A significant number of rabbits are overweight and therefore weight loss can very often be a desirable outcome. However, the converse is often true and unexplained weight loss can be a serious clinical sign that something is wrong with your rabbit.
My rabbit is losing weight... what shall I do?
The obvious and first question (which is sometimes overlooked), is does the rabbit have enough food to eat? Has their food been changed recently or a new bag opened that may taste slightly different? Rabbits can be very picky with anything that tastes slightly different to what they are used to.
Have you recently introduced another rabbit who may be eating more of the food? Is the companion rabbit getting larger? This may indicate that the other rabbit is eating more than their fair share of the food.
It is important to have ruled out these obvious causes prior to your vet commencing any diagnostic tests. If none of the above apply then a medical reason is likely to be causing the weight loss.
Weight loss can be caused by a vast array of reasons, but dental disease is by far and away the most common cause of weight loss in rabbits. Any rabbit, who finds it painful to eat, is unlikely to eat enough food to take in enough calories and will therefore begin to lose weight. There may be no other signs of dental disease other than weight loss.
Tumours and cancer take away vital nutrients leading to weight loss and renal, liver and heart disease can all cause weight loss too.
Coccidiosis (a parasitic disease affecting the intestines), may cause dramatic weight loss or lack of weight gain, especially in young, growing rabbits.
What will my vet do?
Firstly it is important to rule out common causes. A thorough dental examination, which should include a clinical examination and x-rays to assess the tooth roots is vital. This needs to be done under sedation or general anaesthesia, and if the rabbit is not physically well enough to undergo a sedation/GA then supportive treatment by the way of syringe feeding, fluid therapy, pain relief and prokinetic medication to support the gastrointestinal tract should be implemented first to stabilise the rabbit.
Blood work may be needed to assess the rabbits renal and liver parameters.
An echocardiogram (ECG) reading may be required to diagnose heart disease.
A faecal sample may be required to rule out coccidiosis and other internal parasites.
Diabetes mellitus is extremely rare in rabbits, but assessment of a urine sample and glucose level on blood work can help to rule this out.
Diagnostic imaging such as x-rays, CT scan or MRI scan may be required if a tumour is suspected.
Your vet will be able to decide what tests, and in what order they should be run, after clinically assessing your rabbit.
If your rabbit is insured then they should be covered for the costs, but it is a wise idea to check with your insurance company first.
How will my vet treat my rabbit?
Your vet will select the most appropriate treatment depending upon the cause of the weight loss. It is important to remember that weight loss itself is a symptom of a disease process and not a disease in itself and the underlying cause needs diagnosing and treating regardless of what this is found to be. Some causes of weight loss are easier to treat and manage than others. For example, dental disease can be managed with alterations to the diet and regular dental treatments but can often not be cured.
Tumours, such as uterine adenocarcinoma, which is the most common tumour in entire females, may be surgically curable if the disease has not spread. Renal, heart and liver disease can often be managed with medications.
Whilst your vet is diagnosing the cause of the weight loss, the rabbit should be offered syringe feeding and fluid therapy to try and increase their calorie and fluid intake. Other medications may be prescribed by your vet who will be in the best position to know what is best for your rabbit.
What else do I need to know?
Some older rabbits may struggle, especially during the colder months of the year, to keep adequate weight on them. Increasing the calories in the diet by increasing the pellet ration should help with this problem. You could also consider bringing them into a warmer environment, such as the house or an unused garage/shed. This will help them to stay warm without using as many calories to do so.