Special Report on Diseases of the Horse | Page 9

cough. The cough is not painful, as a rule, in the chronic
diseases of the respiratory tract. The force of the cough is considerable
when it is not especially painful and when the lungs are not seriously
involved. When the lungs are so diseased that they can not be filled
with a large volume of air, and in heaves, the cough is weak, as it is
also in weak, debilitated animals. If mucus or pus is coughed out, or if
the cough is accompanied by a gurgling sound, it is said to be moist; it
is dry when these characteristics are not present--that is, when the air in
passing out passes over surface not loaded with secretion.
In the examination of the chest we resort to percussion and auscultation.
When a cask or other structure containing air is tapped upon, or

percussed, a hollow sound is given forth. If the cask contains fluid, the
sound is of a dull and of quite a different character. Similarly, the
amount of air contained in the lungs can be estimated by tapping upon,
or percussing, the walls of the chest. Percussion is practiced with the
fingers alone or with the aid of a special percussion hammer and an
object to strike upon known as a pleximeter. If the fingers are used, the
middle finger of the left hand should be pressed firmly against the side
of the horse and should be struck with the ends of the fingers of the
right hand bent at a right angle so as to form a hammer. The percussion
hammer sold by instrument makers is made of rubber or has a rubber
tip, so that when the pleximeter, which is placed against the side, is
struck the impact will not be accompanied by a noise. After experience
in this method of examination one can determine with a considerable
degree of accuracy whether the lung contains a normal amount of air or
not. If, as in pneumonia, air has been displaced by inflammatory
product occupying the air space, or if fluid collects in the lower part of
the chest, the percussion sound becomes dull. If, as in emphysema, or
in pneumothorax, there is an excess of air in the chest cavity, the
percussion sound becomes abnormally loud and clear.
Auscultation consists in the examination of the lungs with the ear
applied closely to the chest wall. As the air goes in and out of the lungs
a certain soft sound is made which can be heard distinctly, especially
upon inspiration. This sound is intensified by anything that accelerates
the rate of respiration, such as exercise. This soft, rustling sound is
known as vesicular murmur, and wherever it is heard it signifies that
the lung contains air and is functionally active. The vesicular murmur is
weakened when there is an inflammatory infiltration of the lung tissue
or when the lungs are compressed by fluid in the chest cavity. The
vesicular murmur disappears when air is excluded by the accumulation,
of inflammatory product, as in pneumonia, and when the lungs are
compressed by fluid in the chest cavity. The vesicular murmur becomes
rough and harsh in the early stages of inflammation of the lungs, and
this is often the first sign of the beginning of pneumonia.
By applying the ear over the lower part of the windpipe in front of the
breastbone a somewhat harsh, blowing sound may be heard. This is

known as the bronchial murmur and is heard in normal conditions near
the lower part of the trachea and to a limited extent in the anterior
portions of the lungs after sharp exercise. When the bronchial murmur
is heard over other portions of the lungs, it may signify that the lungs
are more or less solidified by disease and the blowing bronchial
murmur is transmitted through this solid lung to the ear from a distant
part of the chest. The bronchial murmur in an abnormal place signifies
that there exists pneumonia or that the lungs are compressed by fluid in
the chest cavity.
Additional sounds are heard in the lungs in some diseased conditions.
For example, when fluid collects in the air passages and the air is
forced through it or is caused to pass through tubes containing
secretions or pus. Such sounds are of a gurgling or bubbling nature and
are known as mucous râles. Mucous râles are spoken of as being large
or small as they are distinct or indistinct, depending upon the quantity
of fluid that is present and the size of the tube in which this sound is
produced. Mucous râles occur in pneumonia after the solidified parts
begin to break down at the end of the disease. They occur in bronchitis
and in tuberculosis, where there is an excess of secretion.
Sometimes a shrill sound