290 DISEASES OP THE HOBSE. 



sion 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 con- 

 tracted with the capsule of the lens, through its inflammatory exu- 

 dations. 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 inflamma- 

 tions pus may form in the choroid or iris, and escaping into the 

 cavity of the aqueous humor show as a yellowish-white stratum be- 

 low. 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 be- 

 hind a widely dilated pupil. In the slighter cases cataract is to be 

 recognized by examination of the eye in a dark chamber, with an ob- 

 lique side light, as described in the introduction to this article. Cata- 

 racts 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 pig- 

 ment adherent to the capsule of the lens. If the pupil is so con- 

 tracted 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 solu- 

 tion 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 exer- 

 tion 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 xagorous, 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 col- 

 chicum and one-half ounce salicylate of soda may be given daily. 



