Heart (cardiac) disease is a relatively common diagnosis in humans, dogs and cats. Many rabbit owners may not be aware that rabbits can also suffer with heart failure and an increasing number of pet rabbits are being diagnosed with heart problems.
What does the heart do?
In all animals the heart acts as a pump to pump the blood from the lungs (oxygenation of the blood) around the body, which supplies all the tissues and organs. The heart is composed of four chambers (two atria and two ventricles). Each of the four chambers has a vital function. The chambers are separated by valves which open and close to allow blood to pass through each of the chambers.
As a prey species rabbits need to be able to evade capture and escape from predators. Rabbits therefore have a much higher heart rate than people, dogs and cats. A rabbit's heart rate can vary dramatically and increases during times of stress and exercise, but a resting heart rate of anywhere from 150-350 beats per minute is normal. Smaller breeds often have a faster heart rate than large rabbits.
Nowadays with better health care for rabbits, we expect them to live longer. Added to this many rabbits live sedentary lives, consequently the incidence of heart failure in rabbits is becoming more common.
What signs will I see if my rabbit has heart disease?
The clinical signs of heart disease can be attributed to other more common disease processes in rabbits, and therefore heart disease is not always the most apparent diagnosis for your vet. On top of this, as a prey species rabbits are designed by nature to conceal signs of pain, illness and weakness; any of which make a wild rabbit easy prey to a predator. Although domesticated our pet rabbits retain this wild instinct.
Clinical signs that can indicate heart disease include:
- Exercise intolerance.
- Anorexia or a reduce appetite.
- Weight loss or weight gain.
- Difficulty breathing, coughing or wheezing.
- Increased respiratory effort with or without difficulty breathing (the rabbit may stretch its head up).
- Blue tinge to the lips and tongue.
- Collapse or episodes of collapse.
- Unexplained sudden death.
As you can see, many of these symptoms are non-specific, and can easily be attributed to more common disease in rabbits.
How will my vet diagnose heart disease?
Firstly, your vet will perform a thorough clinical examination, which will include listening to your rabbit's heart with a stethoscope. Sometimes a heart murmur may be detected, but this is not always apparent there are different types of heart disease.
If your vet suspects a heart problem, then they are likely to recommend one or more of the following diagnostic tests:
- Echocardiography: this is a detailed ultrasound of the heart and enables your vet to look at the chambers and valves, take measurements and look at the blood flow. This can often be done on a conscious rabbit.
- Blood pressure: high blood pressure is a common finding with heart disease, and is measured in the same way as on people. This is easy to perform on a conscious rabbit, but readings need to be interpreted with care as other factors, such as stress or other disease process can increase the blood pressure reading.
- Radiography (x-ray): these may have to be done with sedation or general anaesthetic to get a diagnostic radiography. Radiographs are used to assess the size of the heart. Often with heart disease the heart will get bigger and there may be some build-up of fluid within the chest or lungs.
- Electrocardiography (ECG): an ECG looks at the electrical activity and rhythm of the heart. This is normally done with the rabbit conscious.
- Blood tests: in certain types of heart disease, blood tests may be necessary to look for an infectious/inflammatory component to a rabbit's heart condition.
Is all heart disease the same?
No! Heart disease is a general term and there are many different types of heart disease. By performing diagnostic tests your vet will be able to diagnose what one your rabbit is suffering from.
Some of the more common heart disease conditions in rabbits are:
- Congestive heart failure (CHF): a heart that is failing or no longer functioning properly is termed as CHF. CHF is often seen in middle aged and older rabbits although heart failure can also develop in young rabbits. An enlarged heart and with fluid in the lungs or space between the lungs and chest wall are the most common findings to prompt a diagnosis of CHF.
- Myocarditis: this is when the heart muscle itself is inflamed and is a less common form of heart disease. Typically, this type of heart disease is caused by a bacterial infection of the heart, although E. cuniculi has, in rare cases been known to cause myocarditis.
- Dilated cardiomyopathy (DCM): DCM affects the muscle of the hart and as its name suggests, causes the chambers of the heart to dilate (get bigger). This in turn causes the hearts force to weaken, meaning less blood is able to be pumped around. DCM is thought to be more common in large/giant rabbits and can be a cause of sudden death.
- Congenital heart disease: there are some congenital heart diseases that rabbits may be born with. These often appear when the animal is very young, and often these rabbits die at a young age.
How will my vet treat my rabbit?
Medications are the mainstay of treatments and have different effects. There are no drugs that are licensed to treat heart disease in rabbits. Therefore, your vet will have to use medications 'off license', so will ask you to sign a consent form allowing them to use drugs that are licensed in other animals.
Medication is normally lifelong, but in some cases the rabbit can live a normal, good quality life.
How can I help my rabbit?
It is important to try and minimise stress in the home environment. For a prey species this is often quite difficult.
Try to keep to a routine with feeding, cleaning, etc and don't change anything around in the rabbit's environment which may stress them. Ensure they have adequate places to hide away in a quiet place, do not allow them to become overweight, ensure they have a good quality diet, and get regular, gentle exercise.