The common causes of heart disease in dogs

heart disease in dogs

It’s estimated heart disease affects around 10% of all dogs, with the most common cause of heart disease in dogs being mitral valve disease (MVI).

Mitral valve disease

This condition involves  the degeneration of the mitral valve that separates the chambers in the heart, and can eventually lead to heart failure.

Dogs may develop a heart murmur from a leaking mitral valve as early as four to six years of age. Initially, MVI is asymptomatic (produces no obvious clinical signs). As time progresses, the regurgitation becomes more severe and as more blood flows back into the atrium, the heart’s efficiency is reduced.

It is more common in older dogs, in particular small breed dogs such as Cavalier King Charles Spaniels, Miniature poodles, Shih Tzu, Maltese, Chihuahua, Cocker Spaniels, Miniature Schnauzers, Dachshunds, Whippets, and Pomeranians.

However, this disease can still also be seen in some larger breeds and mixed breed dogs.

Prevention and treatment of MVI

While there is no way to prevent mitral valve disease, early diagnosis and treatment may help to significantly prolong and improve a dog’s life.

A regular veterinary examination is essential, so your vet can listen to your dog’s heart and check for an abnormal heart sound called a murmur – this is often the first sign there might be a problem.

These heart health checks should occur at least once a year, and just part of the standard annual health check and vaccination that is recommended by most vets.

It is not usually feasible in dogs to perform surgery on a leaky heart valve so the treatment usually involves medication to improve a dog’s heart function.


Another less common, but important cause of heart disease in dogs are heartworms.  Infestation with heartworms can lead to severe disease and even sudden death.

Heartworm disease is an infectious condition that can occur in dogs of any age.  Dogs become infected with heartworm when they are bitten by an infected mosquito.

It is more common in the warmer months and the north of the country, however cases have been reported throughout mainland Australia. Even with the best of intentions, mosquitos sometimes make it into our houses, so even indoor animals are at risk.

Heartworm prevention and treatment

In the case of Heartworm, prevention really is better than cure. Treatment for it is not only costly and difficult, but the drug required to treat heartworm infestations can have complications.

Even after the worms have been killed, the dog has to be closely monitored because after the worms are dead, they may cause blockages and other serious problems such as breathing difficulties and even an anaphylactic reaction.

Some dogs may even require surgery to remove all of the worms from their heart chambers and could be left with permanent heart damage.

Heartworm disease is entirely preventable and protection is easier than ever.

Unfortunately though, there are still many people who are unaware of how dangerous the heartworm can be and don’t check if their dog is protected from it with their monthly treatments, so check the pack and again talk to your vet if you are unsure.

Check out the NexGard SPECTRA website for their flea and parasite monthly chew that protects your dog from heartworm disease, as well as fleas, ticks, mites, and intestinal worms.

Or to purchase NexGard SPECTRA from PETstock and earn Member Rewards Brand Cashback, click here.

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