The whole rabbit: physical, immunological and psychological health

Teeth

A rabbit's teeth grow throughout its life, at about 3 mm per week, enabling it to graze on tough grasses and similar foods (Meredith, 2011). If the teeth are in proper alignment and the rabbit eats mainly a high roughage diet, there are no problems; dental disease is rare in wild rabbits. However in domestic rabbits dental problems are unfortunately common.

Dwarf and lop-eared breeds are particularly prone to misalignment of the incisor teeth due to hereditary mandibular prognathism. Acquired abnormalities of the incisors and the molars are also common, leading to overgrowth of the teeth and malalignment. Once teeth are no longer properly aligned relative to their opposite counterparts, overgrowth of the whole tooth or parts of the tooth develops. Overgrown lower incisors protrude from the mouth while the upper ones curl round within the mouth and can grow into the buccal or gingival mucosa. Sharp spikes of overgrown molar teeth can dig into the delicate tissues of the rabbit's mouth, including the tongue. Affected rabbits may show both reduced eating (particularly of hay) and reduced grooming due to pain in carrying out these activities. (Richardson, 2001; Hobson, 2006; Harcourt-Brown, 2007).

Gastrointestinal tract

Rabbits are primarily hind-gut fermenters, like horses. They have evolved a specialised system to ensure that they can extract the maximum possible nutrition from poor forage.

Proper activity of the proximal colon, with is sacculations (haustra) and three longitudinal bands, leads to separation of high-fibre indigestible particles for elimination in hard faecal pellets, versus low-fibre particles to be returned to the caecum for metabolism by the complex microbial population. Periodically, the muscular activity changes to enable nutrient-rich gut contents to pass to the fusus coli, formed into soft pellets, covered in mucus and excreted as caecotrophs, which the rabbit ingests directly from its anus and swallows whole (Meredith and Crossley, 2002).

A diet containing insufficient indigestible fibre leads to reduced gastrointestinal mobility, which can lead to a wide variety of problems such as gas accumulation in the stomach and caecum; development of trichobezoars; altered secretion and absorption of water and electrolytes; changes in the pH of the caecum; changes in the caecal microflora and potentially proliferation of pathogenic bacteria such as Clostridia spp. (Bourne, 2012).

Diet

Incorrect diet is generally agreed to be an important factor in development of tooth problems in rabbits (Bourne, 2009a), and may lead to reduced gastrointestinal motility and associated gut problems. It is important therefore to promote a healthy diet for rabbits. This should be based on fresh grass (not grass clippings from a mower) and/or good-quality (not musty) grass hay, plus a handful of green leafy vegetables and wild plants daily.

A grass/hay-based diet minimises the risks of the rabbit developing tooth problems, gastrointestinal problems or obesity. Small amounts (e.g. an egg-cup full twice a day for a medium sized rabbit) of good quality concentrate foods can help ensure appropriate vitamins and minerals in the diet. If a muesli-type food is offered, then it is important to check that the rabbit is eating all the components, or the nutrition will be unbalanced. Small quantities of higher-sugar vegetables or fruits can be given as treats only.

Fresh clean water should be available at all times, allowing for an expected water intake of 50–150 ml per kg bodyweight per day (Meredith and Crossley, 2002). Bottles are easier to keep clean and harder for the rabbit to spill than bowls, but in general rabbits prefer bowls (Figure 1). It has been shown that rabbits need to lap more times to get the same amount of water from a bottle than from a bowl, which could be a problem particularly for a sick rabbit or one with tooth spurs growing into the tongue, so that lapping is painful (Harcourt-Brown, 2011). Bottles should be checked daily for blockages and leaks. Additionally, for rabbits kept outdoors in winter it is essential to make sure that water remains unfrozen.

Social

Wild rabbits are social animals, living in groups in burrows. They are also prey animals, as indicated by their wide-spaced eyes giving them nearly all-round vision. Both these aspects should be remembered, as they drive their behaviour and behavioural requirements (Bourne, 2011).

In general, rabbits are not suitable for keeping as a solitary pet and certainly not as a single rabbit in a small hutch in the garden (Figure 2). Ideally two rabbits, one male and one female, both of which have been neutered, should be kept together, although two rabbits of the same sex may also form a bond. A brother and sister from the same litter usually provide a good social pairing. Entire males are more likely to spray urine to mark their territory, more likely to be aggressive, and will try to mount a female even if she is spayed; this can lead to fiighting. Entire females may become territorially aggressive, particularly in the spring, and are susceptible to development of reproductive tract diseases (pyometra and neoplasia).

Small breeds may become sexually active as young as 4 to 5 months of age. From this time until they are neutered, the rabbits need to be separated physically to prevent unwanted litters, while maintaining visual and scent contact to avoid disrupting bonding. This can be achieved for example by placing the rabbits in large wire cages next to each other. Note that a fence is inadequate as separation, as rabbits may jump over this if sufficiently motivated (Best, 2008). Neutering not only prevents unwanted litters but also reduces aggression and unwanted territorial behaviours such as urinating outside the litter tray (Todd et al, 2014).

If two rabbits have arrived into a household separately, it is important to introduce them to each other gradually and under supervision in order to avoid fighting and maximise the potential for the rabbits to bond well. Rabbits react strongly to scents and mingling their scents may help. They should have the chance to smell, see and hear each other before they are placed together. Initial contacts must be carried out under careful supervision, preferably in territory which is neutral rather than previously claimed by either rabbit, and with distractions available (piles of hay and green food) as well as hiding places (e.g. cardboard boxes). The rabbits should be left alone together only when they are showing good signs of bonding, such as grooming each other and huddling together (Todd et al, 2014; Bourne, 2011).

Occasionally two rabbits just are not compatible and will have to be kept separately in the same household, or one will need to be rehomed. Some rabbits bond strongly with a human instead of with another rabbit; these individuals are suitable as house rabbits for a person who wants a close human–rabbit bond.

Stress reduction in the hospital

If one of a bonded pair needs to be hospitalised, preferably the other rabbit should accompany it; the veterinary practice should facilitate this if at all possible. Keeping the rabbits together minimises disruption of their social bond, and reduces stress in the rabbit under treatment. The rabbits will need to be separated during anaesthesia and surgery, but should be placed together again once the treated rabbit is fully conscious. If a rabbit is to be kept at the practice without its companion then a familiar toy or used blanket or other bedding should be left with the patient to provide the scent of home and reduce stress.

Whether hospitalised alone or as a bonded pair, a hiding place such as a cardboard box should also be provided. Covering the front of the hospital cage with a towel will give additional privacy. Rabbits should also be housed away from the sight, sound and smell of predators such as cats, dogs and ferrets. Stress reduction should be considered in the waiting room: providing a separate waiting area if possible, or timing rabbit consultations before or after cats or dogs (Brash and Stanton, 2011). Firm but gentle handling and non-slip surfaces are important during the consultation. Tempting foods such as fresh herbs should be used to avoid anorexia.

If it has not been possible to hospitalise bonded rabbits together then the owner should be warned that when the rabbit arrives home it may smell like a stranger, which can lead to rejection. To minimise the risks of rejection, the scent of the returning rabbit should be returned to normal as much as possible, for example by rubbing a towel over the rabbit which stayed home then over the returning rabbit (and vice versa) (McBride, 2012). Additionally, the reintroduction should be supervised, in case they no longer recognise each other.

Housing and exercise

Rabbits are ground-dwelling and burrowing animals. Although they will jump up onto surfaces, they should have safe places to hide in, placed at or near ground level. A shelf they can use as a vantage point is also appreciated (Seaman, 2012).

A rabbit hutch should be large enough to allow the rabbit to stand upright on its hind legs, and to take at least three hops in one direction (Figure 3 and 4). There should also be sleeping areas, one for each rabbit, so they have a choice of sleeping together or separately. For house rabbits, a safe retreat should be placed in a quiet area where the rabbit can feel secure. An indoor hutch or cage should be out of direct sunlight, not too close to any heat source such as a radiator, and should be well ventilated (Bourne, 2009b).

Preferably, any outdoor or indoor hutch should have an exercise area/run permanently attached, allowing the rabbit to choose when to exercise. Unless this is very large, the rabbit will also need periods in a much larger area in which they can exercise.

Litter trays for house rabbits to use as latrines should be provided in quiet, out of the way places where a rabbit will feel safe while using the latrine. If rabbits have access to more than one room, several litter trays are advisable so there is always one nearby.

Safety and enrichment

Rabbits will naturally chew on anything within reach, therefore it is important to ensure that poisonous plants, electric cables etc. are kept well out of reach or protected (e.g. rabbit-proof tubing around electric wires). Safe materials for chewing should be provided, such as branches from fruit trees, and a tub of earth for digging, if they do not have access to an outside area in which they can dig safely, plus e.g. tubing to run through. Concentrate foods can be hidden for rabbits to seek out (e.g. bits of apple in a pile of hay). They should also be given sufficient time and space for exercise, running about and standing upright (Todd et al, 2014; Best, 2008; Bourne, 2011; Staggs, 2012).

Myxomatosis

Myxomatosis is a poxvirus disease, originally a mild disease of some species of cottontail rabbits (Sylvilagus spp.) in North America, but severe and usually fatal in Oryctolagus cuniculus. It was deliberately introduced into Australia in 1950 and into Europe in 1952 in attempts to reduce the population of wild rabbits; it spread to the UK in 1953. This virus is transmitted mainly by biting insects, particularly the rabbit flea, Spilopsylus cuniculi and mosquitoes, although it can also be transmitted by direct contact with an infected rabbit. Rabbits kept outside (including those in hutches), or given access to the outside so that they can hop around and graze, are most likely to be exposed, but house rabbits can also become infected.

Infected rabbits typically develop oedema of the eyelids, face and ears, and the genitals, skin nodules on the body, face and legs, particularly at mucocutaneous borders, and mucopurulent blepharocon-junctivitis due to secondary bacterial infection, with the eyelids often swollen shut (Figure 5). Additionally there is lethargy, depression, pyrexia and usually anorexia.

While supportive nursing care can be given, there is no specific treatment and affected rabbits are generally euthanased on humane grounds. Rabbits which have previously been vaccinated sometimes develop mild clinical signs and can be nursed to recovery. High environmental temperatures (85°F/29.4°C) may improve survival, along with aggressive fluid therapy, supportive feeding, good general nursing, NSAID and antibiotics to protect against secondary infection (Fox, 2009).

Rabbit haemorrhagic disease

Rabbit haemorrhagic disease (RHD), also known as viral haemorrhagic disease (VHD), is another severe, acute and usually fatal viral disease of rabbits. It is caused by a calicivirus and emerged in the 1980s, first being seen in the UK in 1992. This is a disease of adult rabbits, with juveniles becoming susceptible between 4 and 8 weeks of age.

Affected rabbits may be found dead, or show anorexia, lethargy and depression, with high fever, respiratory distress, sometimes foamy bloody discharge from the nostrils, excessive lacrimation and ocular haemorrhage, cyanosis of the eyelids, ears and mucous membranes, abdominal distension, diarrhoea or constipation and neurological signs (ataxia, posterior paralysis, peddling, opisthotonus, convulsions). Terminally, clonic convulsions, lateral torsion of the body, paresis, hypothermia and sometimes epistaxis may be seen; the rabbit may become comatose.

Transmission of the virus is direct (contact with an infected rabbit) or indirect, including by a wide variety of insects from flies to fleas and mosquitoes, also on fomites, including by people contaminated by infected rabbits. There is no treatment, but the disease can be prevented by vaccination (Fox and Bourne, 2009).

Vaccination

In the UK, rabbits can be vaccinated against both myxomatosis and RHD at any age from 5 weeks old using the Nobivac Myxo-RHD combined myxomatosis and rabbit haemorrhagic disease vaccine. Owners should be warned that it is common for rabbits to develop a small, painless lump at the vaccination site. Very rarely, more serious complications may occur. The vaccine is based on myxoma virus which has been altered to also produce an immune response against RHD virus. Note that some rabbits which have previously been vaccinated with other vaccines against myxomatosis, or have survived natural infection, may not develop full immunity against RHD. Rabbits should be re-vaccinated yearly, rather than every 6 months as was recommended for previous live attenuated vaccines against myxomatosis (Meredith, 2012; Spibey, 2012).

Key Points