DISEASES OF THE NERVOUS SYSTEM 115 



met with in all species of domestic animals, but it is most com- 

 mon in horses and mules. Some writers state that meningo- 

 cerebritis is more common during the warm season than it is 

 in the winter. However, this does not hold true in all sections. 

 In the middle west, this disease is more common in late fall and 

 winter. 



It is commonly caused by taking into the body with the feed 

 and water certain organisms and toxins that are capable of pro- 

 ducing an inflammation of the brain. The infectious organism 

 or toxins are taken up by the absorbing vessels of the intestines. 



The secondary form of the disease usually occurs in connec- 

 tion with other diseases such as influenza, tuberculosis and acute 

 pharyngitis, or as a result of wound infection. Unhygienic con- 

 ditions, as unsanitary and poorly ventilated stables and filthy 

 drinking places, play a very important part in the production 

 of the simple or acute form of meningitis. 



Sudden changes in the feed and the feeding of rotten, mouldy 

 feeds may cause it. In the fall and winter it may follow the 

 feeding of too heavy a ration of shredded fodder or any other 

 dry feed. Other exciting causes are overexertion, changes in 

 climate, excitement, injuries to the head and the feeding of too 

 heavy and concentrated a ration. 



The symptoms vary in the different individuals, but in gen- 

 eral they are the same. At first the animal is dull, or extremely 

 nervous and sensitive to sounds. The pupils of the eye are un- 

 evenly contracted at first, later dilated. The eyes may appear 

 staring, or they are rolled about, so that the white portion is 

 prominent. The unusual excitement is manifested in different 

 ways by the different species. During the dull period the animal 

 is indifferent to its surroundings. AMien it is excited, the pulse 

 beats and respirations are accelerated. The body temperature is 

 often elevated early in the disease. There is a partial or com- 

 plete loss of appetite. Paralysis may be the most prominent 

 s}Tnptom. The animal lies in a natural position, or stretched 



