Chapter XVIII: Part 18

_Treatment._--Poulticing to ripen the abscess. If this can not be done, apply camphorated oil two or three times a day until the core is formed. As soon as the central or most prominent part becomes soft, the abscess should be opened to release the core. Then use carbolized cosmoline once a day until the healing is completed. If the animal is in poor condition, give tonics--copperas, gentian, ginger, and sulphur, equal parts by weight, 1 tablespoonful twice a day. If the animal manifests a feverish condition of the system, give half an ounce of saltpeter twice a day, continuing it several days or a week.

FAULTY SECRETIONS AND ABNORMAL GROWTHS OF THE SKIN.

PITYRIASIS (SEBORRHEA, DANDRUFF, OR SCURF).

This is a condition characterized by an excessive secretion of sebaceous matter, forming upon the skin in small crusts or scales.

_Causes._--It is ascribable to a functional derangement of the sebaceous glands, usually accompanied with dryness and loss of pliancy of the skin. The animal is hidebound, as it is commonly termed, thin in flesh, inclined to rub, and very frequently lousy. The condition is observed most often toward the spring of the year. Animals that are continually housed, and the skins of which receive no cleaning, generally present a coat filled with fine scales, composed of epithelium from the epidermis and dried sebaceous matter. This, however, is a physiological condition and compatible with perfect health.

_Symptoms._--Pityriasis may affect the greater portion of the body, though usually only certain parts are affected--the ears, neck, rump, etc. The skin becomes scurfy, the hairy coat filled with branlike gray or whitish scales.

_Treatment._--Nutritious feed, such as oil-cake meal, bran, ground oats, and clean hay. In the spring the disease generally disappears after the animal is turned out to pasture. When lice are present they should be destroyed.

ELEPHANTIASIS (SCLERODERMA).

This condition consists in a chronic thickening of the skin, which may affect one or more limbs or involve the whole integument. It is characterized by recurrent attacks of swelling of the skin and subcutaneous areolar tissue. After each attack the affected parts remain infiltrated to a larger extent than before, until finally the skin may attain a thickness of an inch, becoming wrinkled and fissured. In cattle this disease is confined to hot climates. The predisposing cause is unknown.

EDEMA (ANASARCA OF THE SKIN).

This is a dropsical condition of the skin and subcutaneous areolar tissue, characterized by pitting under pressure, the fingers leaving a dent which remains a short time.

_Causes._--Edema generally results from a weakened state of the system arising from previous disease. It may also be dependent upon a functional derangement of the kidneys, upon weak circulation, or obstruction to the flow of blood through the lungs. In debilitated animals and in some animals highly infested with parasites there is swelling of the dewlap or of the fold of the skin between the jaws.

_Symptoms._--Painless swelling of a limb, udder, lower surface of abdomen, or lower jaw becomes apparent. This may increase in dimensions for several days or may attain its maximum in less than 24 hours. Unless complicated with some acute disease of a specific character, there is not much, if any, constitutional disturbance. The deep layer of the skin is infiltrated with serum, which gives it the characteristic condition of pitting under pressure.

_Treatment._--When the cause can be ascertained and removed we may expect to see the edema disappear. When no direct specific cause can be discovered and the animal is debilitated, give general tonic. If, on the contrary, it is in good flesh, give a purgative, followed by half an ounce of acetate of potassium twice a day. External applications are useless.

Edema may be distinguished from erysipelas or anthrax by the absence of pain and fever.

DERMOID AND SEBACEOUS CYSTS (WENS).

A dermoid cyst is formed by an involution of the skin with a growth of hair on the inner wall of the sac. It may become embedded deeply in the subcutaneous tissues or may just penetrate the thickness of the skin, where it is movable and painless. They are generally found within the ear or at its base, although they may form on any part of the body. Usually they have a small opening, from which a thick, cheesy matter can be squeezed out. The rational treatment is to dissect them out.

Sebaceous cysts appear not unlike the former. They are formed by a dilatation of the hair follicle and sebaceous duct within the skin, and contain a gray or yellowish sebaceous mass. The tumor may attain the size of a cherry stone or a walnut. Generally they are round, movable, and painless, soft or doughy in consistency, and covered with skin and hair. They develop slowly. The best treatment is to dissect out the sac with contents entire.

VERRUCA (WARTS).

Cattle are affected with two varieties of warts. One, the verruca vulgaris, is composed of a cluster of enlarged papillÊ, covered with a thickened epidermis, the number of papillÊ determining the breadth and their length its height. They are generally circular in figure, slightly roughened on the surface, and spring from the skin by a broad base. Occasionally large numbers of very thin, long, pedunculated warts grow from the skin of the ear, lips, about the eyes, and vulva. Another variety, the verruca acuminata, sometimes erroneously denominated epithelial cancers, are irregularly shaped elevations, tufted or club shaped, occasionally existing as thick, short, fleshy excrescences, giving the growth the appearance of granulation tissue. Their color is red or purplish, and oftentimes by friction they become raw and bleeding, emitting then a very offensive odor. They usually grow in clusters and their development is rapid.

_Causes._--An abnormal nutrition of the skin, determined by increased energy of growth operating upon a healthy skin; at other times, upon a weak or impoverished skin.

_Treatment._--When they are small and pedunculated, they may be snipped off with shears and the stump touched with nitrate of silver. When they are broad and flattened, they may be dissected out and the wound cauterized if necessary. If they are large and very vascular, they may be ligated, one by one, by taking a strong cord and tying it as firmly around the base as possible. They will then shrivel, die, and drop off. If there is a tendency to grow again, apply a red-hot iron or nitric acid with a glass rod. Very often warts quickly disappear if they are kept soft by daily applications of sweet or olive oil.

KELIS.

Kelis is an irregularly shaped flat tumor of the skin, resulting from hypertrophy--increased growth of the fibrous tissue of the corium, producing absorption of the papillary layer.

_Causes._--It may arise spontaneously or follow a scar after an injury.

_Symptoms._--Kelis generally appears below the knee or hock, and may occur singly or in numbers. There are no constitutional symptoms. Its growth is very slow and seldom causes any inconvenience. It appears as a flattened, irregular, or spreading growth within the substance of the skin, is hard to the touch, and is especially characterized by divergent branches or roots, resembling the claws of a crab; hence the name. Occasionally some part of it may soften and result in an abscess. It may grow several inches in length and encircle the whole limb.

_Treatment._--So long as it causes the animal no inconvenience it is best not to meddle with it; when it does the animal ought to be fattened for beef, the meat being perfectly harmless to the consumer.

PARASITIC DISEASES OF THE SKIN.

RINGWORM (TINEA TONSURANS AND TINEA FAVOSA).

Ringworm is an affection of the skin, caused by a vegetable parasite.

The form known as tinea tonsurans is produced by the presence of a minute or microscopic fungus--the _Trichophyton tonsurans_, which affects the hair and the epidermic layer of the skin, and is highly contagious, being readily transmitted from one animal to another. This fungus consists of spores and filaments. The spores, being the most numerous, are round and seldom vary much in size. They are very abundant in the hair follicle. The filaments are articulated, waving, and contain granules. This disease is productive of changes in the root and shaft of the hair, rendering it brittle and easily broken off.

This disease becomes manifest by the formation of circular patches on the skin, which soon becomes denuded of hair. The cuticular layer of the skin in slightly inflamed, and vesication with exudation occurs, followed by the formation of scaly, brittle crusts. The patches appear silvery gray when incrusted, and are mostly confined to the head and neck. It is a common disease among young cattle in the winter and spring. Very early in the development of the patches the hairs split, twist, and break off close to the skin. This disease is attended with more or less itching. It is communicable to man.

Tinea favosa comes from another fungus, the _Achorion schˆnleinii._ This enters the hair follicle and involves the cuticle surrounding it, small crusts form which increase in diameter and thickness and then become elevated at their margin, forming a cup-shaped scab, the favus cup, which gives the disease its distinctive character. The number of these cups varies from a few to many hundreds. The hairs involved become brittle and broken, fall off with the crusts, leaving small bald patches. The crusts are of a pale or sulphur-yellow color at first; as they grow older they turn darker, or to a brown color. This form of ringworm has a peculiar odor, resembling that of mice or musty straw. It is occasionally communicated to cattle by man, mice, cats, etc., all being subject to it.

_Treatment._--Remove all crusts by washing with soap and water, then apply acetic acid, sulphur ointment, tincture of iodin or nitrate of mercury ointment once a day. Cleanse the stable and whitewash it to destroy the spores scattered by the crusts.

OTHER PARASITES AND PARASITIC DISEASES OF THE SKIN.

For discussion of mange, itch, scab, lousiness, warbles (grub in the skin), buffalo gnats, hornfly (_Hoematobia serrata_), ticks, flies, etc., see the chapter on "The animal parasites of cattle," page 502.

WOUNDS OF THE SKIN.

SNAKE BITES AND VENOMOUS STINGS.

[See discussion of these subjects in chapter on "Poisons and poisoning."]

BURNS AND SCALDS.

This is a rare accident among cattle, yet in cases of fire it may occur. The application of heat, whether dry or moist, unless sufficient instantly to destroy the life of a part, is always followed by the development of vesicles or blisters, which contain a thin, watery fluid. The blisters may be isolated and not very large, or one blister may cover a very large surface. When the burn is very severe the skin may be wholly devitalized, or the injury may extend into the deeper structures of the skin. Then sloughs will occur, followed by a contraction of the parts in healing; if on a limb, this may render the animal stiff. When the burn or scald has been a severe one, the resulting pain is great and the constitutional disturbance very marked.

_Treatment._--For a superficial burn use a mixture of equal parts of limewater and linseed oil, or common white paint--white lead ground in oil--to exclude the atmosphere and protect the inflamed skin. If it is not convenient to get anything else, chimney soot, flour, or starch may be spread on the wound (dry), and covered with cotton batting and light bandage. The blisters should be opened to let the contained fluid escape, but do not pull off the thin cuticle which has been raised by the blister. When the burn is extensive and deep sloughing occurs, the parts should be treated, like other deep wounds, by poulticing, astringent washes, etc. When the system has sustained much shock, the animal may require internal stimulants, such as 2 drams of carbonate of ammonia every hour until it rallies. When the pain is very great, hypodermic injections of 6 grains of morphia may be administered every six hours.

_Frostbite_ on any portion of the body may be treated as recommended in the article on diseases of the ears.

EMPHYSEMA (AIR OR GAS UNDER THE SKIN).

Emphysema of the skin is not a true disease of the skin, but it is mentioned as a pathological condition. It is characterized by a distention of the skin with air or gas contained in the subcutaneous areolar tissue. It may depend upon a septic condition of the blood, as in anthrax or blackleg, or air may be forced under the skin about the head, neck, and shoulders, as a result of rupture of the windpipe. It occurs in the region of the chest and shoulders from penetrating wounds of the chest and lung, and occasionally follows puncture of the rumen when the escaping gas is retained under the skin.

_Symptoms._--The skin is enormously distended over a greater or less portion of the body; thus any region of the body may lose its natural contour and appear like a monstrosity. There is a peculiar crackling beneath the skin when the hand is passed over it, and on tapping it with the fingers a resonant, drumlike sound is elicited.

_Treatment._--Puncture the distended skin with a clean, broad-bladed knife and press the air out. Further treatment must be directed with a view to the removal of the cause.

DISEASES OF THE FOOT.

By M. R. TRUMBOWER, D. V. S.

[Revised by Leonard Pearson, B. S., V. M. D.]

LAMINITIS (FOUNDER).

Laminitis denotes an active inflammation of the sensitive structures within the wall of the hoof, which in severe cases may result in suppuration and the loss of one or more claws. Owing to the simplicity of the structure of the foot of an ox compared with that of the horse, this disease is rarely seen in an acute form, but a mild form, commonly called "foot soreness," is not of infrequent occurrence.

_Causes._--Laminitis in cattle may be caused by overfeeding, overheating, continued standing without exercise on a stone or cement floor without sufficient bedding, or by driving long distances over rough or stony soil.

_Symptoms._--An unwillingness to maintain the standing position; the animal persists in lying down. The feet will be found unnaturally hot, and frequently some swelling may be noticed above the hoof. Pressure upon the hoof with blacksmith's hoof pincers causes pain and flinching. The general body temperature is increased and the breathing accelerated. Ordinarily the animal eats and drinks as usual. When it is made to move excessive tenderness of the feet becomes manifest, as is shown by reluctance to walk and by the very short, hesitating step. Founder affects the hind as well as the fore feet, although the front feet are more often exposed.

_Treatment._--Cold packs to the feet, or if the animal can be made to stand in a stream of water, having a soft bottom, the inflammation is often relieved without the necessity of any additional treatment. It may be well, however, to give a full dose of Epsom salt, 1 to 1-1/2 pounds, followed by half-ounce doses of saltpeter two or three times a day.

SORENESS (FOOT SORENESS).

Cattle that have been stabled or pastured on soft ground and are driven over stony roads soon wear down the soles of their feet and become lame from foot soreness. Draft oxen, for this reason, require to be shod. When the soreness is excessive it may develop into an active inflammation of all the sensitive structures of the foot--laminitis, or into a local bruise commonly called a "corn."

_Treatment._--Rest, poulticing the feet with moistened clay, followed by astringent washes--strong white-oak bark or alum water.

If the pain and heat last several days, it is probable that pus has formed beneath the wall of the hoof. In this case it is necessary to cut through the wall, usually at the most prominent part of the sole, to allow the accumulation to drain out. The animal should then stand for several hours daily in a tub containing a 3 per cent solution of some good milky coal-tar disinfectant. When not in the disinfecting solution the foot should be dressed with pine tar and cotton and bandaged with bagging.

LOSS OF HOOF.

Cattle sometimes become fastened between planks or otherwise and pull off the wall of one or both claws in the effort to extricate themselves. The claws of one or more feet may be shed as the result of acute laminitis.

_Treatment._--Wash the bleeding surface with an antiseptic and then with an astringent, such as a weak solution of alum, then apply a thick coating of pine tar; cover this with a layer of oakum or absorbent cotton; apply another coat of tar over this, and then bandage closely and firmly. This may remain without disturbance until the new growing wall becomes sufficiently strong to sustain the pressure and weight of the animal. If, however, at any time oozing or bad smell indicates that pus is forming under this dressing, the bandage should be removed and the suppurating surface freshly cleaned and dressed. This may have to be repeated every few days and should be continued so long as there is any pus formation. If the loss of hoof is owing to suppurative laminitis, the parts denuded of the horny covering must be thoroughly cleansed and disinfected with carbolic acid, lysol, or other antiseptic. Then apply a moderately thick layer of absorbent cotton and over this apply the tar and bandage. After this the antiseptic solution may be poured in daily at the top of the dressing. It will thus soak in and saturate the dressing and inflamed tissue. It may become necessary to remove all the dressing at daily or longer intervals to give the parts a fresh cleaning, and then to reapply it.

FOUL IN FOOT (FOOT ROT).

A variety of causes may produce inflammation of the foot between the claws or toes. It may be on account of overgrowth of the claws and inward pressure, as in ingrowing nail of man, or it may be caused by the irritation of stable filth by impaction and hardening of soil between the claws, or by other foreign substances becoming wedged in, causing inflammation and softening or ulceration of the skin in the interdigital space. Under some conditions several cattle in the same herd become affected, which has led some to think that the disease may be contagious. Occurrences have been reported in which foot rot of cattle has appeared within a short time among a large proportion of the cattle in a farming district. This disease is most frequently seen in the hind feet, though all four feet may become affected.

_Symptoms._--The animal is observed to limp. On examination of the foot we discover heat and swelling above the hoof and of the soft parts between the claws which frequently spreads the claws apart to a considerable extent, or the inflammation may have advanced to softening and sloughing of the interdigital membrane. If the disease is neglected at this stage, deep abscesses may form and the pus burrow under the horny wall, or the joint within the hoof may become inflamed and the articular attachments destroyed, in which case the treatment will be difficult and recovery will be very tedious.

_Treatment._--In the earlier stages of the disease, before pus burrows beneath the horn, a thorough cleansing and an application of a carbolic-acid solution--1 ounce to a pint of water--clean stabling, and laxative food will usually remedy the evil. Compound solution of cresol is an excellent remedy at this stage. It should be applied, in its pure or undiluted state, to the suppurating and putrefying tissue between the claws. It is best applied by means of a cotton swab on a thin stick. Care must be taken to keep it from contact with the skin about the coronary band or heels. If deep sloughing has taken place the carbolic solution should be used, and a wad of oakum or cotton smeared with pine tar should be secured firmly in the cleft. This can be done by taking a strip of strong cloth, 2 inches wide, passing the middle between the claws, then tying the ends after winding them in opposite directions above the hoof. Sometimes warm poulticing with flaxseed meal or bran is necessary to relieve excessive fever and pain. If the pus burrows under the horn, its channel must be followed by paring away the horn until the bottom is reached. The aftertreatment is the same as that already recommended. If the joint becomes diseased an amputation of that toe is the quickest and surest method to relieve the suffering of the animal, and offers the best chance for an early recovery.

ULCERATION OF THE HEEL.

Occasionally we find ulcers at the junction of the hair with the hoof at the heel, which present an elevated, raw, or ragged surface, and cause considerable lameness. This is generally caused by a bruise of the fibrous cushion of the back part of the foot. Subsequent sloughing or necrosis may occur, or pus may form deep within the wall and gain an exit at the margin of the heel. Sometimes, from no visible cause, large pieces of skin slough from the heel and pastern. This condition is caused by an infection with certain microorganisms (streptococci, necrosis bacilli) and may be contagious.

_Treatment._--If there is a deep opening, inject carbolic solution once a day until it closes. If the ulcer is only superficial, wash with carbolic solution and apply a mixture of equal parts of blue vitriol and alum in dry powder.

FISSURE OF THE WALL (SPLIT HOOF).

This is rarely seen among cattle. It may occur in weak walls, in heavily bodied cattle, caused by stepping on an uneven surface, especially when the point of the toe is grown out long. One may find the point of the toe broken and the wall split almost up to the hair.

_Treatment._--The divided sections may be brought into approximation and held in place by drilling a small hole from one side into and through the other, commencing half an inch back of the fissure on each side; then drive a light horseshoe nail through the hole and clinch it. Pare the injured claw as short as it will bear.

INTERDIGITAL FIBROMA.

Hard, nodular, fibrous tumors sometimes grow in the cleft of the foot, and cause inconvenience, lameness, absorption, or ulceration of the contiguous parts.

_Treatment._--They should be dissected out and the wound dressed with carbolic-acid lotion and pine tar once a day until healing is completed.

DEFORMITIES.

Deformities in the feet of cattle usually consist in overgrowth of horn, generally from want of wear in animals which are stabled. The hoof may turn inward, outward, or upward, and may give rise to lameness, inability to walk, foul foot, etc. Bulls which are continually stabled and dairy cows very frequently have misshapen feet from want of an occasional trimming, and this deformity may eventually lead to permanent injury.

_Treatment._--Cut the superabundant growth of horn down with saw, knife, or rasp, until the foot assumes its natural form.

PRICKS AND WOUNDS.

If an animal suffers with a penetrating wound from prick of fork or nail, the orifice of the wound should be enlarged to permit a free discharge of pus; then the foot should be soaked in a cresol compound solution (3 per cent) in a tub, or a flaxseed poultice applied, changing it three times a day until the fever has abated. The foot should be kept bandaged and dressed with pine tar and oakum; the animal must also be kept on a clean floor until the wound is closed and all or nearly all lameness has disappeared.

If an animal is cut in the foot with barbed wire, piece of glass, or any other substance, the wound, after proper cleansing, should be dressed with carbolic-acid solution, 1 ounce of the acid to 20 of water. If any uneven edges of horn, skin, or lacerated flesh project, trim them off, and in all cases when it can be done a tarred bandage should be applied. This will serve to sustain the cut surfaces in their place, exclude dirt, and protect against flies, maggots, etc.

When the wound has extended into a joint, surgical treatment, which will require the services of an educated veterinarian, may be necessary.

Occasionally an animal gets caught by the foot in a crevice and sustains severe bruising, wrenching, or fracture of some part of the foot. In such cases cold-water packs to the injured member are of service until the fever and swelling disappear. Afterwards the animal should rest until the usefulness of the foot is restored. Sometimes such an accident, causing fracture, renders necessary plaster bandages or amputation.

DISEASES OF THE EYE AND ITS APPENDAGES.

By M. R. TRUMBOWER, D. V. S.

[Revised by Leonard Pearson, B. S., V. M. D.]

DESCRIPTION.

For the sake of gaining a clear comprehension of the diseases of the eye it becomes necessary to review the anatomy of this important organ. The essential organ of vision, or globe of the eye, will be first described, then its receptacle or orbital cavity, the muscles that move it, the protective membranes, or eyelids, the membrana nictitans, or accessory eyelids, and, lastly, the lacrimal apparatus.

The globe or ball of the eye is almost spherical in form. On closer inspection, however, it appears to be made up of two combined portions from spheres of different sizes. The posterior portion, forming about five-sixths of the ball, is a sphere of comparatively large size with a small segment cut off it in front, and at this point there is applied to it the anterior portion, which, being a segment of a smaller sphere, projects at the front of the ball with a greater convexity than the posterior portion.

The eyeball consists of concentrically arranged coats and of refracting media inclosed in them. The coats are three in number, namely, (1) an external protective tunic made up of the sclerotic and cornea; (2) a middle vascular and pigmentary tunic, the choroid; (3) an internal nervous layer, the retina. The sclerotic is the white, opaque part of the outer tunic, of which it forms about the posterior five-sixths, being coextensive with the larger sphere already mentioned. The cornea forms the remaining one-sixth of the outer tunic, being coextensive with the segment of the smaller sphere. It is distinguished from the sclerotic by being colorless and transparent. The choroid coat will be recognized as the black layer lying subjacent to the sclerotic. It does not line the cornea, but terminates behind the line of junction of that coat with the sclerotic by a thickened edge--the ciliary processes. At the line of junction of the sclerotic and cornea the iris passes across the interior of the eye. This (which may be viewed as a dependency of the choroid) is a muscular curtain perforated by an aperture termed the pupil. The retina will be recognized as a delicate, glassy layer, lining the greater part of the choroid.

The refracting media of the eye are three in number, namely (1) the aqueous humor, a watery fluid inclosed in a chamber behind the cornea; (2) the crystalline lens and its capsule, a transparent, soft solid of a biconvex form, and placed behind the iris; (3) the vitreous humor, a transparent material with a consistence like thin jelly, and occupying as much of the interior of the eye as is subjacent to the choroid.

The sclerotic is a strong, opaque, fibrous membrane, which, in a great measure, maintains the form of the eyeball and protects the more delicate structures within it. Its interior portion, which is covered by the ocular conjunctiva, is commonly known as the "white of the eye." In form it is bell-shaped, and the optic nerve pierces it behind like a handle, the perforation being a little to its inner side. In front, the rim of the bell becomes continuous with the cornea. The outer surface of the membrane receives the insertion of the muscles of the eyeball. The coat is thickest over the posterior part of the eyeball, and is thinnest a little behind its junction with the cornea.

The cornea is the anterior transparent portion of the outer coat of the eyeball. It may be viewed as a part of the sclerotic specially modified to permit the passage of light into the interior of the eye. Its outline is elliptical, nearly circular, and its greatest diameter is transverse. At its periphery it joins the sclerotic by continuity of tissue, and as the edge of the cornea is slightly beveled and has the fibrous sclerotic carried for a little distance forward on its outward surface, the cornea is generally said to be fitted into the sclerotic like a watch glass into its rim. The venous canal of Schlemm runs circularly around the eyeball at the line of junction of the sclerotic and cornea. The anterior surface of the cornea is exquisitely smooth, and is kept moist by the lacrimal secretions. Its posterior surface forms the anterior boundary of the chamber in which the aqueous humor is contained. The cornea is of uniform thickness and is of a dense, almost horny, consistence. Save a few capillary loops of blood vessels at its margin the cornea is without vessels. Its structure is comprised of five distinct layers.

The aqueous humor occupies a chamber which is bounded in front by the posterior surface of the cornea and behind by the capsule and suspensory ligament of the lens and by the ends of the ciliary processes. It is across this chamber that the iris extends. The aqueous humor is composed of water, with a small proportion of common salt in solution.

The iris is a muscular, pigmented curtain extending across the interior of the eye and having about its center an aperture termed the pupil. By variations in the size of this aperture the amount of light transmitted to the retina is regulated. It varies somewhat in color, but is most frequently of a yellowish-brown tint. Its anterior face is bathed by the aqueous humor. The greater part of the posterior surface is in contact with the capsule of the lens and glides on it during the movements of the curtain. The circumferential border is attached within the junction of the sclerotic cornea. The inner border circumscribes the pupil, which varies in outline according to its size. When much contracted the pupil is a very elongated ellipse, the long axis of which is in the line joining the nasal and temporal angles of the eyelids. It contains muscular tissue, which, by contracting or relaxing, lessens or dilates the pupillary opening.

The choroid coat is a bell-shaped, dark membrane which lines the sclerotic. Its outer surface has a shaggy appearance, caused by the tunica fusca, which unites the two coats. Between the two the ciliary vessels and nerves pass forward. Behind it is pierced by the optic nerve; in front it is continued as the ciliary processes, which form, as it were, the rim of the bell. The ciliary processes form a fringe around the slightly inverted rim of the choroid.

The retina is the most delicate of the coats of the eyeball. It is formed by the expansion of the optic nerve on the inner surface of the choroid, and, like that coat, it is bell-shaped. Its inner surface is molded on the vitreous humor. The nervous structures of the retina terminate at a wavy line, the ora serrata, behind the ciliary processes. Ten distinct layers are described as composing the thickness of the retina.

The lens is situated behind the pupil and is contained within a capsule of its own.

The capsule is a close-fitting, firm, transparent membrane. The anterior surface forms the posterior boundary of the cavity containing the aqueous humor, and the iris in its movement glides on it. The posterior surface is in contact with the vitreous humor.

The vitreous humor occupies four-fifths of the interior of the eyeball. It is globular in form, with a depression in front for the lodgment of the lens. It is colorless, transparent, and of a consistency like thin jelly. It is enveloped by a delicate capsule--the hyaloid membrane--which is connected in front with the suspensory ligament of the lens, and ends by joining the capsule behind the lens.

The orbital cavity, at the side of the head, is circumscribed by a bony margin; posteriorly, however, there are no bony walls, and the cavity is often confounded with the depression above and behind the orbit--the temporal fossa. A fibrous membrane completes this cavity and keeps it distinct from the temporal fossa. This membrane--the ocular sheath or periorbita--is attached posteriorly around the opening in the back part of the orbital cavity (the orbital hiatus) and anteriorly to its inner face; then it becomes prolonged beyond the margin to form the fibrous membrane of the eyelids. When complete the orbital cavity has the form of a regular hollow cone, open at its base and closed at the apex. The opening of this cone is directed forward, downward, and outward. Independently of the globe of the eye, this cavity lodges the muscles that move it, the membrana nictitans, and the lacrimal gland.

The muscles of the eye are seven in number--one retractor, four straight, and two oblique. The retractor oculi envelops the optic nerve between the brain and the ball of the eye and becomes attached upon the external face of the sclerotic tunic. When this muscle contracts, it draws the globe back into the orbit, away from the light. The superior, inferior, external, and internal recti or straight muscles are attached to the back part of the orbital sheath and spread forward in four bundles over the globe of the eye, where they are inserted by a fibrous expansion into the sclerotic at the margin of the cornea. When they act singly, they turn the globe either upward, downward, inward, or outward. The great oblique, by its action, pivots the eye inward and upward in the orbit. The small oblique turns the eye outward and downward.

The eyelids are two movable curtains, superior and inferior, which cover and protect the eye in front. They are attached to the circumference of the orbit and have a convex external face formed by the skin and a concave internal face molded on the anterior surface of the eye and are lined by the conjunctiva, which is reflected above and below on the eyeball. The border of each lid is slightly beveled on the inner side and shows the openings of the Meibomian glands. These glands secrete an unctuous fluid, which is thrown out on the border of the lids, the function of which is to facilitate their movements and enable them to retain the tears in the ocular cavity. The eyelid is composed of a fibrous inner membrane ending in a stiff arch near the border, a muscle to close the lid, another to open it, the skin externally, and the conjunctival mucous membrane internally. The border of each lid is covered and protected by long hairs to prevent floating particles of matter in the atmosphere from gaining entrance to the eye.

The membrana nictitans, which is also named the third eyelid, winking eyelid, haw, etc., is placed at the inner angle of the eye, whence it extends over the eyeball to relieve it from foreign bodies which may fall upon it. It has for its framework a fibro-cartilage, irregular in shape, thick, nearly prismatic at its base, and thin anteriorly where it is covered by the conjunctiva; behind, it is loosely attached to a fatty cushion.

The lacrimal gland is situated between the orbital process and the upper part of the eyeball. It secretes the tears destined to lubricate the anterior surface of the eye. This fluid escapes upon the organ at the outer angle of the lids and is carried between them and the eyeball toward the inner angle.

The caruncula lacrimalis is a small round body, frequently entirely or partially black, situated in the inner angle of the eye, and is designed to direct the tears toward the puncta lacrimalia.

The puncta lacrimalia are two little openings, situated one in each eyelid, a short distance from the inner corner, which admit the tears into the lacrimal ducts leading to the lacrimal canal, whence they are emptied into the nasal passages.

CONJUNCTIVITIS (SIMPLE OPHTHALMIA).

This is an inflammation of the conjunctival mucous membrane of the eyeball and lids; in severe cases the deeper coats of the eye are involved, seriously complicating the attack.

_Causes._--It may result from a bruise of the eyelid; from the introduction of foreign matters into the eye, as chaff, hayseed, dust, gnats, etc.; from exposure to cold; poisonous or irritating vapors arising from filthiness of stable. Dust, cinders, or sand blown into the eyes during transportation frequently cause conjunctivitis.

_Symptoms._--A profuse flow of tears, closure of the eyelids from intolerance of light, retraction of the eyeball and corresponding protrusion of the haw, disinclination to move, diminution of milk secretion, etc. On parting the lids the lining membrane is found injected with an excess of blood, giving it a red and swollen appearance; the sclerotic, or white of the eye, is bloodshot and the cornea may be cloudy. If the disease advances, keratitis results, with its train of unfavorable symptoms.

_Treatment._--Careful examination should be made to discover particles of chaff, etc., which may have lodged in the eye, and upon the discovery of such a cause prompt removal is indicated. This may be accomplished by flushing the eye with warm water by means of a syringe, or, if the foreign substance is adherent to the eyeball or lid, it may be scooped out with the handle of a teaspoon or some other blunt instrument. To relieve the congestion and local irritation, a wash composed of boracic acid in freshly boiled water, 20 grains to the ounce, or acetate of zinc, 5 grains to the ounce of pure soft water, may be used, to which may be added 20 drops of laudanum. A few drops of this should be placed in the eye with a camel's-hair pencil or soft feather three or four times daily. The animal should be placed in a cool, darkened stable; then a cloth folded into several thicknesses should be fastened to the horns in such manner as to reach below the eyes. This should be kept wet with cold water during the day and removed at night. If there is much fever and constitutional disturbance, it becomes advisable to administer 1 pound of Epsom salt dissolved in 1 quart of water.

INFECTIOUS CATARRHAL CONJUNCTIVITIS (SPECIFIC OPHTHALMIA).

This generally appears in an enzootic or epizootic form and affects a considerable number in the herd. It is distinctly a contagious disease and may be brought into a previously healthy herd by one infected animal. It may continue in a herd for a season or for several years, affecting all newly purchased animals. It is seldom seen in the winter months. It affects old and young animals alike.

_Symptoms._--This form of catarrh conjunctivitis is characterized chiefly by a mucopurulent discharge from the eyes, an intense degree of inflammation of the mucous membrane, accompanied with swelling of the eyelids and an early opacity of the cornea. The flow of tears is mixed with pus, sometimes streaked with blood, and the skin of the face is kept moist and soiled. The eyes are kept continually closed. The implication of the cornea in the disease frequently blinds the animal for a time, and occasionally suppurative keratitis, ulcers of the cornea, or staphyloma supervene. The attack is marked from the onset by fever, partial loss of appetite, partial loss of milk, suspended rumination, and separation from the herd.

_Treatment._--The animal should be housed in a cool, dark stable, supplied with plenty of fresh water to drink and soft, succulent feed. Administer 1 pound of Epsom salt--if a very large animal, use 1-1/2 pounds--dissolved in 2 or 3 pints of water. For an eyewash, take boracic acid, 1 dram, and pour 4 ounces of boiling water over it. Use this as often as is convenient, applying it directly to the eye. In the majority of cases improvement becomes manifest in a few days, and the eye becomes clear and free from inflammation in 10 days or 2 weeks. Where the disease develops ulceration of the cornea, or well-marked, deep-seated keratitis, the treatment recommended for those conditions should be adopted.

_Prevention._--Whenever this affection appears in a herd all the unaffected animals should be moved to fields which possess a different character of soil and feed. The water should also be changed, especially if they have been obtaining it from a stagnant pond.

KERATITIS (CORNEITIS).

This is an inflammation of the cornea proper, although the sclerotic at the corneal border becomes involved to some extent. It may be divided into diffuse and suppurative.

_Causes._--The cornea constitutes the most prominent portion of the eyeball, hence it is subject to a variety of injuries--scratches, pricks, contusions, lacerations, etc. Inflammation of the cornea may also be due to the extension of catarrhal conjunctivitis or intraocular disease, and it may occasionally occur without any perceptible cause.

_Symptoms._--Diffuse keratitis is characterized by an exudation into and an opacity of the cornea. The swelling of the anterior part of the eyeball may be of an irregular form, in points resembling small bladders, or it may commence at the periphery of the cornea by an abrupt thickening, which gradually diminishes as it approaches the center. If the whole cornea is affected, it has a uniform gray or grayish-white appearance. The flow of tears is not so marked as in conjunctivitis, nor is the suffering so acute, though both conditions often exist together. Both eyes usually become affected, unless it is caused by an external injury.

In favorable cases the exudate within the cornea begins to disappear within a week or 10 days, the eye becomes clearer and regains its transparency, until it eventually is fully restored. In unfavorable cases blood vessels form and are seen to traverse the affected part from periphery to center, vision becomes entirely lost, and permanent opacity (albugo or leucoma) remains. When it arises from constitutional causes recurrence is frequent, leaving the corneal membrane more cloudy after each attack, until the sight is permanently lost.

Suppurative keratitis may be a sequel of diffuse keratitis; more commonly, however, it abruptly becomes manifest by a raised swelling on or near the center of the cornea that very soon assumes a yellow, turbid color, while the periphery of the swelling fades into an opaque ring. Suppurative keratitis is seldom noticed for the first day or two--not until distinct pus formation has occurred. When it is the result of diffuse keratitis, ulceration and the escape of the contained pus is inevitable; otherwise the pus may be absorbed. When the deeper membranes covering the anterior chamber of the eye become involved, the contents of this chamber may be evacuated and the sight permanently lost.

_Treatment._--Place the animal in a darkened stable, give green or sloppy feed, and administer 4 ounces of Glauber's salt (sulphate of soda) dissolved in a quart of water once a day. If the animal is debilitated a tablespoonful of tonic powder should be mixed with the feed three times a day. This may be composed of equal parts by weight of powdered copperas (sulphate of iron), gentian, and ginger. As an application for the eye, nitrate of silver, 3 grains to the ounce of soft water, with the addition of 1 grain sulphate of morphia, may be used several times a day. If ulceration occurs, it is well to dust powdered calomel into the eye twice daily, or apply to the eyelids a salve of yellow oxid of mercury, 5 per cent in lanolin. Some of this may go on to the cornea and beneath the lids. Apply twice daily. (See "Ulcers of the cornea.")

To remove opacity, after the inflammation has subsided, apply a few drops of the following solution twice a day: Iodid of potassium, 15 grains; tincture sanguinaria, 20 drops; distilled water, 2 ounces; mix.

Sometimes keratitis exists in a herd as a transmissible disease, spreading like infectious conjunctivitis. Calomel, applied to the eye, is especially useful in such cases.

ULCERS OF THE CORNEA.

An ulcer comes from erosion or is the consequence of the bursting of a small abscess, which may have formed beneath the delicate layer of the conjunctiva, continued over the cornea; or, in the very substance of the cornea itself, after violent keratitis, or catarrhal conjunctivitis. At other times it is produced by bruises, scratches, or other direct injury of the cornea.

_Symptoms._--The ulcer is generally at first of a pale gray color, with its edges high and irregular, discharges instead of pus an acrid, watery substance, and has a tendency to spread widely and deeply. If it spreads superficially upon the cornea, the transparency of this membrane is lost; if it proceeds deeply and penetrates the anterior chamber of the aqueous humor, this fluid escapes, the iris may prolapse, and the lens and the vitreous humor become expelled, thus producing destruction of the whole organ.

_Treatment._--It is of the greatest importance, as soon as an ulcer appears upon the cornea, to prevent its growing larger. The corroding process must be converted into a healthy one. For this purpose nothing is more reliable than the use of solid nitrate of silver. A stick of this medicine should be scraped to a point; the animal's head should be firmly secured; an assistant should part the lids; if necessary, the haw must be secured within the corner of the eye and then all parts of the ulcer should be lightly touched with the silver. After waiting a few minutes the eye should be thoroughly washed out with a very weak solution of common salt. This operation generally has to be repeated at the end of three or four days. If healthy action succeeds, the ulcer assumes a delicate fleshy tint, and the former redness around the ulcer disappears in proportion as the ulcer heals.

In superficial abrasions of the cornea, where there is no distinct excavation, this caustic treatment is not needed. The eye should be bathed several times a day with sulphate of zinc, 30 grains to half a pint of soft water, and protected against exposure to cold air and sunlight. Excessive ulceration sometimes assumes the form of fungous excrescence upon the cornea, appearing to derive its nourishment from loops of blood vessels of the conjunctiva. Under these circumstances the fungoid mass must be cut away and the wound cauterized with the nitrate of silver, or else the eye will soon be destroyed. When ulcers of the cornea appear indolent, with a tendency to slough, in addition to the treatment already prescribed, tonic powders of copperas, gentian, and ginger, equal parts by weight, should be given twice a day, mixed with the feed; dose, one tablespoonful.

STAPHYLOMA.

This is a disease of the eyeball, in which the cornea loses its transparency, rises above the level of the eye, and even projects beyond the eyelids in the form of an elongated, whitish, or pearl-colored tumor, which is sometimes smooth, at other times uneven.

_Causes._--Inflammation is the only known cause, although it may not occur immediately; it frequently follows catarrhal conjunctivitis and keratitis as a sequela.

_Treatment._--In a few cases restoration of sight may be effected by puncturing the projecting tumor and treating it afterwards with nitrate of silver in the same manner as prescribed for ulceration of the cornea. In some cases spontaneous rupture has occurred, and healing without any treatment at all.

CATARACT.

In cataract the crystalline lens becomes opaque and loses its transparency, the power of refraction is lost--the animal can not see.

_Causes._--Cataract generally arises from a diminution (atrophy) or other change in the nutrition of the lens; it may occur as a result of inflammation of the deep structures of the eye. Cataract may be simple, or complicated with amaurosis, adhesions, etc.

_Symptoms._--It is known by the whiteness or loss of transparency of the lens, although the pupil dilates and contracts. Sight may be totally lost; however, evidence is usually manifested that the animal distinguishes light when brought out of a darkened stable. For the most part the formation of cataract takes place slowly, the cases in which it originates very quickly being but few.

_Treatment._--There is only one method for the treatment of cataract--a surgical operation for the removal of the lens; but this is not advisable, for the sight can not be perfectly restored, and objects would be seen imperfectly without the aid of glasses.

AMAUROSIS.

This is a paralysis of the nerve of sight or the expansion of the retina.

_Causes._--This is the result of concussion from a blow upon the forehead, fracture of bone over the eye (causing downward pressure), rheumatic inflammation of the optic nerve, or from extension of deep inflammation of the eye involving the retina. It sometimes occurs as the result of excessive loss of blood or of great debility.

_Symptoms._--In this disease observation is seldom made until the animal in its gait and by its action indicates blindness. Generally both eyes are affected. The eyeball remains clear, and the pupil is permanently dilated. No response to light is manifested.

_Treatment._--If caused by debility, loss of blood, or associated with rheumatism, general blood tonics may be given in the feed, namely, powdered sulphate of iron, 1 dram; gentian, 2 drams; nux vomica, one-half dram; to be given twice a day. In cases of rheumatism, one-half ounce of saltpeter may be added.

FILARIA OCULI (WORM IN THE EYE).

_Filaria oculi_ (provisionally taken as the larva of _F. cervina_) is a small white worm, found swimming in the aqueous fluid in the anterior chamber. It may be apparently harmless for a long time, but will eventually induce keratitis with inflammatory exudations.

_Treatment._--The cornea may be punctured at its upper and outer margin, and the worm squeezed out with the aqueous humor. The latter will be formed again. This operation results disastrously unless the greatest care and skill are employed.

CORNEAL DERMATOMA (HAIRY TUMOR ON THE EYEBALL).

In a few instances this has been seen as a congenital growth. The tumor arises from the cornea or the sclerotic, covered by its respective membrane, with a growth of hair upon its surface. These tumors may be quite prominent or flattened, and are dark in color; the hair may protrude between the eyelids, giving the animal the appearance of having a double eyelid.

_Treatment._--A surgical operation becomes necessary for their removal-- one requiring a skilled operator.

STRABISMUS (SQUINTING).

This is a very rare affection among cattle. Strabismus may be either single or double--affecting one eye or both. It is caused by a paralysis, or a weakening of one of the straight muscles of the eyeball. Generally it is a congenital defect, and the squinting is toward the nose--strabismus convergens. It is best not to attempt to remedy the defect, as the risk in an operation is greater than the chances of success warrant.

PTERYGIUM.

This term is applied to a flesh-colored membrane, triangular in form, which most frequently grows from the inner angle of the eye and extends over the cornea, thus interfering with vision. It may grow from the outer angle, or even from either the superior or inferior hemisphere of the eyeball. The figure is invariably that of a triangle, with its base on the white of the eye and its apex more or less advanced over the cornea toward its center.

The distinguishing characteristics are the constancy of the triangular form, and the facility with which the whole of it may be taken hold of with a pair of forceps and raised into a fold on the cornea. Every other kind of excrescence attached to this membrane continues firmly adherent to it, and can not be folded and raised from the surface of the cornea in any manner whatever.

_Treatment._--Raise the fold and dissect it away from all points of attachment.

TRICHIASIS (INVERSION OF THE EYELASHES).

In the simplest form the eyelashes bend inwardly, touching the eyeball, causing irritation and simple conjunctivitis. It may be also associated with entropion.

_Treatment._--The offending eyelashes should be cut off or pulled out. In case the natural growth of the eyelashes is directed inward, an operation similar to that for entropion becomes necessary.

ENTROPION (INVERSION OF THE EYELID).

In inversion of the eyelid the eyelashes soon irritate the anterior face of the cornea and produce more or less inflammation and opacity. The inversion may be due to the growth of a tumor within or without the lid, to abscess, laceration, or injury, causing the lid to lose its natural conformity to the eyeball, ulcerations, etc. Surgical interference in either case becomes necessary to restore the lid to its natural direction.

ECTROPION (EVERSION OF THE EYELID).

This serves to injure the eye by permitting dust or other foreign substances to enter the eye and interferes with the natural removal of them.

_Treatment._--A delicate surgical operation--the removal of an elliptic section of the palpÊbral conjunctiva--may remedy the defect.

TUMORS OF THE EYELIDS.

Occasionally tumors form upon or within the substance of the eyelid. They may be of a fibroid nature and arise from the follicles of the hair as sebaceous tumors or may be in the form of an abscess. In debilitating diseases the lids sometimes become swollen and puffy, a condition which may possibly be taken for the growth of a tumor. This generally disappears with the improvement of the health of the animal. Warts not uncommonly appear on or about the eyelids of cattle.