Chronic Valvular Heart Disease in Dogs
Overview of Caine Valvular Heart Disease (VHD)
Valvular heart disease (VHD) is a condition characterized by degeneration and thickening of the heart valves. Valvular heart disease is very common and represents the most important of adult canine heart diseases.
Valvular heart disease is a progressive disease that is common in older dogs. Commonly affected dogs include poodles, Yorkshire terriers, schnauzers, cocker spaniels and small mixed-breeds. Some breeds, such as Cavalier King Charles spaniels, can be affected early in life.
VHD can affect a dog causing valve malfunction, which can lead to heart enlargement or heart failure with accumulation of fluid in the lungs (pulmonary edema) or the abdomen (ascites).
What to Watch For
Signs of Chronic Valvular Heart Disease in dogs may include:
- Difficulty breathing
- Exercise intolerance
Diagnosis of Chronic Valvular Heart Disease in Dogs
Veterinary care should include diagnostic tests and subsequent treatment recommendations. Diagnostic tests are needed to recognize VHD, and exclude other diseases, including:
- Complete medical history and physical examination including auscultation (listening with a stethoscope).
- Chest X-rays
- An electrocardiogram (EKG), which is a record of the heart’s electrical action
- An echocardiogram (ultrasound) can confirm the diagnosis
Treatment of Chronic Valvular Heart Disease in Dogs
Treatments for VHD may include one or more of the following:
- Diuretics such as furosemide (Lasix)
- Angiotensin inhibitors such as enalapril (Enacard) or benazepril
- Positive inotropic drugs (increase contractions of cardiac muscles) such as digoxin (lanoxin)
- Sodium (salt) restricted dietNOTE: Treatment or therapy is not consistently prescribed for mildly-affected dogs.
Home Care and Prevention
Administer any prescribed medications and observe your pet’s general activity level, appetite and interest. Watch your dog for labored breathing, cough or intolerance. If possible, learn to take a respiratory (breathing) rate when your dog is resting (ask your vet about this).
VHD is often a progressive disease and cannot be prevented. Regular veterinary examinations that include examination of the heart with a stethoscope can identify it in its earliest stages.
In-depth Information on Canine Chronic Valvular Heart Disease
Chronic valvular heart disease is the most important heart disease in dogs. Many breeds are affected, especially smaller breeds. Most aged dogs have some degree of valvular degeneration (called endocardiosis), however, only those with substantial valve disease develop heart symptoms. This condition is a degenerative condition, probably predisposed by genetic factors. It is not caused by an infection or related to bad teeth (though this is a common misconception).
The essential valvular abnormalities are either increased “floppiness” of the mitral valve in the heart, or more often, shortening and thickening of this valve. The tricuspid heart valve is also affected in some dogs. The degeneration causes the valves to close improperly. Leaking of the valve causes blood to move backwards creating a heart murmur and limiting the amount of blood that can be pumped to the body. Severe leaking can occur when one or more of the fine strands that support the valve (the chordae tendineae) rupture.
A percentage of dogs with chronic mitral disease develop a condition called pulmonary hypertension, which is high blood pressure in the arteries of the lung. These dogs often develop fluid accumulation in the abdominal cavity and are prone to bouts of weakness or fainting.
The consequence of moderate to severe valvular heart disease is typically congestive heart failure. The symptoms of heart failure include exercise intolerance, breathing difficulties or coughing and obvious fluid accumulation in the chest cavity or the abdomen.
Mild cases of chronic valvular disease do not limit the dog, but severe cases cause heart failure and can be lethal.
Other medical problems can lead to symptoms similar to those encountered in valvular heart disease. It is important to exclude these conditions before establishing a definite diagnosis:
- Congenital heart disease (birth defects of the heart)
- Cardiomyopathy (heart muscle disease, common in dogs)
- Pericardial disease (fluid accumulation around the heart)
- Bronchitis (inflammation of the bronchial tree, similar to chronic “smoker’s cough”)
- Lung diseases (a variety of diseases of the lung, including pneumonia and lung cancer)
- Heartworm disease
- Pulmonary fibrosis (scarring of the lung)
Veterinary care should include diagnostic tests and subsequent treatment recommendations.
Diagnosis In-depth of Chronic Valvular Heart Disease in Dogs
Diagnostic tests may be needed to recognize chronic valvular heart disease and exclude all other diseases, including:
- Complete medical history and physical examination. Special attention is paid to auscultation (stethoscope examination) of the heart. Heart murmurs, abnormal heart sounds, and irregular heart rhythms may indicate a problem with the heart.
- Thoracic radiographs (X-rays of the chest) can identify heart enlargement and fluid accumulations in the chest. Chest X-rays can also be useful in excluding a number of other diseases.
- An electrocardiogram (EKG) is often abnormal in dogs with serious heart disease, it can be normal in some dogs with heart disease.
- Arterial blood pressure measures hypertension (a complicating disease) or low blood pressure.
- An echocardiogram (ultrasound examination of the heart) is the diagnostic test required for establishing the diagnosis of VHD and is especially useful when the diagnosis is in doubt. Important examination issues include the severity of valvular changes, the size of the heart, and heart muscle function. This examination often requires referral to a specialist.Additional diagnostic tests may be recommended on an individual basis:
- A complete blood count (CBC). This blood test may be needed to identify anemia or other problems such as infection or inflammation.
- Serum biochemistry tests. These blood tests are especially important if there is heart failure or complications in other organs.
- Thyroid function tests are necessary if there is evidence of hyperthyroidism.
- Urinalysis. This urine test may be recommended to better evaluate the kidneys and bladder.
Treatment In-depth of Chronic Valvular Heart Disease in Dogs
Treatment for chronic valvular heart disease may include one or more of the following:
- Treatment of canine valvular heart disease must be individualized. It is based on the severity of the condition and other factors that must be analyzed by your veterinarian. If your dog has only mild or moderate valvular heart disease without symptoms, no treatment is currently recommended or proven beneficial. In this situation, regular follow-up visits to your veterinarian are important to detect disease progression that might prompt treatment. Once heart failure develops, medications are dispensed to improve the heart function, reduce the regurgitant blood flow, and control fluid retention.
- If congestive heart failure does occur, initial hospital treatment may include oxygen, diuretics (furosemide) and possibly vasodilator medications such as nitroglycerine, nitroprusside, or hydralazine. Hospitalization is mandatory in cases of severe valvular heart disease associated with uncontrolled fluid accumulation in the lung or chest cavity (congestive heart failure), abnormal heart rhythms (arrhythmias), kidney failure or hypotension (low blood pressure).
- Chronic home therapy of heart failure caused by mitral regurgitation includes a diuretic to prevent fluid retention, dietary modifications, such as a sodium-restricted diet, and an angiotensin converting enzyme inhibitors such as enalapril (Enacard) or benazepril (Lotensin). The ACE inhibitors reduce the activity of harmful hormones and minimize salt (sodium) retention. Advanced heart failure is also treated with digoxin, a drug that increases heart muscle contraction and helps restore balance in the autonomic nervous system. A cough suppressant may be needed if there is mechanical compression of the bronchus by the left atrium.
Follow-up care for Dogs with Chronic Valvular Heart Disease
Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical. Administer prescribed medications as directed, and be certain to contact your veterinarian if you are experiencing problems treating your pet. Remember: Inability to medicate is a common reason for treatment failure. Follow-up veterinary care for valvular heart disease often includes the following recommendations:
- Observe your dog’s general activity level, appetite and interest. These are quality-of-life issues of importance to you and your dog.
- Watch your dog for labored, rapid breathing or coughing.
- If possible, learn to take a respiratory (breathing) rate when your dog is resting (ask your veterinarian about this). Schedule regular veterinary visits to monitor the condition.
- Chest X-rays may be needed to monitor of your pet’s response to therapy, especially when there is fluid accumulation in the chest cavity.
- Blood samples should be checked periodically to monitor the effect of drugs on the kidneys and blood chemistries (such as potassium).