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Heart disease in large dogs

Our dogs have big hearts. But, sometimes they become too big…

We love our dogs for their big personalities and big hearts, but sometimes their hearts can become a little too big. An enlarged heart can be a sign of heart disease and unfortunately it can lead to heart failure.

One in ten dogs have heart disease.1 Large to giant-sized dogs, from middle-age onwards, are prone to a type of heart disease known as dilated cardiomyopathy or DCM for short. DCM accounts for around 10% of heart disease in all dogs and can progress to heart failure very quickly.2

The risk of developing DCM increases dramatically as dogs get older. But early diagnosis can give your dog the best chance of a longer, happier life. Find out more below.

What is DCM?

Your dog’s heart pumps blood, carrying oxygen and nutrients to its organs. But DCM causes the heart to become stretched, floppy and enlarged, making it weaker and less efficient.

DCM gets worse very quickly, causing irreversible damage to the heart. Eventually, the heart can become so inefficient it’s no longer able to pump enough blood around the body, and this leads to heart failure.

The exact cause of DCM is usually unclear, but certain breeds are more likely to develop it, especially larger dogs. For example, up to half of Dobermans go on to develop DCM in their lifetime.3

Heart screening for your dog

If you aren’t checking for DCM, you won’t know it’s there. That’s why regular heart screening is so important. Your dog could live with DCM for many months or years and not show any symptoms at all – they are likely to appear as though they are in perfect health.

This is referred to as the ‘asymptomatic’ or silent’ phase of DCM. In fact during this time, your dog’s body is merely compensating for the disease while their heart is slowly getting worse.

In some cases, your dog could show some very subtle signs of DCM, such as a reduced tolerance for exercise, changes in their resting breathing rate or some abnormal heart sounds detected by your vet. But asymptomatic DCM is very hard to spot and in the majority of cases, dogs will appear perfectly normal.

Symptoms of heart failure

As the disease progresses, the heart becomes so weak and inefficient that it is unable to pump blood around the body which results in heart failure. At this stage the symptoms are much more obvious. Signs of heart failure include:

  • Increased<br>breathing rate

    breathing rate

  • Tiredness


  • Difficulty<br>exercising


  • Difficulty<br>breathing


  • Fainting/<br>collapse


If you recognise any of these symptoms in your dog, please speak to your vet urgently.

How can you help?

The good news is that something as simple as a regular heart screen by your vet can help spot the early signs of the disease, before symptoms are even visible. Detecting heart disease early is vital to prolong your dog’s quality of life.

One of the ways that your vet can screen your dog to check if they have DCM is by a simple blood test. Measuring a substance in the blood called proBNP can help determine whether a dog is likely to have DCM, even in the asymptomatic stage when no symptoms will be present.

If your dog has a raised proBNP level your vet may recommend further tests including a heart scan (heart ultrasound) or an electrocardiogram (ECG) where they’ll be able to look at their heart in more detail and check its rhythm.

By diagnosing and treating these diseases early, it’s possible to:

  • Slow the disease progression
  • Extend your dog’s symptom-free time by delaying the onset of heart failure
  • Improve your dog’s quality and length of life

At-risk dogs should have regular check-ups, at least once a year.
Is your dog due a check-up?

  1. Atkins C, Bonagura J, Ettinger S, et al. Guidelines for the diagnosis and treatment of canine chronic valvular heart disease. J Vet Intern Med 2009; 23(6):1142–1150.
  2. Texas A&M University. Small Animal Clinical Sciences: Cardiology Service. College of Veterinary Medicine & Biomedical Sciences. Available at: cardiology-DCMHalfBooklet.pdf Accessed October 2018.
  3. Summerfield NJ, Boswood A, O’Grady MR, et al. Efficacy of pimobendan in the prevention of congestive heart failure or sudden death in Doberman Pinschers with preclinical dilated cardiomyopathy (the PROTECT study). J Vet Intern Med 2012;26:1337–1349.
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