Canine Mitral Valve Disease Symptoms

Canine mitral valve disease is by far the most common cause of heart failure in dogs. Heart failure can occur in dogs of every age, but it is increasingly common in elderly dogs. When younger dogs are diagnosed with canine mitral valve disease, it is generally the result of a congenital defect which affects the overall function of heart. In elderly dogs, however, it often occurs as the result of overuse and weakening caused by age. Identifying and recognizing the symptoms of canine mitral valve disease are the keys to increasing the dog’s longevity and prognosis.

Function of the Mitral Valve

In order to understand the etiology of canine mitral valve disease, it is important to first understand the function of the mitral valve within the cardiovascular system. The heart is responsible for receiving blood from the body, sending blood to the lungs for oxygen, and then pumping blood to the organs of the body. Essentially, the heart is a pump that works to keep the dog’s body alive and functioning. 

Within the heart are four valves which work to ensure that there is no backward flow of blood. The strongest of these valves is known as the mitral valve, which is located between the left atrium and left ventricle where oxygenated blood is received from the lungs.  Because the left ventricle receives the most pressure as it contracts and releases blood to the body, the mitral valve must be strong enough to resist this pressure and maintain the forward movement of blood.

Canine mitral valve disease occurs when, either by congenital defect or age, the mitral valve is becomes too weak to withstand the pressured contractions of the left ventricle. This result is the backward flow of blood into the left atrium by a faulty mitral valve.

Signs and Symptoms of Mitral Valve Disease in Dogs

Canine mitral valve disease is a form of heart disease, and the condition can be life-threatening to dogs. It is imperative that dog owners be cognizant of the signs of canine mitral valve disease so that proper treatment can be sought.

Signs and symptoms can include:

  • Persistent hacking cough
  • Gurgling cough upon awakening
  • Shortness of breath with activity
  • Decreased stamina during normal activities

Canine mitral valve disease causes elevated pressures within the lungs and heart. With elevated pressure in the lungs, fluid begins leaking into the tissues of the lungs. This is known as pulmonary edema. The cough that dogs have at the onset of mitral valve disease is caused of excess fluid within the lungs. Often times the sound of this cough resembles that of a regular head cold.

As the disease progresses, however, the heart muscles become extremely weak as they try to compensate for the dysfunction within the mitral valve. When the heart muscles weaken, the dog will lack the energy stamina needed to partake in normal activities. Additionally, the lack of oxygenated blood will cause increasingly severe shortness of breath.