The pet rabbit is descended from the european wild rabbit. They have evolved to graze on low calcium european grass by developing very specific dentistry and digestive tracts. When they are fed an alternative diet, it can lead to major problems than can be life threatening.
As it forms the majority of a rabbit’s diet it is essential that the grass products and hay are of good quality. We recommend feeding a minimum of 70% grass based diet (fresh grass, dried grass, mixed meadow hay, timothy hay, haylage etc). Most rabbits will consume their body size in hay each day. 28% of the diet should be made up of fresh produce – leafy vegetables high in cellulose are best. Only 2% of the diet should be made up of a good quality commercial rabbit pellet, which ensures a balance of vitamins, minerals and proteins are obtained (this equates to one tablespoon of pellets once daily for rabbits under 3.5kg, and twice daily for rabbits over 3.5kg).
Rabbit teeth are open rooted and grow continually in a healthy rabbit (averaging 2-2.5mm/week for incisors and 2.5-3mm/week for cheek teeth). As the rabbit eats, the grinding of the teeth wears down the crown and keeps the teeth at a constant length. The amount of dental wear is affected by how abrasive the diet is. Grass diets are very abrasive and prolonged grazing ensures the teeth maintain their correct length. Rabbits fed on diets low in abrasive particles that are rapidly consumed are the most likely to have overgrown teeth.
Gastro-intestinal tract problems
The high fibre nature of the rabbit’s diet is also essential for normal function of its gastro-intestinal tract. Indigestible fibres, provided by the grass and hay are essential for normal gut motion. This low calorie high fibre food eaten by a rabbit is designed to pass through the digestive tract twice. Initially it will pass through the stomach and small intestine and into the caecum (a larger version of the appendix that humans have). Here bacteria ferment the grass and overnight the rabbit passes caecotrophs (large soft faecal pellets) which it will eat as they are produced. These caecotrophs then get digested and absorbed in the stomach and small intestine, allowing vitamins and proteins to be extracted). The remaining material passes through the large intestine and is passed as the recognisable small hard rabbit faecal pellets. If the rabbit eats a lower fibre, higher calorie diet, they often do not have the appetite to eat the caecotrophs and so these sticky pellets become stuck round the rear end, and attract flies, often leading to flystrike.
If there is not enough fibre in the diet, there is a risk of gut stasis (lack of movement of food through the intestine) which can lead to bloat. Other causes of gut stasis include pain and stress. Stress can be caused by proximity to predators, bullying, loss of a companion, change in housing, routine or diet.
Unfortunately flystrike is a relatively common condition in rabbits. Urine and faecal soiling of fur attracts flies, which lay eggs in the fur. In warm weather, within 24 hours these eggs hatch into maggots which initially feed on the material in the fur and then go on to feed on the rabbit. They burrow into the skin and eat away at the muscle, causing a lot of damage in a relatively short period of time.
This urine/faecal contamination occurs secondary to urinating in an abnormal position, excessive drinking, incontinence, diarrhoea or caecotrophs sticking to the fur. The main methods of prevention are to ensure good digestive function, good hygiene and the use of insect repellants if the rabbit is high risk. It is crucial to check your rabbit daily during the warm months as flystrike can be lethal in a very short period of time.
Myxomatosis is a life threatening viral disease of rabbits. It is usually spread by fleas and mosquitos, and occasionally by direct contact with an infected rabbit. All rabbits are at risk, but outdoor ones more so.
The classic clinical signs of myxomatosis start with runny eyes (similar to conjunctivitis) which then rapidly progresses to a severe conjunctivitis and blindness, with swellings on the head and swollen genitals. The eyes produce a lot of thick discharge which tends to glue the eyelids shut. There are other atypical forms which can cause pneumonia or lumpy nodules in the skin.
Domestic rabbits do not have any innate resistance to the virus, and will generally die if they get infected. Survival in unvaccinated rabbits is rare even with intensive treatment and nursing.