272 DISEASES OF THE HOBSE. 



knocking out the wolf teeth and cutting out the haw can only be con- 

 demned. 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. 



CATARACT. 



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. 



Causes. — The causes of this affection are tumors or other disease 

 of the brain implicating the roots of the optic nerve, injury to the 

 nerve between the brain and eye, and inflammation of the optic nerve 

 within the eye (retina) , or undue pressure on the same from dropsical 

 or inflammatory effusion. It may also occur from overloaded stom- 

 ach, from a profuse bleeding, and even from the pressure of the 

 gravid womb in gestation. 



SymptoTThs. — The symptoms are wide dilatation of the pupils, so as 

 to expose fully the interior of the globe, the expansion remaining the 

 same in light and darkness. Ordinary eyes when brought to the 

 light have the pupils suddenly contract, and then dilate and contract 

 alternately until they adapt themselves to the amount of light. The 

 horse does not swerve when a feint to strike is made unless the hand 

 causes a current of air. The ears are held erect and turn quickly 

 toward any noise, and the horse steps high to avoid stumbling over 

 objects which it can not see. ' 



Treatment is only useful when the disease is symptomatic of some 

 removable cause, like congested brain, loaded stomach, or gravid 

 womb. When recovery does not follow the termination of these con- 

 ditions, apply a blister behind the ear and give one-half dram doses of 

 nux vomica daily. 



TUMORS OF THE EYEBALX. 



A variety of tumors attack the eyeball — -dermoid, papillary, fatty, 

 cystic, and melanotic — but perhaps the most frequent in the horse is 

 encephaloid cancer. This may grow in or on the globe, the haw, the 

 eyelid, or the bones of the orbit, and is only to be remedied, if at all, 

 by early and thorough excision. It may be distinguished from the 

 less dangerous tumors by its softness, friability, and great vascularity, 

 bleeding on the slightest touch, as well as by its anatomical structure. 



