Pet Owner information
Leaky heart valves are common as dogs age. Some dogs need treatment and some don’t. This information guide will help you to understand what is going on, what to watch out for and what treatment may be required.
What is Mitral Valve Disease?
Leaky heart valves affects most smaller breed dogs as they get older. Most commonly it is the mitral valve (the main valve on the left side of the heart) that is affected and we therefore call it Mitral Valve Disease (or MVD). There are various names used for MVD such as Myxomatous Mitral Valve Disease and Endocardiosis, they all mean the same thing.
Heart valves are one-way valves; they open to allow blood to move forwards through the heart, then close to stop blood from leaking backwards. As a dog ages so does the heart valve, it gets knobbly and irregular and allows some blood to leak backwards even when the valve is shut. This backwards leak of blood creates the “whoosh” that we hear using a stethoscope and this is what we call a “heart murmur”. As the leaking worsens, the heart murmur will usually get louder. Over time, the heart also starts to enlarge to help cope with the back flow of blood.
How do we diagnose MVD?
We can be fairly confident your dog has MVD by listening to their heart carefully with a stethoscope. However in order to properly diagnose MVD (and more importantly, to see if they need treatment), we recommend some tests.
Echocardiogram
The most common (and safest) test is an ultrasound scan of the heart (called an echocardiogram, or “echo”). This is usually performed consciously and is just like a pregnancy scan in people. If your dog is nervous, then we may recommend some medicines to help reduce stress before coming to the practice, or we may give some medicines whilst your dog is in the practice for the scan. To preform the echocardiogram we will need to shave some small squares of fur from either side of your dog’s chest.
X-Rays and ECG
In addition to an echo, we may also need to do some other tests, including an ECG (looking at the heart rhythm), chest X-rays (this will usually require some light sedation) and blood tests.
Does my dog need treatment?
Good news, most dogs with MVD don’t need any treatment at all. We recommend regular monitoring (every 6-12 months) to monitor and assess if the leak is getting worse. If we find from the ultrasound scan that your dog does need treatment, then we typically start a medication called pimobendan (the drug name is Vetmedin or Cardisure). Pimobedan improves the hearts ability to cope with the leaky valve and is proven to help dogs with MVD live not only longer but happier lives. Pimobedan is given twice a day (spread out evenly so for example 7am and 7pm). The medication is best given on an empty stomach (at least one hour before or after food) thankfully the tablets are very Tasty!
What happens as MVD gets worse?
Most dogs with MVD live normal lives and don’t show any symptoms of the leaky valve. But as the heart enlarges -to help cope with the leak - some dogs will develop problems. Most commonly, fluid building up in the lungs. This fluid will make your dog breath more heavily and struggle to exercise. You may notice your dog breathing more quickly at rest as well as exercise, and you may notice more effort in the breathing too. As there is fluid in the lungs, this can be a serious problem, ultimately resulting in severe difficulty breathing. If you notice this, then it is important to make an urgent appointment to see your vet. The good news is, there is treatment to clear the lungs of fluid and get the breathing back to normal.
It’s important we know if there is fluid in the lungs - we may perform an ultrasound scan or chest X-rays to confirm this. We would then add in extra tablets, usually diuretics (“water tablets”). These will help get rid of the excess fluid; the body does this by weeing out the excess fluid. To compensate, your dog will drink more water (this is normal). These medications will continue for life, although we will vary the dose depending on how your dog is doing. Frequent check ups are required in order to make sure the medications and the doses are correct. You should make an appointment earlier if you notice your dog not doing as well.
These medicines work very well to help your dog feel better. Of course, over time, the leaky valve continues to get worse and at some stage the amount of fluid in the lungs will continue to get worse despite the treatment. If we cannot make your dog feel better, then this is when we would discuss what your dog’s quality of life is like and whether we should discuss euthanasia before they start to suffer. For more challenging cases, or if you want more advice, your vet may recommend an appointment with a Cardiologist (either in your practice, or by visiting a Specialist hospital).
Some dogs will cough as they get older. Most commonly this is due to underlying lung problems (eg inflammation and/or collapse of the airways). We may need to perform X-rays (and sometimes other tests) to help us understand what the causes are and help us treat it.
Checking breathing
As fluid in the lungs makes breathing more difficult, then your dog’s breathing will get faster and often deeper. As such, a great, cheap and accurate way of monitoring your dog is by checking their breathing rates. This is best done when they are sleeping (as breathing rates increase when they are awake, and even more so when they are excited/exercising). Try and do this at the same time each day, when your dog has been asleep for 20 minutes or so.
Count how many times your dog’s chest rises in 30 seconds (note that your dog’s chest will move up once and down once in each breath) - double your number to get a breathing rate per minute. In most dogs, a normal rate is less than 20 breaths per minute. We get concerned if the rate is above 30 breaths per minute. Any dog will occasionally have a rate over 30 breaths per minute (eg if they are dreaming, or really hot). Dogs with CHF tend to have a gradual increase in their breathing rates over a number of days, and this is sustained. If your dog’s breathing rate is consistently over 30 breaths per minute, then you should contact your vet ASAP. This may have to be an urgent or emergency appointment if you are concerned. There is also a free app you can download on your phone (search "Cardalis") to help you measure and record the breathing rates; you can then show these to your vet at recheck appointments.
Are there operations which can help?
Until recently, MVD was controlled when necessary using medicines. Modern medicines are very good at improving quality and quantity of life. But they do not stop the valve from being leaky and getting worse over time. More recent advances means that a couple of Specialist veterinary hospitals in the UK can now offer surgical treatments for MVD - just like in humans. They are expensive procedures (also just like in humans!), costing between £12,000 and £25,000 depending on the operation performed. They are showing some very good results of reducing the leaky valve, reducing heart size and importantly often reducing or stopping the need for medicines.