198 Common Diseases of the Horse 



Symptoms. — An opacity or cataract may take the form of a pin 

 head, streak, triangle, star, or it may involve the whole lens, so that 

 the whole space that should be transparent will appear cloudy or 

 milky-white in colour. 



Another method of examination is to place the horse in a dark 

 box and examine the eye with a wax match or candle, when three 

 images should be seen; two moving in the same direction as the 

 candle is moved, the third upside down and moving in the opposite 

 direction. These images in a fully-expanded healthy pupil should 

 be perfectly clear and distinct. Should an opacity form, the in- 

 verted image will become indistinct; as the disease progresses it 

 will disappear altogether, and in complete cataract only one image 

 may appear. Cataract, if acquired, is usually preceded by several 

 attacks of inflammation of the eye. Generally the experienced 

 man who has an animal twice affected in this manner considers it 

 advisable to dispose of him, because when a cataract has developed 

 there is no cure. 



Before, however, deciding that the animal is affected, it must be 

 distinctly understood that an opacity such as has been described, 

 exists inside the eyeball and not on the outside transparent cover- 

 ing. The latter form is fairly common, and is usually caused by an 

 injury or superficial inflammation, and it will soon clear up when 

 the surface of the eye recovers. Such a condition is of very little 

 detriment and need cause no alarm. 



Complete cataract may cause total blindness, but however slight 

 the disease may .be, vision is bound to be interfered with. Some 

 cases of shying are caused in this way. 



Treatment. — In the case of the human being, where spectacles 

 can be worn, there are several methods of operating, but these are 

 rarely if ever applied to the lower animals. 



Rheumatism 



It is very probable that considerable dissension may be expressed 

 as to whether rheumatism should be classed as hereditary, but in 

 the writer's experience it is most certainly transmissible. 



Opinions differ as to its cause. By some it is stated that a 

 microbe is responsible, but up to the present time this has not been 

 absolutely proved; by others, that it is due to an excess of lactic 

 acid in the blood. It is much more common among the lower 

 animals than is generally supposed, and in many cases of lameness 

 that are attributed to sprains, and in animals that will not thrive, 

 rheumatism is responsible. Colour has apparently something 



