Heart disease is very common in middle-aged to older dogs and is often known as ‘the silent killer’. Without regular check-ups the early signs of heart disease can go unnoticed, making it harder to treat when it finally shows. We’ll check your dog’s heart at the annual vaccination, but if you have an older dog it is always worth booking check-ups every six months to make sure we’re keeping a close eye out for any issues.
There are several diseases that can affect a dog’s heart. Some occur from birth, just as in people, but the most common types show up in older age. Mitral Valve Disease is the most common heart condition of dogs – it affects about 1 in 25 of our fluffy friends across all age brackets, and 85% of dogs over 13 years of age. It is more common in smaller breed dogs (those under 20kg) and some breeds are more likely to get it than others. Cavalier King Charles Spaniels are very prone to it, but Yorkshire Terriers, Jack Russell Terriers and small crossbreeds are also over-represented. Mitral Valve Disease may also be called Canine Chronic Mitral Valvular Disease or Myxomatous Valve Degeneration.
Mitral Valve Disease occurs when the valves in your dog’s heart start to fail in old age. The mitral valve is a one-way valve that sits inside the heart, ensuring that when the heart pumps blood it all moves the right way out of the heart and around the body. Of all the valves in the heart, the mitral valve is possibly the most important and takes a lot of force every time your dog’s heart beats. Due to the aging process and other diseases, over time the mitral valve becomes warped and doesn’t fit snugly which results in a leaky valve – every time the heart pumps, a small amount of blood escapes backward.
This has two consequences. One: less blood makes it out of the heart, meaning the body has to cope with a little bit less at each beat; and two: the backflow of blood means that there’s too much blood in the previous heart chamber, causing higher pressure and damage to the chamber. At the next beat the heart must try to get rid of the extra blood, but again a small amount leaks backwards, so it never quite catches up. To make up for this the heart beats a little faster and like any muscle, it grows bigger as it works harder – a process called remodelling.
So what signs might you see? The backflow of blood through the leaky valve results in your dog being unable to exercise as they used to because their heart is not pumping as well. They might go for a short walk before giving up, or give up halfway through play. They may pant more than previously, even after only minor exercise, or they might develop a cough as the larger heart begins to cause irritation. Any of these signs are a real concern and we recommend that you call us to book an appointment the same day if at all possible.
Luckily, the sound of blood moving the wrong way through the heart is easy to hear with a stethoscope in most dogs with Mitral Valve Disease. We call this a heart murmur and it can often be heard long before there are any obvious changes in your dog’s behaviour. This is why it is so important to bring your dog in to us for his or her annual check over. It might not look like much, but we’re trying to pick up these changes early before they become a problem.
If we suspect a heart condition in your dog, we will advise some further tests. There is a blood test that has been linked to heart disease, and we use this to find whether a heart murmur is causing any stress to the heart. We might also want to take chest x-rays or ultrasound your dog’s heart to look for changes in size and shape caused by the leaky valve. Each case is different, but we will give you all of the options and advise you as to the best course of investigation for your dog.
Once we know exactly what is going on and how much damage has been done, we will suggest medications for your dog. There are lots of different types of medication designed to increase the heart’s pumping ability, reduce your dog’s blood pressure, and reduce the fluid build-up on the lungs. It is likely your dog will need to take medication for the rest of their life, and once a heart problem has been diagnosed, we will want to see them regularly – at least every three months and often more frequently. Unfortunately, most cases of mitral valve disease are life-limiting, especially once they start to show symptoms at home.
Modern medicine, early diagnosis and simple, easy-to-give medications mean that Mitral Valve Disease is not the heartache it used to be. If you’re worried your dog might have heart disease, or you know a relative of your dog had heart disease, it’s worth getting it checked out, so give us a call and book an appointment with one of our vets. Remember: we check for signs of heart disease at your annual vaccination appointment, but if for any reason you have missed this it’s best to get booked in, even if your dog seems healthy.