DISEASES OF THE BRAIN. 203 



this form of brain affection. We should also remember that it is 

 never safe to drench a horse with large quantities of medicine when 

 he is unconscious, for he is very liable to draw the medicine into the 

 lungs in inspiration. 



Prevention. Young horses, when harnessed or bitted for the first 

 few times, should not have their heads checked up high, for it fre- 

 quently causes them to rear up, and, being unable to control their 

 balance, they are liable to fall over sideways or backwards, thus 

 causing brain concussion when they strike the ground. 



ANEMIA OF THE BRAIN. 



This is a physiological condition in sleep. 



Causes. It is considered a disease or may give rise to disease when 

 the circulation and blood supply of the brain are interfered with. 

 In some diseases of the heart the brain becomes anemic, and fainting 

 fits occur, with temporary loss of consciousness. Tumors growing 

 within the cranium may press npon one or more arteries and stop the 

 supply of blood to certain parts of the brain, thus inducing anemia, 

 ultimately atrophy, softening, or suppuration. Probably the most 

 frequent cause is found in plugging, or occlusion, of 'the arteries by 

 a blood clot. 



Symptoms. Imperfect vision, constantly dilated pupils, frequently 

 a feeble and staggering gait, and occasionally cramps, convulsions, or 

 epileptic fits occur. 



Pathology. The exact opposite of cerebral hyperemia. The blood 

 vessels are found empty, the membranes blanched, and the brain sub- 

 stance softened. 



Treatment. Removal of the remote cause when possible. General 

 tonics, nutritious food, rest, and removal from all causes of nervous 

 excitement. 



HYDROCEPHALUS, OR DROPSY OF THE BRAIN. 



This condition consists in an unnatural collection of fluid about or 

 in the brain. Depending upon the location of the fluid, we speak of 

 external and internal hydrocephalus. 



External hydrocephalus is seen chiefly in young animals. It con- 

 sists in a collection of fluid under the meninges, but outside of the 

 brain proper. This defect is usually congenital. It is accompanied 

 by an enlargement of the skull, especially in the region of the fore- 

 head. The pressure of the fluid may cause the bones to soften. The 

 disease is incurable and usually fatal. 



Internal hydrocephalus is a disease of mature horses, and consists 

 in the accumulation of an excessive quantity of fluid in the cavities 

 or ventricles of the cerebrum. The cause of this accumulation may 

 be a previous inflammation, a defect in the circulation of blood 



