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Recognizing and Managing
Megacolon in Rabbits

What is Megacolon (MC)?

MC is a genetic digestive condition that affects the function of a rabbit’s gastrointestinal (GI) tract in rabbits with certain genes. The condition is progressive and each rabbit may be affected differently, showing varying degrees of symptoms at different life stages. Rarely, rabbits may develop MC from trauma, surgery, or injury (“aquired MC”).

So what does this mean for an MC rabbit?

These bunnies are predisposed to gut problems and have trouble absorbing essential nutrients from food. While some may remain healthy for the first few years of their lives, others will show symptoms from birth. Many MC rabbits will show worsening symptoms around the age of 3-5 years. Detecting and treating the condition at the onset of symptoms and as early in their lives as possible is essential to keeping them happy and healthy. However, humane euthanasia in severe cases may be recommended.

One of the most common ailments that affects MC rabbits is impaction of the gut due to slow motility. If left untreated, the colon can become severely distended and painful for the rabbit. These slowdowns can lead to serious gut infections and death. At some point in most MC rabbits’ lives, daily oral medications will be necessary. This can include medications for managing pain, motility, and/or softening stool.

How do you know if you have an MC rabbit?

There are currently no tests that can diagnose MC. Instead, we look at coat coloration, fecal/cecal output, and ruling out other conditions that may present similar symptoms. Typically, genetic MC rabbits are mostly white with some spotting around the eyes, nose, ears, and spine. Not every rabbit with this coloration will have this condition.

A healthy rabbit’s fecals are consistently spherical with little to no varying in size/shape, they are not overly small or large for the rabbit’s size, and aren’t too dry or too wet in consistency.  You may have a megacolon rabbit if his typical fecal output is very large, misshapen, or varies in size. Sometimes fecals are overly dry, or conversely, they can be overly moist.

(top row) Normal fecal output from a 4-5lb rabbit.

(bottom 3 rows) Normal fecal output from various 4-5lb megacolon rabbits, note the irregular sizes and shapes.

Cecotropes of a healthy rabbit come in shiny clusters that resemble the size, shape, and lustre of a blackberry. The cecotropes of an MC rabbit are overly large, and can be sausage-like in shape, and/or shiny in appearance and resemble tar.

Additional symptoms of MC: gut leakage, poor body condition with muscle wasting around the spine, potbelly, staining around the tail and back paws, weight loss with a voracious appetite.

Cecotropes from a non-megacolon in relation to the size of a pinkie finger.

Cecotropes from a megacolon rabbit in relation to the size of a pinkie finger.

How can you best support your Megacolon (MC) rabbit?

Believe it or not, many veterinarians do not yet acknowledge MC as a condition in rabbits. Therefore, it is important to find a rabbit-savvy veterinarian who believes that megacolon exists in rabbits, or one who is willing to learn from vets who do. Once you have found a trusted veterinarian, work on a diet and in some cases, a medication plan, to keep your rabbit’s MC symptoms as mild as possible. Each MC rabbit is different, so a diet and medication plan for one MC bunny may not work for another. Once you find a diet that works, stick to it! Only make modifications as needed. Take your MC rabbit for wellness exams 2x a year and bring along a sample of their fecal output which will help your veterinarian assess how they are doing.

Get to know the subtle signs before a serious GI crisis arises. Often, an MC rabbit’s gut will begin to slow down and become backed up but the rabbit will continue to eat voraciously, and your first sign may be a decrease in fecal production. They may also show a decrease in appetite but won’t refuse their favorite treats. It can be tough to notice the early stages of an episode, but the better you know your rabbit, the clearer it will be.

Signs that may point to a GI Slowdown in an MC rabbit:
  • Fewer or no fecals produced
  • Decrease in appetite or disinterest in foods they normally enjoy
  • Behavioral changes
  • Body posturing: belly pressing, hunched look
  • Change in fecals from their “normal”
  • Distended abdomen that feels hard to the gentle touch

MC-friendly treats:

The Well Kept Rabbit: Delilah’s Megacolon Tonic Forage, Delilah’s Megacolon Tablets 

Pre & Probiotics:

(May be useful to maintain a balance of bacteria in the gut. Please note it’s use and results are anecdotal.)

Tips:

  • Avoid fresh or dried fruit and other sugary treats.
  • Indroduce new foods slowly and one at a time so you can observe what helps or worsens symptoms.
  • Feel (palpate) your rabbit along it’s spine regularly and note any changes. If the spine feels thin, contact your  rabbit-savvy veterinarian to reassess their diet.
  • When it comes to greens, feed herbs such as parsley, dill, mint, oregano, thyme, basil, rosemary, lavender, sage, cilantro. Avoid kale, lettuces, spinach, etc. 
  • Introduce greens one at a time each week. Discontinue any that cause soft stool.
  • Some MC rabbits have a “dry gut” and will do better with very wet greens as it will add hydration to the gut. Others have a “wet gut,” and may or may not be able to tolerate greens at all.
  • Offer fresh or dried Plantain (a plant also known as “ribwort,”and not the banana). Plantain is a great motility aid for rabbits. You can purchase dried from sources such as Small Pet Select, or Elliot’s Awesome Treats. Fresh is easy to grow from seed in a window sill.
  • Make sure they get plenty of exercise time. Exercise promotes better motility.
  • Keep them well hydrated:
  • Offer water in a bowl rather than a bottle.
  • If your MC rabbit tolerates fresh greens, serve them wet.
  • For increased hydration when early signs of a GI slowdown are suspected, you can offer a 50/50 mix of water and plain (unflavored) green coconut water in addition to their plain water.
  • You may ask your veterinarian to teach you when and how to administer sub-q fluids at home in the event of a GI crisis.
  • It has been reported that the following supplements may be helpful for treating MC:

References & further learning:

http://www.vgr1.com/mc/

https://www.youtube.com/watch?v=bbSrsXeSMNY

http://www.medirabbit.com/EN/GI_diseases/Differential/mega_differential.htm

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0093750

Dani Tomlin (2017). Megacolon In The Domestic Rabbit. Bunny Mad! Magazine: http://www.pva-apeldoorn.nl/megacolon%20konijnen.pdf

Genetic Megacolon Bunnies on Facebook: A private, invite-only group for Genetic MC bunny owners only. If you have an MC rabbit, you may email katie@longislandrabbitrescue.org to be introduced to the group admin to be invited.

©2022 Katie Scarr. Created in consultation with Mary Ann Maier and Jennifer L. Saver, DVM