176 DISEASES OF THE HOG, 
CHAPTER XX. 
DISEASES OF THE NERVOUS SYSTEM. 
Phrenitis. (Inflammation of the Brain.) Menin- 
gitis, Inflammation of the Membrane of the Brain. 
These two diseases are so much alike that it is im- 
possible in the animal to discriminate accurately 
between them. There is no doubt but that 
at times the inflammation may exist sepa- 
rately in either the brain itself or its cov- 
ering, but it is only on dissection that the true 
nature of the disease is demonstrated. It is of lit- 
tle practical importance, as the treatment would 
be the same in either case. In the vast majority 
of cases both the brain and its membranes are 
more or less affected at the same time. 
Causes: One of the most common causes of in- 
flammation is a rich state of the blood caused by 
over feeding, short thick necks and a weak circula- 
tion, some kinds of food, such as brewers’ grains 
and distillery slops, often produce it. It is often 
the result of other diseases and injuries, such as 
kicks and blows, over-exertion, such as being pur- 
sued on a hot day. It also sometimes occurs with- 
out any apparent cause. 
Symptoms: The attack sometimes comes on sud- 
denly or it may be preceded by dulness, loss of 
