General Information
Chronic degenerative valve disease (CVD) is a progressive degeneration of the valves in the heart (primarily the mitral valve) that results in thickening of the valve leaflets and a valvular leak that eventually causes heart enlargement and signs of heart failure. In general, this is seen more frequently in small breed dogs, with up to 75% of small breed dogs showing evidence of CVD by 7 years of age. Certain breeds, such as the Cavalier King Charles Spaniel and Dachshund are predisposed, and may even present at a younger age.
Diagnosis
The first sign of CVD is typically a murmur heard by your veterinarian on a routine examination. The murmur is caused by the turbulent blood flow as blood leaks backwards across the affected valve. Once a murmur is heard, thoracic radiographs are taken to evaluate for heart enlargement and evidence of congestive heart failure (fluid in the lungs or abdomen). The next step is referral to a cardiologist for an echocardiogram (ultrasound of the heart) to evaluate for specific heart chamber enlargement, to evaluate heart function, and to evaluate for other complications or sequelae of CVD. Other diagnostics, such as a blood pressure or blood work may be recommended to further evaluate for other concurrent diseases or factors which may complicate management of CVD.
Complications and Sequelae
The progression of the disease is variable in each dog and should be monitored on a regular basis, which in the asymptomatic stages means periodic thoracic radiographs to evaluate for progressive heart enlargement. Over time (which is often months to years), signs of heart failure may develop. These signs include cough, difficulty breathing, weakness, lethargy, exercise intolerance, and collapse. Less commonly, abdominal distension from fluid build-up in the abdomen may occur.
Coughing due to compression of the major airways (mainstem bronchi) may result when heart enlargement is severe, without evidence of heart failure.
Pulmonary hypertension (PH), or high blood pressure in the lungs, may develop secondary to mitral valve disease. PH is best controlled by managing the underlying valvular disease. Medications can be added in if the PH increases in severity resulting in more pronounced clinical signs including exercise intolerance and collapse.
Treatment
In the asymptomatic stages of CVD, treatment is often not indicated unless there is severe heart enlargement. Diet changes and exercise restrictions are also often not indicated, other than high sodium diets and treats are discouraged.
Prognosis
CVD is a progressive disease. With careful monitoring, appropriate medical therapy can be implemented earlier in hopes of prevent rapid decline into severe heart failure. This way, we can hopefully limit visit to the hospital or emergency room, and keep your pet feeling as good as possible for as long as possible.
If your pet begins to show any signs of cough, breathing difficulty, abdominal distension, exercise intolerance, or collapse, he or she should be evaluated sooner. Please call us if any of the above clinical signs become apparent.
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