In our clinics we are presented with rabbits with a variety of different-looking diseases such as tooth problems, gut stasis, urine scalding, fly strike, obesity, anorexia and soiling under the tail, all of which originate from inappropriate diet. In fact, 75% of illnesses of domesticated rabbits in the UK are as a result of feeding inadequacy; so we make no apology in concentrating on this subject to explain how these diseases occur. It is sobering to learn that on the continent, where pet rabbits tend to be ‘put out to grass’ and their owners are less keen to purchase commercial feeds, the incidence of these diseases is reduced.
In the wild, rabbits evolved to live on natural grasslands where they eat grass and some other plants, and grass, and grass…and grass. They also adapted to run away quickly from scary creatures that wanted to eat them. Rabbits naturally feed in the early morning, the evening and at night; their stomach is a food reservoir that should never be empty. The hindgut (caecum and colon) is about ten times the size of the stomach and deals with food in a highly specialised way by separating the indigestible fibre from the nutrient-rich soluble food. The fibrous balls are quickly excreted (so as not to weigh the rabbit down when running away from predators), and in the early morning the caecotrophs (soft mucus-covered excreta, which contain valuable nutrients) are consumed direct from the anus (coprophagy), allowing them to undergo secondary digestion, and are an important source of amino acids and B and K vitamins.
Rabbits are selective feeders and, when presented with a muesli mix, will pick out the seeds and nuts, much like children preferring chocolate to more wholesome food. The rabbit gut is not used to large amounts of simple carbohydrates, which promote the growth of toxin producing bacteria, which cause diarrhoea and life-threatening disease. Although rabbits derive little nutrition from insoluble fibre, it is vitally important in the regulation of gut motility (i.e. keeping the gut moving); bloat and obstruction may occur if there is gut stasis. The ideal diet is high in fibre and low in simple carbohydrates, such as grass or hay made from older pastures, which contains a mixture of grasses, herbs and wild plants (modern pastures tend to be monocultures and may not meet all the dietary requirements). Some high fibre commercial pellets are acceptable, together with high fibre greens such as kale, beetroot and carrot tops, broccoli, cabbage, mustard, watercress, chicory and raspberry leaves. Dandelion leaves are a good post-operative appetite stimulant.
Many domesticated rabbits have a sedentary lifestyle and this, combined with energy-rich diets, can lead to obesity. Perineal soiling (faecal matter stuck under the tail) can result from obesity, inability or reluctance to groom, or true diarrhoea. In most cases perineal soiling is due to the accumulation of uneaten caecotrophs (see first paragraph). The stimulus to eat these is the odour produced by them, which occurs only if the right food has been eaten: high levels of protein and carbohydrate in the diet will inhibit coprophagy, while low levels enhance it. Fruit and lettuce with a high water content (tomatoes, cucumber and iceberg lettuce) contain little fibre, and caecotrophs are produced that are very soft and remain uneaten. If rabbits do not perform this task they will not fulfil their dietary requirement and the soiled area will scald the skin and attract flies and maggots.
Flies will be attracted to moist, damaged skin and especially to areas of faecal soiling, where they will feed and lay eggs that hatch to produce maggots that will burrow into the skin to feed – all in a matter of days. This usually occurs in the summer, when it is hot and flies are at their most numerous. It can be hard to spot at first, because rabbits tend to sit on the area that is most likely to be affected (under the tail). It is essential to get fly strike treated quickly as it is debilitating and can be life-threatening (it is usually worse than you think). Obviously the way forward is to prevent it happening by providing conditions that don’t predispose to it: appropriate feeding, adequate exercise, shelter in a cool place, fly control and vigilance.
How can misshapen teeth be linked to improper diet? Rabbits chew very quickly; in fact there are up to 120 jaw movements per minute, with a pronounced lateral grinding action, and the teeth wear down against each other and against hard, fibrous food, which is swallowed only when it has been ground up enough. To compensate for this dental attrition, their teeth grow at the rate of 2mm each week. If they eat food that doesn’t require much chewing, their teeth will grow long and splay out sideways, and be useless. Furthermore, continued pressure on splayed teeth will cause fractures at the tooth roots, which turn into abscesses. These abscesses eventually burst out in the face, usually do not heal and threaten the life of the rabbit. In addition to the foregoing, poor diet and lack of access to sunlight creates mineral deficiencies, with adverse effects on bone and tooth development. In addition, as with people, foods high in sugars promote dental caries.
The backs of the thighs and hocks become damp with urine, eventually leading to raw areas and soreness. This is most frequently seen in overweight rabbits, and prevention should be aimed at dietary modification and exercise. Diets rich in calcium promote the formation of crystals in the urine, which turn it ‘sludgy’ and it leaks out down the legs. Avoid alfalfa hay, spinach, parsley and celery.
Myxomatosis is a viral infection, transmitted between rabbits by fleas and flies. It is prevalent in wild rabbits and causes death after about three weeks. Viral Haemorrhagic Disease is another fatal disease that we see in this country. There is no treatment for either, but rabbits can be successfully inoculated to protect them against both. If you want to know more please find it at: Vaccinating Your Rabbit.
If you would like further information about caring for your rabbit please contact one of our Veterinary Nurses on (Usk) 01291 672637 (Caerleon) 01633 430053.