238 PRACTICE OF EQUINE MEDICINE. 



Meningitis is an inflammation of the membranes covering the 

 brain exclusive of the dura mater. 



Arachnitis is an inflammation of the arachnoid membrane. 



Pachymeningitis is an inflammation of the dura mater of the 

 brain. 



Leptomeningitis is an inflammation of the cerebral pia mater. 



What are the causes? 



It may be caused in about the same manner as congestion; it 

 may be the result of traumatism or it may be an extension from 

 some adjacent organ ; parasites, emboli, thrombi are also among the 

 causes as well as bacterial ferments from mouldy food. 



Give the morbid anatomy. 



Cerebritis may be non-suppurative or suppurative. In the 

 non-suppurative form there are irregular foci, more or less rounded 

 and about the size of a pea, distributed throughout a portion of 

 the cerebral hemisphere. 



In the suppurative form abscesses are found, either single or 

 multiple. 



In pachymeningitis suppurative changes usually occur. The 

 dura mater is reddened, thickened, and extravasations of blood 

 are found. The surface of the dura is covered with a flbrino- 

 purulent exudation. 



In leptomeningitis the pia mater is swollen, reddened, and a 

 serous fluid is present, the ventricles containing fluid. 



In arachnitis about the same condition is shown as in lepto- 

 meningitis. 



What symptoms are shown ? 



Symptoms of congestion are present in the beginning, which 

 are usually vague. 



The head becomes elevated, the nose thrown in the air, there 

 is a fixed and anxious expression, muscular trembling, associated 

 with paroxysms of fear, during which the animal will run forward, 

 pull backward. 



The pulse becomes full, in some cases slow, while in others 

 quickened; the respirations are more or less labored and at times 

 noisy; the temperature is elevated, being usually about 103° F. 

 When in motion they walk like a partially blind horse, lifting the 

 legs high, going sideways, pulling hack, trembling, etc. 



