The most common cause of canine heart disease is degeneration of the valves within the heart, commonly known as valvular heart disease, degenerative valve disease, chronic valve disease, valvular regurgitation or endocardiosis.
The valve most commonly involved is the mitral valve, the valve between the left atrium and the left ventricle. Less commonly, the tricuspid valve is the affected valve. The tricuspid valve is located between the right atrium and the right ventricle. Very rarely, the pulmonic valve or the aortic valves are affected.
Reasons for Treatment of Heart Disease in Dogs Caused by Valvular Heart Degeneration
There are two reasons for treating dogs for heart disease caused by degeneration of the mitral and/or tricuspid valves.
- To attempt to stop or slow the progress of the heart disease.
- To control the signs of congestive heart failure resulting from the heart disease.
Currently, there are no drugs available that can stop the progress of the heart disease. Some veterinarians feel that some of the medications available can slow the progress of disease. However, in most cases, the primary reason for treatment is to control the signs of congestive heart failure.
Medications for Treatment of Canine Valvular Heart Disease
Not all dogs diagnosed with heart disease caused by degenerative valve disease will need to be treated. Dogs that are not symptomatic beyond having an audible heart murmur usually do not require treatment, although they should be monitored to track the progress of their disease.
For those dogs that require treatment, there are a number of medications that are commonly used in treating degenerative heart valve disease.
- Diuretics are among the most frequently used medications for treating heart disease of any kind. These medications help to keep excess fluid accumulation under control. They include furosemide (Lasix®), spironolactone and hydrochlorothiazide.
- Angiotensin-converting enzyme inhibitors (ACE inhibitors) are used to help control blood pressure. These include enalapril and benazepril.
- Drugs which dilate the blood vessels outside of the heart help to reduce the load on the heart. These include amlodipine and hydralazine.
- Pimobendan (Vetmedin®) is used to dilate blood vessels and to increase the force of heart muscle contractions.
- Digoxin and digitoxin were previously used to treat congestive heart failure relatively commonly. However, newer and safer drugs have largely replaced their usage.
Other Techniques for Treating Valvular Heart Disease in Dogs
In dogs with right-sided heart failure in which fluid has accumlated in the abdominal cavity or in the chest cavity, manual removal of the fluid by your veterinarian may be necessary. This is known as abdominocentesis (when fluid is removed from the abdomen) or thoracocentesis (when fluid is removed from the chest cavity).
Many veterinarians recommend a special diet that is low in sodium and sometimes also low in protein for dogs that suffer from heart failure. There is disagreement about the value of these diets in treating heart disease however.
Though surgery to replace the heart valves or otherwise improve their function is not widely available currently, there are some facilities working to perfect such procedures. In future, these procedures may become more widely available as a treatment option for valvular heart disease in dogs.