second is
caused by the rebound of blood in the aorta and the closure of the valves
that prevent it from flowing backward into the heart, whence it came. The
first sound is the longer and louder of the two, though of low pitch. The
second sound is sharper and shorter, and is not always easy to hear. There
is a brief interval between them.

To distinguish these sounds, the ear is placed against the left side of the
chest, a little above the point where the elbow rests when the animal is
standing in a natural position, and about opposite the sixth rib. Both
heart sounds are reduced in intensity when the animal is weak or when the
heart is forced away from the chest wall by collections of fluid or by
tubercular or other growths. Nonrhythmical heart sound is often caused by
pericarditis or by disease of the valves. It may also be attributable to
overfilling of the heart upon the right side, as occurs in severe
congestion of the lungs and in some febrile diseases.

In pericarditis, sounds like scraping, rubbing, or splashing may be heard,
entirely apart from the two normal sounds above described.

The impulse of the heart, as felt by placing the hand against the chest, is
of some consequence in reaching a conclusion in respect to disease of the
heart; but it must be remembered that the impulse may be very much
increased by diseases other than those of the heart, as, for example,
inflammation of various organs, severe pains, etc. The impulse may be
increased also (when disease does not exist) by work, exercise, fright, or
any cause of excitement, or, in general, by anything that causes
acceleration of the pulse.

The impulse of the heart may be felt and the sounds may be heard fairly
well in lean cattle, but in fat ones it is difficult and often impossible
to detect either impulse or sound with any degree of satisfaction.

PALPITATION.

When the impulse of the heart is excessive--that is, when it beats more or
less tumultuously--the familiar expression "palpitation of the heart" is
applied; by many it is called "thumps." The hand or ear placed against the
chest easily detects the unnatural beating. In some cases it is so violent
that the motion may be seen at a distance. Palpitation is but a symptom,
and in many instances not connected with disease of the structure of the
heart or its membranes. A badly frightened animal may have palpitation.
When it comes on suddenly and soon passes away, it depends on some cause
ot