612 THE DISEASES AND DISORDEES OF THE OX. 



KETINITIS OR SPECIFIC OPHTHALMIA. 



Retinitis or specific ophthalmia is a disorder of a much more 

 serious nature, and it may return again and again, and bring on 

 blindness. If the disorder manifests itself in an obstinate form, 

 the best course is to fatten the animal, when the disorder has 

 been alleviated or cured, with the purpose of ultimate consign- 

 ment to the shambles. As we have said above, the retina is a 

 layer of nerve-tissue which lines the interior of the eyebalL 

 Inflammation of it may ensue as a complication of the simpler 

 form of the inflammation of the eye. 



An animal afflicted with retinitis seeks quiet and solitude, 

 avoids the light, and closes the eyelids. In the early stages of 

 the disease also, the pupil is contracted, the inflamed and sensi- 

 tive retina not being able to bear the light. There is a profuse 

 discharge of tears, and the animal suff'ers considerably in regard 

 to its general state. 



If the eyelids are separated, great pain seems to be produced, 

 tears flow forth, the haw covers the eyeball, and it, too, is then 

 seen to be inflamed. If the eye can be well seen, a red tinge 

 of the fundus may be noticed. 



GUTTA SERENA. 

 Another disease of the eye of a severe kind, and rather fre- 

 quently met with in the sheep, is called gutta serena. This 

 malady seems to be in reality due to a loss of power of the optic 

 nerve and retina. It may, moreover, accompany either gid or 

 apoplexy. The derangement seems to arise from the optic nerve 

 being pressed upon, and in consequence of this pressure the retina 

 is paralysed. Our readers will understand that this disease is 

 more serious in nature than any lack of transparency of the eye 

 itself can be. If there is any undue opacity of the visual organ, 

 of course the rays of light from the exterior cannot pass through 

 the various media so as to impinge upon the retina ; but very 

 often in such cases there may be a chance of restoring the normal 

 transparency. Moreover, in even marked cloudiness of the media 

 the animal can distinguish between different degrees of light, and 

 it is capable of being fattened. On the other hand, if there is 

 any disease of the retina itself, or of the other nervous structures 

 concerned in vision, there is very little chance of cure. 



