194 DISEASES OF THE HOESE. 



symptoms may follow one another in rapid succession, and the disease 

 approach a fatal termination in less than twelve hours. In subacute 

 attacks the symptoms are better defined, and the animal seldom dies 

 before the third day. Within three or four days gradual improve- 

 ment may become manifest, or cerebral softening with partial paral- 

 ysis may occur. In all cases of encephalitis there is a marked rise 

 in temperature from the very onset of the disease, with a tendency to 

 increase until the most alarming symptoms develop, succeeded by a 

 decrease when coma becomes manifest. The violence and character 

 of the symptoms greatly depend upon the extent and location of the 

 structures involved. Thus, in some cases there may be marked paral- 

 ysis of certain muscles, while in others there may be spasmodic 

 rigidity of muscles in a certain region. Very rarely the animal be- 

 comes extremely violent early in the attack, and by rearing up, strik- 

 ing with the fore feet, or falling over, may do himself great injury. 

 Usually, however, the animal maintains the standing position, prop- 

 ping himself against the manger or wall, until he falls from inability 

 of muscular control or unconsciousness. Occasionally 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 constipation of the bowels 

 is a marked symptom in nearly all acute affections of the brain; re- 

 tention of the urine, also, is frequently observed. 



Following these symptoms there are 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 eyes partly 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 poison- 

 ing, etc. This form may not be characterized in its initial stages by 

 excitability, 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 

 sluggish 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 may affect an animal for ten days or two weeks without 

 much variation in the symptoms before the crisis is reached. If im- 

 provement 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 very common result of chronic, subacute, and 



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