224 DISEASES OF THE HOESE. 



an enlargement of the skull, especially in the region of the forehead. 

 The pressure of the fluid may cause the bones to soften. The dis- 

 ease 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 

 through the brain, heat stroke, overwork, excessive nutrition, or long- 

 continued indigestion. Common, heavy-headed draft horses are pre- 

 disposed to this condition. 



Symptotns. — The symptoms are an expression of dullness and stu- 

 pidity, and from their nature this disease is sometimes known as 

 " dumminess " or " immobility." A horse so afflicted is called a 

 " dummy." Among the symptoms are loss of intelligence, stui)id ex- 

 pression, poor memory, etc. The appetite is irregular ; the horse may 

 stop chewing with a wisp of hay protruding from his lips ; he seems 

 to forget that it is there. Unnatural positions are sometimes as- 

 sumed, the legs being placed in clumsy and unusual attitudes. Such 

 horses are difficult to drive, as they do not respond readily to the 

 word, to pressure of the bit, or to the whip. Gradually the pulse 

 becomes weaker, respiration becomes faster, and the subject loses 

 weight. Occasionally there are periods of great excitement due to 

 temporary congestion of the brain. At such times the horse becomes 

 quite uncontrollable. A horse so afflicted is said to have "staggers." 

 The outlook for recovery is not good. 



Treatment is merely palliative. Regular work or exercise and 

 nutritious feed easy of digestion, with plenty of fresh water, are 

 strongly indicated. Intensive feeding should not be practiced. The 

 bowels should be kept open by the use of appropriate diet or by the 

 use of small regular doses of Glauber's salt. 



TUMORS WITHIN THE CRANIUM. 



Tumors within the cranial cavity and the brain occur not infre- 

 quently, and give rise to a variety of symptoms, imperfect control of 

 voluntary movement, local paralysis, epilepsy, etc. Among the more 

 common tumors are the following : 



Osseous tumors, growing from the walls of the cranium, are not 

 very uncommon. 



Dentigerous cysts, containing a formation identical to that of a 

 tooth, growing from the temporal bone, sometimes are found lying 

 loose within the cranium. 



Tumors of the choroid plexus, known as brain sand, are frequently 

 met with on post-mortem examinations, but seldom give rise to any 



