Small Dogs

Mitral Valve Disease (MVD)

Mitral Valve Disease (MVD) is the most common form of acquired heart disease in dogs. It generally occurs in small to medium size dogs rather than big dogs. There seems to be a genetic predisposition to the development of disease as some breeds are more susceptible than others. These include: Cavalier King Charles Spaniel, Poodle, Schnauzer, Chihuahua, Fox Terrier and Boston Terrier.

Male dogs are more commonly affected than females and it is mostly older dogs who tend to show signs of this disease but young dogs can be affected too. MVD is a disease affecting the surface of the heart valves. Other names you may hear used to describe MVD are endocardiosis or Valvular Insufficiency.

Fox terrier running in field

In MVD, the heart valve(s) gradually become thickened, lumpy, distorted and leaky, so that when the ventricle pumps, some of the blood flows backwards into the atrium.This backward flow creates a noise that your veterinary surgeon can hear with a stethoscope. This noise is called a murmur. Vets often grade a murmur depending on how loud they are compared to the normal sounds when the heart beats.

Normal Heart Beat

Murmur Heart Beat

Because the heart valves are now leaky, circulation becomes impaired.

Eventually, MVD progresses and the disease overrides the adjustments that have been made. With time, your dog can become unwell and show signs of heart failure. MVD may affect your dog’s body in a number of different ways.

How do I recognise MVD in my dog?

Congestive Heart Failure

Signs of heart failure can initially be quite mild and so may be difficult to pick up. However, as the disease progresses, the signs can become more severe as the heart’s function deteriorates. This stage is known as congestive heart failure, when the heart is no longer able to pump sufficient blood around the body.

These signs occur because of fluid build up or because the vital organs are not supplied with enough blood, and therefore the oxygen, they require. Signs include:

  • Reduced ability to exercise
  • Coughing
  • Difficulty in breathing or a change to breathing rate
  • Lack of energy or depressed appearance
  • Poor appetite
  • Weakness
  • Anxiety and restlessness during the night
  • Fainting

How is MVD Diagnosed by my Vet?

Cocker-poo with vet


Regular veterinary visits are very important for early detection of heart disease and to monitor the treatment of a dog with heart disease.

When your vet examines your dog, they may find signs relating to heart disease and congestive heart failure. Listening to your dog’s heart with a stethoscope will allow a vet to pick up a murmur if it is present. The heart rate and rhythm can also be assessed using a stethoscope. Your vet may also detect harsh sounds when listening to the lungs.

The vet may also pick up other signs that your dog’s heart is not working well such as fluid in the abdomen and poor pulses. Your vet may also recommend further tests to help determine the cause of your dogs problem.

These may include:

Blood tests

Blood tests may be recommended to check your dog’s health to see if they are suitable for medication and to check that the rest of their body is healthy.


X-rays are very useful to assess your dog’s heart and lungs. Commonly when a heart is having problems it will get larger and fluid may build up on the lungs. Both of these can be detected with x-rays.


This is an ultrasound scan of the heart and can be used to assess the heart whilst in action. The heart’s walls, chambers, valves and blood vessels can be accurately observed in 3D. Whilst ultrasound is the most accurate method of diagnosing heart disease, it may not be necessary in some of the more straightforward heart disease cases.


Electrocardiograms (ECGs) can record the electrical activity of the heart and can be used to diagnose rhythm problems. These problems are more common in heart muscle disease (DCM) than in heart valve disease(MVD).