RECURRENT OPHTHALMIA OF SOLIPEDS. PERIODIC OPHTHALMIA. MOONBLINDNESS.
Definition. Causes: wet impermeable soil, clay, river bottoms, deep valleys, inundations, enclosing forests, damp air, lack of sunshine, rank fodders, wet seasons, damp, cold, basement stables, heating constipating fodder (corn, buckwheat, wheat), dentition, training, age of domestication, sale, etc., spring, shedding coat, heredity, debility, ill health, worms, debilitating infectious diseases, over work, insufficient, indigestible food, local irritants. Microbes. Rheumatism. Parasitism. Symptoms: fever variable, lack of vigor, sudden attack, irritation, photophobia, lachrymation, closed lids, contracted pupils, retracted eye, redness, swelling of lids, conjunctiva, haw, sclera, slight corneal opacity, with vascularity, aqueous turbid, flocculent, iris of dull color, sluggish, pupil contracted, hypopion, posterior chamber yellowish green, intraocular tension, crisis seventh to tenth day, convalescence fifteenth day. Recurrence. Obscurity of vision. Eye between attack: blue zone around cornea, eye seems smaller, retracted, prominent haw, angle in upper lid, dull iris, tint lighter, contracted pupil, cataract, alert ears. Lesions: exudates back of cornea, narrowed anterior chamber, sizy aqueous, thickened iris, adhesions of lens capsule, or iris, torn iris, lens opaque, fibroid, calcareous, atrophied, black cataract, vitreous opaque, yellow, black, shrunken, choroid uneven, discolored, detached, retina with exudate, detached, posterior chamber contracted. Prevention: drainage, mature horses for damp lands, liming soil, get fodder from dry locality, don’t breed in cloudy regions, good diet and regimen, avoid corn, wheat and buckwheat, Glauber salts, pure dry stable, exclude debilitating diseases and parasites, keep in hard muscular condition, change to dry locality, don’t breed from blind stock, legislation. Treatment: remove causes, cure rheumatism or other morbid factor, darkness, antiphlogistics, laxative, diuretic, local bleeding, cupping, blister, seton, locally atropine, cocaine, pyoktannin, sublimate, lead, puncture, tonics, treat corneal opacities. Jurisprudence: return a newly bought horse in 30 days, (France) or more: extend the time if suspected.
Definition. This is an inflammatory affection of the interior of the eye, intimately related to certain constitutions, soils, climates, and systems of management, showing a strong tendency to recur again and again, and usually ending in blindness from cataract or other destructive lesion.
Causes. A wet, impermeable, swampy or undrained soil is a potent cause of this disease. Heavy clays, which absorb and retain moisture, river bottoms and deltas which are frequently overflowed and constantly wet, hollow basins where no effective drainage has been secured, and the coasts of seas and lakes which scarcely rise above the level of the water and are submerged at intervals, are the especial homes of the affection. In time past the disease was very prevalent in the low districts of France (Reynal), Belgium, Alsace-Loraine (Zundel, Miltenberger,) Germany, Holland (Möller), the English fen country and above all the damp lands of Ireland. Lafosse mentions a whole family of horses in South Western France which were characterized by blindness. Reynal records the terrible devastation which it caused in former times in the government studs at Limousin and Pompadour. It also prevails on the low banks of the Guadalquivir near Seville (Hurtrel d’Arboval), around Ostend, Cassel and Frankfort (Hofgeismar). Wet soils surrounded by forests or hills, which hinder free circulation of air, are especially injurious (Reynal). At Schlestadt, Alsace, at the beginning of this century, Miltenberger found 75 per cent. of the horses of the environs affected, whereas after great drainage works and the removal of all stagnant water Zundel found in 1870 not more than 2 per cent. In many localities in England, Ireland, France, Belgium and Germany the disease has greatly diminished in connection with land drainage and improved methods of culture. Harmon tells how in different parts of Brittany, drainage supplemented by the free use of marl and lime on the soil has caused a striking decrease in the prevalence of the malady. In the department of Ain a ratio of 333 per 1000 was thus reduced to 100 per 1000 (Reynal). On the contrary in the absence of such drying of the soil the previous high ratio of attacks was maintained. This has been notorious in the damp lands of Northern France and Belgium (Picardy, Artois, Flanders, where it often reaches 40 to 70 per cent. Reynal): Alsace-Loraine, Holland, Hanover, Mecklenberg, North and East Prussia, Lithuania, the low parts of Austria and Hungary and the Danubian Principalities—Moldavia and Walachia.
Reynal further shows that dealers are in the habit of taking young horses, which have so far escaped, or which have suffered but one moderate attack, away from the low damp soils of the low Pyrenees or of the Jura Valley in France to the dry elevated lands of Dauphiny, Provence and Languedoc in France, or to the mountainous regions of Catalonia in Spain in the well justified confidence that few of them will suffer a second attack.
As a direct test the French Government sent ten yearling foals from the affected depot at Limousin to the healthy depot at Tarbes, retaining an equal number at home as test animals: it also sent ten yearlings from Tarbes to Limousin, retaining an equal number at Tarbes as test cases. Then the twenty yearlings at Limousin were divided, five of the home bred and five drawn from Tarbes having been sent into a very low wet country at Lariviere, and the rest were sent to a high dry location at Maraval. The result was that but one of the ten yearlings sent from Limousin to Tarbes contracted the disease, while on the damp land at Lariviere one Limousin-bred and four Tarbes-bred colts suffered; and finally on the dry soil at Maraval not a single colt, from either Limousin or Tarbes was attacked.
The other conditions that usually attach to a low, damp soil are important factors. Damp air and a cloudy, rainy climate are potent accessory causes. Hence the great prevalence of the disease formerly in Ireland, on the west coast and in the fen country in England, in Belgium, in the Low Pyrenees, in the valleys of the Loire, Jura, Meuse, Moselle, the Guadalquivir, etc., (Reynal). Such an atmosphere relaxes the system, induces a heavy lymphatic temperament, with coarse bones and muscles, an excess of connective tissue, thick hide and hair, and thick, shaggy and often gummy legs. All this implies a low tone of health which will less effectually withstand inimical influences.
The rank, aqueous fodders grown on such damp localities have a similar effect. These are more bulky and less nutritive and fail to maintain the highest tone and vigor. The animals must overload the stomach and intestines in order to obtain the requisite amount of nutriment, so that with a large, pendent belly they are still in poor condition. The case is even aggravated when they go on the succulent grasses of early spring, as they continue to gorge and may even make fat, but they lack in muscle and tone and in this condition even the rapid formation of blood seems to favor the attack. Möller records the great prevalence of the disease in Central Germany in 1884, in connection with excessive rainfall, inundations, and spoiled fodder.
Dard records that a low, overflowed meadow in the Soane bottom near Chalons, caused blindness in nearly all horses put upon it. Bouin quotes a case of a sewage irrigated meadow in Vendée which almost infallibly produced recurrent ophthalmia in the horses fed on its products. On the other hand, oats and hay from a dry, rich soil and well harvested, are the most trustworthy food when the disease is to be dreaded.
Damp night air on wet, impermeable soils is to be especially feared as not only relaxing the system and lowering its power of resistance, but also producing a chill and thereby increasing the susceptibility.
Damp, cold basement stables are concurrent causes acting like the wet soils, the damp air, and the attendant relaxing conditions. Thierry long ago noticed that improved stable hygiene around Strassburg led to a notable decrease of recurrent ophthalmia. In 1807 horses were blind to the extent of 16.5 per cent., in 1821 to 8.5 per cent., and in 1870 Zundel found but 1.79 per cent., and few of the latter from recurrent ophthalmia.
Again the ventilation, lighting and drying of close, low, dark damp stables where the disease had previously prevailed has often practically banished the affection. Hofgeismar states that during the prevalence of the disease in a detachment of the German army in Alsace, out of 84 attacks in 700 horses 52 appeared in February and March, the period of severe weather and close stabling.
Fodders of a heating, or starchy nature, like Indian corn, buckwheat, or wheat strongly predispose to the disease, probably by inducing costiveness, slight impactions and indigestions, and in bad, frequently recurring cases the writer rarely fails to find that the animal is being fed on corn. Beans, peas, vetches and other leguminous fodders are less injurious and when grown on high, dry soils and fed judiciously they are as a rule harmless. When grown rank, badly harvested, and used to excess they become distinctly hurtful. Any fodder which has been allowed to become musty is to be avoided, since any condition which lowers the general tone of health strongly predisposes to an attack. The same remark applies to irregularities and faults in feeding. The best food and the most abundant supply will fail under such circumstances to maintain the condition, and the horse that is losing condition is becoming increasingly susceptible to this malady.
The period of dentition and training is the most common occasion for the attack, partly because this is the time when the colt is taken from the pure air and exercise of the field, into the hot, close, impure atmosphere of the stable, partly because he is made to exchange the cooling succulent grass for the stimulating ration of hay and grain, partly because he is subjected to severe constraint and much excitement in the hands of the trainer, and partly because of the irritation of the gums, the jaws and the whole head in connection with the shedding and eruption of the teeth. When injudicious biting is resorted to, to give a special curve to the neck, the consequent obstruction of the jugulars and capillary congestion in the head is another potent cause. Heavy draught and overdriving have a similar effect. In 53 cases Schmidt found that 3 occurred under one year old, 5 in the 2d year, 10 in the 3d year, 16 in the 4th, 15 in the 5th, and 4 from the 5th to the 9th years.
Influence of Season. Mayer gives a statement of the percentages seen in the various months of the year as follows: January 4.9%, February 4.7%, March 10.1%, April 15.1%, May 13.4%, June 9.9%, July 11.9%, August 6.4%, September 4.9%, October 6.2%, November 6.7%, December 5.2%. The high rate in March, April and May may have a significance in connection with the debility connected with shedding the coat, and the resumption of more active work, when somewhat out of condition, it must also be noted that this is in Germany the season of the most active trade in horses and consequent change of ownership, stabling, feeding, work and management.
Heredity must be accepted as one of the most potent accessory causes. The lymphatic constitution is of course transmitted and with it the special susceptibility. This is notorious in the case of both parents, and is of course more potent if both sire and dam were predisposed, and have themselves suffered. In the latter case the heredity of the lymphatic temperament, and of the impaired organ of vision combine to render transmission more certain. A mare may have borne a number of sound foals before suffering from the malady and then have offspring that do contract the disease. So with the stallion. Möller quotes the case of the eastern horse Turk-Mayn-Atty which served for a length of time in Prussian Studs and left a great stock of blind progeny. Lafosse records the existence of a family of horses in Southern France all of which went blind. The same cause has greatly extended the disease among fast American horses in which the great strain of the track served to intensify the tendency. The writer has seen a colt which was born blind, by a blind dam and got by a sire with diseased eyes, but still held at $300 for service. Mangin, Marimpocy and Hamon record congenital cases from parents with affected eyes.
This hereditary susceptibility 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 at the Government studs in France not only is every unsound stallion rejected but the service of the healthy stallion is refused to any mare which has suffered from disease of the eyes. A consideration for the future of our horses would demand that no stallion shall stand for the public service of mares unless he has been examined and licensed as a sound animal.
Yet, as already stated, heredity is not the one controlling factor, since the offspring of the victims of this disease will often escape when brought up in a high, dry locality.
Reynal records the appearance of the disease in alternate generations, the stallion offspring of blind parents remaining sound himself but producing foals which became victims of the disease in large numbers. A partial explanation may be found in the better conditions under which the stud horse was kept, while under less favorable surroundings his offspring developed the disease.
It must be added that every condition which induces debility or ill health is favorable to the development of the malady. The presence of worms in the bowels is a familiar example. Any debilitating disease like strangles, influenza, contagious pneumonia, indigestion, etc., and overwork or insufficient or indigestible food act in the same manner.
Again, local irritants may rouse the latent tendency. Street or stable dust, sand, hay seeds, chaff, blows on the eye with whip or other object, wounds, irritant gases, smoke, fierce light, cold draughts, storms, and whatever determines inflammation of the eye may be the occasion of an outbreak of recurrent ophthalmia.
Microbiology. It will be recognized that none of these causes fully account for the specific and recurrent nature of this affection, and it is felt that something more is wanted to furnish a full and satisfactory explanation of the malady. This explanation is sought in a direct infection, but in spite of extended investigations by many observers no specific microbe has been demonstrated as uniformly present in all cases.
Potapenke found in the blood of the affected horses a plasmodium like that of ague. This agrees with the damp regions in which the malady prevails and no less with its intermittent or periodic character.
Vigezzi found in the aqueous and tissues a micrococcus (ophthalmo-coccus) which, cultivated on gelatin agar and inoculated in the anterior chamber or under the conjunctiva, produced an affection which he recognized as recurrent ophthalmia.
Trinchera found in the aqueous of the affected animals a bacillus and cocci. Drawing this aqueous into a sterilized syringe and injecting it into the anterior chamber of sound horses produced in 12 to 48 hours characteristic periodic ophthalmia. This was repeated by Schütz and Schwartznecker.
Robert Koch found in the affected aqueous, cocci, singly or in chains and bacilli with rounded ends. Injection of the latter into a sound horse’s eye led to characteristic inflammation and loss of vision. In the cornea of the rabbit it had no effect.
Richter found in the eyes of a foal born with recurrent ophthalmia, of sound parents, diplococci and triplococci.
These observations do not demonstrate the constant presence of one definite microbe, nor that the disease is invariably due to any one particular organism, yet they may be held as strongly suggestive that any one of a variety of microörganisms may prove an exciting etiological factor in a susceptible system, or that, along with the organisms heretofore demonstrated, there exists an essential microbian cause which has up to the present eluded detection.
Other points which give circumstantial support to the microbian theory may be shortly stated:
1. The recrudescence of the disease after its various intermissions, and its preference for low, damp, cloudy localities seem to ally it to the malarial diseases of man.
2. Its appearance in certain predisposed systems, whenever an injury or debility of the eye seems to open the way for the admission of the hypothetical microbe.
3. The increased susceptibility to the malady when the system has been debilitated by disease, overwork, heating food, bad hygiene, or parasitisms, which have undermined the native power of resistance.
4. The prevalence of the affection in given localities has been supposed to imply the preservation and perhaps the multiplication of the germ in such places.
5. The increasing number of victims, year by year, when the same regiment or stud has been kept for a number of years in the same place. The theory is that with the presence of infected horses the hypothetical microbes become increasingly prevalent in the locality and above all in the stables, until even the more resistent subjects tend to succumb under the repeated infections. Thus Zundel says that in 1878, 700 army horses were stationed in Saarsburg, in 1879, 6 were attacked with recurrent ophthalmia, and in 1880, 84, Hofgeismar mentions that a dragoon regiment in Frankfort had 5 horses attacked in 1876, 12 in 1877, 11 in 1878, 14 in 1879, and 42 in 1880. We have, however, no assurance that the excessive rainfall, spoiled food or other unhygienic condition, may not have been a potent factor in the increase.
6. The obvious connection of certain cases of recurrent ophthalmia with a rheumatic condition suggests the probable operation of the same microbian cause.
Up to the present the microbian causation of this malady cannot be taken as proved, yet as a hypothesis it explains satisfactorily many of the observed morbid phenomena. That there is no such rapidly spreading infection, as would warrant us in listing this with animal plagues, is conceded, and that constitutional conditions have a potent influence is allowed, but that, in addition to these, microbian invasion is often a means of precipitating the malady is altogether probable. It may not be necessary that the microbe should in every case be of the same kind, yet the addition of a germ as the last item in the chain of causes is presumptively true.
Parasitism. Willach claims that many cases are directly due to parasites in the eye. In 19 affected eyes he found one young filaria, a number of rhabditis (?), 1 cysticercus, and a number of distomata. Leider also found round worms in such eyes. Mayer and Dexler examined a number of cases, using the centrifuge on the liquids of the eye, without in any case finding such parasites. It may be assumed that the presence of embryo worms may rouse a latent predisposition into activity, but they cannot be adduced as active causes in the vast majority of cases.
Symptoms. These vary with the severity of the attack. In some cases there is high fever while in others this may be absent, yet a lack of vigor and energy bespeaks a general constitutional disturbance. The attack is sudden with marked local irritation, photophobia and lachrymation. The eyelids are closed some times so firmly as to suggest blepharospasm, and if opened the pupil is seen to be contracted. The affected eye is retracted and appears smaller, the conjunctiva is the seat of diffuse redness and swelling, and there is a bright red peri-corneal injection, occupying the anterior portion of the sclera. The outer zone of the cornea is already the seat of a bluish white opacity, the surface appearing dull and as it were smeared with oil. The centre of the cornea may be opalescent but not so obscure as to prevent examination of the interior of the eye. In a few days the outer margin of the cornea may show vascularity, and the aqueous humor a certain degree of turbidity. The iris if still visible is seen to be swollen and rigid, and to have parted with some of its lustre, assuming a grayish or lighter color owing to congestion and exudation. The pupil is usually contracted and dilates only sluggishly and imperfectly in darkness or under the action of atropia. The iris arches forward more than is normal and may even approximate and adhere to the back of the cornea. Bayer noticed that in a partial albino (watch eye) the iris becomes sulphur yellow. The anterior chamber of the aqueous humor usually shows a grayish yellow sediment which in severe cases may fill one-third or even one-half of its depth. This may be grayish white flocculi of lymph only, or it may be colored with blood or in suppurative cases by pus. In the first day of its appearance this may be diffused through the humor, but from the fifth to the seventh day it precipitates and leaves the iris and pupil open to inspection. The pupil if not already open, may be partially dilated with atropia and then discloses the interior of the eye of a dark green, or sometimes with much exudate on the choroid, of a more yellowish green. This greenish discoloration appears to depend on opacity of the vitreous, on an exudate between the choroid and retina or on some opacity of the cornea and aqueous. At the same time under a good light some opacity of the lens or its capsule may be detected, or, with direct illumination, of the vitreous as well.
The tension and hardness of the bulb is materially increased in some cases but not at all perceptibly in others.
From the seventh to the tenth day the acute inflammation subsides, the lids and pupils dilate, and the deposit in the anterior chamber is rapidly reabsorbed. It may first assume a dull brownish green or brownish tint. Meanwhile the opacity of the cornea commences to clear up, and any redness or congestion of its margin to diminish or disappear.
With this disappearance of opacities in the cornea, lens and humors, all the symptoms of congestion subside and by the tenth or fifteenth day from the commencement of the attack the eye may have become approximated to its normal condition.
The characteristic of the disease, however, is its tendency to return again and again until the eye is destroyed. From five to seven attacks usually result in blindness, and then the second eye is likely to have a similar experience until both are useless. In some instances the eye which is first attacked may recover and remain well, while the second to suffer is rapidly ruined by a succession of severe attacks. The intervals between the attacks may be thirty, forty or sixty days and upward according to the state of the health, the condition, the food, the regimen, the exposure, and perhaps of other accessory causes.
Reynal claims that some eyes which have retained their normal function after one or two attacks will sometimes gradually lose the power of vision without any new appearance of inflammation. In other cases an eye which has been clear and transparent becomes suddenly filled up with an inflammatory exudation in the anterior chamber which obscures the iris and lens and in a few days vision is permanently lost, yet without conjunctivitis or apparent suffering.
Condition of the eye between attacks. After one, two or more attacks the eye is not restored to its former condition in the intervals, but continues to exhibit morbid phenomena which betray the previous existence of the disease. The recognition of such persisting lesions is all the more easy that one eye only is usually attacked at first and a comparison between this and the sound eye renders the modifications all the more patent. Even after a first attack there is usually a hazy bluish white zone round the outer margin of the cornea and this becomes more distinct after each successive attack. The faulty eye is distinctly smaller in appearance, at first because it is retracted in its sheath and later in certain cases because of actual atrophy. In proportion to the retraction of the bulb, is the protrusion of the membrana nictitans which covers a greater part of that eye than of its fellow. The upper eyelid in place of forming a continuous and regular arch shows a distinct abrupt bend between its inner and middle thirds caused by the contraction of the levator muscle. The front of the iris has lost something of its normal lustre, and the posterior chamber is liable to show an abnormally light reflection, greenish yellow or yellowish blue. Under direct illumination, lines of opacity may be detected in the aqueous humor, or in the lens, or dark filaments in the vitreous. After several attacks the lens is very distinctly obscure and this increases with each relapse to a white or yellowish white complete opacity. After the first or second attack the pupil may be distinctly contracted, while later in the disease, with advanced cataract it is usually widely dilated. Another feature is the erect, attentive carriage of the ear, to compensate for the waning vision.
Lesions. These are not often seen, as animals do not often die of this disease. Beside the superficial lesions of the conjunctiva and cornea which may be seen during life, exudates have been found on the posterior surface of the cornea, in some cases binding that to the iris. In advanced cases the greatly contracted anterior chamber may contain a little mucilaginous liquid strongly pigmented with debris from the iris, the whole mixed with shreds of exudation. The iris is thickened by congestion and by exudation on its surface and in its substance, and is displaced forward so as to diminish the size of the anterior chamber, and it may have contracted adhesions with the cornea (anterior synechia) or with the lens (posterior synechia). This leads to unevenness in the pupillary margin, where the iris is often torn into shreds. The crystalline lens is usually opaque, and may have undergone various changes, fibrous, calcareous, or atrophic. The anterior surface of its capsule has often adherent masses of black pigment derived from the urea in previous adhesions.
The vitreous humor and hyaloid membrane are sometimes clear, but usually yellowish or blackish and reduced to one-half their normal bulk by accumulations under the retina. A dense exudate often exists on the lamina cribrosa. The choroid is very uneven showing irregular rounded elevations, and like the iris is the seat of active congestion, exudation and thickening. The exudate on its surface raises and detaches the retina and, as shown by Eversbusch, this may increase so that the retina from the two sides may come together in the centre of the eye, the vitreous having been absorbed and removed. Reynal records instances in which the exudate had become cretified, or as he claimed transformed into true bony tissue. Finally the optic nerve is atrophied, often in advanced cases to half its natural thickness.
Prevention. As treatment is somewhat unsatisfactory there is the greater reason to give attention to measures of prevention.
In view of the great evil of low, damp, overflowed lands, it is important to drain and improve such lands whenever possible, and when this cannot be done, to abandon the breeding of horses upon them, and to buy the animals necessary for agricultural purposes from high, dry, healthy localities and introduce them only after they have passed the age of five years at least.
The improvement of wet lands by liming, so as to lessen the amount of decomposing organic matter, and improve the character of the vegetation has proved very beneficial in different parts of England. The substitution for the products of marshy meadows and wet lands, of those of dry cultivated meadows and lands is important.
Misty cloudy regions in the vicinity of sheets of water, or cold mountain ranges cannot be made wholesome, but they can be abandoned for horse breeding, and devoted to more remunerative uses. Something may also be done by stabling the working horses at night.
An insufficient or debilitating diet, for example, in winter, should be carefully avoided, the more so if it is to be followed by a sudden access to rich grass in the spring.
All forms of spoiled food, damp, musty, or fermented fodders should be withheld, especially in the case of young and growing horses.
Indian corn, wheat and buckwheat should be carefully excluded from the grain ration or if used should be combined with 1 oz. sulphate of soda for each animal daily.
Damp, close, filthy and underground (basement) stables should be avoided, the building on the other hand should be placed on high, porous and well drained ground, and should be clean, moderately well lighted and well ventilated but without draughts. While such special stable hygiene is demanded for all it is doubly demanded for young horses under six years of age.
As every debilitating condition renders the already predisposed animal more open to attack, all causes of ill health should be guarded against, and especially for the young, and in the case of such as are inevitable, every effort should be made to curtail and lessen the evil influence. Food or water which contains the eggs and embryos of intestinal worms, must be avoided and parasites which have already invaded the system must be got rid of as far as possible. Care must be taken to exclude the various infectious diseases, and in case of their introduction, to adopt every measure to mitigate their violence and to prevent debility and weakness. Overwork and irregular feeding and watering must be guarded against.
At the same time moderate work or exercise daily which will develop the highest tone of the muscles, nervous system, digestion, assimilation and other functions is a measure that can never be neglected. Idleness with resulting fatness, softness and weakness of muscle, and lowering of the power of endurance is always an invitation to renewed attacks. Regular invigorating work is essential; exhausting work is injurious.
Change of locality to a drier soil, clearer, drier atmosphere, and more abundant sunshine, when it can be availed of, is a most important preventive measure. Reynal who made an extended official inquiry into this matter found conclusive evidence of its truth. Young horses removed from the low affected regions of Cantal, Poitou, Brittany and Anjou rarely suffered another attack when taken to the high land of Catalonia, and those moved from the damp lands of Franche Compté, Bresse, Dauphiny, Provence, Languedoc, Bassigny and Belgium to the dry, calcareous portions of Champaigne also escaped further trouble. In many such cases the eyes already slightly affected would materially and permanently improve.
Finally the influence of heredity is never to be over looked. The ideal system would be to have all stallions professionally examined, and licenses granted to such only as are free from this affection, and to place the owners of such horses under obligation to serve only, mares the eyes of which are sound. This might be enforced as a state or county ordinance. Serious difficulties it is true stand in the way of such a measure. The horse which has an extraordinary record on the track, and to the development of the ophthalmia of which, overwork has doubtless contributed, will be run after by breeders who seek speed at any cost, and it may be questioned whether the State has any right to interfere with the prospective profit which may be expected from the reproduction of the strain of blood. But aside from such fancy products as racers and trotters, this objection has much less force. For carriage, riding and road horses and for the draught and agricultural animal the advantage of sound eyes so greatly over balances all consideration of special values with imperfect eyes, that a statute which will prevent the propagation of such unsoundness is more than justified in every case. The importance of this will be admitted when it is considered that in the great majority of cases, the young animal is attacked after it leaves the hands of the breeder, and therefore a high price is secured for a subject which is almost certainly doomed to become blind in given surroundings. Such a law would work well in every locality. In the low, damp region where the disease prevails habitually, the unprofitable breeding would practically cease, unless a race could be secured which was proof against the infection. The value of such a race could hardly be over-estimated. On the high, dry lands, on the other hand, the natural tendency to immunity would be still further enhanced, as the most susceptible animals which contracted the disease, in even such a healthful district, could be in no sense fit for reproduction, and should therefore be doubly condemned.
In the case of the mare the proprietor is under strong temptation to ignore the sanitary measure under consideration. When her eyes fail, her value in the public market is greatly depreciated, yet she can yearly produce a foal, which is finely developed and will bring a high price if sold young, before it has been attacked by the disease. Hence the great importance, at least in the case of all horses which are not intended for exclusive use on the race course, that a law shall be strictly enforced which will put an absolute limit to the breeding from horses that have been affected with recurrent ophthalmia.
Blows, dust, sand, smoke, irritant gases, fierce light, and all sources of irritation must be avoided as in other eye diseases.
Treatment. Radical treatment for the disease is far from generally satisfactory. Too often the affected animal is still in the environment which has tended strongly to its development, and it is impossible to secure a satisfactory change. As far as possible, however, every available sanitary measure mentioned under the head of prevention should be enjoined, and largely in proportion to the thoroughness of such measures, and the slightness and recentness of the attack will be the hope of a successful treatment.
In some instances in which there appears to be a rheumatic complication, the employment of anti-rheumatic agents have proved of essential value. Powdered colchicum corms may be given twice a day in doses of 1 scruple, combined with salicylate of soda, salicylic acid, or salicin in 2 drachm doses. To these may be added bicarbonate of soda or of potash in drachm doses.
In cases attended with marked fever, hyperthermia and anorexia, antiphlogistic treatment may be desirable, but with the primary consideration that it must not be materially depleting, nor calculated to induce debility or atony. A laxative dose of aloes will sometimes benefit, but should be avoided in the absence of manifest fever. Two or three ounces of Glauber salts, twice a day, will effect the same purpose with less danger. Or saltpeter or other cooling diuretic may be given daily. In most cases bitters may be added with advantage.
In severe cases, rest is essential until the violence of the inflammation shall have abated, and a dark stall or a cloth to obscure the light is equally important.
Trasbot advises bleeding from the jugular, but such a depleting measure finds little support in England or America. Local bleeding from the angular vein of the eye or by leeching or cupping is not open to the same objection.
Counter-irritants are, however, more suitable. A stout silk thread may be inserted above the lower end of the zygomatic ridge and bathed and moved daily to prevent the lodgment of pus. Or a blister of cantharides or biniodide of mercury may be rubbed in on an area as large as a silver dollar in the same situation.
In all cases a strong solution of atropia sulphate (2 per cent.) may be instilled into the eye once or twice daily. Or a mixture of atropia and cocaine (1 per cent. of each) will give even greater relief. If to these is added 1 per cent. of pyoktannin we get a collyrium which is at once anæsthetic, midriatic and antiseptic. This is often of material value. Vigezzi advises a mercuric chloride lotion (1 ∶ 1000) as a collyrium, and for injection in the submucosa.
If the local inflammation runs high an astringent lotion may be applied externally on a soft rag hung over the eye and kept constantly wet. Sugar of lead or acetate of zinc may form the basis of such lotion with a little atropia or morphia added.
Puncture of the cornea and iridectomy have been strongly advocated on the ground that the disease is identical with glaucoma, but the burden of evidence is decidedly against their use as a regular method of treatment. In case of increased intraocular tension, however, the puncture of the cornea can be very profitably employed, but it should be reserved for such special cases. Theoretically, iridectomy should be advantageous in preventing a relapse, but experience has not fully sustained this. When employed, the most careful disinfection should be secured. Under rational treatment the attack subsides in ten days and the eye may appear to be restored to the normal condition in two weeks. This natural tendency to a temporary recovery has served to give a wide acceptance to the most irrational methods of treatment, which have not in any sense hastened the recovery.
As soon as active inflammation and hyperthermia subside, every attention should be given to prevent a relapse, and to this end all the measures mentioned under prevention and which can be applied to the individual case should be adopted. Among these, moderate exercise or regular work must never be omitted.
A course of tonics embracing preparations of iron and bitters, is equally essential, and may be begun as soon as fever and active inflammation subside.
Special lesions, like corneal opacities and ulcers, must be treated as in other affections.
Jurisprudence. The question of the right to return upon the seller a horse attacked with recurrent ophthalmia has been beset with difficulty, mainly because of the intermissions during which, to the ordinary observer, the eyes may appear sound. In France a period of thirty days is allowed in which to return such a horse after purchase. This is, however, too narrow a margin as the second attack may not appear until after two, four or six months. It does, however, provide for the return of the worst cases in which the recurrence is likely to take place at an early date. Another provision is that a suspected horse may be put in pound under veterinary observation for thirty days, in anticipation of a second attack, and if such fails to appear the purchaser is debarred from returning him.
In many cases the symptoms during an attack and between attacks are such as to identify the recurrent inflammation, and the expert can pronounce positively as to the nature of the malady. In other cases there is a degree of uncertainty, and the animal must either be returned on the general plea of diseased eyes, if they can be shown to have been faulty at the time of sale, or otherwise the horse must be put in the hands of a veterinarian and the seller notified of the action, until it can be shown whether it is the recurrent disease or not. If it can be shown that the disease is the recurrent affection the seller is responsible at common law for selling a diseased animal for a sound one. If on the other hand, it is a non-specific ophthalmia, it must be shown that it existed prior to sale, and that a warranty of soundness was given, in order to hold the seller responsible.