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morbid elianges. Practically, we can not separate inflammation of the 

 pia mater from that of the brain proper. Inflammation may, however, 

 exist in the center of the great nerve masses, the cerebrum, cerebellum, 

 pons Varolii, or medulla at the base of the brain, without involving 

 the surface. When, therefore, inflammation invades the brain and its 

 enveloping membranes it is properly called encephalitis ; when the 

 membranes alone are affected it is called meningitis ; or the brain sub- 

 stance alone, cerebritis. 



ENCEPHAL-ITIS — INFLAMMATION OF THE BKAIN AND ITS MEMBRANES. 



Causes. — Exposure to extreme heat or cold, excessive continued cere- 

 bral excitement, direct injuries to the brain, such as concussion, or from 

 fracture of the cranium, sometimes as a sequelae to influenza, pysemia, 

 jioisons having a direct influence upon the encephalic mass, etc. 



Symptoius. — Acute encephalitis may be ushered in by an increased 

 sensibility to noises, with more or less nervous excitability, contraction 

 of the pupil of the eyes, and a quick, hard pulse. In very acute attacks 

 these symptoms, however, are not always noted. This condition will 

 soon be followed by muscular twitchiugs, convulsive or spasmodic move- 

 ments, eyes wide open with shortness of sight. The animal becomes 

 afraid to have his head handled. Convulsions and delirium will develop, 

 with inability of muscular control, or stupor and coma may supervene. 

 Where the membranes are greatly implicated convulsions and delirium 

 with violence may be expected, but where the brain substances is prin- 

 cipally affected stupor and coma will be the prominent symptoms. In 

 the former condition the pulse will be quick and hard, in the latter soft 

 or depressed with often a dilatation of the pupils, and deep, slow, ster- 

 terous breathing. The symptoms. may follow one another in rapid suc- 

 cession, and the disease approach a fatal termination in less than twelve 

 hours. In subacute attacks the symjitoms are better defined, and the 

 animal seldom dies before the third day. Within three or four days 

 gradual imjirovement may become manifest, or cerebral softening with 

 partial paralysis 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, suc- 

 ceeded by a decrease when coma becomes manifested. The violence 

 and character of the symptoms greatly depend upon the extent and 

 location of the structures involved. Thus, in some cases wo may find 

 marked paralysis of certain muscles, while in others we may have spas- 

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

 becomes extremely violent early in the attack, aifd 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, propping 

 himself against the manger or wall until he falls from inability of mus- 

 cular control or unconsciousness. Occasionally he may go through a 



