What is it?Cystitis is an inflammation of the bladder (also known as a ‘water infection’). Unlike in people, it is not usually caused by bacterial infection in rabbits, but is frequently associated with crystals in the urine. Occasionally it can be associated with bladder tumours.
Why is it important?It can be a very painful condition and is often associated with crystals or stones in the urine. These crystals form as a result of a rabbit’s unique calcium metabolism - most mammals excrete roughly 2% calcium into their urine, whereas rabbits excrete 45-60%. This excreted calcium forms calcium carbonate crystals which can then develop into urinary stones (called ‘calculi’).
What’s the risk?
All rabbits are at risk due to their metabolism; however, several factors can increase this such as high calcium in the diet, anatomy and occasionally infection. Rabbits’ calcium metabolism isn’t an issue providing that they drink enough water, have space (and are physically able) to move around actively, and they don’t have excessive calcium in their diets.
Older rabbits may be slightly higher risk due to arthritis or other conditions limiting their movement. Male rabbits are at higher risk of blockage as their urethras (the tube carrying urine out of the body) are longer and narrower than those of females, so more likely to block if a stone tries to pass through.
What happens to the rabbit?
Clinical signs can include:
Normal rabbit urine varies dramatically in colour and turbidity (how cloudy or clear it is) and it can range from colourless to red. The degree of clouding is directly related to the amount levels of calcium that have been consumed - so more calcium = more cloudy. However, any blood or sludge in urine is always abnormal.
Straining or failing to pass urine is an emergency and requires immediate veterinary attention.
How do you know what’s going on?
A clinical examination by a vet is important, particularly to rule out the chance of a blockage. The urethra can become blocked by a stone or mucus and the bladder will fill up like a balloon - risking irreversible kidney damage, severe pain, burst bladder and death.
X-rays can be taken as the stones contain calcium and so are visible on the image; often in the urethra, bladder or kidneys. A urine sample will check for the presence of crystals, infection or blood and we can measure levels of other substances. Blood samples can be taken to check for kidney function.
What can be done?
This depends on the cause and severity - in mild cases a change in diet and management can be enough. If bacterial infection is present then the urine may need to be cultured and treatment with antibiotics prescribed if required.
The bladder may be flushed out under anaesthetic to remove any calcium ‘sand’ (a collection of small stones). If there are larger stones present in the bladder then surgery is required to remove then.
What can I do to protect my pet?
The level of calcium excreted into the urine (and therefore risk of crystals/stones forming) is directly linked to the amount of calcium the rabbit eats in its diet. Ensure you do not feed excessive calcium and avoid high calcium vegetables such as kale and spinach (except in small amounts).
Ensure the housing allows space for rabbits to exercise and hop around - helping reduce the calcium ‘sand’ in the bladder by shaking it up and allowing it to exit the bladder rather than just settling in the bladder and staying there (think of a snowglobe!).
Make sure there is unrestricted access to fresh water to encourage water intake and offer water in different bowls/bottles. Rabbits are likely to drink more from a bowl. Offer good quality hay ad lib - this will increase water intake.