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.
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.
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 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.
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.
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.
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° 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.
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.
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.
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.
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.
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."
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.
To avoid unnecessary repetition the following general directions are given for the examination of the eye: The eye, and to a certain extent the mucous membrane lining the eyelids, may be exposed to view by gently parting the eyelids with the thumb and forefinger pressed on the middle of the respective lids. The pressure, it is true, causes the protrusion of the haw over a portion of the lower and inner part of the eye, but by gentleness and careful graduation of the pressure this may be kept within bounds, and oftentimes even the interior of the eye can be seen. As a rule it is best to use the right hand for the left eye, and the left hand for the right, the finger in each case being pressed on the upper lid while the thumb depresses the lower one. In cases in which it is desirable to examine the inner side of the eyelid further than is possible by the above means, the upper lid may be drawn down by the eyelashes with the one hand and then everted over the tip of the forefinger of the other hand, or over a probe laid flat against the middle of the lid. When the interior of the eye must be examined it is useless to make the attempt in the open sunshine or under a clear sky. The worst cases, it is true, can be seen under such circumstances, but for the slighter forms the horse should be taken indoors, where all light from above will be shut off, and should be placed so that the light may fall on the eye from the front and side. Then the observer, placing himself in front of the animal, will receive the reflected rays from the cornea, the front of the lens and the back, and can much more easily detect any cloudiness, opacity, or lack of transparency. The examination can be made much more satisfactory by placing the horse in a dark chamber and illuminating the eye by a lamp placed forward and outward from the eye which is to be examined. Any cloudiness is thus easily detected, and any doubt may be resolved by moving the lamp so that the image of the flame may be passed in succession over the whole surface of the transparent cornea and of the crystalline lens. Three images of the flame will be seen, the larger one upright, reflected from the anterior surface of the eye; a smaller one upright, reflected from the anterior surface of the lens; and a second small one inverted from the back surface of the lens.
So long as these images are reflected from healthy surfaces they will be clear and perfect in outline, but as soon as one strikes on an area of opacity it will become diffused, cloudy, and indefinite. Thus, if the large, upright image becomes hazy and imperfect over a particular spot of the cornea, that will be found to be the seat of disease and opacity. Should the large image remain clear, but the small upright one become diffuse and indefinite over a given point, it indicates opacity on the front of the capsule of the lens. If both upright images remain clear while the inverted one becomes indistinct at a given point, then the opacity is in the substance of the lens itself or in the posterior part of its capsule.
If in a given case the pupil remains so closely contracted that the deeper parts of the eye can not be seen, the eyelids may be rubbed with extract of belladonna, and in a short time the pupil will be found widely dilated.
Some faulty conditions of the eyelids are congenital, as division of an eyelid in two, after the manner of harelip, abnormally small opening between the lids, often connected with imperfect development of the eye, and closure of the lids by adhesion. The first is to be remedied by paring the edges of the division and then bringing them together, as in torn lids. The last two, if remediable at all, require separation by the knife, and subsequent treatment with a cooling astringent eyewash.
Spasm of eyelids may be owing to constitutional susceptibility, or to the presence of local irritants (insects, chemical irritants, sand, etc.) in the eye, to wounds or inflammation of the mucous membrane, or to disease of the brain. When due to local irritation it may be temporarily overcome by instilling a few drops of a 4 per cent solution of cocaine into the eye, when the true cause may be ascertained and removed. The nervous or constitutional disease must be treated according to its nature.
Drooping eyelids, or ptosis.—This is usually present in the upper lid, or is at least little noticed in the lower. It is sometimes but a symptom of paralysis of one-half of the face, in which case the ear, lips, and nostrils on the same side will be found soft, drooping, and inactive, and even the half of the tongue may partake of the palsy. If the same condition exists on both sides, there is difficult, snuffling breathing, from the air drawing in the flaps of the nostrils in inspiration, and all feed is taken in by the teeth, as the lips are useless. In both there is a free discharge of saliva from the mouth during mastication. This paralysis is a frequent result of injury, by a poke, to the seventh nerve, as it passes over the back of the lower jaw. In some cases the paralysis is confined to the lid, the injury having been sustained by the muscles which raise it, or by the supraorbital nerve, which emerges from the bone just above the eye. Such injury to the nerve may have resulted from fracture of the orbital process of the frontal bone above the eyeball.
The condition may, however, be due to spasm of the sphincter muscle, which closes the lids, or to inflammation of the upper lid, usually a result of blows on the orbit. In the latter case it may run a slow course with chronic thickening of the lid.
The paralysis due to the poke may be often remedied, first, by the removal of any remaining inflammation by a wet sponge worn beneath the ear and kept in place by a bandage; secondly, when all inflammation has passed, by a blister on the same region, or by rubbing it daily with a mixture of olive oil and strong aqua ammonia in equal proportions. Improvement is usually slow, and it may be months before complete recovery ensues.
In paralysis from blows above the eyes the same treatment may be applied to that part.
Thickening of the lid may be treated by painting with tincture of iodin, and that failing, by cutting out an elliptical strip of the skin from the middle of the upper lid and stitching the edges together.
The eyelids suffer more or less in all severe inflammations of the eye, whether external or internal, but inasmuch as the disease sometimes starts in the lids and at other times is exclusively confined to them, it deserves independent mention.
Among the causes may be named: Exposure to drafts of cold air, or to cold rain or snow storms; the bites or stings of mosquitoes, flies, or other insects; snake bites, pricks with thorns, blows of whip or club; accidental bruises against the stall or ground, especially during the violent struggles of colic, enteritis, phrenitis (staggers), and when thrown for operations. It is also a result of infecting inoculations, as of erysipelas, anthrax, boil, etc., and is noted by Leblanc as especially prevalent among horses kept on low, marshy pastures. Finally, the introduction of sand, dust, chaff, beards of barley and seeds of the finest grasses, and the contact with irritant, chemical powders, liquids, and gases (ammonia from manure or factory, chlorin, strong sulphur fumes, smoke, and other products of combustion, etc.) may start the inflammation. The eyelids often undergo extreme inflammatory and dropsical swelling in urticaria (nettlerash, surfeit) and in the general inflammatory dropsy known as purpura hemorrhagica.
The affection will, therefore, readily divide itself into (1) inflammations due to constitutional causes; (2) those due to direct injury, mechanical or chemical; and (3) such as are due to inoculation with infecting material.
(1) Inflammations due to constitutional causes are distinguished by the absence of any local wound, and the history of a low, damp pasture, exposure, indigestion from unwholesome feed, or the presence elsewhere on the limbs or body of the general, doughy swellings of purpura hemorrhagica. The lids are swollen and thickened; it may be slightly or it may be so extremely that the eyeball can not be seen. If the lid can be everted to show its mucous membrane, that is seen to be of a deep-red color, especially along the branching lines of the blood vessels. The part is hot and painful, and a profuse flow of tears and mucus escapes on the side of the face, causing irritation and loss of the hair. If improvement follows, this discharge becomes more tenacious, and tends to cause adhesion to the edges of the upper and lower lids and to mat together the eyelashes in bundles. This gradually decreases to the natural amount, and the redness and congested appearance of the eye disappears, but swelling, thickening, and stiffness of the lids may continue for a time. There may be more or less fever according to the violence of the inflammation, but so long as there is no serious disease of the interior of the eye or of other vital organ, it is usually moderate.
The local treatment consists in astringent, soothing lotions (sugar of lead 30 grains, laudanum 2 teaspoonfuls, rain water—boiled and cooled—1 pint), applied with a soft cloth kept wet with the lotion, and hung over the eye by tying it to the headstall of the bridle on the two sides. If the mucous membrane lining of the lids is the seat of little red granular elevations, a drop of solution of 2 grains of nitrate of silver in an ounce of distilled water should be applied with the soft end of a clean feather to the inside of the lid twice a day. The patient should be removed from all such conditions (pasture, faulty feed, exposure, etc.) as may have caused or aggravated the disease, and from dust and irritant fumes and gases. He should be fed from a manger high enough to favor the return of blood from the head, and should be kept from work, especially in a tight collar which would prevent the descent of blood by the jugular veins. The diet should be laxative and nonstimulating (grass, bran mashes, carrots, turnips, beets, potatoes, or steamed hay), and any costiveness should be corrected by a mild dose of raw linseed oil (1 to 1-1/2 pints). In cold weather warm blanketing may be needful, and even loose flannel bandages to the limbs, but heat should never be sought at the expense of pure air.
(2) In inflammations due to local irritants of a noninfective kind a careful examination will usually reveal their presence, and the first step must be their removal with a pair of blunt forceps or the point of a lead pencil. Subsequent treatment will be in the main the local treatment advised above.
(3) In case of infective inflammation there will often be found a prick or tear by which the septic matter has entered, and in such case the inflammation will for a time be concentrated at that point. A round or conical swelling around an insect bite is especially characteristic. A snake bite is marked by the double prick made by the two teeth and by the violent and rapidly spreading inflammation. Erysipelas is attended with much swelling, extending beyond the lids and causing the mucous membrane to protrude beyond the edge of the eyelid (chemosis). This is characterized by a bright, uniform, rosy red, disappearing on pressure, or later by a dark, livid hue, but with less branching redness than in noninfecting inflammation and less of the dark, dusky, brownish or yellowish tint of anthrax. Little vesicles may appear on the skin, and pus may be found without any distinct limiting membrane, as in abscess. It is early attended with high fever and marked general weakness and inappetence. Anthrax of the lids is marked by a firm swelling, surmounted by a blister, with bloody serous contents, which tends to burst and dry up into a slough, while the surrounding parts become involved in the same way. Or it may show as a diffuse, dropsical swelling, with less of the hard, central sloughing nodule, but, like that, tending to spread quickly. In both cases alike the mucous membrane and the skin, if white, assumes a dusky-brown or yellowish-brown hue, which is largely characteristic. This may pass into a black color by reason of extravasation of blood. Great constitutional disturbance appears early, with much prostration and weakness and generalized anthrax symptoms.
Treatment.—The treatment will vary according to the severity. Insect bites may be touched with a solution of equal parts of glycerin and aqua ammonia, or a 10 per cent solution of carbolic acid in water. Snake bites may be bathed with aqua ammonia, and the same agent given in doses of 2 teaspoonfuls in a quart of water, or alcohol may be given in pint or quart doses, according to the size of the animal. In erysipelas the skin may be painted with tincture of chlorid of iron, or with a solution of 20 grains of iodin in an ounce of carbolic acid, and one-half an ounce of tincture of chlorid of iron may be given thrice daily in a bottle of water. In anthrax the swelling should be painted with tincture of iodin, or of the mixture of iodin and carbolic acid, and if very threatening it may have the tincture of iodin injected into the swelling with a hypodermic syringe, or the hard mass may be freely incised to its depth with a sharp lancet and the lotion applied to the exposed tissues. Internally, iodid of potassium may be given in doses of 2 drams thrice a day, or tincture of the chlorid of iron every four hours.
This is an inflammation of limited extent, advancing to the formation of matter and the sloughing out of a small mass of the natural tissue of the eyelid. It forms a firm, rounded swelling, usually near the margin of the lid, which suppurates and bursts in four or five days. Its course may be hastened by a poultice of camomile flowers, to which have been added a few drops of carbolic acid, the whole applied in a very thin muslin bag. If the swelling is slow to open after having become yellowish white, it may be opened by a lancet, the incision being made at right angles to the margin of the lid.
These are respectively caused by wounds, sloughs, ulcers, or other causes of loss of substance of the mucous membrane on the inside of the lid and of the skin on the outside; also of tumors, skin diseases, or paralysis which leads to displacement of the margin of the eyelid. As a rule, they require a surgical operation, with removal of an elliptical portion of the mucous membrane or skin, as the case may be, but which requires the skilled and delicate hand of the surgeon.
This consists in the turning in of the eyelashes so as to irritate the front of the eye. If a single eyelash, it may be snipped off with scissors close to the margin of the eyelid or pulled out by the root with a pair of flat-bladed forceps. If the divergent lashes are more numerous, the treatment may be as for entropion, by excising an elliptical portion of skin opposite the offending lashes and stitching the edges together, so as to draw outward the margin of the lid at that point.
The eyelids form a favorite site for tumors, and above all, warts, which consist in a simple diseased overgrowth (hypertrophy) of the surface layers of the skin. If small, they may be snipped off with scissors or tied around the neck with a stout, waxed thread and left to drop off, the destruction being completed, if necessary, by the daily application of a piece of sulphate of copper (blue vitriol), until any unhealthy material has been removed. If more widely spread, the wart may still be clipped off with curved scissors or knife, and the caustic thoroughly applied day by day.
A bleeding wart, or erectile tumor, is more liable to bleed, and is best removed by constricting its neck with the waxed cord or rubber band, or if too broad it may be transfixed through its base by a needle armed with a double thread, which is then to be cut in two and tied around the two portions of the neck of the tumor. If still broader, the armed needle may be carried through the base of the tumor at regular intervals, so that the whole may be tied in moderately sized sections.
In gray and in white horses black, pigmentary tumors (melanotic) are common on the black portions of skin, such as the eyelids, and are to be removed by scissors or knife, according to their size. In the horse they do not usually tend to recur when thoroughly removed, but at times they prove cancerous (as is the rule in man), and then they tend to reappear in the same site or in internal organs with, it may be, fatal effect.
Encysted, honeylike (melicerous), sebaceous, and fibrous tumors of the lids all require removal with the knife.
The eyelids are torn by attacks with horns of cattle, or with the teeth, or by getting caught on nails in stall, rack, or manger, on the point of stumps, fences, or fence rails, on the barbs of wire fences, and on other pointed bodies. The edges should be brought together as promptly as possible, so as to effect union without the formation of matter, puckering of the skin, and unsightly distortions. Great care is necessary to bring the two edges together evenly without twisting or puckering. The simplest mode of holding them together is by a series of sharp pins passed through the lips of the wound at intervals of not more than a third of an inch, and held together by a thread twisted around each pin in the form of the figure 8, and carried obliquely from pin to pin in two directions, so as to prevent gaping of the wound in the intervals. The points of the pins may then be cut off with scissors, and the wound may be wet twice a day with a weak solution of carbolic acid.
Though cruelly excised for alleged "hooks," when itself perfectly healthy, in the various diseases which lead to retraction of the eye into its socket, the haw may, like other bodily structures, be itself the seat of actual disease. The pigmentary, black tumors of white horses and soft (encephaloid) cancer may attack this part primarily or extend to it from the eyeball or eyelids; hairs have been found growing from its surface, and the mucous membrane covering it becomes inflamed in common with that covering the front of the eye. These inflammations are but a phase of the inflammation of the external structures of the eye, and demand no particular notice nor special treatment. The tumors lead to such irregular enlargement and distortion of the haw that the condition is not to be confounded with the simple projection of the healthy structure over the eye when the lids are pushed apart with the finger and thumb, and the same remark applies to the ulceration, or caries, of the cartilage. In the latter case, besides the swelling and distortion of the haw, there is this peculiarity, that in the midst of the red inflamed mass there appears a white line or mass formed by the exposed edge of the ulcerating cartilage. The animal having been thrown and properly fixed, an assistant holds the eyelids apart while the operator seizes the haw with forceps or hook and carefully dissects it out with blunt-pointed scissors. The eye is then covered with a cloth, kept wet with an eyewash, as for external ophthalmia.
The escape of tears on the side of the cheek is a symptom of external inflammation of the eye, but it may also occur from any disease of the lacrimal apparatus which interferes with the normal progress of the tears to the nose; hence, in all cases when this symptom is not attended with special redness or swelling of the eyelids, it is well to examine the lacrimal apparatus. In some instances the orifice of the lacrimal duct on the floor of the nasal chamber and close to its anterior outlet will be found blocked by a portion of dry mucopurulent matter, on the removal of which tears may begin to escape. This implies an inflammation of the canal, which may be helped by occasional sponging out of the nose with warm water, and the application of the same on the face. Another remedy is to feed warm mashes of wheat bran from a nosebag, so that the relaxing effects of the water vapor may be secured.
The two lacrimal openings, situated at the inner angle of the eye, may fail to admit the tears by reason of their deviation outward in connection with the eversion of the lower lid or by reason of their constriction in inflammation of the mucous membrane. The lacrimal sac, into which the lacrimal ducts open, may fail to discharge its contents by reason of constriction or closure of the duct leading to the nose, and it then forms a rounded swelling beneath the inner angle of the eye. The duct leading from the sac to the nose may be compressed or obliterated by fractures of the bones of the face, and in disease of these bones (osteosarcoma, so-called osteoporosis, diseased teeth, glanders of the nasal sinuses, abscess of the same cavities).
The narrowed or obstructed ducts may be made pervious by a fine, silver probe passed down to the lacrimal sac, and any existing inflammation of the passages may be counteracted by the use of steaming mashes of wheat bran, by fomentations or wet cloths over the face, and even by the use of astringent eyewashes and the injection of similar liquids into the lacrimal canal from its nasal opening. The ordinary eyewash may be used for this purpose, or it may be injected after dilution to half its strength. The fractures and diseases of the bones and teeth must be treated according to their special demands when, if the canal is still left pervious, it may be again rendered useful.
In inflammation of the outer parts of the eyeball the exposed vascular and sensitive mucous membrane (conjunctiva) which covers the ball, the eyelids, the haw, and the lacrimal apparatus, is usually the most deeply involved, yet adjacent parts are more or less implicated, and when disease is concentrated on these contiguous parts it constitutes a phase of external opththalmia which demands a special notice. These have accordingly been already treated of.
Causes.—The causes of external opththalmia are mainly those that act locally—blows with whips, clubs, and twigs, the presence of foreign bodies, like hayseed, chaff, dust, lime, sand, snuff, pollen of plants, flies attracted by the brilliancy of the eye, wounds of the bridle, the migration of the scabies (mange) insect into the eye, smoke, ammonia arising from the excretions, irritant emanations from drying marshes, etc. Road dust containing infecting microbes is a common factor. A very dry air is alleged to act injuriously by drying the eye as well as by favoring the production of irritant dust; the undue exposure to bright sunshine through a window in front of the stall, or to the reflection from snow or water, also is undoubtedly injurious. The unprotected exposure of the eyes to sunshine through the use of a very short overdraw check is to be condemned, and the keeping of the horse in a very dark stall, from which it is habitually led into the glare of full sunlight, intensified by reflection from snow or white limestone, must be set down among the locally acting causes. Exposure to cold and wet, to wet and snow storms, to cold drafts and wet lairs must also be accepted as causes of conjunctivitis, the general disorder which they produce affecting the eye, if that happens to be the weakest and most susceptible organ of the body, or if it has been subjected to any special local injury, like dust, irritant gases, or excess of light. Again, external opththalmia is a constant concomitant of inflammation of the contiguous and continuous mucous membranes, as those of the nose and throat—hence the red, watery eyes that attend on nasal catarrh, sore throat, influenza, strangles, nasal glanders, and the like. In such cases, however, the affection of the eye is subsidiary and is manifestly overshadowed by the primary and predominating disease.
Symptoms.—The symptoms are watering of the eye, swollen lids, redness of the mucous membrane exposed by the separation of the lids—it may be a mere pink blush with more or less branching redness, or it may be a deep, dark red, as from effusion of blood—and a bluish opacity of the cornea, which is normally clear and translucent. Except when resulting from wounds and actual extravasation of blood, however, the redness is seen to be superficial, and if the opacity is confined to the edges, and does not involve the entire cornea, the aqueous humor behind is seen to be still clear and limpid. The fever is always less severe than in internal ophthalmia, and runs high only in the worst cases. The eyelids may be kept closed, the eyeball retracted, and the haw protruded over one-third or one-half of the ball, but this is due to the pain only and not to any excessive sensibility to light, as shown by the comparatively widely dilated pupil. In internal ophthalmia, on the contrary, the narrow, contracted pupil is the measure of the pain caused by the falling of light on the inflamed and sensitive optic nerve (retina) and choroid.
If the affection has resulted from a wound of the cornea, not only is that the point of greatest opacity, forming a white speck or fleecy cloud, but too often blood vessels begin to extend from the adjacent vascular covering of the eye (sclerotic) to the white spot, and that portion of the cornea is rendered permanently opaque. Again, if the wound has been severe, though still short of cutting into the anterior layers of the cornea, the injury may lead to ulceration that may penetrate more or less deeply and leave a breach in the tissue which, if filled up at all, is repaired by opaque fibrous tissue in place of the transparent cellular structure. Pus may form, and the cornea assumes a yellowish tinge and bursts, giving rise to a deep sore which is liable to extend as an ulcer, and may be in its turn followed by bulging of the cornea at that point (staphyloma). This inflammation of the conjunctiva may be simply catarrhal, with profuse mucopurulent discharge; it may be granular, the surface being covered with minute reddish elevations, or it may become the seat of a false membrane (diphtheria).
Treatment.—In treating external ophthalmia the first object is the removal of the cause. Remove any dust, chaff, thorn, or other foreign body from the conjunctiva, purify the stable from all sources of ammoniacal or other irritant gas; keep the horse from dusty roads, and, above all, from the proximity of a leading wagon and its attendant cloud of dust; remove from pasture and feed from a rack which is neither so high as to drop seeds, etc., into the eyes nor so low as to favor the accumulation of blood in the head; avoid equally excess of light from a sunny window in front of the stall and excess of darkness from the absence of windows; preserve from cold drafts and rains and wet bedding, and apply curative measures for inflammation of the adjacent mucous membranes or skin. If the irritant has been of a caustic nature, remove any remnant of it by persistent bathing with tepid water and a soft sponge, or with water mixed with white of egg, or a glass filled with the liquid may be inverted over the eye so that its contents may dilute and remove the irritant. If the suffering is very severe, a lotion with a few grains of extract of belladonna or of morphia in an ounce of water may be applied, or, if it is available, a few drops of 4 per cent solution of cocaine may be instilled into the eye.
In strong, vigorous patients benefit will usually be obtained from a laxative, such as 2 tablespoonfuls of Glauber's salt daily, and if the fever runs high from a daily dose of half an ounce of saltpeter. As local applications, astringent solutions are usually the best, as 30 grains of borax or of sulphate of zinc in a quart of water, to be applied constantly on a cloth, as advised under "Inflammation of the eyelids." In the absence of anything better, cold water may serve every purpose. Above all, adhesive and oily agents (molasses, sugar, fats) are to be avoided, as only adding to the irritation. By way of suggesting agents that may be used with good effect, salt and sulphate of soda may be named, in solutions double the strength of sulphate of zinc, or 7 grains of nitrate of silver may be added to a quart of distilled water, and will be found especially applicable in granular conjunctivitis, diphtheria, or commencing ulceration. A cantharides blister (1 part of Spanish fly to 4 parts lard) may be rubbed on the side of the face 3 inches below the eye, and washed off next morning with soapsuds and oiled daily till the scabs are dropped.
As a result of external ophthalmia, opaque specks, clouds, or haziness are too often left on the cornea and require for their removal that they be daily touched with a soft feather dipped in a solution of 3 grains nitrate of silver in 1 ounce distilled water. This should be applied until all inflammation has subsided, and until its contact is comparatively painless. It is rarely successful with an old, thick scar following an ulcer, nor with an opacity having red blood vessels running across it.
These may be treated with nitrate of silver lotion of twice the strength used for opacities. Powdered gentian, one-half ounce, and sulphate of iron, one-fourth ounce, daily, may improve the general health and increase the reparatory power.
Although inflammations of the iris, choroid, and retina—the inner, vascular, and nervous coats of the eye—occur to a certain extent independently of each other, yet one usually supervenes upon the other, and, as the symptoms are thus made to coincide, it will be best for our present purposes to treat the three as one disease.
Causes.—The causes of internal ophthalmia are largely those of the external form only, acting with greater intensity or on a more susceptible eye. Severe blows, bruises, punctures, etc., of the eye, the penetration of foreign bodies into the eye (thorns, splinters of iron, etc.), sudden transition from a dark stall to bright sunshine, to the glare of snow or water, constant glare from a sunny window, abuse of the overdraw checkrein, vivid lightning flashes, drafts of cold, damp air; above all, when the animal is perspiring, exposure in cold rain or snowstorms, swimming cold rivers; also certain general diseases like rheumatism, arthritis, influenza, and disorders of the digestive organs, may become complicated by this affection. From the close relation between the brain and eye—alike in the blood vessels and nerves—disorders of the first lead to affection of the second, and the same remark applies to the persistent irritation to which the jaws are subjected in the course of dentition. So potent is the last agency that we dread a recurrence of ophthalmia so long as dentition is incomplete, and hope for immunity if the animal completes its dentition without any permanent structural change in the eye.
Symptoms.—The symptoms will vary according to the cause. If the attack is due to direct physical injury, the inflammation of the eyelids and superficial structures may be quite as marked as that of the interior of the eye. If, on the other hand, from general causes, or as a complication of some distant disease, the affection may be largely confined to the deeper structures, and the swelling, redness, and tenderness of the superficial structures will be less marked. When the external coats thus comparatively escape, the extreme anterior edge of the white or sclerotic coat, where it overlaps the border of the transparent cornea, is in a measure free from congestion, and, in the absence of the obscuring dark pigment, forms a whitish ring around the cornea. This is partly due to the fact that a series of arteries (ciliary) passing to the inflamed iris penetrate the sclerotic coat a short distance behind its anterior border, and there is therefore a marked difference in color between the general sclerotic occupied between these congested vessels and the anterior rim from which they are absent. Unfortunately, the pigment is often so abundant in the anterior part of the sclerotic as to hide this symptom. In internal ophthalmia the opacity of the cornea may be confined to a zone around the outer margin of the cornea, and even this may be a bluish haze rather than a deep, fleecy white. In consequence it becomes impossible to see the interior of the chamber for the aqueous humor and the condition of the iris and pupil. The aqueous humor is usually turbid, and has numerous yellowish-white flakes floating on its substance or deposited in the lower part of the chamber, so as to cut off the view of the lower portion of the iris. The still visible portion of the iris has lost its natural, clear, dark luster, which is replaced by a brownish or yellowish sere-leaf color. This is more marked in proportion as the iris is inflamed, and less so as the inflammation is confined to the choroid. The quantity of flocculent deposit in the chamber of the aqueous humor is also in direct ratio to the inflammation of the iris. Perhaps the most marked feature of internal ophthalmia is the extreme and painful sensitiveness to light. On this account the lids are usually closed, but when opened the pupil is seen to be narrowly closed, even if the animal has been kept in a darkened stall. Exceptions to this are seen when inflammatory effusion has overfilled the globe of the eye, and by pressure on the retina has paralyzed it, or when the exudation into the substance of the retina itself has similarly led to its paralysis. Then the pupil may be dilated, and frequently its margin loses its regular, ovoid outline and becomes uneven by reason of the adhesions which it has contracted with the capsule of the lens, through its inflammatory exudations. In the case of excessive effusion into the globe of the eye that is found to have become tense and hard so that it can not be indented with the tip of the finger, paralysis of the retina is liable to result. With such paralysis of the retina, vision is heavily clouded or entirely lost; hence, in spite of the open pupil, the finger may be approached to the eye without the animal's becoming conscious of it until it touches the surface, and if the nose on the affected side is gently struck and a feint made to repeat the blow the patient makes no effort to evade it. Sometimes the edges of the contracted pupil become adherent to each other by an intervening plastic exudation, and the opening becomes virtually abolished. In severe inflammations pus may form in the choroid or iris, and escaping into the cavity of the aqueous humor show as a yellowish-white stratum below. In nearly all cases there is resulting exudation into the lens or its capsule, constituting a cloudiness or opacity (cataract), which in severe and old-standing cases appears as a white, fleecy mass behind a widely dilated pupil. In the slighter cases cataract is to be recognized by examination of the eye in a dark chamber, with an oblique side light, as described in the introduction to this article. Cataracts that appear as a simple haze or indefinite, fleecy cloud are usually on the capsule (capsular), while those that show a radiating arrangement are in the lens (lenticular), the radiating fibers of which the exudate follows. Black cataracts are formed by the adhesion of the pigment on the back of the iris to the front of the lens, and by the subsequent tearing loose of the iris, leaving a portion of its pigment adherent to the capsule of the lens. If the pupil is so contracted that it is impossible to see the lens, it may be dilated by applying to the front of the eye with a feather some drops of a solution of 4 grains of atropia in an ounce of water.
Treatment.—The treatment of internal ophthalmia should embrace, first, the removal of all existing causes or sources of aggravation of the disease, which need not be repeated here. Special care to protect the patient against strong light, cold, wet weather, and active exertion must, however, be insisted on. A dark stall and a cloth hung over the eye are important, while cleanliness, warmth, dryness, and rest are equally demanded. If the patient is strong and vigorous, a dose of 4 drams of Barbados aloes may be given, and if there is any reason to suspect a rheumatic origin one-half a dram powdered colchicum and one-half ounce salicylate of soda may be given daily. Locally the astringent lotions advised for external ophthalmia may be resorted to, especially when the superficial inflammation is well marked. More important, however, is to instill into the eye, a few drops at a time, a solution of 4 grains of atropia in 1 ounce of distilled water. This may be effected with the aid of a soft feather, and may be repeated at intervals of 10 minutes until the pupil is widely dilated. As the horse is to be kept in a dark stall, the consequent admission of light will be harmless, and the dilation of the pupil prevents adhesion between the iris and lens, relieves the constant tension of the eye in the effort to adapt the pupil to the light, and solicits the contraction of the blood vessels of the eye and the lessening of congestion, exudation, and intraocular pressure. Should atropia not agree with the case, it may be replaced by morphia (same strength) or cocaine in 4 per cent solution. Another local measure is a blister, which can usually be applied to advantage on the side of the nose or beneath the ear. Spanish flies may be used as for external ophthalmia. In very severe cases the parts beneath the eye may be shaved and three or four leeches applied. Setons are sometimes beneficial, and even puncture of the eyeball, but these should be reserved for professional hands.
The diet throughout should be easily digestible and moderate in quantity—bran mash, middlings, grass, steamed hay, etc.
Even after the active inflammation has subsided the atropia lotion should be continued for several weeks to keep the eye in a state of rest in its still weak and irritable condition, and during this period the patient should be kept in semidarkness, or taken out only with a dark shade over the eye. For the same reason heavy drafts and, rapid paces, which would cause congestion of the head, should be carefully avoided.
This is an inflammatory affection of the interior of the eye, intimately related to certain soils, climates, and systems, showing a strong tendency to recur again and again, and usually ending in blindness from cataract or other serious injury.
Causes.—Its causes may be fundamentally attributed to soil. On damp clays and marshy grounds, on the frequently overflowed river bottoms and deltas, on the coasts of seas and lakes alternately submerged and exposed, this disease prevails extensively, and in many instances in France (Reynal), Belgium, Alsace (Zundel, Miltenberger), Germany, and England it has very largely decreased under land drainage and improved methods of culture. Other influences, more or less associated with such soil, are potent causative factors. Thus damp air and a cloudy, wet climate, so constantly associated with wet lands, are universally charged with causing the disease. These act on the animal body to produce a lymphatic constitution with an excess of connective tissue, bones, and muscles of coarse, open texture, thick skins, and gummy legs covered with a profusion of long hair. Hence the heavy horses of Belgium and southwestern France have suffered severely from the affection, while high, dry lands adjacent, like Catalonia, in Spain, and Dauphiny, Provence, and Languedoc; in France, have in the main escaped.
The rank, aqueous fodders grown on such soils are other causes, but these again are calculated to undermine the character of the nervous and sanguineous temperament and to superinduce the lymphatic. Other feeds act by leading to constipation and other disorders of the digestive organs, thus impairing the general health. Hence in any animal predisposed to this disease, heating, starchy feeds, such as maize, wheat, and buckwheat, are to be carefully avoided. It has been widely charged that beans, peas, vetches, and other Leguminosæ are dangerous, but a fuller inquiry contradicts the statement. If these feeds are well grown, they invigorate and fortify the system, while, like any other fodder, if grown rank; aqueous, and deficient in assimilable principles, they tend to lower the health and open the way for the disease.
The period of dentition and training is a fertile exciting cause, for though the malady may appear at any time from birth to old age, yet the great majority of victims are from 2 to 6 years old, and if a horse escapes the affection till after 6 there is a reasonable hope that he will continue to resist it. The irritation about the head during the eruption of the teeth, and while fretting in the unwonted bridle and collar, the stimulating grain diet and the close air of the stable all combine to rouse the latent tendency to disease in the eye, while direct injuries by bridle, whip, or hay seeds are not without their influence. In the same way local irritants, like dust, severe rain and snow storms, smoke, and acrid vapors are contributing causes.
It is evident, however, that no one of these is sufficient of itself to produce the disease, and it has been alleged that the true cause is a microbe, or the irritant products of a microbe, which is harbored in the marshy soil. The prevalence of the disease on the same damp soils which produce ague in man and anthrax in cattle has been quoted in support of this doctrine, as also the fact that, other things being equal, the malady is always more prevalent in basins surrounded by hills where the air is still and such products are concentrated, and that a forest or simple belt of trees will, as in ague, at times limit the area of its prevalence. Another argument for the same view is found in the fact that on certain farms irrigated by town sewage this malady has become extremely prevalent, the sewage being assumed to form a suitable nidus for the growth of the germ. But on these sewage farms a fresh crop may be cut every fortnight, and the product is precisely that aqueous material which contributes to a lymphatic structure and a low tone of health. The presence of a definite germ in the system has not yet been proved, and in the present state of our knowledge we are only warranted in charging the disease to the deleterious emanations from the marshy soil in which bacterial ferments are constantly producing them.
Heredity is one of the most potent causes. The lymphatic constitution is of course transmitted and with it the proclivity to recurring ophthalmia. This is notorious in the case of both parents, male and female. The tendency appears to be stronger, however, if either parent has already suffered. Thus a mare may have borne a number of sound foals, and then fallen a victim to the malady, and all foals subsequently borne have likewise suffered. So it is in the case of the stallion. Reynal even quotes the appearance of the disease in alternate generations, the stallion offspring of blind parents remaining sound through life and yet producing foals which furnish numerous victims of recurrent ophthalmia. On the contrary, the offspring of diseased parents removed to high, dry regions and furnished with wholesome, nourishing rations will nearly all escape. Hence the dealers take colts that are still sound or have had but one attack from the affected low Pyrenees (France) to the unaffected Catalonia (Spain), with confidence that they will escape, and from the Jura Valley to Dauphiny with the same result.
Yet the hereditary taint is so strong and pernicious that intelligent horsemen everywhere refuse to breed from either horse or mare that has once suffered from recurrent ophthalmia, and the French Government studs not only reject all unsound stallions, but refuse service to any mare which has suffered with her eyes. It is this avoidance of the hereditary predisposition more than anything else that has reduced the formerly wide prevalence of this disease in the European countries generally. A consideration for the future of our horses would demand the disuse of all sires that are unlicensed, and the refusal of a license to any sire which has suffered from this or any other communicable constitutional disease.
Other contributing causes deserve passing mention. Unwholesome feed and a faulty method of feeding undoubtedly predisposes to the disease, and in the same district the carefully fed will escape in far larger proportion than the badly fed; it is so also with every other condition which undermines the general health. The presence of worms in the intestines, overwork, and debilitating diseases and causes of every kind weaken the vitality and lay the system more open to attack. Thierry long ago showed that the improvement of close, low, dark, damp stables, where the disease had previously prevailed, practically banished the affection. Whatever contributes to strength and vigor is protective; whatever contributes to weakness and poor health is provocative of the disease in the predisposed subject.
Symptoms.—The symptoms vary according to the severity of the attack. In some cases there is marked fever, and in some slighter cases it may be almost altogether wanting, but there is always a lack of vigor and energy, bespeaking general disorder. The local symptoms are in the main those of internal ophthalmia, in many cases with an increased hardness of the eyeball from effusion into its cavity. The contracted pupil does not expand much in darkness, nor even under the action of belladonna. Opacity advances from the margin, over a part or whole of the cornea, but so long as it is transparent there may be seen the turbid, aqueous humor with or without flocculi, the dingy iris robbed of its clear, black aspect, the slightly clouded lens, and a greenish-yellow reflection from the depth of the eye. From the fifth to the seventh day the flocculi precipitate in the lower part of the chamber, exposing more clearly the iris and lens, and absorption commences, so that the eye may be cleared up in ten or fifteen days.
The characteristic of the disease is, however, its recurrence again and again in the same eye until blindness results. The attacks may follow one another after intervals of a month, more or less, but they show no relation to any particular phase of the moon, as might be inferred from the familiar name, but are determined rather by the weather, the health, the feed, or by some periodicity of the system. From five to seven attacks usually result in blindness, and then the second eye is liable to be attacked until it also is ruined.
In the intervals between the attacks some remaining symptoms betray the condition, and they become more marked after each successive access of disease. Even after the first attack there is a bluish ring around the margin of the transparent cornea. The eye seems smaller than the other, at first because it is retracted in its socket, and often after several attacks because of actual shrinkage (atrophy). The upper eyelid, in place of presenting a uniform, continuous arch, has, about one-third from its inner angle, an abrupt bend, caused by the contraction of the levator muscle. The front of the iris has exchanged some of its dark, clear brilliancy for a lusterless yellow, and the depth of the eye presents more or less of the greenish-yellow shade. The pupil remains a little contracted, except in advanced and aggravated cases, when, with opaque lens, it is widely dilated. If, as is common, one eye only has suffered, the contrast in these respects with the sound eye is all the more characteristic. Another feature is the erect, attentive carriage of the ear, to compensate to some extent for the waning vision.
The attacks vary greatly in severity in different cases, but the recurrence is characteristic, and all alike lead to cataract and intraocular effusion, with pressure on the retina and abolition of sight.
Prevention.—The prevention of this disease is the great object to be aimed at, and this demands the most careful breeding, feeding, housing, and general management, as indicated under "Causes." Much can also be done by migration to a high, dry location, but for this and malarious affections the improvement of the land by drainage and good cultivation should be the final aim.
Treatment is not satisfactory, but is largely the same as for common internal ophthalmia. Some cases, like rheumatism, are benefited by 1-scruple doses of powdered colchicum and 2-dram doses of salicylate of soda twice a day. In other cases, with marked hardness of the globe of the eye from intraocular effusion, aseptic puncture of the eye, or even the excision of a portion of the iris, has helped. During recovery a course of tonics (2 drams oxid of iron, 10 grains nux vomica, and 1 ounce sulphate of soda daily) is desirable to invigorate the system and help to ward off another attack. The vulgar resort to knocking out the wolf teeth and cutting out the haw can only be condemned. The temporary recovery would take place in one or two weeks, though no such thing had been done, and the breaking of a small tooth, leaving its fang in the jaw, only increases the irritation.
The common result of internal ophthalmia, as of the recurrent type, may be recognized as described under the first of these diseases. Its offensive appearance may be obviated by extraction or depression of the lens, but as the rays of light would no longer be properly refracted, perfect vision would not be restored, and the animal would be liable to prove an inveterate shyer. If perfect blindness continued by reason of pressure on the nerve of sight, no shying would result.