DIAGNOSTIC PRINCIPLES.
_To observe attentively is to remember distinctly._--_Poe_.
Before treatment is administered in constitutional disturbances
resulting in disease, _cause_ is logically sought; so, in order to
handle effectively any case of lameness, it is necessary first to
discover the source of the trouble and contributing conditions affecting
the structures. Hence, diagnostic ability is the prime requisite; and a
thorough knowledge of pathologic anatomy or of surgical technic is of
little value if this knowledge is not applied with the insight of the
trained diagnostician.
The cruel and unnecessary methods employed by those untrained for
diagnostics, cannot be too vigorously condemned. For instance, the
application of an active and depilating vesicant upon a large area on
the gluteal or crural region, in a case where the practitioner "guesses"
the condition to be one of "hip lameness," constitutes an exposition of
gross ignorance, and at once stamps the perpetrator as a crude bungler
without scientific insight whose works are no credit to his profession.
How much better it would be, if the practitioner does not see fit to
call in a competent consultant, to prescribe a suitable agent to be
given internally, and to recommend complete rest for the subject.
In establishing a diagnosis in such cases, the student or practitioner
seldom has recourse to laboratory assistance, and his work is done by
means of physical examination; therefore, a thorough knowledge and a
clear conception of the physiology of locomotion are essential.
Memorizing nosological facts without an understanding of underlying
principles is of no more practical benefit for qualification as a
diagnostician in cases of lameness, than is the employment of similar
methods in the study of theory and practice. A knowledge of the dosage
of drugs does not in itself qualify one as being competent to administer
such therapeutic agents to a proper effect. How much is a practitioner
benefited by the knowledge that a high temperature is usually present in
septic intoxication, if he is not possessed of a scientific
understanding of anatomy, physiology, bacteriology and pathology, as
well as the principles of clinical diagnosis?
In order to determine the reasons for certain symptoms manifested by the
subject, an analysis of these symptoms is the proper method of
procedure, insofar as this is possible. If one may reason that an animal
assumes a certain position while at rest to allow relaxation of an
inflamed tendon or ligament, such a fact enables the diagnostician to
recall that this is indicative of some specific ailment. In acute
tendinitis, the subject while at rest, maintains the affected member in
volar flexion because this position permits relaxation of the inhibitory
apparatus, including the inflamed tendon. Likewise, the various abnormal
positions assumed,--adduction, abduction, undue flexion or
pointing--have their own significance and are taken into account by the
trained diagnostician in the course of an examination.
In the examination of lame subjects, where the cause is not obvious, a
systematic method of diagnosis is pursued even by the most expert
practitioners. In all obscure cases of lameness a methodical and
thoroughly practical examination of the animal according to an
established procedure is necessary to determine the nature and source of
the affliction.
Anamnesis.
The first thing to be given consideration in diagnosis is the fact that
related history of the case is not always dependable, because of lack of
accurate observation or wilful deceit on the part of the owner or
attendant. The successful veterinarian soon acquires the faculty of
obtaining information in a manner best adapted to his client,--either by
direct interrogation or by subtle means of suggestion, and in this way
he draws out evaded facts essential to his diagnosis. In time he learns
to make allowance for misstatements made to shield the owner or driver
and to hide the facts of apparent neglect or abuse that the subject may
have experienced. A suppurating cartilaginous quittor, complicated by
the presence of a large amount of hyperplastic tissue, cannot be
successfully represented to be an acute and recently developed
affection, where a trained practitioner is left to judge the validity of
the statement.
In complicated conditions, where there is evident a chronic disturbance
which could not be conceived as sufficient cause for a marked
manifestation of lameness, accurate history of the case may be of great
aid in arriving at a diagnosis. An aged animal, having recently become
very lame, showing a small exostosis on the first phalanx, and with the
history given that the osseous deposit was of long standing, should at
once lead the veterinarian to seek the source of trouble elsewhere.
Visual Examination.
As in all diagnostic work, a careful visual examination of the subject
should be made before it is approached. The novice is given to hasty
examination by palpation, not realizing how much may be revealed by a
careful scrutiny of the subject. In this way he is led to erroneous
conclusions which the skilled diagnostician has learned from experience
to avoid. _Too much emphasis cannot be placed on the importance of
making a thoughtful visual examination in every instance before the
subject is approached._ In this examination, type, conformation and
temperament are taken into account at once, for each of these qualities
is in itself, a determining factor in predisposing a subject to certain
ailments or inherent attributes, which may exert a favorable or
unfavorable influence upon existing conditions and thus make recovery
probable or otherwise.
Draft animals are less likely to be permanently incapacitated as a
result of tendinitis, than are thoroughbreds. Likewise, one would not
expect to find this affection present in heavy harness horses as
frequently as in light harness animals.
Mal-formation of a part, or an asymmetrical development of the body as a
whole, may render an animal susceptible to certain affections which
cause lameness. A "tied in" hock predisposes the subject to curb, and an
animal having powerful and well-developed hips and imperfectly formed
hocks, will, if subjected to heavy work, be a favorable subject for bone
spavin.
The matter of temperament cannot be disregarded in diagnosis, for in
some instances, it is the chief determining factor which materially
influences the outcome of the case. A nervous, excitable animal, that is
kept at hard work, may, under some conditions, be expected to experience
disturbances which more lethargic subjects escape. Nervous subjects, it
is known, are more prone to azoturia than are those of lymphatic
temperament. Furthermore, the lymphatic subject often recovers from
certain bone fractures which are successfully treated only when the
animal is sufficiently resigned by nature to remain confined in a sling
for weeks without resistance.
The physiognomy of a subject is often indicative of the gravity of its
condition. The facial expression of an animal suffering the throes of
tetanus, azoturia, or acute synovitis, is readily recognized by the
experienced eye, and upon physiognomy alone, in many instances, may the
opinions regarding prognosis be based. Particularly is this true where
death is a matter of minutes, or at most is only a few hours distant.
Due allowance should be made for restiveness manifested by some more
nervous animals when the surroundings are strange and unusual. In such
instances, even pathognomic symptoms may be masked to the extent that
little, if any, sign of pain or malaise is evinced. In these cases the
subject should be given sufficient time to adjust itself to the new
environment, or it should be removed to a more suitable place for
examination. Animals quickly detect the note of friendly reassurance in
the human voice and can very often be calmed by being spoken to.
By visual examination one may detect the presence of various swellings
or enlargements, such as characterize bruises and strains of tendons
where inflammation is acute. Inflammation of the plantar
(calcaneocuboid) ligament in curb is readily detected when the affected
member is viewed in profile. Spavin, ringbone, splints, quittor and many
other anomalous conditions may all be observed from certain proper
angles.
The fact that the skins of most animals are pigmented and covered with
hair, precludes the easy detection of erythema by visual examination,
consequently this indicator of possible inflammation is not often made
use of in the examination of equine subjects.
Attitude of the Subject.
The position assumed while the subject is in repose, is often
characteristic of certain affections and this, of course, is noted at
once. The manner in which the weight is borne by the animal at rest,
should attract the attention of the diagnostician and if the attitude of
the subject is abnormal or peculiar, the examiner tries to determine the
reason for it. If weight-bearing causes symptoms of pain, the affected
member will invariably be favored and held in some one of a number of
positions. The foot may contact the ground squarely and yet the leg may
remain relaxed and free from pressure; volar flexion, in such cases, is
indicative of inflammation of a part of the flexor apparatus. If the
condition be very painful, position of the afflicted member is
frequently shifted, but in all cases where the pain is not so keenly
felt, the inflamed member is held in a state of relaxation. There is
need then, for a knowledge of anatomy and certain principles in physics
to enable the observer to determine just which structures are purposely
eased in this manner. Where palpation of parts is possible, one does not
need to depend on visual examination alone, and it is always wise to
take into consideration every factor that may influence conditions.
Manipulation or palpation of the structures thought to be involved,
should not be resorted to until a careful and thorough observation of
the subject has revealed all that it can reveal to the diagnostician.
In all conditions where extreme pain is manifested by the constant
desire of the animal to keep its foot in motion off the ground,
examination should be made for local cause. This is seen in certain
septic inflammations of the feet such as those caused by nail punctures
invading the navicular joint, or in newly made wounds where nerves have
been divided and the proximal end of such a nerve is exposed to pressure
or irritation.
"Pointing" affords a comfortable position in some cases of navicular
disease, and in a unilateral affection, one may observe the subject
bearing weight with one sound member, while the affected foot is planted
well ahead of the sound one. In a bilateral involvement of this kind,
weight may be frequently shifted from one foot to the other, or in
chronic cases, where no marked pain is experienced, the subject stands
squarely upon both front feet and no peculiar shifting of weight or
pointing is evident.
In some cases of hip or shoulder involvement, complete relaxation of all
parts of the affected member may be noticed. In brachial paralysis, the
pectoral member is held limply; if the patient is made to move, it is
evident there is lack of innervation to the afflicted part. In some
cases where contusion has caused acute inflammation of the member, the
subject instinctively tries to keep it inactive to relieve the pain
which movement occasions.
Where there is an active and painful inflammation of the prescapular
lymph glands and contiguous structures, in some cases of "levator-humeri
abscess," the scapulohumeral joint is extended. This is brought about by
flexion of the elbow and carpal joints.
There are some cases of bi-lateral affections which occasion such pain
during weight-bearing that the subject shifts its weight from one
affected leg to the other; an example of this condition may be observed
in any acute case of gonitis which affects both patellar regions, making
it equally painful to bear the weight on either member.
A peculiar characteristic position is assumed in acute laminitis of the
fore feet. In such instances, the hind feet are brought forward under
the body sufficiently to relieve the front feet of the weight, insofar
as is possible by the abnormal position taken in cases of acute
laminitis.
So in each position that is abnormal to any degree, assumed by a
suffering animal, there may be deduced, the fact that the subject is
attempting to relieve the affected structures, and in each clinical
picture of this kind, the trained diagnostician sees some index to the
nature and source of the trouble. Further examination is rendered more
effective because of this preliminary visual examination which has
precluded the unnecessary annoyance of the animal by manipulating
unaffected structures.
It has been presupposed in the foregoing, that the one making visual
examination of a lame animal for diagnostic purposes, will remember that
with the normal animal the weight is borne equally well with both fore
legs; and that this is done without shifting from one to the other; and
that the pelvic limbs do not support the body in this manner. Normal
subjects shift their weight from one hind leg to the other and the one
relaxed, rests in a state of flexion with the toe on the ground and the
heel raised.
Examination by Palpation.
In nearly every case where lameness exists an examination of the
affected parts, by palpation or by digital manipulation, is necessary
before an accurate conclusion may be drawn; but in making this kind of
an examination one needs to exercise good judgment lest he fail to
acquire a correct impression of the actual existent conditions. There is
need for the diagnostician, here, as well as in other conditions where
physical examination is made, to approach the subject in a manner that
will not excite or disturb to the extent that the animal will, in one
way or another, resist or object to the approach of the diagnostician,
thereby masking the symptoms sought. The practitioner would best acquire
skill as a horseman--if he is not possessed of such--and handle each
individual subject in the manner calculated to best suit the temperament
of the animal examined. The unbroken subject is not handled as
satisfactorily as is the intelligent family horse; in the former, in
some cases, little dependence is placed upon digital examination.
By palpation one is enabled to recognize hyperthermia and this, _in
lieu_ of dependable history, is at times sufficient evidence upon which
to determine the duration of any given inflammatory affection.
By comparison of different parts of the same member or with an analogous
portion of another member any marked increase in the apparently normal
temperature of a part at once signalizes inflammation. In this manner,
in examining a case where laminitis or other inflammation of the feet is
suspected, one may arrive at a fairly accurate conclusion without the
employment of other means. Throbbing vessels are not always easily
recognized if the subject is a victim of chronic lymphangitis.
In some instances, where a moderate degree of lameness exists and cause
is apparently obscure, the recognition of hyperthermia may be the
deciding factor in establishing a diagnosis. In cases of sprained
ligaments in the phalangeal region, because of the dense character of
the structures involved, little if any evidence of the cause of
lameness, other than local heat, may be found twenty-four hours after
the injury has been inflicted.
In order to determine the amount or extent of hyperthermia with a fair
degree of accuracy in any given case, one must make due allowance for
external conditions affecting temperature; also the effect of a
considerable amount of hair covering an area, as well as any possible
dirt contacting the surface of the skin must be taken into account. All
dirt should be removed if practicable, so that the diagnostician's palms
may come as nearly in contact with the inflamed structures as possible.
Then, too, the sense of touch if the operator's hands are chilled, is
not dependable. In such instances the novice will need to be deliberate
as to his findings--whether or not hyperthermia really exists. Such an
examination is of little value where the subject's feet are wet and an
examination is hurriedly made, as in cases of suspected laminitis.
Often, before being able to distinguish the presence of a hyperthermic
condition, one is impressed with the fact that an animal manifests
evidence of being supersensitive. In fact, some animals in the
anticipation of pain at the touch of an injured part, will instinctively
withdraw--in self-protection--such an ailing member or resist the
approach of the practitioner. This sensitiveness is more apparent in
animals that have been subjected to previous manipulation or treatment
which has occasioned pain, and consequently, allowance must be made for
this exhibition of fear. No better example of this condition can be
imagined than is present in cases of "shoe boil," where there exists an
extensive area of acute inflammation of the elbow. There is always more
or less surface disturbance wherever vesication has been produced, and
in cases where irritants of any kind have been employed for several days
or a week previous to an examination, more or less supersensitiveness is
to be expected.
One must not lose sight of the fact that unscrupulous
dealers,--"traders"--make use of their knowledge of this principle in
various way usually for the purpose of attracting attention to a part,
which, presumably might have been blistered in order to intentionally
produce inflammation of tissues, in this way, causing lameness which is
not manifested until an animal has been kept by its new owner for
twenty-four hours or more. This, to be sure, usually makes a
dissatisfied purchaser who is willing to dispose of his newly acquired
animal at a sacrifice, thus enabling the original owner or his agent to
regain possession of the victimized animal at less than its real value.
Some nervous animals, because of the manner of approach of the
practitioner, are wont to flinch, and there is manifested a
pseudo-supersensitiveness. Young animals not accustomed to being handled
are likely to be timorous, and one must not hastily conclude that a part
is painful to the touch because the subject resents even gentle digital
manipulation of such parts. In instances of this kind, one needs to
compare sensibility by manipulation of different parts of the subject's
body in a careful and gentle manner; and by exercising patience and good
judgment in such work, it is possible to actually distinguish between
normal sensibility and abnormal sensitiveness, in most cases. Here,
again, the diagnostician needs to possess skill as a horseman and good
judgment as to individual temperament of different animals, under any
condition which may exist at the time he makes his examination.
By palpation alone, one can recognize the presence of fluctuating
enlargements; one may not only recognize such conditions, but
distinguish between a fluctuating mass such as exists in
non-strangulated hernia and a large fibrous tumor. By palpation, for the
recognition of density and for determining the presence or absence of
hyperthermia, one may decide that there exists an abscess and not a
tumor. Edematous swellings are recognized by palpation,--the
characteristic indentations which may be made in dropsical swellings are
pathognomonic indicators. In this manner it is easy to differentiate
post-operative or post-traumatic edemas which may or may not cause
lameness. At any rate, it is essential to take into account all
determinate conditions that may assist in the prognosis of any given
case, for the purpose of being able to outline rational remedial
measures. To be able to distinguish between the generalization of a
septic infection in its incipiency, and a more or less benign edema, is
largely possible by digital manipulation alone. An extremity may be
greatly swollen because of the existence of chronic lymphangitis,
influenza, or an acute septic infection occasioned by the introduction
of pathogenic and aerogenic organisms. Since the effect produced by
these dissimilar ailments are productive of conditions that may
terminate favorably or unfavorably, it becomes necessary for the
diagnostician to develop a trained, discriminating, tactile-digital
sense, in order to correctly interpret existing conditions, and handle
cases in a rational and skillful manner.
In order to ascertain the extent and exact location of a tumor, an
exostosis, or other enlargements, the diagnostician, here also, needs to
be in possession of a trained tactile sense and in addition if he be
fortified with an accurate knowledge of normal anatomy and pathology, he
is able to arrive at proper conclusions, when digital manipulations have
been employed. Fibrous tumors are sometimes located in the inferior part
of the medial side of the tarsus--exactly over the seat of bone-spavin.
Such tumors, when the affected member is supporting weight, are not to
be distinguished from exostoses; but as soon as the affected leg ceases
to bear weight, it may be passively flexed and the nature of the
enlargement recognized because it may be slightly displaced by digital
manipulation. Displacement, of course, is not possible with an
exostosis.
A necessary qualification, which the diagnostician must possess, is that
of being able to judge carefully the nearness of any given exostosis to
articular structures. Also, the extent or area of the base of an
exostosis as well as its exact position, needs be determined before one
may estimate the probable outcome in any case,--whether treatment should
be encouraged or discouraged by the practitioner. Periarticular ringbone
may, because of the size and location of the exostosis, constitute a
condition which cannot be relieved in any way in one case, and in
another, because of the manner of distribution of such osseous
deposits, the condition may be such that prompt recovery will follow
proper treatment. In the examination of an exostosis of the tarsus, it
is particularly important to determine the exact location of the
exostosis--whether or not the spavin involves the tibial tarsal
(astragulus) bone very near its tibial articular portions. Obviously, if
articular surfaces of joints are involved, complete recovery cannot
result despite the most skillful attention given the subject.
Passive Movements.
Wherever it is possible to gain the confidence of a tractable animal to
the extent that it will relax the structures sufficiently to make
possible passive movement of affected parts, much is to be learned as a
result of such manipulation. By this method one may differentiate true
crepitation, false crepitation, luxation and inflammation of ligaments
that have been injured, as in sprains of such structures in the
phalangeal region.
_True crepitation_ is recognizable by the characteristic vibration which
is interpreted by tactile sense. It is possible to recognize fracture by
the use of other methods--auscultation, tuning fork tests, etc., but in
ordinary veterinary practice one must rely upon the sense of touch for
recognition of crepitation.
Where pain is not so great that relaxation of parts does not occur, one
can, by gently moving an extremity in various directions--as in flexion,
extension and lateral motion as well as by rotation--cause to be
manifested this peculiar grating,--the friction of newly broken bone.
This is known as _true crepitation_. Where the subject, suffering
phalangeal fracture, manifests evidence of pain due to tensing the
structures about a fractured part, one may anesthetize the parts by
using about two cubic centimeters of a two per cent. solution of cocain
upon the plantar nerves, proximal to the fracture. It is perhaps best to
deposit the cocain solution by means of two hypodermic punctures at
different points along the course of each nerve, though closely situated
to one another, thereby making more sure of the solution actually
contacting the nerve. In some multiple fractures of the first or second
phalanx this is quite necessary; otherwise, pain produced by passive
manipulation causes the subject to keep the tendons so tense that
crepitation may not be detected. The unnecessary infliction of pain is
always to be avoided.
We know as _false crepitation_ a vibrating impulse occasioned by normal
contact of articular portions of bones such as in the metacarpophalangeal
joint when this structure is passively moved, where the subject permits
the parts to remain in a state of complete relaxation.
Attempts to recognize supersensitiveness or inflammation by means of
passive movement of the shoulder or hip, whether gently or forcefully,
is not productive of good, in any case, in large animals. Because of the
bulk and weight of parts so manipulated, as well as the resistance the
subject offers even in normal cases, no accurate conclusion is to be
arrived at in this manner in the average instance. Animals nearly always
resist the placing of members in any position that is so unusual and
uncomfortable as that which is required to materially displace the
component tissues of the shoulder or hip; therefore, such practice is
useless because one can not distinguish between normal resistance and
flinching caused by painful sensations in injured parts. Such
manipulations are practical in small animals.
Observing the Character of the Gait.
In order to determine the degree of lameness as well as its character,
it is necessary to cause the subject which is being examined, to move in
some manner. The degree of inconvenience or distress experienced by a
lame animal that is being so examined is manifested by the character of
the claudication; and where much pain is occasioned in locomotion there
is disturbance of respiration; perspiration may be noticeable and in
some instances manifestation of nervous shock are very evident--this in
timid, nervous animals that anticipate being punished when approached
and, consequently, make every effort possible to move when urged to do
so. An animal, then, should be moved only sufficiently to cause it to
exhibit the degree of lameness present in any given case, and if a
marked impediment is manifested it is not necessary to cause the subject
to be exerted to the extent of inflicting, in such manner, unnecessary
punishment. Further or conclusive examination is made by palpation. To
cause the subject to move, an assistant may simply lead the animal with
a halter and compel it to walk a few steps. In this way, lameness,
whether manifested during the weight-bearing period of an affected
member, or when such a member is being advanced, or whether a
combination of the two conditions exists, is made apparent. In the words
of Dollar, one is thus enabled to recognize the existence of
"supporting-leg-lameness," "swinging-leg-lameness" or "mixed lameness."
When the cause of lameness is not strikingly apparent it becomes
necessary to have the subject moved farther than a few steps and at
different paces. Depending then, upon the character of lameness
manifested, as well as upon its degree of intensity, one needs to
exercise the subject in various ways, but this should not be overdone.
The first thing apparent in the lame subject in action, is the lame leg.
If this is not readily determinable, as in some complicated cases, the
leg or legs which are at fault are to be discovered by further
examination, and to do this,--word-pictures convey little that is
helpful in difficult cases,--long practice is the one route by which one
may become efficient; that is, by experience gained after fundamental
principles in the diagnosis of lameness have been mastered.
For a careful study of supporting-leg-lameness involving a fore limb,
the subject is driven or led _toward_ the one making such examination.
If a hind leg is to be observed, the animal is made to travel _away
from_ the examiner. Where there exists swinging-leg-lameness, the
subject should be caused to move past the diagnostician, so that he may
get a side view of the subject while it is in motion.
In every case such examinations are made to the best advantage if the
practitioner can view his patient from a little distance. Here, again, a
visual examination is made but this cannot be successfully executed, in
difficult cases, if the practitioner is stationed at too close range.
The average subject is best observed by being led, rather than being
ridden, and in so doing the animal should be given moderately free
rein. A close grasp on the lead may interfere somewhat with head
movements. Nodding of the head with the catching up of weight by a sound
member in supporting-leg-lameness of a fore leg, constitutes the chief
symptom considered in detecting the lame leg.
Where supporting-leg-lameness affects a hind limb the head is raised at
the time weight is caught by the sound member--here the long axis of the
subject's body may be likened unto a lever of the first class. The
posterior part of the body, at the time weight is taken upon the sound
leg, is as the long arm: the fore limbs the fulcrum, and the subject's
head the weight, which is lifted. The head movements of a horse at a
trot, in supporting-leg-lameness of a front leg, synchronize with the
discharge of weight from a lame leg to the opposite one if sound; but in
pelvic limb affections, the head is thrown or jerked upward as weight is
caught by the sound member,--this peculiar nodding movement is
_opposite_ in the two instances.
In pacing horses, since front and hind legs of the same side are
advanced at the same time, there occurs in supporting-leg-lameness, a
nodding of the head with discharge of weight from the lame leg, and a
dropping of the hip as weight is caught by the sound pelvic member. In
observing animals that are limping, (as in supporting-leg-lameness) one
notices particularly the sacro-iliac region in hind leg affections and
the occipital region in lameness of the front legs.
Where there exists a bilateral affection, (such as characterizes some cases
of navicular disease or other affections causing supporting-leg-lameness)
there occurs no nodding of the head; weight is supported for an equal
length of time upon each one of the two legs, but the stride[4] is
shortened. The gait, in such cases, is peculiar, animals appearing stiff
and they are said, by horsemen, to have a "choppy" gait.
It is desirable, in some cases, to cause an animal to move from side to
side; in other instances the subject is best made to walk or trot in a
circle, and if the circle be very small the animal then particularly
employs the inner fore leg as a pivotal supporting member. To augment
the manifestation of certain affections, it is necessary to cause the
patient to walk backward, and each one of these tests of locomotion
serves to point out in a more or less characteristic manner, the site of
the affection which is causing lameness in different cases.
Sprains or injuries of lateral ligaments of the extremities, ringbone
and certain foot affections, are made manifest by a side to side
movement or a pivotal movement. In fact, wherever it is possible to
cause undue or unusual tension to be exerted upon an inflamed structure,
manifestation of pain is the response. In an inflamed condition of the
lateral side of the phalanges, unequal weight-bearing such as a rough
road surface will, by virtue of the leverage which the solar surface of
the foot affords, cause undue strain upon such inflamed parts, and
increased lameness is evident.
When an animal is made to travel in a circle, when a member affected
with supporting-leg-lameness is on the inner side of the circle,
lameness is accentuated because weight is borne by the lame leg for a
greater length of time, the result of such circuitous manner of
locomotion. In swinging-leg-lameness, on the other hand, because pain is
increased at the time an affected member is being advanced, lameness is
increased when the subject is made to travel in a circle, with the lame
leg on the outside of a circle thus described.
In supporting-leg-lameness, the transientness of the weight-bearing
period upon the affected member is the determining factor in the
production of lameness. This unequal period of weight-bearing upon the
front legs, for instance, causes an acceleration in the advancement of
the sound member, in order to relieve the diseased one which is bearing
weight. In other words, when an animal that is affected with
supporting-leg-lameness travels in a straight line, since weight is
borne by the diseased leg for an abnormally short period of time, the
sound member needs be in the act of advancement a correspondingly short
period. The result is then, an unequal division of stride; a nodding of
the head with the catching up of weight by the sound leg,--in front leg
affections--and this is termed _limping_.
With continuous exertion as in travel for a considerable distance, in
some cases, lameness becomes less evident--as in spavin. This "warming
out" process is due in a measure to the parts becoming less sensitive
upon exertion, and is to be seen, to a limited extent, in all
inflammatory affections that are not too severe; consequently, in some
cases, examination of a lame animal should begin in the stall, for in
instances where the impediment is not marked, there may be no evidence
of lameness after the subject has walked a few steps. In other cases,
lameness increases as the subject continues to travel, and often to the
extent that the impediment becomes too severe to allow the animal being
serviceable. Therefore, one can not, in every case of lameness observed,
positively determine the gravity of the situation, without having seen
the affected animal in action for a sufficient length of time to
understand the nature of the condition existing. This necessitates
driving the animal for several miles in certain cases.
Sometimes it is impossible to arrive at any definite conclusion, as the
result of a single examination, and it then becomes necessary to see the
subject again at a later date, or under more favorable circumstances.
This is to be expected in some conditions where there exists rheumatic
affections, and also in some foot diseases.
In the examination of young animals, unused to harness and to other
strange incumbrances, one is obliged to make allowance for impediments
of gait, which are not occasioned by diseased conditions. Such
affections have been termed "false lameness." Young mules that are not
well broken to harness, are difficult subjects for examination and in
some cases it is necessary to have them led or driven for a considerable
distance before one can definitely interpret the nature of the
impediment in the gait when lameness is not pronounced. It is especially
difficult to satisfactorily examine such subjects, for the reason that
their normal rebellious temperaments cause resistance whenever a strange
person approaches them, as it is necessary to do for an examination by
palpation. In such cases--if an examination does not reveal the cause of
trouble, rest must be recommended and further examination made at a
later date, whereupon any new developments may be noted, if such changes
exist.
Special Methods of Examination.
After having completed a general examination of a lame animal--obtaining
the history of the case, noting its temperament, type, size,
conformation, position assumed while at repose, swellings or
enlargements if present, causing the subject to move to note the degree
and character of lameness manifested; palpating and manipulating the
parts affected to acquire a fairly definite notion of the nature of an
inflammation or to recognize crepitation it becomes necessary in some
cases to employ peculiar means of examination in singular instances.
This may be done by making use of cocain in solution for the production
of local anesthesia as in lameness of the phalanges. Such means are not,
in themselves, dependable but are valuable when used in conjunction with
all other available and practical methods.
Trial use of various shoes in order to shift the weight from one part of
the foot to another or to cause an animal to "break over" in a different
manner so that the gait may be changed, constitutes a special test
procedure. The use of hoof testers or of a hammer to note the degree or
presence of supersensitiveness is another means that is of practical
service. No examination, in any case of lameness, is complete without
having removed the shoe and scrutinized the solar surface of the foot.
[Illustration: Fig. 1--Hoof testers with special jaws of sufficient size
to grasp the largest foot.]
Diagnosis by exclusion, finally, is resorted to, and, as in any other
case where the recognition of cause is difficult, exclusion of the
existence of conditions,--one at a time, by an analysis of
symptoms--generally enables the practictioner to eliminate all but the
disturbing element.
FOOTNOTES:
[Footnote 4: By stride is meant the distance between two successive
imprints of the same foot. The term is not used in this work as being
synonymous with step.]