A rabbit with decreased stool that has stopped eating is often thought to have hairballs, also known as "wool block." True hairballs, however, such as are found in cats and ferrets, are made up entirely of hair. While rabbits do ingest hair during grooming, the hair is usually mixed with food and does not form a true hairball. These masses in the rabbit's stomach, however, can become dehydrated and contribute to gastric stasis, which is a slowdown of the gut. When gastric stasis occurs, the matter in the rabbit's stomach hardens and becomes a dried compact mass that is hard to pass. Without treatment, an intestinal blockage can form, from which rabbits can die.
The best treatment for hairballs is prevention through a proper diet. Rabbits need a lot of fiber in their diet, and Timothy Hay is a good source. Pet rabbits should have a steady supply of Timothy Hay available at all times. Clean water should also be supplied at all times so that the rabbit can stay properly hydrated. Stools should be checked every few days for any changes in color, size or texture. Normal rabbit stool should be round, hard, and formed. Any decrease in size could signal gastric stasis and is cause for treatment.
A veterinarian will confirm a diagnosis of gastric stasis, and if the rabbit is in any obvious discomfort or has stopped eating or drinking entirely, an emergency trip to the veterinarian is needed. In serious cases, the veterinarian may prescribe intestinal stimulants, such as metacloprimide.
If your rabbit is continuing to eat, and appears alert and not showing any signs of pain, then treatment at home can be started, and the rabbit's condition carefully monitored. Over-the-counter rabbit or cat hairball medicines like Petromalt can be given to rabbits in small dosages, taking into account the rabbit's weight and adjusting the dosage accordingly. Hairball medicines may help to keep the hair and feces mass from compacting and increase the motility of the gut. Once the rabbit's bowels are back to normal, hairball medicine can be used once or twice a month as a preventative measure.
Commercial treats should be eliminated from the diet, as they are not healthy for the rabbit to begin with, and stress the rabbit's delicate system. Decrease pellets in the diet, as they are low in moisture content, and not required for proper nutrition as long as a quality hay like alfalfa or Timothy Hay is supplied. If the rabbit is used to receiving fresh garden greens like Romaine lettuce, parsley or radish tops, then continue feeding these as they are high in moisture content and will help hydrate the mass so that the rabbit can pass it.
Home remedies such as pineapple juice in the water or papaya enzyme tablets can be given. The rabbit should be allowed increased exercise to help stimulate the bowels, and as a matter of regular preventative care should receive regular brushing to prevent future hairballs.