One class of drug, called ACE inhibitors, is recommended as the mainstay of treatment in nearly all cases of heart failure in dogs. ACE inhibitors work at a number of different levels, primarily suppressing the body's compensation system to relieve stress on the heart. There has been no other drug in the history of veterinary cardiology that has undergone such extensive controlled clinical trials proving its value.
 

Diuretics
Diuretics are usually used, often long term, to stimulate the kidneys in removing excess fluid from the body.

Nitroglycerin is used short term to dilate the veins throughout the body, thereby redistributing fluids and easing pressure on the heart or lungs. Nitroglycerin is only effective for a day or two, after which the body builds a tolerance. It is commonly administered by the veterinary surgeon.
 

Digitalis is primarily used to control an excessively fast heart rate. It needs to be prescribed with care as it is relatively easy to overdose. Concurrent regular blood testing is often recommended to reduce the risk of overdose.
 

Inodilators directly stimulate the heart muscle and are therefore used when the heart muscle fails, i.e. in dilated cardiomyopathy or in end stage valvular disease.
 

Note that in the treatment of congestive heart failure, other drugs should always be used in addition to, rather than in place of ACE inhibitors.