Rabbits are often referred to as "guts with fur" due to how often they come down with ileus, also known as gastrointestinal stasis. If something is going wrong in a rabbit's body, their intestines—or guts—will typically be the first things affected.
What Is Ileus?
When the intestines of a rabbit stop moving the normally ingested food out through the colon and finally the rectum, it is called ileus, or gastrointestinal stasis. A rabbit should always be eating and defecating but when they stop doing one or both of those things the bacteria inside their intestines start producing excessive gas. This gas is painful (you should know if you've ever had bad gas!) and prevents your rabbit from wanting to eat more. Since rabbits cannot vomit, their owners need to help them work the gas and whatever food that may remain out of their body using medications and stimulation.
Medications Used for Ileus
Your exotics vet may have a combination of drugs that work for them or may want to try a few different things. Regardless of what specific medication that is prescribed there are usually certain types of drugs that work well to relieve symptoms of ileus.
Gut motility drugs, such as metoclopramide (Reglan) or cisapride (not commonly available) are usually prescribed along with a pain medication. Drugs to decrease the amount of gas, such as simethicone (Gas-X), are sometimes recommended, as well as probiotics and other medications. Force-feeding is a must if your rabbit isn't eating since food needs to be put in to get waste coming out.
Food to Feed for Ileus
Oxbow Critical Care is a popular and effective choice for rabbits with ileus. It is a powdered hay formula that you add water to so it can be pushed through a syringe. It has more complete nutrition than other similar products and rabbits typically like it. It is fed using a syringe and comes in two flavors, anise (the original flavor) and apple-banana flavor.
If your rabbit won't take Critical Care or you do not have access to any, grind up rabbit pellets mixed with water, or mixed vegetable baby food (without potato or starch in it) as alternatives. Your vet will tell you how much food you should syringe feed your rabbit but it will probably be 20–30 ml's twice a day or so. If your rabbit is eating a little on its own it could be less.
What Should a Rabbit Eat to Prevent Ileus?
Rabbits should eat a pile of grass hay (timothy, orchard, Bermuda, etc.) the size of their body per day (if not more). Alfalfa hay is too high in calcium for an adult rabbit. Fresh, dark, leafy greens (dandelion greens, kale, escarole, endive, parsley, etc.) should be offered at about 1 cup per five pounds of body weight a day as well. Pellets are the least important part of a pet rabbit's diet. A pet rabbit can get 1/4 cup of pellets daily, but no more. Fruit is considered a treat but also isn't really recommended and broccoli, cauliflower, and other gas-forming vegetables should be avoided. Soaking the leafy greens in a water dish is also recommended to increase water intake.
Exercise and Ileus
A rabbit that may have ileus should also be encouraged to exercise. Create ample and safe spaces for your rabbit to run around in or, at the very least, massage your rabbit's belly to encourage its guts to move food through.
Other Diseases With Ileus
Your rabbit may have another medical reason for why it is not eating or defecating. Its teeth may be overgrown, it may have a bladder stone, or it may just be stressed out. It is important to diagnose the reason why your rabbit has ileus and not just treat the ileus, or else the ileus may not go away and your rabbit may contract it again even if it does pass.
If you start seeing small stools, don't stop your efforts! Until your rabbit is eating and defecating normally you should treat it as an ileus case. With quick action and proper treatment, your rabbit will be back to normal in no time at all. Ileus can be deadly if left untreated though, so within 24 hours of your rabbit not eating or defecating you should be starting treatment. If you can't get into an exotics vet in that time frame, start by syringe feeding (mixed vegetable baby food or Critical Care) and offering water in a dish or via syringe.