194 BUREAU OF ANIMAL INDUSTRY. 



develop, succeeded b}' a decrease when coma becomes manifest. The 

 A iolence and character of the symptoms greatly depend upon the 

 extent and location of the structures involved. Thus, in some cases 

 there may be marked paralysis of certain muscles, while in others 

 there may be spasmodic rigidity of muscles in a certain region. Very 

 rarely the animal becomes extremely violent earh' in the attack, and 

 by rearing up, striking with the forefeet, or falling over, may do 

 liin)self great injury. Usually, however, the animal maintains the 

 standing position, propping himself against the manger or wall, until 

 he falls from inability of muscular control or unconsciousness. Occa- 

 sionallj' he may go through a series of automatic movements in his 

 delirium, such as trotting or walking, and, if loose in a stall, will 

 move around in a circle persistently. Early and persistent constipa- 

 tion of the bowels is a marked symptom in nearlj^ all acute affections 

 of the brain; retention of the urine, also, is frequently observed. 



Following these symptoms there is depression, loss of power and 

 consciousness,, lack of ability or desire to move, and usually fall of 

 temperature. At this stage the horse stands with legs propped, the 

 head hanging or resting on the manger, the e3^es parti}' closed, and 

 does not respond when spoken to or when struck with a whip. 



Chronic encephalitis or meningitis may succeed the acute stage, or 

 may be due to stable miasma, blood poison, narcotism, lead poisoning, 

 etc. This form may not be characterized in its initial stages by excit- 

 ability, quick and hard pulse, and high fever. The animal usually 

 appears at first stupid; eats slowly; the pupil of the eye does not 

 respond to light quickly; the animal often throws up his head or 

 shakes it as if suffering sudden twinges of pain. He is slow and slug- 

 gish in his movements, or there may be partial paralysis of one limb, 

 one side of the face, neck, or body. These symptoms, with some 

 variations, may be present for several days and then subside, or the 

 disease may pass into the acute stage and terminate fatally. Chronic 

 encephalitis ma}^ affect an animal for ten da3"s or two weeks without 

 much variation in the s3'mptoms before the crisis is reached. If 

 improvement commences the symptoms usually disappear in the reverse 

 order in which they developed with the exception of the paralytic 

 effects, which remain intractable or permanent. Paralysis of certain 

 sets of muscles is a ver}-- common result of chronic, subacute, and 

 acute encephalitis, and is due to softening of the brain or to exuda- 

 tion into the cavities of the brain or arachnoid space. 



Softening and abscess of the brain is one of the terminations of 

 cerebritis. It may also be due to an insufficient supply of blood as a 

 result of diseased cerebral arteries and of apoplex3^ The s3^mptoms 

 are drowsiness, vertigo, or attacks of giddiness, increased timiditv, or 

 fear of familiar objects, paralysis of one limb, hemiplegia, imperfect 

 control of the limbs, and usually a weak, intermittent pulse. In some 



