pathetic system. The smaller arteries terminate
in the system of minute vessels known as the capillaries, which are
interposed between the termination of the arteries and the commencement
of the veins. Their average diameter is about one three-thousandth of an
inch.

DISEASES OF THE HEART AND BLOOD VESSELS.

In considering diseases of the heart we meet with many difficulties,
depending much upon the position which this organ occupies in the
animal. The shoulders cover so much of the anterior portion of the
chest, and often in very heavy-muscled horses the chest walls are so
thick that a satisfactory examination of the heart is attended with
difficulty. Diseases of the heart are not uncommon among horses; the
heart and its membranes are frequently involved in diseases of the
respiratory organs, diseases of the kidneys, rheumatism, influenza, etc.
Some of the diseases of this organ are never suspected by the ordinary
observer during life, and are so difficult to diagnose with any degree
of certainty that we will have to confine ourselves to a general
outline, giving attention to such symptoms as may serve to lead to a
knowledge of their existence, with directions for treatment, care, etc.

Nervous affections often produce prominent heart symptoms by causing
functional disturbance of that organ, which, if removed, will leave the
heart restored to perfect vigor and normal action. Organic changes
involving the heart or valves, however, usually grow worse and
eventually prove fatal. Therefore it is necessary that we arrive at an
appreciation of the true nature and causes so that we may be able to
form a true estimate of the possibilities for recovery or encouragement
for medical treatment.

Disease of the heart may occur at any age, but it is witnessed most
frequently in young horses, which, when being trained for fast work, are
often subjected to excessive hardship and fatigue. Nervous or timid
animals also suffer from such diseases more frequently than those of a
sluggish disposition. Any cause which induces a violent or sudden change
in the circulation may result in injury to the heart. Symptoms which may
frequently denote disease of the heart are difficult breathing or
short-windedness, dropsies of the limbs, habitual coldness of the
extremities, giddiness or fainting attacks, inability to stand work,
although the general appearance would indicate strength and ability,
etc.

MYOCARDITIS, OR INFLAMMATION OF THE M