ays of primary
importance to ascertain the cause of illness. A knowledge of the origin and
development of a disease is important, both in making a diagnosis and in
formulating the treatment. Exposure to cold and dampness is frequently the
exciting cause of affections of the organs of respiration.

The experienced practitioner is always sure to ascertain whether the
particular animal he is called on to attend is the only one in the stable
or on the premises that is similarly affected. If several animals are
similarly affected, the disease may have a common cause, which may or may
not be of an infectious nature.

Another thing that the experienced practitioner ascertains is what previous
treatment, if any, the animal has had. Medicine given in excessive doses
sometimes produces symptoms resembling those of disease.

The hygienic and sanitary conditions must always be considered in
connection with the cause as well as the treatment of disease. Much of the
disease which occurs in large dairies and elsewhere could be prevented if
owners and those in charge of animals had proper regard for the fundamental
laws of animal hygiene and modern sanitation. Disregard for these laws is
the cause of most of the diseases under consideration in this chapter.

_Attitude and general condition._--The feeling of pain in animals suffering
from serious affections of the organs of respiration is expressed to the
close observer in no uncertain language--by their flinching when the
painful part is touched; by the care with which they move or lie down; by
walking or standing to "favor" the part; by the general attitude and
expression of the eye; by the distress and suffering apparent in the face;
and by other evidences.

The general physical condition and attitude of the sick animal tell the
careful observer much that aids him in making a diagnosis and prognosis.
Cows suffering from affections of the organs of respiration usually assume
a position or attitude that is characteristic, well known to experienced
stockmen, as well as to veterinarians. When an animal has a fever or is
suffering from an inflammation, the skin is one of the first parts to
undergo a change that is apparent to the average observer, for it soon
loses its elasticity and tone, and the hair becomes dry and staring.

From the general condition or state of nutrition one is able to judge the
effect that the disease has already had upon the animal and to estimate the
strength