110 The Diseases of Animals 
trols the whole body, making the different parts act In 
harmony. It enables the animal to comprehend what 
is going on around him, and to regulate his own activ- 
ities. The brain, spinal cord and nerves, together with 
small masses of nervous tissue known as ganglia, con- 
stitute the nervous system. 
When all of these different systems and parts of 
the body are complete and in their normal working 
order, the animal is said to be in a state of health. 
But when some parts of the body are injured, or their 
work is in any way interfered with, an abnormal con- 
dition occurs to which the term “disease” is applied. 
It is essential that the observer be familiar with the 
actions of the animal, not only in a state of health, but 
also in disease,—since it is by comparison of these two 
conditions that disease is recognized. Signs of disease 
are commonly known as “symptoms.” The study of these 
symptoms and the recognition of their causes is called 
“diagnosing the disease,” or “diagnosis.” The expression 
of an opinion as to the probable future course of the 
disease is called ' prognosis,” and, if favorable, indicates 
that the observer believes that the animal will recover; 
if unfavorable, that it will not. The following points 
are be particularly noted in examining sick animals. 
PULSE 
The pulse is the throbbing of an artery. By it is 
determined the heart’s action and also the condition of 
the nervous system. In the horse, the pulse is usually 
taken where the submaxillary artery winds under the 
