Causes.—Some defect in the valvular apparatus, allowing the blood to regurgitate and to distend the cavity, which, by pressure on the walls, causes absorption and attenuation; loss of power in the nervous system; fevers of a sthenic or typhoid character, which weaken the muscular fibres.
Symptoms.—The action of the heart is feeble and tremulous; the pulse small, soft and weak; the least exertion brings on Dyspnœa; there are languor, giddiness, or “Megrims”; the horse is “off his food”; the ears and legs are cold; and ultimately there is œdema of the legs, belly and chest.
Pathology.—Dilatation may exist either with Hypertrophy or with Atrophy of the walls of the heart, and in the latter case is most probably an effect of the emaciated state of the muscular substance of the heart, which allows the blood to accumulate, and to distend one or more of the auricles or ventricles.
Treatment.—Dilatation and atrophy of the heart admit of very little help in the majority of cases, moderate work and occasional or daily use of A.A., will be proper, and do something towards improving the condition and prolonging the usefulness of the animal.
Palpitation
Definition.—An abnormal increase in the action of the heart.
Irregularity in the action of the heart is a functional derangement, and not do to organic disease. It occurs in horses that are in feeble health and out of condition, or that have been subject to severe and straining exercise, such as pulling a heavy load uphill or running hard with the hounds.
Anemic Palpitation
Cause.—Poverty of blood.
Symptoms.—A dull, thumping sound is heard to proceed from the cavity of the chest, which, in extreme cases, may be heard on both sides, and may even be audible at a distance of some yards, corresponding to the beatings of the heart and pulse; tumultuous breathing, redness of the mucous membranes, increased temperature of the body. Auscultation will detect blood sounds in the neighborhood of the heart, large arteries, and veins. These “anemic murmurs” vary with the condition of the blood, and are caused by its “churning” as it passes through the traversing channels of the heart. They constitute a continuous hum, or the “bruit de diable” of the French. In some cases the action of the heart is so great that it causes shaking or jerking of the whole body.