Rabbits are very clean animals and groom themselves constantly, which means the stomach contents always contain hair. This hair is normally passed through the digestive system and excreted with the faecal pellets.
True hairballs are very rare in rabbits since it is a normal finding for a rabbit to have some hair within their stomach and digestive system. Problems occur when excessive amounts of hair are ingested or the hair already within the stomach dehydrates. True hairballs are called trichobezoars.
Normal grooming should not cause a problem, but excessive grooming or hair chewing can occur as a result of a low fibre diet. These problems can also be a bad habit (vice) which is usually associated with boredom or stress.
Problems normally creep up slowly and you will notice over several days or weeks that your rabbit will eat less, produce fewer and smaller droppings, move around less, produce droppings which are strung together with hair and possibly tooth grind in pain.
If you notice any unusual behaviour regarding your rabbits eating habits you should contact your vet immediately, as rabbits who stop eating for any length of time are often very sick rabbits. Since a rabbits digestive system is designed to have a constant supply of food going through it, any disruption to this will quickly send the rabbit into gastrointestinal stasis (GI stasis), where the digestive system stops or slows down completely. This is serious and life-threatening and requires immediate veterinary attention in order to have any chance of saving the rabbit.
Feeding hay ad lib, thus ensuring that the rabbit has a high-fibre diet and a constant source of food to nibble on to reduce boredom, is the single and best way to help prevent hairballs.
However, hairballs are often associated to a primary cause which has meant that the rabbit has reduced its food and water intake and the hair within the stomach has become dehydrated. Any form of pain (dental, spinal, abdominal etc), stressful occurrence (new companion, loss of a companion, vet visits, predators within the garden, sudden changes in environmental temperatures etc) can mean a rabbit will eat and drink less, resulting in a hairball. However, it must be remembered that the hairball is a secondary condition and the primary cause needs identifying and treating correctly.
To ensure that your rabbit doesn’t ingest excess quantities of hair, try and groom them regularly especially during a moult. Long-haired rabbits are more susceptible to suffering from a true hairball since they will naturally ingest more hair through grooming. Try and groom them daily or get an experience person to clip the rabbits long hair.
Since the hairball is a secondary finding and often not the true cause of the problem, then the treatment needs to be aimed at the primary cause.
Whilst this is being identified it is imperative that the rabbit receives adequate fluid therapy (often intravenous fluids are the best route) syringe feeding or naso-oesophageal tube feeding if the rabbit is unwilling to accept syringe feeding, pain killers (analgesia), medication to keep and encourage the digestive system to start or keep moving (prokinetic medication) and encouragement to eat by offering lots of fresh hay, grass, greens, etc.
Investigations to identify the primary cause may include: a thorough dental examination, often requiring sedation, x-rays of the spine and hips/pelvis to look for arthritic or spondylosis changes, skull x-rays to assess the tooth roots, blood tests and a thorough history from the owner to ascertain if any stressful occurrence has happened recently to explain the rabbits condition.
If a true hairball is diagnosed (which is very rare), then mineral oil and laxatives are often ineffective in treating hairballs. Pineapple juice which contains the digestive enzyme bromelain has been reported as helping to dissolve the hair but no scientific evidence has ever been produced to prove this, and all pineapple juice will do is help to rehydrate the rabbit.
Surgical removal is an option but is a last resort and carries a very poor prognosis.
The only way to try to treat true hairballs is with fluids to hydrate the stomach contents, analgesia and syringe/ naso-oesophageal feeding. Prokinetic medication is often not advised when there is a blockage due to the risk of the stomach rupturing. Roughage (hay or grass) should be fed during the treatment to help carry the hair fibres through the digestive system and out with the faeces.