Pet Factsheets

Megacolon syndrome

Rabbit megacolon syndrome refers to a rare disease process observed in rabbits which exhibit long-standing, unresponsive, intermittent diarrhoea, accompanied by weight loss. Much is still unknown about the condition in rabbits, but information can be taken from other species.

What does megacolon mean?

As the name suggests, the term megacolon literally means large or dilated colon. The colon is the end of the digestive system. Megacolon seems to be much rarer in rabbits than other species. Cats are frequently diagnosed with it, but in rabbits there is still some debate as to whether the condition truly occurs in them.

What causes the condition?

The cause of the condition in rabbits is unknown, and as yet, vets cannot agree if it is in fact a disease or a symptom of several different diseases, all described under the one umbrella term ‘megacolon’.

Although the cause is unknown, the condition seems to predominately occur in English breeds and is thought to be linked to genetics. It normally affects older rabbits, and the disease worsens over time. The bouts of illness generally become more severe and more frequent each time.

How do I know if my rabbit has megacolon?

Firstly, there are lots of reasons why rabbits suffer with diarrhoea, and true diarrhoea is rare in adult rabbits. Those that do suffer from diarrhoea are generally affected by megacolon.

Affected rabbits are generally underweight, have intermittent diarrhoea which resembles cow pat consistency or the formation of faecal pellets of dramatically different sizes and consistency. No caecotrophs or normal pellets are produced during the flare ups. The rabbits often fluctuate between a ravenous appetite and complete anorexia.

What will my vet do to diagnose and treat my rabbit?

It is important to rule out a dietary cause! Your vet will ask you lots of questions about your rabbit’s diet. They may want to rule out other causes of diarrhoea and are likely to request a faecal sample to send to the laboratory to look for any parasitic or bacterial cause for the diarrhoea. If these come back clear they may recommend x-rays or ultrasound to look for abnormalities within the gastrointestinal tract and caecum. Investigations often show evidence of large amounts of gas in the caecum. Blood sampling may reveal low protein levels and anaemia.

However, none of these signs is specific for one disease and can be seen with many other diseases in rabbits. As yet, there is no one single test that will tell us if your rabbit has megacolon. The condition is only suspected based on clinical signs and ruling out other causes for the symptoms.

What treatment will be needed?

There is no one set treatment for rabbits suspected of having megacolon, and many different treatments have been trialled. Drugs to promote normal movement of the gastrointestinal tract are often prescribed as well as high fibre diets and intravenous fluid to correct dehydration. Pain relief is important as dilation of the gut is particularly painful.

Each rabbit seems to respond differently to the same treatment plans and any improvements are usually temporary, with rabbits having repeated bouts of the clinical signs throughout their life. Treatment will not cure the problem, but aims to improve quality of life, although this will be temporary until the next flare up.

What other problems does megacolon predispose my rabbit to?

Rabbits with chronic diarrhoea are at a higher risk of flystrike particularly throughout the warmer months of the year. You must ensure you keep your rabbit clean and dry and check them at least 3 times a day for any signs of flystrike. Use a preventative treatment, such as F10 or Rearguard applied at the correct intervals. Placing fly netting and traps around their enclosure can also help minimise the likelihood of flystrike.

It is also important to make sure they aren’t getting sore with the repeated contamination of faeces on the skin. Your vet can advise what you can apply to the skin if this is the case. If their rear end if dirty, then a sponge bath with minimal water may be necessary but you should never submerge a rabbit or give them a full bath as the shock can kill them as well as the risk of hypothermia.

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