Valvular Heart Disease in Dogs

Canine valvular heart disease is characterized by degeneration and thickening of the heart valves. This is a progressive disease found in older dogs and affects breeds such as:

  • poodles
  • cocker spaniels
  • Yorkshire terriers
  • Lhasa Apsos
  • Chihuahuas
  • toy poodles
  • Cavalier King Charles spaniels

Chronic valvular heart disease is the leading cause of heart failure in dogs and affects 20 to 40 percent of the canine population.

The Canine Heart

Dogs have 4 chambered hearts consisting of 2 upper chambers namely the right and left atrium and 2 lower chambers, termed as the right and left ventricles. The left atrium receives the purified blood from the lungs and the right atrium receives the impure blood from the body. The left ventricle pumps the purified blood to the rest of the body through the aorta and the right ventricle pumps the impure blood to the lungs through the pulmonary artery.

The heart also has 4 one-way valves that keep the blood flowing in the correct direction. The mitral valve connects the left atrium to the left ventricle and the tricuspid valve connects the right atrium to the right ventricle. While the aortic valve is responsible for regulating the flow of blood from the left ventricle into the aorta, the pulmonic valve is responsible for blood being pumped into the pulmonary artery from the right ventricle. Since the mitral valve is the most fragile of these 4 valves, it undergoes a lot of wear and tear.

Canine Valvular Heart Disease

This disease is caused due to degenerative changes in the heart valves when the sides of the valves become thick and distorted. As a result, the free edges can’t make contact when the valve shuts. Hence, some blood is pushed back into the atrium when the ventricle contracts. The atrium then enlarges because of the extra volume of blood. Apart from this, the cords that attach the valve to the heart often get worn out. If the cords rupture, that part of the valve is rendered useless.

Although the mitral valve is affected in most case the tricuspid valve is involved in a third of the cases. Cardiac function is impaired due to the malfunction of these valves. To compensate, the heart pumps harder, resulting in an increase in the size of the heart over a period of time. This can lead to congestive heart failure with fluid in the lungs or abdomen.

Symptoms of Canine Valvular Heart Disease

  • Difficulty in breathing or rapid breathing
  • Fainting
  • Coughing
  • Fatigue
  • Loss of appetite
  • Intolerance to exercise
  • Pale gums
  • Rapid and weak pulse 
  • Heart murmur heard through a stethoscope

Diagnosis and Treatment of Valvular Heart Disease

The vet will confirm diagnosis after performing various tests such as the EKG, ultrasound and chest X-rays. Angiotensin inhibitors such as enalapril or benazepril are generally prescribed in conjunction with diuretics such as furosemide or drugs that increase heart muscle contractions. Your pet should also be put on a salt free diet.

For proper management and control of this progressive disease, early detection is important. It is also essential that your pet is regularly checked by a vet.