TABLE CONTRASTING THE MAIN SYMPTOMS OF HYPERTROPHY AND DILATATION.
A. General Physical Signs.
SIMPLE HYPERTROPHY. HYPERTROPHY WITH DILATATION. SIMPLE DILATATION.
Heart’s impulse slow and heaving as if pressing steadily against an obstacle—in rythm regular, in force unequal. Force increased, sharper, more knocking, may impart a shake to the body. May be felt on the right side. Impulse conveys a feeble undulatory sensation; force of successive beats unequal; rythm irregular.
First sound is dull, muffled, prolonged and weakened almost to extinction. Second sound full and clanging; period of silence shortened. Sounds gain greatly in loudness and extent of transmission, especially if the valves are thickened. First sound short, abrupt and clear. Second sound not specially affected.
Murmur with the first sound present at one time and absent at another. Murmur with the first sound may be present, from altered direction of the orifice of the aorta. Murmur with the first sound from insufficiency of the auriculo-ventricular valves.
B. General Functional Symptoms.
SIMPLE HYPERTROPHY. HYPERTROPHY WITH DILATATION. SIMPLE DILATATION.
Strength unimpaired. Power of continued exertion (especially uphill) limited by shortness of breath. Strength tends to become impaired. Strength fails.
Visible mucous membranes healthy or of a bright red. Purpleness and lividity of the mucous membranes proportionate to the valvular or pulmonary obstruction. Lividity of the mucous membranes. Dropsical effusions of the limbs and other dependent parts which pit on pressure.
Difficulty of breathing occasional. Difficulty of breathing occurs in paroxysms. Difficulty of breathing great and constant, with occasional aggravations.
Pulse full, strong, firm, tense, resisting and prolonged without jerk or thrill. Fulness of pulse continues but strength and power of resistance lost. Pulse small and feeble, much later than the heart beat. Regular or feeble, fluttering and irregular. Venous pulse in the jugulars.
Rarely and never rapidly the direct cause of death. Indirectly and more or less rapidly fatal. Palpitation frequent. Faintness occurs from time to time, and may lapse into fainting and sudden death.

Pure hypertrophy rarely implies imminent danger unless dependent on some pre-existing structural disease which impedes the freedom of the circulation. If excessive, however, or if associated with dilatation the animal is short-winded and unfit for all but the slowest work. It predisposes to congestion or apoplexy of the lungs when its seat is the right ventricle, and to congestions and hemorrhage in other parts of the system, brain, kidney, lungs, liver, bowels, if in the left.

Asthma (dogs), heaves (horses), emphysema and tuberculosis in cattle are occasional complications attended by grave symptoms.

Treatment. In advanced cases and such as are dependent on irremovable structural changes in the lungs or elsewhere no treatment is of any avail. In recent and uncomplicated cases in the horse and cow and in some more advanced conditions in other animals, not used for work, a palliative treatment may be profitably adopted. This consists in a nitrogenous restricted and gently laxative diet, perfect rest in fattening oxen and other animals, or in the horse moderate and carefully regulated work, and as a medicament the use of digitalis or aconite. No known remedy has any power to directly check the growth of the heart and the utmost that can be expected of these agents is to lessen the activity of the heart’s action and retard its growth. Digitalis may be given as recommended for palpitation, or aconite in the form of tincture 20 drops for horses and cattle and 1 to 2 drops for dogs, repeated four times daily. Strophanthus may replace digitalis. When depletion seems advisable purgatives or diuretics should be given as appears most applicable to the particular case. Iodide of potassium has been strongly recommended.

When extreme dilatation exists with the hypertrophy, sedatives should be given cautiously and their effects carefully watched as the heart is often dangerously susceptible to depressing influences. When the disease has advanced so far as to cause abundant dropsical effusions it is futile to resort to treatment as amelioration can rarely be looked for, not even to the extent of allowing an animal to be fattened.

The value of arsenic in most cases of broken wind (heaves) has suggested the inquiry whether it does not operate directly on the heart. Leblanc who advances this query might have quoted in explanation the known power of arsenic to retard and arrest tissue change, with its natural consequences, the diminished amount of effete matter thrown into the blood in any given time, and the lessened necessity for an active circulation to supply any great waste of structure. It may benefit such cases in this way but does so probably to a far greater extent by an influence on the nervous function analogous to its action in neuralgia and other purely nervous disorders. Dilatation of the heart which usually exists in heaves is usually benefited by tonics which like arsenic are destitute of stimulating properties.

ATROPHY.

Simple, eccentric, concentric. Usually eccentric. Causes, effusion in pericardium, obstruction of coronary arteries, by false membranes, etc., general inanition. Symptoms, beats weak, sounds loud, clear, decreased area of dulness on percussion, pulse slow, weak, under excitement unequal, irregular, intermittent with palpitation, dropsy of limbs, etc., murmur with 1st sound. Treatment only in early stages by removal of the cause.

The loss of substance in the muscular walls of the heart is either simple when there is no change in the capacity of its different cavities:—eccentric when the chambers of the heart are enlarged; or concentric when these chambers are reduced in size. Like hypertrophy it may affect the walls of one chamber to the exclusion of the others.

Atrophy is much less frequent in the lower animals than hypertrophy and in nearly all cases on record it was associated with dilatation.