The principles of therapy for congestive heart failure include improving heart function, preventing fluid accumulation, preventing further deterioration of the heart muscle and antagonizing chemicals and hormones produced in excessive quantities in heart failure. Rarely is it possible to "cure" the heart disease. The most important causes of heart failure in dogs are valve degeneration
(heart muscle disease). Definitive treatment usually requires valve replacement (which is rarely done in dogs) or heart transplantation (not done currently). Heart failure caused by fluid accumulation in the sac around the heart (pericardial effusion) is not treated by drugs but instead requires drainage of the fluid or removal of a portion of the pericardial membrane. Congenital heart defects (heart problems present at birth) should be referred to a specialist for management. Initial treatment for heart failure may require hospitalization with a diuretic, oxygen and other hospital-administered treatments. Vasodilator drugs, such as nitroglycerine or nitroprusside, may be administered. In some forms of heart failure, the use of dobutamine or other potent stimulators of the heart muscle may be necessary. Fluid accumulation around the lungs (pleural effusion) may require drainage with a needle (thoracocentesis).
Treatment usually includes a diuretic ("water-pill") such as the drug furosemide (Lasix). Diuretics prevent the kidney from retaining excessive salt (sodium) and water leading to increased volume of urine is produced. Diuretics are usually prescribed for home care to prevent fluid retention. The dose must be sufficient to prevent fluid retention but, at the same time, cannot be so high as to cause kidney failure or excessive loss of potassium.
Other diuretics may be prescribed in selected patients. For example, spironolactone prevents fluid retention and may protect the heart muscle for further damage in dilated cardiomyopathy.
A potassium supplement may be recommended in some patients.
Most patients with chronic heart failure are treated with an angiotensin-converting enzyme inhibitor such as enalapril (Enacard) or benazepril. Enalapril, benazepril and related drugs block some of the harmful hormones that circulate in heart failure, prolong life and reduce clinical symptoms in canine heart failure. This class of drug treatment, sometimes called ACE-inhibitors, prevents salt retention as well. Dosing is critical as these drugs can excessively lower blood pressure or lead to kidney failure.
The diet may be modified to limit sodium intake and prevent fluid retention. There are specialized diets available for this purpose though some senior diets are also relatively low in sodium.
The drug digoxin (Lanoxin; Cardoxin) is prescribed in some patients. The dose of this drug must be critically determined to prevent side effects such as loss of appetite and vomiting.
Dietary supplements are used in some forms of cardiomyopathy. The amino acids taurine is sometimes prescribed for cardiomyopathy in spaniel breeds. L-carnitine is sometimes recommended for treatment of dilated cardiomyopathy. Other nutritional supplements, such as vitamin E and coenzyme Q10, are recommended by some but there is no evidence of their benefit in heart failure in dogs.
Special treatments are needed for some causes of heart failure. Antiarrhythmic drugs are used to control the heart rhythm. Beta-blockers, such as metoprolol, propranolol or atenolol, may be prescribed to control heart rate, to control arrhythmias and protect the heart muscle. Calcium channel blockers, such as the drug diltiazem or amlodipine, are used in some circumstances. Direct vasodilator drugs are sometimes prescribed for dogs with advanced heart failure. There are special circumstances for the recommendation of these treatments and the use of some of these drugs is best guided by a specialist.