DISEASES OF THE OX AND SHEEP. 611 



mixture of castor oil and corrosive sublimate in proportions 

 dictated by the stage and severity of the affection. 



When the disease is cured, and the sheep have regained their 

 power of vision, they should be allowed to go back to the 

 pasture ; but great care should be taken not to let them get near 

 healthy sheep, for the disease is highly infectious in nature, 

 albeit that in the first instance it is apparently brought on by 

 exposure. Moreover, sheep-farmers will, in most cases, do well 

 to give sheep an extra allowance of food when winter is beginning 

 to set in, and during the course of that season, since in cold 

 weather more food is necessary in order to keep up the heat 

 of the body, and if an additional quantity of food is suitably 

 allowed with this view, there will probably be less predis- 

 position on the part of sheep to catching cold, going down with 

 ^* the blind," or with other diseases. 



CORNEITIS. 

 Traumatic ophthalmia is often secondary to corneitis. 



IRITIS. 

 When the iris is inflamed, there may be little or no inflamma- 

 tion of the cornea, nor, indeed, is there necessarily any affection 

 whatever of the cornea, though there is frequently congestion 

 of sclerotic vessels all round the margin of the cornea. The 

 iris itself may be of a reddish yellow hue, or may present a 

 muddy appearance. The iris cannot contract and dilate properly, 

 as it does in the natural state of health. This incapacity is 

 partly owing to paralysis of its muscle, and partly to the 

 exudation from it binding it down by adhesions to the lens, 

 and it is owing to irregularities of these adhesions that the 

 \ margin of the pupillary opening may sometimes be seen to be 

 corrugated. Inflammation of the iris may extend to the adjacent 

 structures, and it may result in blindness. 



GLAUCOMA. 



There is a peculiar affection of the eye in sheep which is pro- 



1 bably glaucoma, which leads to the organ becoming quite hard 



I -and blind. Very little good can be done, unless the disease be 



detected in the very earliest stages, in which case sclerotomy 



should be practised. 



89 * 



