6.7.3 Treatment of myocardial disease
There are limited options for treatment of myocardial disease. Most of these are palliative rather than aimed at correcting the underlying disease.
The most important treatment for myocardial disease is rest. Animals which show more severe clinical signs should be box rested, but pasture rest is sufficient in most cases. A rest period of two months prior to re-evaluation is a guide in most cases.
A number of treatments have been used in myocardial disease, most of which are largely empirical. Corticosteroids have been used, and appear to reduce the incidence or severity of arrhythmias in some cases of post-viral myocarditis. There is always a risk of inducing a recrudescence of the viral disease, but a gradually reducing dose of corticosteroid may be appropriate. There is little rationale for the use of antibiotics in myocardial disease. Vitamin E and selenium supplements have been used with apparent success, but rest may have been a more significant part of treatment. Digoxin and frusemide are indicated in aniwith CHF and may allow time for the animal to recover. Some animals have recovered from severe myocardial disease and returned to previous racing form. However, the prognosis for animals with CHF and volume overload resulting from myocardial disease is usually poor. Anti-arrhythmic drugs such as quinidine may be helpful in some instances in which arrhythmias are life-threatening.
Vasodilators may be beneficial, although little is known about the pharmacology of these drugs in the horse and they would be extremely expensive.
As a general rule, rest alone should be the first line of treatment except in cases where the myocardial disease is life-threatening, or there is great pressure to return the animal to work as soon as possible.
Clinical features of myocardial disease are summarised in Table 6.6.