Mitral valve disease is the most common heart disease diagnosed in dogs, normally affecting smaller to medium breeds in their middle-age or geriatric years.
Many dogs don’t show any symptoms in the early stages of the disease.
One of the very early signs is a heart murmur that your vet may pick up with a stethoscope during their routine health check
Treatment involves monitoring and lifelong medications. While we can’t cure the disease, if we detect it early enough we can use medications give your dog a longer and happy life.
What is mitral valve disease?
The heart has four chambers. Blood should flow in just one direction from the left side of the heart, into the lungs to pick up oxygen, then to the right side of the heart, and the it is pumped to the rest of the body to deliver the oxygen.
Heart valves prevent the blood from flowing backwards. The mitral valve is a small flap between the two chambers in the left side of the heart. This valve can degenerate or ‘wear out.’ This means the valve no longer provides an effective seal and so it allows blood to leak backwards in the wrong direction, otherwise known as ‘regurgitation.’ Over time, this regurgitation becomes more severe, and eventually leads to heart failure.
What are the symptoms of mitral valve disease?
When the disease is mild, most dogs will not show any clinical signs of mitral valve disease. Instead, your vet may pick up an abnormal heart sound caused by turbulent blood flow- a heart murmur- on routine examination. It may take month or years for the disease to progress to congestive heart failure (CHF). However, as CHF develops, you may begin to notice the following signs:
Tiring on activity
Difficulty breathing or excessive panting
Swelling in the abdomen
How is mitral valve disease diagnosed?
A heart murmur is often picked up on your pet’s annual health check. Your vet may recommend follow up blood tests and/or imaging. proBNP is a very clever blood test that allows us to decide which patients already have some heart changes and need further investigations. The heart is a muscle and like any muscle that’s working hard, it gets bigger. When it gets bigger, it leaks something called proBNP into the blood which we can detect by taking a small amount of blood from your dog’s vein.
Diagnostic imaging plays an important role in establishing exactly what is going on with your dog’s heart. It usually involves an echocardiogram (ultrasound of the heart), and/or chest x-rays.
Other tests that might be recommended are further blood tests, urine tests and blood pressure checks, just like we have when we visit the doctor.
Once we have all these results, we fit all the pieces of the puzzle together to give us the full picture and that lets us decide what medications, if any, are needed.
What is the treatment for mitral valve disease?
Treatment for mitral disease is not a one size fits all approach. Your vet will consider lots of factors such as how advanced the mitral valve disease is and whether your dog is showing signs of heart failure. The aim of treatment is to improve heart function, minimising clinical signs and maximising quality of life. The medications we need to use are lifelong, and as time goes on doses may need to be adjusted or new medications added. The most common medications include:
Pimobendan to improve how well the heart pumps, heart muscle strength, and lower blood pressure.
ACE-inhibitors, such as benazapril, to help to lower blood pressure, taking taking pressure off the heart.
Diuretics to relieve fluid build-up in the chest. The most commonly used diuretics are called frusemide and spiranolactone.
How long will my dog live for?
A prognosis is the likely course or outcome of a medical condition. The prognosis of mitral valve disease depends on how early in the disease we can diagnose it. If we pick this disease up and start treating at the heart murmur stage, before the signs of heart failure appear, the your dog may live many years happily and healthily.
However, as congestive heart failure develops, the prognosis becomes less favourable. In most studies involving dogs that have developed mitral disease which has progressed to heart failure, sadly only 50% survive beyond 10 months, and 20% beyond 18 months. This makes it vital to keep up with regular monitoring and make little lifestyle adjustments that can make the world of difference to your closest companion.
If your dog is coughing or has less energy than usual, it's important to get this checked out quickly as it could be signs of heart failure. If your dog has recently been diagnosed with heart failure, book a consultation with one of our friendly vets to learn more about the ongoing management.