such wound, fortunately, remains aseptic. We may
thus have this condition accompanying ordinary cases of pricked foot, of
treads in the anterior region of the coronet, and of accidental injuries of
other kinds.
In simple acute periostitis the membrane is thicker and redder than normal,
and is easily stripped from the bone. As it is pulled off it is noticed
that there are numerous fibril-like processes hanging to its inner surface,
and which draw out from the substance of the bone. These are simply the
vessels (bloodvessels and nerves) which, loosened by the inflammatory
exudate, are readily detached and drawn from the Haversian canals into
which they normally run. In addition to its increased redness, the membrane
has a swollen and gelatinous appearance owing to its infiltration with the
inflammatory discharges. Simple acute periostitis may and often does end
in resolution. On the other hand, it may end in suppuration or may become
chronic. If the latter, then the osteoblasts of the innermost layer become
active, and abnormal deposits of bone are the result.
_(b) Suppurative Periostitis_.--This condition simply indicates that
the inflammation is complicated by the presence of pus organisms. It is,
therefore, a common termination of the simple acute form attending the
infliction of a wound. The wound becomes contaminated, and the case of
simple periostitis is soon changed into the suppurative form. Once having
gained entrance to the wound, the pus increases in quantity, and slowly
runs between the membrane and the bone. This, however, it does not do to
any large extent, showing rather a tendency to penetrate the outer fibrous
layer and gain the outside of the membrane.
Suppurative periostitis is met with in foot cases, commonly in connection
with punctured foot. It occurs, too, as a complication in suppurating corn,
in severe tread, in complicated sand-crack, as a result of the spread of
suppurative matter in acute coronitis, and in sub-horny quittor.
In ordinary cases of suppurative periostitis the pus formed is yellow
in colour, creamy thick, and free from pronounced odour--the so-called
'laudable' pus of the older writers. It so happens in many cases of foot
trouble, however, that putrefactive organisms gain entrance side by side
with those of pus. In this case the characters of the discharge are
very different. It is distinctly more fluid, is of a pink or even light
chocolate colour, and extremely offensive. In these instances the pus
shows a marked tendency to spread, strips the periosteum from the bone,
perforates the outer layer of the membrane, and finally infiltrates the
surrounding tissues.
This forms a near approach to what is known in human surgery as an
_infective_ periostitis, and in our subjects is nearly always met with in
cases of severe prick. Its rapidly spreading character makes it always
a dangerous condition, and a punctured foot exuding a discharge of this
nature should always be regarded as serious. The close contiguity of
the joint (it can never be _far_ distant in foot cases), the spreading
character of the disease, and the rapidity with which the horse succumbs to
arthritis, are all factors to be taken into consideration, and to lead to a
warning-note being struck when attending a case of such kind.
A further instance of infective periostitis is that met with in acute
laminitis. The discharge obtained from the sole in these cases very often
bears the character we have just described, and when one considers the
thinness of the keratogenous membrane, one is bound to admit that changes
so grave occurring in it cannot fail to spread and infect the periosteum.
_(c) Osteoplastic Periostitis_.--This is more particularly a chronic
process, and is, as the suffix '_plastic_' indicates, associated with
bone-forming changes in the membrane. It may occur as a consequence of
slight but continued irritation, often without ascertainable origin (see
Case 2, p. 392), or it may be the sequel of acute disease.
In this form of periostitis the membrane is again swollen and more vascular
than in health, and is also easily separable from the bone. The exposed
bone is generally rough, in some cases even spicular, and the inner layer
of the removed membrane is rough and gritty to the touch--characters
imparted to it by numerous minute fragments of bone that have been torn
away with it from the more compact osseous tissue beneath.
The results of an osteoplastic periostitis are frequently met with in the
bones of the foot, and are described by veterinary writers under
such headings as 'Pedal Exostoses,' 'Ossifying Ostitis,' and 'Pedal
Ossification' (see Figs. 152, 153, 154, and 155). In many of these cases
the disease is purely chronic, and the original cause nearly always
wanting. When the foot has been subjected to laminitis of some weeks'
duration, the same condition is also met with, being at the same time
associated with rarefactive osteoplastic ostitis, conditions which we
shall shortly describe. Cases we have examined have undoubtedly shown this
condition of osteoplastic periostitis, the rarefactive and osteoplastic
changes in the bone itself, met with in older cases, occurring no doubt
as a result of non-expansion of the horny box. So far as we are able to
ascertain, there is every reason to believe that in chronic laminitis the
accompanying periostitis leads to the formation of bone, and would, if it
were possible, lead to increase in the size of the os pedis. If proof were
wanted of this, it is only necessary to point out the increased growth at
points where resistance is nil--namely, along the upper margin of the bone
(see Fig. 118). However, increase in size elsewhere is prevented by the
resistance of the hoof, so that, as the bone-forming process progresses, as
it inevitably _must_ under the inflammatory changes going on, it is, as it
were, compensated for by rarefaction or bone-absorption changes occurring
simultaneously with it.
2. OSTITIS.
We shall next deal with the inflammatory changes occurring in the bones
themselves, and shall consider them under (_a_): Rarefying or Rarefactive
Ostitis, (_b_): Osteoplastic Ostitis, and (_c_): Caries and Necrosis.
Inflammatory changes occurring in the medulla we may pass without
consideration, for in the bones of the foot the medullary cavity is so
small, and the changes taking place in it of such minor importance, that we
may do this without in any way seriously prejudicing our work.
_(a) Rarefying or Rarefactive Ostitis_.--By this term is indicated an
inflammation of the bone attended by its absorption, the absorption being
due to the action of certain cells, termed _osteoclasts_. This condition
may be due to the pressure of tumours, may occur as the result of injury
when a piece of bone is stripped of periosteum, or may be the result of an
inflammation occurring in the periosteum elsewhere.
A piece of bone undergoing rarefactive ostitis is redder than normal, and
the openings of the Haversian canals are distinctly increased in size. As a
result a greater number of them become visible. Their increase in size is
due to the inflammatory absorption of the bony tissue forming them, and in
the larger of them may be seen inflammatory granulation tissue surrounding
the bloodvessels. This enlargement of the Haversian canals is well seen
when the bone is macerated, the whole then giving the appearance of a piece
of very rough pumice-stone.
This process of rarefaction or absorption of bone tissue may be confined
to quite a small portion, or it may be spread over the whole of the bone,
rendering it more porous than is normal, but stopping short of complete
destruction of the bone tissue (a condition which is sometimes known
as inflammatory osteoporosis (see Fig. 118)). In this latter case the
condition is a chronic one, and the bone tissue remaining often appears to
be strengthened by a compensatory process of condensation. For an example
of rarefactive ostitis as met with in cases of disease of the feet,
we refer the reader to laminitis (see Fig. 118). The osteoplastic or
condensing process that appears to exist simultaneously with it explains,
no doubt, how it is that bones so affected do not more commonly fracture.
A further example of this process is illustrated in Fig. 133. The pressure
of a tumour (in this case a keraphyllocele) has led to rarefactive changes
in the bone, forming a neat indentation in the normal contour of the bone
which serves to accommodate the tumour.
_(b) Osteoplastic Ostitis, Osteosclerosis, or Condensation of Bone_.--This,
too, is essentially a chronic process. It may occur as a result of, or, as
we have just shown, exist simultaneously with the condition of, diffuse
rarefactive ostitis. In this case there is a formation of new bone in the
connective tissue surrounding the vessels in the Haversian canals. As a
consequence the bone affected is greatly increased in density, and many
of the Haversian canals by this means obliterated. The end result is an
increase in size of the bones in such positions as the horny box admits of
it, and a peculiar ivory-like change in their consistence.
For an example of this, we again refer the reader to the changes occurring
in chronic laminitis.
_(c) Caries and Necrosis_.--_Caries_ is a word which appears to be used
with a considerable amount of looseness. In addition to the meaning implied
by necrosis (namely, 'death' of the part), caries is generally used to
indicate that there is also a condition of rottenness, decay, and stench.
It is particularly applied, in fact, when the death of the bone is slowly
progressive, and is due to the inroads made upon it by putrefactive or
septic matter.
_Necrosis_ of bone may be the result of any injury, such as severe blows,
or pricks and stabs. In such cases it would appear that it is loss of a
portion of periosteum that is the starting-point. With death of a portion
of this membrane the vascular supply to a portion of the bone is cut off,
and necrosis ensues. It may also result from the extension of inflammatory
affections of the structures adjoining it, as, for instance, the spread of
the infective material in severe tread, or the encroaches made by pus in
cases of quittor, suppurating corn, or complicated sand-crack.
When the necrosed portion of bone is small, and is free from infective
properties, it is quite possible that it may, as is the case with small
spots of necrosis in softer tissues, be removed by a process of absorption.
It must be remembered, however, that where the necrosis has occurred as a
result of septic invasion this cannot be looked for, for in every case such
reparative changes are worked solely by healthy tissue. If the tissues
around the necrosis are engaged in dealing with organismal invasion and
the poisonous products thus poured into their working area, their state of
health is so weakened that they are unable to successfully combat with the
two conditions simultaneously. As a consequence, the necrotic piece of bone
persists, and acts as a permanent source of irritation.
It must be remembered, too, that if the dead portion of bone--even though
it be free from septic matter--is very large, that it may itself act as a
continual irritant, in which case it again persists, and cannot by natural
means be removed.
In our cases necrosis of bone may be met with in punctured foot, in severe
cases of tread, in cases of complicated crack, and in suppurating corn.
It is met with, too, in navicular disease, in the extension of irritating
discharges in cases of quittor, and in cases of chronic laminitis where the
solar margin of the os pedis has penetrated the sole. In this latter case
the protruding portion of bone is quickly denuded of its periosteum. Its
blood-supply is destroyed, and necrosis follows.
_Treatment_.--In simple cases of periostitis, those caused by a blow but
free from an actual wound, the most beneficial treatment is the continued
application of cold by means of a hose-pipe or by swabs. If by these means
we are successful in holding the inflammatory phenomena in check, any large
formation of new bone is prevented, and the case does well.
When the case is complicated by a wound, then antiseptic measures, such as
those described in the treatment of punctured foot, will at the same time
have to be practised.
It must be admitted, however, that in all but the most simple cases
ordinary treatment such as this is of very little use; for with only a
slight exostosis in almost any position in the foot, excessive lameness
presents itself and remains. In such cases nothing is left to us but the
operation of neurectomy.
When the periostitis and ostitis is the result of a wound, and is
complicated by caries or necrosis of the bone, the diseased portion of
bone must in every case be laid bare and removed. It so happens that the
majority of cases of this kind occur in positions where the diseased bone
is easily got at. The lower margin of the os pedis or portions of the wings
are commonly the seat of such changes. We meet with the former in cases
of pricked foot, and with the latter in severe cases of tread, or as a
complication in suppurating corn or in quittor. In such cases the animal
must be cast and the foot secured. The wound is then followed up, the horn
if necessary removed, and the bone curetted with a Volkmann's spoon; or, if
showing itself as a sequestrum, removed with a scalpel and a strong pair
of forceps. Care must be taken that every particle of the diseased bone
is removed, and that no part of it is left to act as an after-source of
irritation. With removal of the diseased portion and a strict attention to
antisepsis healing soon takes place.
_Reported Cases of Periostitis and Ostitis_.--1. 'Figs. 150 and 151
represent the phalangeal bones of the off fore-leg of a thoroughbred horse
named Osman, who was well known as a hunt steeplechaser of considerable
merit in the Midland counties some twenty years ago. I may say that this
horse was under my observation pretty regularly during the whole of his
career, and up to the time of his death, from ruptured aorta, when eight
years old. My attention was called to him as a yearling by his owner, who
told me that he sometimes fancied the colt was lame. I went over to see
him, and found that he was unmistakably lame on the off fore-leg. Careful
examination showed no heat or enlargement anywhere. I advised rest and the
colt became pretty sound, though not quite so--in fact, he never did become
quite sound, and sometimes he was very lame indeed.
[Illustration: FIG. 150.--EFFECTS OF PERIOSTITIS ON THE PEDAL AND NAVICULAR
BONES.]
'Every imaginable sort of treatment was tried short of neurectomy, without
avail. The curious part of the case was that there never was much heat or
any apparent change of structure, nor was "pointing" a very noticeable
feature. The foot always remained a good-looking one. As the horse won a
good number of races he was of some value, and was seen by a good many
members of the profession, who were by no means unanimous as to the cause
of lameness. The favourite theory was that it was a sequence of "split
pastern." A post-mortem examination showed that there was no fracture.
There was no adherence of the tendon to the navicular bone nor any
ulceration. The morbid changes consisted entirely of osseous deposit as
shown in the photographs. The under surface of the navicular bone was much
enlarged and roughened by this bony deposit, which extended on to the os
pedis, causing complete anchylosis at each extremity of the navicular. The
lateral cartilages were healthy. The interesting points in connection with
the case are the insidious commencement of osseous disease, its extensive
development, and the entire absence of any external manifestation, through
its being confined entirely within the limits of the hoof.
[Illustration: FIG. 151.--EFFECTS OF PERIOSTITIS ON THE PEDAL AND NAVICULAR
BONES.]
'It should also be noted that the animal was able to undergo a severe
course of training for some years, and to gallop successfully over some of
the most trying courses in England. During the whole of this time he walked
and galloped apparently sound, but trotted always lame, and generally dead
lame.'[A]
[Footnote A: W. E Litt, M.R.C.V.S., _Veterinary Record_, vol. viii., p.
527.]
[Illustration: FIG. 152.--EFFECTS OF PERIOSTITIS ON THE OS PEDIS.]
2. 'I herewith send you photographs of three cases of the above disease,
occurring in the internal surfaces of the wings of the os pedis. The photos
were kindly done for me by Dr. A. Lingard, Imperial Bacteriologist to
Government of India. It is a cause of many cases of obscure foot lameness
in India, and frequently accounts for the numerous entries on veterinary
medical history sheets under the heading "Contused Foot."
'The course of the disease is as follows: The disease makes its appearance
very soon after arrival in India, the animal being admitted to hospital
suffering with undoubted foot lameness, generally slight. One is soon led
to suspect this disease by negative symptoms of other disease being in
existence. No coronary enlargement or flinching on pressure to the coronet,
no shrinkage or wiring in of the heels, neither is the characteristic
pointing of navicular present. In the early stages one has false hopes
of recovery by finding gradual improvement for a time by fomentation and
poultices, followed by irrigation and stimulants to the coronet, and
perhaps the animal is discharged from hospital, to be returned after a
few days worse than ever. The disease then becomes insidious and more
pronounced, the nodding of the head, even at a walk, more exaggerated, and,
in fact, the animal seems afraid to put his foot to the ground, and much
resembles a horse with an abscess in his foot, either from prick or picked
up nail. He absolutely nurses his foot. There is a certain amount of heat
always present. The disease being now well developed, pressure is caused by
the ends of the navicular bone, and they become involved at their points
by bony deposits. The causes of this disease I attribute, firstly, to
hereditary predisposition; and, secondly the exciting cause, standing
confined on board ship, where no doubt pedal congestion takes place. And
perhaps some subjects start it in their marches in mobs down country
in Australia. Concussion may be the cause among older horses, but the
specimens photographed were taken from remounts, that had either done no
work or only very gentle work, in a deeply littered riding school.
[Illustration: FIG. 153.--EFFECTS OF PERIOSTITIS ON THE OS PEDIS.]
'_Treatment_.--It is obvious from the position of this disease that
treatment will be of no avail in producing a cure. As already stated, the
disease is insidious and progressive, and it is hopeless to expect to
arrest the growths once they are started. Unnerving would no doubt remove
the symptom (lameness) of the disease, but an unnerved horse is not of much
good for army purposes. I therefore consider that once the disease becomes
firmly established it is an unfortunate and incurable one.
[Illustration: FIG. 154, 155--EFFECTS OF PERIOSTITIS ON THE OS PEDIS.]
'Post-mortem reveals the small nodular growths on the inner surfaces of the
wings of the pedal bone, and if long established the ends of the navicular
bone are also involved. Exudation and gradual growth of false material
around the nodules takes place, which also serves to increase pressure.'[A]
[Footnote A: Captain L.M.Smith, A.V.D., _Veterinary Record_, vol. xi., p.
229.]
3. 'This case was brought for my opinion. The horse was lame, and walked
similar to one that had had laminitis, putting the heel down first upon
the ground. I ordered the patient to be destroyed. You will note the
ossification of the flexor pedis at its attachment to the pedal bone.
I enclose photos of the ground, also of the articular, surfaces of the
bone.'[A]
[Footnote A: F.B.Jones, M.R.C.V.S., _Veterinary Record_, vol. xi., p. 230.]
B. PYRAMIDAL DISEASE, BUTTRESS FOOT, OR LOW RINGBONE.
_Definition_.--A condition of periostitis and ostitis in the region of
the pyramidal process of the os pedis, usually preceded, but sometimes
followed, by fracture of the process, and characterized by deformity of the
hoof and an alteration in the normal angle of the joint.
_Causes_.--In the majority of cases buttress foot is brought about by
fracture of the pyramidal process. Thus, although distinct evidence of such
is nearly always wanting, we may assume that the original cause is violent
injury to the part in question. Properly, therefore, one would say that
this condition should be described under Fractures of the Os Pedis. It
appears, however, that other cases of the kind arise in which fracture is
altogether absent, or in which it is plainly seen to be subsequent to the
diseased processes in the bone. For that reason, and also for the reason
that the condition has come to be known by the name we have given, we give
it special mention.
_Symptoms and Diagnosis_.--Even when the condition arises as the result
of fracture, the ordinary manifestations of such a lesion are absent. By
reason of the situation of the parts within the hoof we are unable to
detect crepitation, and the resulting lameness is perhaps--in fact, nearly
always is--neglected until such time as any heat or swelling caused by the
injury has disappeared, in which case we are denied what evidence we might
have obtained from that. All that is presented is lameness, and lameness
that is at times excessive. But with the lameness there is nothing
distinctive. The foot is tender on percussion, and the gait suggestive of
foot lameness, that is all. We are unable, therefore, to make an exact
diagnosis, and the condition goes for some time undetected.
Later, however, changes in the form of the hoof and the coronet begin to
appear. The skin of the coronet, especially in the region of the toe,
becomes more or less thickened and indurated, and the same remark applies
to the subcutaneous tissues. The most marked change, however, is the
alteration in the shape of the hoof. The wall protrudes at the toe in a
manner that has been termed 'buttress-like,' and has given to the condition
one of its names. This, of course, entirely alters the contour of the horny
box. From being more or less U-shaped, it approaches nearer the formation
of the letter V, the point of the V being at the toe.
In the later stages the coronary enlargement is plainly seen to be due to
an extensive formation of bone. It is, in fact, a reparative callus, and
the reason it reaches so large a size is probably to be accounted for by
the pull of the extensor pedis upon the detached pyramidal process. As
might be expected, this displacement of the fractured portion, with its
effect of giving greater length to the extensor pedis, leads to a backward
displacement of the os coronæ upon the pedal bone. As a result there is a
marked depression at the coronet, the depression being heightened in effect
by the exostosis in front. Pyramidal disease is, as a rule, met with in the
hind-feet, but occurs also in the fore.
_Pathological Anatomy_.--When occurring without fracture, the first
observable change is a thinning of the articular cartilage of the pyramidal
process, through which the bone beneath appears abnormally white. Later
the thinning of the cartilage progresses until at last it becomes entirely
obliterated. This destruction of the cartilage commences first at the
highest point of the articular surface of the pyramid, and gradually
reaches further backward into the joint. While this is taking place the new
bone is being formed on the front of the os pedis, below and around the
process, until, as we have already seen, an exostosis is formed, large
enough to be noticeable at the coronet. This, of course, partly implicates
the joint and the points of the insertion of the extensor tendon.
Finally, fracture may, or may not, take place. When it does, the exostosis
is larger, and the general deformity of the hoof greater.
_Treatment_.--Ordinary treatment, such as point or line firing, repeated
blisters, or hoof section, each of which we have tried, appears to be
utterly useless. So far as we have been able to gather from the writings of
other practitioners, however, neurectomy returns the animal for a time to
usefulness. If the fore-limb is the seat of trouble, either plantar or
median neurectomy may be practised; if the hind, then the best results are
obtained by section of the posterior tibial.
_Reported Cases_.--1. This animal, a mare, had been rested for lameness
behind for two or three weeks, and then sent out to work, going sound. This
was repeated several times, and each time the coachman reported, "Goes very
lame behind after she has been at work about fifteen to twenty minutes."
She always pulled out sound when I saw her in a halter on the following
day, so I had her ridden, and after about seven or eight minutes she began
to go lame in a hind-limb. Her lameness got rapidly worse as she was being
ridden, and within a quarter of mile of her first showing lameness, she
dropped and carried the lame foot in a way that suggested a badly fractured
pastern. There was no recognisable disease in the limb to account for this
lameness.
'I divided the posterior tibial nerve, and she went back to work moving
sound, and continued to work sound up to her death from one of the
regularly fatal bowel lesions twist or rupture.
'She worked nearly two years after unnerving, and developed the usual
thickening at the coronet.'[A]
[Footnote A: W. Willis, M.K.C.V.S., _Journal of Comparative Pathology and
Therapeutics_, vol. xv., p. 366.]
2. 'The subject of this note was a chestnut mare, nine years old, and used
for omnibus work.
'_History_.--For about two months the mare was lame on the off fore-leg,
and in spite of treatment the condition became steadily worse. The off
fore-foot was rather long and narrow, and the fetlock-joint was inclined
to be bowed outwards, but the degree of lameness was out of proportion to
these defects, and the diagnosis was obscure.
'Median neurectomy was performed on May 10, 1902, and reduced the lameness
to about half of what it was before. On June 5 ulnar neurectomy was
performed, with the result that the mare became sound, and went to work
three weeks later. She continued to work soundly and well, being inspected
from time to time.
'During February of 1903 the coronet began to enlarge in front and slightly
to the outer side, and gradually a ridge of bone grew down from the coronet
to the toe. The case, in fact, became a typical one of so-called "buttress
foot," which my friend Mr. Willis has described as diagnostic of disease
of the pyramidal process of the pedal bone. Meanwhile the swelling of the
coronet, which appeared to be mainly composed of fibrous tissue, increased
in size, until the whole of the front and sides became involved, assuming
the appearance shown in Fig. 156.
'In spite of the coronary enlargement the mare worked well, and remained
free from lameness till June 8, 1903, on which day the limb became swollen
up to the site of the median operation. The appearance of the limb closely
simulated an attack of lymphangitis. The mare was kept under observation
till the 13th of the same month, during which time the swelling increased,
as did also the lameness to a slight degree. During progression she brought
the heel to the ground and "rocked the toe," as in a case of rupture of the
perforans tendon. The mare was killed on June 13.
[Illustration: FIG. 156.--A CASE OF BUTTRESS FOOT.]
[Illustration: FIG. 157.--FRACTURE OF THE PYRAMIDAL PROCESS IN BUTTRESS
FOOT.]
'_Post-mortem_.--In trying to pull away the hoof from the sensitive
structures with a pair of farrier's pincers, the tendons and ligaments of
the corono-pedal articulation gave way, leaving the pedal bone _in situ_.
The flexor perforans tendon showed inflammatory softening, and was very
nearly ruptured through at the level of the navicular bone. There was
slight evidence of navicular disease. The articular cartilage of the
corono-pedal joint had been almost completely removed, and there was
sclerosis of the opposed bony surfaces, which by unequal wear had brought
about deformity of the os coronæ and os pedis.
There was very old-standing fracture of the pyramidal process (see Fig.
157), with the formation of a false joint between the process and the pedal
bone. There was also a recent fracture of the part of the pedal bone which
carries the articulation for the navicular bone, and this and the tendon
lesions probably accounted for the final symptoms of 'break-down.'
Neurectomy enabled us to get a year's useful work out of what would
otherwise have been a hopeless cripple.[A]
[Footnote A: A.R. Routledge, M.R.C.V.S., _Journal of Comparative Pathology
and Therapeutics_, vol. xvi., p. 371.]
C. FRACTURES OF THE BONES.
More or less by reason of the protection afforded them by the hoof
fractures of the bones of the foot are rare. When occurring they are more
often than not the result of direct injury, as, for example, violent blows,
the trapping of the foot in railway points, the running over of the foot
with a heavily-laden waggon, or violent kicking against a gate or a wall.
They occur also as a result of an uneven step upon a loose stone when going
at a fast pace, and as a result of sudden slips and turns, in which latter
case they are met with when animals have been galloping unrestrained in
a field, or when an animal, ridden or driven at a fast pace, is suddenly
pulled up, or just as suddenly turned.
At other times fractures in this region take place without ascertainable
cause, and cases are on record where animals turned overnight into a
loose box in their usual sound condition have been found in the morning
excessively lame, and fracture afterwards diagnosed.
1. FRACTURES OF THE OS CORONÆ.
Fractures of the os coronæ result from such causes as we have just
enumerated, and are nearly always seen in conjunction with fractured
os suffraginis. When this latter bone is also fractured diagnosis is
comparatively easy, a certain amount of crepitus, even when the suffraginis
is only split, being obtainable. When the os corona alone is fractured
then diagnosis is extremely difficult, the smallness of the bone and the
comparative rigidity of the parts rendering manipulation almost useless,
and effectually preventing the obtaining of crepitus. It is, in fact, only
when the bone is broken into many pieces that crepitus may be detected, and
even then it is slight.
_Reported Cases_.--1. 'The subject was a four-year old hunter. While at
exercise in the morning of August 10 he bolted, got rid of his rider, and
ran about in a mad fashion, came into contact with a wheelbarrow in a
narrow passage, and finally came into violent contact with a wall, which
had the effect of throwing him down. The rider stated that the animal
suddenly put down his head and managed to get off the bridle; he then
bolted, and the only chance for the rider was to throw himself off.
'On examination I found the horse unable to place any weight on the off
fore-leg, the pastern was swollen and painful, the hollow of the heel was
also swollen, and there was marked constitutional disturbance.
'After a short time he would place the heel on the ground and elevate the
toe to a slight degree. On manipulating the pastern slight crepitation
could be discovered, and there was abnormal mobility in the corono-pedal
articulation. On the near fore-leg there were extensive wounds in the
region of the knee, and great laceration of the tissues. The animal was
destroyed.
'On examining the leg I found the subcutaneous tissues infiltrated from
below the knee to the foot, large masses of gelatinous blood-stained
material being present along the flexor tendons and in the hollow of the
heel. The inferior articular surface of the os suffraginis was denuded
of cartilage anteriorly; the os coronæ was fractured into eight moderate
sized, irregular fragments, and ten minute pieces. The surface of the
perforans tendon as it glides over the smooth surface at the back of the os
coronæ was lacerated, and minute portions of the bone were found embedded
therein.'[A]
[Footnote A: E. Wallis Hoare, F.R.C.V.S., _Veterinary Record_, vol. xiv.,
p. 133.]
2. 'Here, again, fracture was the result of the animal bolting with his
rider. Trying to avoid collision with a conveyance coming towards him, the
animal slipped on a wooden pavement, sliding along until his near fore-leg
came in contact with the wheel of a standing cab. There was considerable
swelling from the knee downwards, great pain, and evidence of fracture in
the region of the pastern.
'Post-mortem revealed the os suffraginis broken into about thirty pieces,
and the os coronæ with a piece broken off the inside of its proximal
end.[A]
[Footnote A: A.F. Appleton, M.R.C.V.S., _Veterinary Journal_, vol. xiii.,
p. 411.]
3. 'The patient was a brown mare used for heavy van work in London. About
January 10 she was lame, and as she had a cracked heel, was treated by
poulticing for a day, and then by antiseptic lotions. In a week she was
sent to work, but the following day lameness returned, and continued till
about February 15. No special symptom was detected which indicated the
exact position of any cause of lameness. Then the lameness increased in
severity, and some swelling around the coronet began to show itself.
'In consultation with another veterinary surgeon, two possible causes of
this intense lameness were discussed: one, that we had septic infection of
the coronet, and that probably the swelling of this part would soften, and
sloughs occur; the other, that a fracture of the os pedis or os coronæ
existed. The enlargement of the coronet was hard and firm, not particularly
sensitive. It was decided to do nothing for a few days. In a week the
pain abated, and the mare would put her foot on the ground, and ceased to
"nurse" the limb as she had done. When moved over in the box she put a
little weight on the foot, but limped very decidedly.
'Another week passed, and the pain and lameness further abated, but the
swelling around the coronet continued. Perhaps it was a little less in
front, but it had not decreased on the inside. It remained firm, and was
not painful on pressure. It showed no soft places, and the upper part of
the leg remained free from oedema.
[Illustration: FIG. 158.--FRACTURE IN SITU (OS CORONÆ).]
'The diagnosis was now that a fracture existed, and it was proposed to
send the mare to grass for a few months. The consulting veterinary surgeon
suggested that before doing so a blister might be applied to the coronet.
This was done. The mare was found next day again on three legs. She had
apparently been down during the night. In a few days the coronet increased
again in size, and within a week "broke out" in two places.
'The opinion now formed was that, with a fracture and this additional cause
of inflammation around the joint, it would be most economical for the owner
to have her killed. This was done, and a post-mortem examination was made
by Mr. Hunting and Mr. Willis.
[Illustration: FIG. 159.--WITH BROKEN PORTION REMOVED.]
'_Post-mortem_.--The foot, cut off at the fetlock-joint, showed extensive
swelling all round the coronet. There were two wounds on the skin--one on
the front of the coronet, the other on the inner side. From both pus and
blood had escaped. They both communicated under the skin with a large
abscess cavity. The abscess did not communicate with the joint. The pastern
bone was sound. On separating the pastern from the coronet bone the
articular surfaces were of a healthy colour, but the soft tissues
immediately surrounding them were inflamed. On the centre of the articular
surface of the coronary bone a thin red ring was noticed, and the portion
of cartilage within it seemed raised. With the point of a scalpel this
portion was lifted, and was found to be not only cartilage, but a layer of
bone completely detached from the os coronæ. On removing the bones from the
hoof the rest of the bone was quite normal, as was the pedal bone.
'Fig. 158 shows the articular surface of the coronet with the fracture _in
situ_; and Fig. 159 the surface from which the broken portion is removed
and laid to the side of the foot.
'Some interesting questions arise. How was the fracture caused? When did it
occur? Between the broken portion and the main bone there was a layer of
granulation tissue, so that it is certain the injury existed before the
blister was applied, and it may possibly have existed from the commencement
of the lameness.'[A]
[Footnote A: R. Crawford, M.R.C.V.S., _Veterinary Record_, vol. viii., p.
478.]
2. FRACTURES OF THE OS PEDIS.
These also are a result of the causes we have before given. The os pedis
is also liable to fractures from pricks, from treads in the region of the
wings, and from the malnutrition and careless use of the foot sometimes
following neurectomy.
It is interesting to note that, with fracture of this bone, lameness is
nearly always excessive, but that at times it may be entirely absent.
Crepitus is, of course, denied us, and in nearly every instance the case
is only diagnosed when the lameness persists and pus commences to form, or
when grave changes in the normal shape of the foot compel our attention to
the parts. When it is the continued formation of pus that draws our notice
to something more than ordinarily grave, it is in giving exit to the pus
that the fracture is nearly always discovered.
_Reported Cases_.--Two interesting cases of fractured os pedis are reported
by Mr. Gladstone Mayall, M.R.C.V.S., in the _Veterinary Record_, vol. xiv.,
p. 54:
1. 'The horse was brought in markedly lame on the off hind-foot, knuckling
at the fetlock, and taking a long stride with the injured limb. There was
a punctured wound at the toe. The horn was pared, and antiseptic poultices
applied. Notwithstanding the antiseptic treatment pus continued to form. At
the end of a week sufficient horn was removed to ascertain the cause of
the constant suppuration. A movable object was found at the bottom of the
wound, and a piece of bone as large as a sixpence finally removed. Recovery
was uneventful.'
[Illustration: FIG. 160.--FRACTURED OS PEDIS.]
2. 'A filly was attended for a discharging fistula at the coronet.
Externally it had all the appearances of a quittor. At first no history
was given. The filly went scarcely lame at all, and had never been shod.
Treatment with poultices and caustic injections was useless. Finally the
filly was cast and the foot examined. A piece of bone, apparently part of
the wing of the os pedis, was removed, and the case made a good recovery.
Subsequent inquiries elicited the fact that the animal had kicked at and
hit a gate-post, and it was judged that then the injury had occurred.'
3. 'The subject was a bay horse, nine years old, used for railway shunting.
On August 7 he was found to be intensely lame of the near hind-limb, and,
after inquiries, there was no evidence bearing on the cause, as is often
the case, and at times this comes to light when least expected.
'I was called in consultation on September 2, and found him suffering
acute pain, with great swelling around the coronet. The foot was examined
thoroughly, and the diagnosis was fracture of the pedal bone, and immediate
slaughter was recommended. However, that was not carried out, and he died
on September 22.
'The post-mortem inspection revealed a complete fracture of nearly the
whole of the articulating surface and the left wing of the pedal bone (as
shown in Fig. 160).'[A]
[Footnote A: J. Freeman, M.R.C.V.S., _Veterinary Journal_, vol. xxxi., p.
324.]
4. A further interesting case is reported by Mr. William Hurrell.[A] Here
the cause was presumably galloping in the field, for the subject, a cart
mare running out at grass with her foal, was suddenly found to be lame.
[Footnote A: _Ibid_., vol. v., p. 408.]
As the lameness continued to increase in severity, Mr. Hurrell was called
in on August 1, and diagnosed the case as one of foot lameness. On this
date the foot was pared out, and a large accumulation of pus discovered,
Poulticing and antiseptic dressings were continued until August 16, when a
movable piece of the os pedis was found at the toe.
On August 25 this detached portion of the bone was removed, and turned out
to be the whole of the anterior margin of the os pedis, measuring 3-1/2
inches long, and varying in width from 1/2 inch to 1-1/2 inches. On
September 20 the mare was working without lameness.
3. FRACTURES OF THE NAVICULAR BONE.
Hidden within the wings of the os pedis, and protected as it is by its
tendinous covering and the yielding substance of the plantar cushion, the
navicular bone is even less liable to fracture than either of the other
bones of the foot.
The most common cause of fracture of the navicular is that of stabs or deep
pricks in the region of the point of the frog (see p. 216). Following that,
the next most common cause is violent injury. We thus find the navicular
bone fractured, together with one or both of the other bones of the foot,
when the foot is run over by a heavy vehicle. One such case is reported
by Mr. J.H. Carter, F.R.C.V.S., where the horse's foot was run over by a
tram-engine, in which the os pedis and the navicular were fractured in
several places.[A] A further case is on record where a sharp blow on the
front of the hoof was the cause. In this case the os pedis and other
structures were uninjured, but the navicular bone was fractured into three
large, and about half a dozen small, pieces.[B]
[Footnote A: _Veterinary Journal_, vol. xxxi., p. 246.]
[Footnote B: _Veterinarian_ for 1857, p. 73.]
Fractures of the navicular may occur, however, in which history of a prick
or of a violent injury is absent. See reported case below.
As with fractures of the os pedis and the os coronæ, so with this exact
diagnosis is difficult--we may say almost impossible. With a history of
violent injury, however, some little regard may be paid to a continued heat
and tenderness of the foot, and a distinct inclination on the part of the
animal to go on the toe. Even when the fracture is the result of a prick,
and the bone is plainly felt with the probe, we still cannot be positive as
to fracture.
_Reported Case_.--'The animal was a Hungarian, a troop-horse in the 3rd
Hussars (G. 15). On November 22, 1881, on the march from Norwich to
Aldershot, the horse suddenly made a violent stumble, very nearly coming
on to his knees. The rider declared that he put his foot on a stone. The
accident caused great lameness in the near fore-leg, and the horse had to
be led the remainder of that day's march. On the following day he was also
led; but, after going some sixteen or eighteen miles, he was so lame that
he was left at the nearest billet (in Edmonton). He was here attended by
Mr. Stanley, M.R.C.V.S., of Edmonton, who pronounced it a case of navicular
disease. I first saw the animal on December 1, 1881, and quite agreed with
Mr. Stanley that it was a case of foot lameness, though, from the horse's
former history, I could not think it a case of ordinary navicular disease.
I diagnosed it a case of fracture, without displacement, either of the os
coronæ or the navicular bone, but was more inclined to the former than the
latter. This was after a full hour's examination. I failed to find any heat
in, or any flinching by manipulation of, any part of the limb; but, in
walking, the horse was excessively lame, going on the toe, and, indeed,
trying if possible to keep the foot entirely off the ground.
'On December 6 the horse was sent on to Aldershot by rail. He was then
walking better, though still very lame. My only treatment for a short time
was to apply cold water constantly to the coronet and foot. For two hours
daily this was done by a hose, the remainder of the time by a cold swab. On
December 14 I applied a strong blister over the coronet, reaching up to the
fetlock. This was washed off about the end of December. The horse was then
not nearly so lame. I then resumed the cold-water treatment, and he got
gradually better, and was sent to light duty on February 18, 1882. He,
however, only attended one field-day, and was taken into the Horse
Infirmary again on March 8, very lame. Again, there was an entire absence
of heat or pain on pressure, but the same action, viz., going on the toe.
I forgot to remark that he always pointed the toe of the affected leg when
standing in the stable, and this symptom continued. I put him under the
cold-water treatment for a short time, and about the middle of March again
applied a strong blister over the coronet up to the fetlock. This was
washed off about the end of the month, and was succeeded by the cold water
again. Towards the end of April there was no improvement at all, and I
applied for permission to destroy the horse. This was carried out on April
27, at the recommendation of Mr. Gudgin, I.V.S., Aldershot, and a Board of
veterinary surgeons.
'On making the post-mortem examination I first thought the bone was only
partly fractured or cracked, but on manipulating it, after its being in hot
water a short time, I saw the fracture was complete.'[A]
[Footnote A: S.W. Wilson, M.R.C.V.S., A.V.D., _Veterinary Journal_, vol.
xv., p. 12.]
_Treatment of Fractures of the Bones of the Foot_.--It will be seen at once
that in most cases anything in the way of bandaging is well-nigh useless.
When the os coronæ is fractured, however, a little more may be added to the
natural rigidity of the parts by enclosing the region of the pastern and
the foot in a plaster-of-Paris bandage. The main treatment, however, in
every case, will be a continual use of the slings for at least seven to
eight weeks, by that means compelling the animal to give to the injured
parts the necessary amount of rest.
With fracture of the os pedis, when such is caused by pricks and
complicated by a flow of pus, then attention must be given to removal of
the displaced piece of bone. The pus track is to be followed up with the
searcher, sufficient horn removed with the knife, and the broken piece of
bone removed with a scalpel and a pair of strong forceps, the operation to
be afterwards followed up by antiseptic dressings to the opening. Until
this is done the wound refuses to heal.
Fracture of the navicular bone, if in any way diagnosed with certainty,
offers us an almost hopeless case, for it appears to be a commonly reported
fact that attempts at reunion are rare. This, in all probability, is due
to the pressure put upon it every now and again, when the animal's weight
presses the bone between the os coronæ and the os pedis above and the
perforans tendon below. Even should reunion take place, the resulting
callus, interfering as it does with the movements of the perforans, leaves
us a case of incurable lameness. When the fracture is complicated by
the formation of pus, as in the case of prick, then the case, with the
attendant purulent synovitis and arthritis, is even more hopeless still.
Diagnosis of fracture of either of the bones of the foot is, as we have
said before, extremely difficult. It so happens, therefore, in those cases
caused by violent blows, that anything approaching an accurate opinion
cannot be given until some months after the injury. After some time we are
met with unmistakable changes in the form of the foot, and are able to
assume that the persisting lameness is due to pressure of a reparative
callus within the hoof. In such cases the only treatment of any use is that
of neurectomy.
CHAPTER XII
DISEASES OF THE JOINTS[A]