Mitral Valve Disease in Dogs
Added on 16 November 2017
Mitral valve disease (MVD) is the most common heart disease in dogs.
The disease is encountered in all breeds, although it is most common in small to medium-sized dogs. In MVD, the valve between the two chambers on the left side of the heart becomes thick, lumpy, distorted and leaky. With each heartbeat, blood is forced through the damaged valve in the wrong direction. MVD is a progressive disease that gets worse over time.
The Clinical Signs of MVD are graded:
- Stage A - No heart disease detected
- Stage B1 - Heart disease present without any change to heart size
- Stage B2 - Heart disease present with increase in heart size but with no signs of congestive heart failure
- Stage C - Heart disease with increased heart size and congestive heart failure
A dog with a leaky, damaged mitral valve can live for many years without showing any symptoms apart from a heart murmur. However, for many dogs, the leak gets worse over time. As more blood flows the wrong way through the heart, the murmur gets louder and more pressure is put on the heart. To compensate, the heart must grow larger and pump harder. Eventually, there comes a point when the heart cannot cope with the additional strain any longer and fails to pump enough blood around the body. This is known as heart failure.
Signs of heart failure include:
- Increased breathing rate
- Difficulty exercising
- Difficulty breathing
Exciting new developments in the treatment of MVD
Until recently no benefit could be proved in treating before signs of heart failure became evident (congestive failure). Therefore, all we could do was monitor small-breed dogs with murmurs and start treatment when signs were noticed. However, an excellent new study has clearly shown that once in any heart enlargement is detected, treatment with a drug called Pimobendan can markedly improve the overall survival time of dogs with MVD (by up to 15 months!). These findings will be greatly beneficial for both pets and their owners.
How do I know if my dog may benefit from this treatment?
If your vet detects an acquired murmur with an intensity of at least grade 3 out of 6 then it is likely that an echo examination would be beneficial in determining the stage of disease. You will be advised to book an appointment to see our cardiologist with a view to at least an echo examination.
Sometimes it transpires that the patient is not yet at Stage B2 so a follow-up examination should be performed after a number of months. If Stage B2 disease is diagnosed then it is likely that treatment will be advised in order to take advantages of the associated benefits in quality of life and longevity.