Restrictive cardiomyopathy is a type of heart disease. Heart disease in rabbits is becoming more common, likely because our pet rabbits are now living longer. Read on and learn how to spot heart disease in rabbits. 

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What is restrictive cardiomyopathy?

‘Cardiomyopathy’ means disease of the myocardium, or heart muscle. This group of diseases affects the size, shape or thickness of the heart muscle; interfering with its ability to pump blood. There are three main types of cardiomyopathies seen in rabbits: 

  • Restrictive: where the heart muscle stiffens, meaning the chambers can’t fill with blood as they should, 
  • Hypertrophic: where the heart muscle becomes thickened
  • Dilated: where the heart muscle becomes thin and weak, and the main pumping chamber of the heart dilates (enlarges).

Cardiomyopathy can be primary (where the cause is usually unknown) or secondary (i.e. caused by something else, such as infection or another illness). 

What causes heart disease in rabbits?

Most cases of rabbit heart disease are acquired, meaning the heart disease develops later in life. Rarely, rabbits can be born with a congenital heart condition.

Most of the time, the cause is unknown. There are some infections that have been associated with cardiomyopathy, such as Pasteurella multocida (a bacterial infection) and E. cuniculi (Encephalitozoon cuniculi- a type of parasite). Stress and overcrowding in rabbits have also been associated with a certain type of cardiomyopathy known as ‘catecholamine-induced cardiomyopathy’. 

Which rabbit breeds are most susceptible to heart disease?

Any rabbit can suffer from heart disease, at any age. However, large and giant breed rabbits are more prone to cardiomyopathy, and the likelihood of heart disease increases with age.  

Symptoms of heart disease in rabbits

Rabbits are a prey species, meaning they hide signs of illness or injury very well. While this would be of benefit to a rabbit masking weakness from a predator in the wild, it can cause problems for rabbit owners! 

Signs of heart disease in rabbits include:

  • Reduced appetite
  • Weight loss 
  • Lethargy (reduced energy)
  • Fast breathing (tachypnoea)
  • Increased effort to breathing, or struggling to breath (dyspnoea)
  • Collapse
  • A swollen tummy
  • Blue-tinged or pale mucous membranes (gums or eyes).

Sometimes, sadly, there are no signs at all until sudden death. Symptoms can also be vague and non-specific, and rabbits can deteriorate very quickly, so if you notice any unusual symptoms in your rabbit, contact your vet straight away.

Diagnosis

Your vet would start by asking you some questions about your rabbit’s behaviour and symptoms at home, then would examine your bunny. Following on from this, tests could include:

  • X-rays: to assess the lungs, the size and shape of the heart and to check for any abnormal fluid build-up
  • An ECG (electrocardiogram): this measures the electrical activity of the heart and detects any abnormal heart rate and/or rhythm
  • Echocardiography (an ultrasound scan of the heart): this can be used to assess blood flow, the size and thickness of the heart muscle and chambers, and how well the heart is pumping
  • Blood pressure: to see how well the heart is pumping blood around the body
  • Blood tests: to check for underlying disease problems, like signs of infection or organ disease

Your rabbit may need sedation for some of these tests. Depending on their clinical exam findings, your vet may recommend some of these tests, all of them, or they may suggest referral to an exotics specialist (yes, rabbits are classified as exotic pets!). 

What is the treatment for heart disease in rabbits?

Sadly, there is no cure for heart disease in rabbits. Treatment is aimed at improving the bunny’s quality of life, and hopefully extending their life (but not at the expense of quality of life). 

The exact treatment will depend on the underlying cause. For example, there are medicines to help the heart contract more effectively or to remove excess fluid build-up. Often, a combination of treatments is required. 

It’s important to note that there are currently no medicines licensed for treating heart failure in rabbits. The drugs given are used under the ‘veterinary cascade’, meaning they can be given because there is no licensed alternative. Usually, the medicines are licensed for treating heart disease in another species. 

Can rabbits live with heart disease?

Sadly, the prognosis for rabbits with heart disease is guarded. However, with the right medicine and regular vet checks, rabbits can often live a happy life while receiving treatment. Rabbits may respond well to treatment initially, but will eventually fail to respond and so deteriorate. At that point, unfortunately, humane euthanasia is often the kindest option. 

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