extension of inflammation from surrounding tissue, such as in abscess,
formation of tumor, or malignant growth. It is often due to embolism of
infective material, gangrenous matter, etc. Blood-letting from the
jugular vein is occasionally followed by dangerous phlebitis.
_Symptoms._--The symptoms vary according to the extent and severity of
the inflammation. In most cases the vein is swollen, thickened, and
indurated to such a degree as to resemble an artery. A diffused
swelling, with great tenderness, may extend along the affected vessel
and the animal manifest all the symptoms connected with acute fever and
general functional disturbance.
_Pathology._--The disease is only serious when large veins are affected.
The coats undergo the same changes as in arteritis; clots of blood and
lymph plug the inflamed vessel, and, if the inflammatory process
continues, these are converted into pus, which ruptures the vessel and
produces a deep abscess; or it may be carried away in the circulation
and produce metastatic abscess in the lungs or other remote organs. In
mild cases the clots may become absorbed and the vessel restored to
health. Phlebitis in the course of the veins of the limbs frequently
leads to numerous abscesses, which may be mistaken for farcy
ulcerations. A very common result of phlebitis is an obliteration of the
affected portion of the vein, but as collateral circulation is readily
established this is seldom of any material inconvenience.
_Treatment._--Phlebitis should be treated by the application of a smart
blister along the course of the inflamed vessel; early opening of any
abscesses which may form; the animal should have complete rest, and the
bowels be kept loose with bran mashes. When the fever runs high,
half-ounce doses of nitrate of potassium may be given in the drinking
water, which may be changed in two or three days for 1-dram doses of the
iodid of potassium. If the animal becomes debilitated, carbonate of
ammonia, 1 dram, and powdered gentian, 3 drams, may be given every six
hours.
VARICOSE VEINS, VARIX, OR DILATATION OF VEINS.
This may be a result of weakening of the coats from inflammatory disease
and degeneration. It may also be due to mechanical obstruction from
internal or external sources. It is sometimes found in the vein which
lies superficial over the inside of the hock joint, and may be due to
the pressure of a spavin. Occasionally it may be observed in stallions,
which are more or less subject to varicocele, or dilatation of the veins
of the testicular cord. Hemorrhoidal veins, or piles, are occasionally
met with, generally in horses which run at pasture. Varicose veins may
ulcerate and form an abscess in the surrounding tissues, or they may
rupture from internal blood pressure and the blood form large tumors
where the tissues are soft.
_Treatment._--Stallions which manifest a tendency to varicocele should
wear suspensory bags when they are exercised. Piles may often be reduced
by astringent washes--tea made from white-oak bark or a saturated
solution of alum. The bowels should be kept loose with bran mashes and
the animal kept quiet in the stable. When varicose veins exist
superficially and threaten to produce inconvenience, they may be ligated
above and below and thus obliterated. Sometimes absorption may be
induced by constant bandages.
AIR IN VEINS, OR AIR EMBOLISM.
It was formerly supposed that the entrance of air into a vein at the
time of the infliction of a wound or in blood-letting was extremely
dangerous and very often produced sudden death by interfering with the
circulation of the blood through the heart and lungs. Danger from air
embolism is exceedingly doubtful, unless great quantities were forced
into a large vein by artificial means.
PURPURA HEMORRHAGICA.
Purpura hemorrhagica usually occurs as a sequel to debilitating
diseases, such as strangles, influenza, etc. It may, however, arise in
the absence of any previous disease in badly ventilated stables, among
poorly fed horses, and in animals subject to exhausting work and extreme
temperatures. The disease is probably due to some as yet undiscovered
infectious principle. Its gravity does not depend so much upon the
amount of blood extravasated as it does upon the disturbance or
diminished action of the vasomotor centers.
_Symptoms._--This disease becomes manifested by the occurrence of sudden
swellings on various parts of the body, on the head or lips, limbs,
abdomen, etc. These swellings may be diffused or very markedly
circumscribed, though in the advanced stages they cover large areas.
They pit on pressure and are but slightly painful to the touch. The
limbs may swell to a very large size, the nostrils may become almost
closed, and the head and throat may swell to the point of suffocation.
The swellings not infrequently disappear from one portion of the body
and develop on another, or may recede from the surface and invade the
intestinal mucous membrane. The mucous lining of the nostrils and mouth
show more or less dark-red or purple spots. There may be a discharge of
blood-colored serum from the nostrils; the tongue may be swollen so as
to prevent eating or closing of the jaws. In the most intense cases,
within from twenty-four to forty-eight hours bloody serum may exude
through the skin over the swollen parts, and finally large gangrenous
sloughs may form. The temperature is never very high, the pulse is
frequent and compressible, and becomes feebler as the animal loses
strength. A cough is usually present. The urine is scanty and high
colored, and when the intestines are much affected a bloody diarrhea may
set in, with colicky pains. Some of the internal organs become
implicated in the disease, the lungs may become edematous, extravasation
may occur in the intestinal canal, or effusion of serum into the cavity
of the chest or abdomen; occasionally the brain becomes affected. A few
cases run a mild course and recovery may commence in three or four days;
generally, however, the outlook is unfavorable. In severe cases septic
poisoning is liable to occur, which soon brings the case to a fatal
issue.
_Pathology._--On section we find the capillaries dilated, the connective
tissue filled with a coagulable or coagulated lymph, and frequently we
may discover gangrenous spots beneath the skin or involving the skin.
The lymphatic glands are swollen and inflamed. Extensive extravasations
of blood may be found embedded between the coats of the intestines, or
excessive effusion into the substance of the lungs.
_Treatment._--Diffusible stimulants and tonics should be given from the
start. Carbonate of ammonia, 1 dram, fluid extract of red cinchona bark,
2 drams, and tincture of ginger half an ounce, with half a pint of
water; thin gruel or milk should be given every four or six hours. But
especial care should be exercised to avoid injury by drenching. If the
horse has difficulty in getting the head up and swallowing, smaller
doses must be given with a small hard-rubber syringe. Sulphate of iron
in 1-dram doses may be dissolved in water and given every six hours.
Chlorate of potassium, in 2-ounce doses, may be given every eight or
twelve hours. Colloidal silver may be administered intravenously in
doses of from 5 to 12 grains. Washings with lead and alum water are
useful and may be repeated several times each day. If the swellings are
very great, they may be incised freely and the resulting wounds should
be washed at least twice daily with a warm 3 per cent solution of
carbolic acid or other good antiseptic. Tracheotomy may be necessary.
Complications, when they arise, must be treated with proper
circumspection.
DISEASES OF THE LYMPHATIC SYSTEM.
The lymphatic, or absorbent, system is connected with the blood-vascular
system, and consists of a series of tubes which absorb and convey to the
blood certain fluids. These tubes lead to lymphatic glands, through
which the fluids pass to reach the right lymphatic vein and thoracic
duct, both of which enter the venous system near the heart. Through the
excessively thin walls of the capillaries the fluid part of the blood
transudes to nourish the tissues outside the capillaries; at the same
time fluid passes from the tissues into the blood. The fluid, after it
passes into the tissues, constitutes the lymph, and acts like a stream
irrigating the tissue elements. Much of the surplus of this lymph passes
into the lymph vessels, which in their commencement can hardly be
treated as independent structures, since their walls are so closely
joined with the tissues through which they pass, being nothing more
than spaces in the connective tissue until they reach the larger lymph
vessels, which finally empty into lymph glands. These lymph glands are
structures so placed that the lymph flowing toward the larger trunks
passes through them, undergoing a sort of filtration. From the fact of
this arrangement lymph glands are subject to inflammatory diseases in
the vicinity of diseased structures, because infective material being
conveyed in the lymph stream lodges in the glands and produces
irritation.
LOCAL INFLAMMATION AND ABSCESS OF LYMPHATIC GLANDS.
Acute inflammation of the lymph glands usually occurs in connection with
some inflammatory process in the region from which its lymph is
gathered. Several or all of the glands in a cluster may become affected,
as in strangles, nasal catarrh, or nasal gleet, diseased or ulcerated
teeth, the lymph glands between the branches of the lower jaw almost
invariably become affected, which may lead to suppuration or induration.
Similar results obtain in other portions of the body; in pneumonia the
bronchial glands become affected; in pharyngitis the postpharyngeal
glands lying above the trachea become affected, etc.
_Symptoms._--The glands swell and become painful to the touch, the
connective tissue surrounding them becomes involved, suppuration usually
takes place, and one or more abscesses form. If the inflammation is of a
milder type, resolution may take place and the swelling recede, the
exudative material being absorbed, and the gland restored without the
occurrence of suppuration. In the limbs a whole chain of the glands
along the lymphatic vessels may become affected, as in farcy, phlebitis,
or septic poisoning.
_Treatment._--Fomentation with hot water and the application of
camphorated soap liniment or camphorated oil may produce a revulsive
action and prevent suppuration. If there is any indication of abscess
forming, poultices of linseed meal and bran made into a paste with hot
water should be applied, or a mild blistering ointment rubbed in over
the swollen gland. As soon as fluctuation can be felt a free opening
must be made for the escape of the contained pus. The wound may
subsequently be washed out with a solution of chlorid of zinc, 5 grains
to the ounce of water, three times a day.
LYMPHANGITIS.
Specific inflammation of the lymphatic structures usually affects the
hind legs; very seldom a fore leg. This disease is very sudden in its
attack, exceedingly painful, accompanied by a high temperature and great
general disturbance.
_Causes._--Horses of lymphatic or sluggish temperament are predisposed
to this affection. It usually attacks well-fed animals, and in such
cases may be due to an excess of nutritive elements in the blood. Sudden
changes in work or in the habits of the animal may induce an attack.
_Symptoms._--It is usually ushered in by a chill, rise in temperature,
and some uneasiness; in a very short time this is followed by lameness
in one leg and swelling on the inside of the thigh. The swelling
gradually surrounds the whole limb and continues on downward until it
reaches the foot. The limb is excessively tender to the touch, the
animal perspires, the breathing is accelerated, pulse hard and quick,
and the temperature may reach 106 deg. F. The bowels early become very
constipated and urine scanty. The symptoms usually are on the increase
for about two days, then they remain stationary for the same length of
time; the fever then abates; the swelling recedes and becomes less
painful. It is very seldom, though, that all the swelling leaves the
leg; generally it leaves some permanent enlargement, and the animal
becomes subject to recurrent attacks. Occasionally the inguinal
lymphatic glands (in the groin) undergo suppuration, and pyemia may
supervene and prove fatal. In severe cases the limb becomes denuded of
hair in patches, and the skin remains indurated with a fibrous growth,
which is known by the name of elephantiasis.
_Treatment._--The parts should be bathed freely and frequently with
water as hot as the hand can bear and then fomented with vinegar and
water, equal parts, to which add 2 ounces of nitrate of potassium for
each gallon. This should be applied frequently, after the hot water, for
the first day. Afterwards the leg may be dried with a woolen cloth and
bathed with camphorated soap liniment. Internally administer artificial
Carlsbad salts in 2 to 4 ounce doses three times daily. Feed lightly and
give complete rest. This treatment, if instituted early in the attack,
very frequently brings about a remarkable change within 24 hours.
DISEASES OF THE EYE.
BY JAMES LAW, F. R. C. V. S.,
_Formerly Professor of Veterinary Science, etc., Cornell University_.
We can scarcely overestimate the value of sound eyes in the horse, and
hence all diseases and injuries which seriously interfere with vision
are matters of extreme gravity and apprehension, for should they prove
permanent they invariably depreciate the selling price to a considerable
extent. A blind horse is always dangerous in the saddle or in single
harness, and he is scarcely less so when, with partially impaired
vision, he sees things imperfectly, in a distorted form or in a wrong
place, and when he shies or avoids objects which are commonplace or
familiar. When we add to this that certain diseases of the eyes, like
recurring inflammation (moon blindness), are habitually transmitted from
parent to offspring, we can realize still more fully the importance of
these maladies. Again, as a mere matter of beauty, a sound, full, clear,
intelligent eye is something which must always add a high value to our
equine friends and servants.
STRUCTURE OF THE EYE.
(Pl. XXII.)
THE EYEBALL.
A full description of the structure of the eye is incompatible with our
prescribed limits, and yet a short description is absolutely essential
to the clear understanding of what is to follow.
The horse's eye is a spheroidal body, flattened behind, and with its
posterior four-fifths inclosed by an opaque, white, strong fibrous
membrane (the sclerotic), on the inner side of which is laid a more
delicate, friable membrane, consisting mainly of blood vessels and
pigment cells (the choroid), which in its turn is lined by the extremely
delicate and sensitive expansion of the nerve of sight (the retina). The
anterior fifth of the globe of the eye bulges forward from what would
have been the direct line of the sclerotic, and thus forms a segment of
a much smaller sphere than is inclosed by the sclerotic. Its walls, too,
have in health a perfect translucency, from which it has derived the
name of transparent cornea. This transparent coat is composed, in the
main, of fibers with lymph interspaces, and it is to the condition of
these and their condensation and compression that the translucency is
largely due. This may be shown by compressing with the fingers the eye
of an ox which has just been killed, when the clear transparent cornea
will suddenly become clouded over with a whitish-blue opacity, and this
will remain until the compression is interrupted. The interior of the
eye contains three transparent media for the refraction of the rays of
light on their way from the cornea to the visual nerve. Of these media
the anterior one (aqueous humor) is liquid, the posterior (vitreous
humor) is semisolid, and the intermediate one (crystalline lens) is
solid. The space occupied by the aqueous humor corresponds nearly to the
portion of the eye covered by the transparent cornea. It is, however,
divided into two chambers, anterior and posterior, by the iris, a
contractile curtain with a hole in the center (the pupil), and which may
be looked on as in some sense a projection inward of the vascular and
pigmentary coat from its anterior margin at the point where the
sclerotic or opaque outer coat becomes continuous with the cornea or
transparent one. This iris, or curtain, besides its abundance of blood
vessels and pigment, possesses two sets of muscular fibers, one set
radiating from the margin of the pupil to the outer border of the
curtain at its attachment to the sclerotic and choroid, and the other
encircling the pupil in the manner of a ring. The action of the two sets
is necessarily antagonistic, the radiating fibers dilating the pupil and
exposing the interior of the eye to view, while the circular fibers
contract this opening and shut out the rays of light. The form of the
pupil in the horse is ovoid, with its longest diameter from side to
side, and its upper border is fringed by several minute, black bodies
(corpora nigra) projecting forward and serving to some extent the
purpose of eyebrows in arresting and absorbing the excess of rays of
light which fall upon the eye from above. These pigmentary projections
in front of the upper border of the pupil are often mistaken for the
products of disease or injury in place of the normal and beneficent
protectors of the nerve of sight which they are. Like all other parts,
they may become the seat of disease, but so long as they and the iris
retain their clear, dark, aspect, without any tints of brown or yellow,
they may be held to be healthy.
The vitreous or semisolid refracting medium occupies the posterior part
of the eye--the part corresponding to the sclerotic, choroid, and
retina--and has a consistency corresponding to that of the white of an
egg, and a power of refraction of the light rays correspondingly greater
than the aqueous humor.
The third or solid refracting medium is a biconvex lens, with its
convexity greatest on its posterior surface, which is lodged in a
depression in the vitreous humor, while its anterior surface corresponds
to the opening of the pupil. It is inclosed in a membranous covering
(capsule) and is maintained in position by a membrane (suspensory
ligament) which extends from the margin of the lens outward to the
sclerotic at the point of junction of the choroid and iris. This
ligament is, in its turn, furnished with radiating, muscular fibers,
which change the form or position of the lens so as to adapt it to see
with equal clearness objects at a distance or close by.
Another point which strikes the observer of the horse's eye is that in
the darkness a bright, bluish tinge is reflected from the widely dilated
pupil. This is owing to a comparative absence of pigment in the choroid
coat inside the upper part of the eyeball, and enables the animal to see
and advance with security in darkness where the human eye would be of
little use. The lower part of the cavity of the horse's eye, into which
the dazzling rays fall from the sky, is furnished with an intensely
black lining, by which the rays penetrating the inner nervous layer are
instantly absorbed.
MUSCLES OF THE EYE.
These consist of four straight muscles, two oblique, and one retractor.
The straight muscles pass from the depth of the orbit forward on the
inner, outer, upper, and lower sides of the eyeball, and are fixed to
the anterior portion of the fibrous (sclerotic) coat, so that in
contracting singly they respectively turn the eye inward, outward,
upward, and downward. When all act together they draw the eyeball deeply
into its socket. The retractor muscle also consists of four muscular
slips, repeating the straight muscles on a smaller scale, but as they
are only attached on the back part of the eyeball they are less adapted
to roll the eye than to draw it down into its socket. The two oblique
muscles rotate the eye on its own axis, the upper one turning its outer
surface upward and inward, and the lower one turning it downward and
inward.
THE HAW (THE WINKING CARTILAGE, OR CARTILAGO NICTITANS).
This is a structure which, like the retractor muscle, is not found in
the eye of man, but it serves in the lower animals to assist in removing
foreign bodies from the front of the eyeball. It consists, in the horse,
of a cartilage of irregular form, thickened inferiorly and posteriorly
where it is intimately connected with the muscles of the eyeball and the
fatty material around them, and expanded and flattened anteriorly where
its upper surface is concave, and, as it were, molded on the lower and
inner surface of the eyeball. Externally it is covered by the mucous
membrane which lines the eyelids and extends over the front of the eye.
In the ordinary restful state of the eye the edge of this cartilage
should just appear as a thin fold of membrane at the inner angle of the
eye, but when the eyeball is drawn deeply into the orbit the cartilage
is pushed forward, outward, and upward over it until the entire globe
may be hidden from sight. This protrusion of the cartilage so as to
cover the eye may be induced in the healthy eye by pressing the finger
and thumb on the upper and lower lids, so as to cause retraction of the
eyeball into the socket. When foreign bodies, such as sand, dust, and
chaff, or other irritants, have fallen on the eyeball or eyelids it is
similarly projected to push them off, their expulsion being further
favored by a profuse flow of tears.
[Illustration: PLATE XXII.
DIAGRAMMATIC VERTICAL SECTION THROUGH HORSE'S EYE.]
This is seen, to a lesser extent, in all painful inflammations of the
eye, and to a very marked degree in lockjaw, when the spasm of the
muscles of the eyeball draws the latter deeply into the orbit and
projects forward the masses of fat and the cartilage. The brutal
practice of cutting off this apparatus whenever it is projected
necessitates this explanation, which it is hoped may save to many a
faithful servant a most valuable appendage. That the cartilage and
membrane may become the seat of disease is undeniable, but so long as
its edge is thin and even and its surface smooth and regular the mere
fact of its projection over a portion or the whole of the eyeball is no
evidence of disease in its substance, nor any warrant for its removal.
It is usually but the evidence of the presence of some pain in another
part of the eye, which the suffering animal endeavors to assuage by the
use of this beneficent provision. For the diseases of the cartilage
itself, see "Encephaloid cancer."
LACRIMAL APPARATUS.
This consists, first, of a gland for the secretion of the tears, and,
second, of a series of canals for the conveyance of the superfluous
tears into the cavity of the nose.
The gland is situated above the outer part of the eyeball, and the tears
which have flowed over the eye and reached the inner angle are there
directed by a small, conical papilla (lacrimal caruncle) into two minute
orifices, and thence by two ducts (lacrimal) to a small pouch (lacrimal
sac) from which a canal leads through the bones of the face into the
nose. This opens in the lower part of the nose on the floor of the
passage and a little outside the line of union of the skin which lines
the false nostril with the mucous membrane of the nose. In the ass and
mule this opening is situated on the roof instead of the floor of the
nose, but still close to the external opening.
EXAMINATION OF THE EYE.