Reposted with permission of the House Rabbit Society.
Megacolon is an inherited genetic condition that causes the nerve endings in a rabbit's intestinal tract not to function properly, and it often gets progressively worse as the rabbit gets older. It can lead to a slowing or stoppage of food through the digestive system and needs to be regulated with motility medication(s), which help move the food through a rabbit's system so that blockages or back ups don't occur. Rabbits with megacolon typically have poops that are irregular shapes and sizes. Without treatment, a rabbit's abdomen can become distended from backed up materials in the cecum.
Spotted rabbits that are mostly white with fewer spots, or rabbits with only color around their eyes, or Himalayan/Californian-type rabbits with irregular markings on their nose/ears have more genetic predisposition to megacolon. Rarely, a white bunny with pink eyes can be affected. If a bunny has this coat pattern and irregular size/shape poops, we recommend visiting a rabbit-savvy veterinarian to get a fecal test to rule out coccidia and inquire about the possibility of megacolon and whether they would recommend starting regular motility medications before there is a problem.
For rabbits with megacolon, it's critical to notice any signs of discomfort, lack of appetite, decrease in poops, or change in poops, as these are signs the condition could be worsening and veterinary help should be sought immediately. Rabbits with megacolon require more regular preventive vet visits than other rabbits as their condition should be checked by a veterinarian to see if any medications need to be changed or adjusted. At HRS headquarters, motility medications have helped lengthen the lives of many rabbits with megacolon and they can help prevent stasis in these rabbits, too. A GI crisis for a rabbit with megacolon can further damage their intestinal function, so prevention is key. The good news is that many oral motility medications can be compounded and flavored with yummy tastes like banana and many rabbits love taking them!