DETACHMENT OF THE CHOROID.
The choroid is detached from the sclera by exudates, blood effusions, or blows with blunt articles. The lesion is especially common in recurrent ophthalmia, choroiditis, and cyclitis. The ophthalmoscope will show the detached portion as a rounded elevation on the otherwise smooth concave surface, with normal or diminished intraocular tension. A tumor of the choroid is usually associated with increase of tension. After inflammation has been subdued these cases may be left to rest and time, and will often recover through absorption of the exudate. Rupture of the choroid from violence is to be similarly dealt with.
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.