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Dental disease in rabbits

Rabbit's teeth are open-rooted, meaning that they continuously erupt and grow throughout its life. If a rabbit has congenital or acquired dental disease, then the teeth may overgrow or grow distorted, which can cause life-long problems. This factsheet aims to discuss the common causes and treatments for dental disease in rabbits.

Your questions answered

How many teeth do rabbits have?

Rabbits have four upper incisors and two lower incisors which are used to slice and cut food into smaller pieces that are then transported by the tongue to the premolars and molars for chewing. Rabbits also have "peg teeth", wihch are the small teeth that sit directly behind the upper incisors. Unlike dogs and cats, rabbits do not have any canines, but have a gap where the canines would be, called a diastema.

The upper jaw has six cheek teeth, consisting of three premolars and three molars on each side. The lower jaw has ten teeth, consisting of two premolars and three molars on each side. It is not possible to distinguish between premolars and molars and they form a row of teeth which are all used for grinding.

The incisors grow approximately 2-3 mm per week with the cheek teeth grow approximately 2-3 mm per month. Growth rate and dental wear is variable; dental wear is affected by the abrasive nature of the diet and duration of grazing.

How do rabbit's teeth function?

Wild rabbits live on a grass-based diet, which is naturally abrasive. It is this constant abrasive chewing action that allows wearing down of the constantly growing teeth, and maintains normal occlusion.

Domestic rabbit's teeth act in exactly the same way, however, their diets differ, as does the variety of breeds and head shapes. Wild rabbits have slim, long heads, whereas many breeds of domestic rabbits are brachycephalic, which means they have a short-nosed face; this can affect proper alignment of the teeth in the mouth.

If the rate of eruption of the teeth is not balanced by correct attrition, as can happen if the diet is not appropriate, eg rabbits fed only a pelleted diet, then dental disease may result.

What can go wrong?

There are several things that can go wrong with your rabbit's teeth. Firstly, dental disease can be congenital, this means that rabbits that are bred from parents who have dental problems, or known problems in the breeding line, and are likely to inherit the problem themselves.

Congenital malocclusion is normally apparent by the age of 9-18 months and normally require life-long treatment in order to keep the rabbit comfortable and eating normally. Incorrect or poor diet however, is the most common cause of malocclusion. Rabbits need a high fibre, abrasive diet in order to guarantee adequate gut function and dental wear. If fed a diet low in abrasive particles that is consumed rapidly, their teeth will quickly become overgrown.

A rabbit's diet should consist of at least 70% grass/good quality hay, which should always be available. Most rabbits will consume their body weight in hay each day. A variety of fresh greens and vegetables (28% of the diet) should be fed daily (one handful morning and evening). A small amount (only 2% of the diet) of good quality extruded nugget-type commercial pellet should be fed to prevent selective feeding to ensure provision of the necessary vitamins, minerals and proteins. This is the main way to prevent dental disease from occurring.

Trauma is another potential trigger for dental disease. Rabbits that are dropped and bang their mouth or may pull on the wire of their hutch/enclosure are prone to traumatic dental disease. Any factor that alters the position of the teeth may, in fact, result in their elongation and malocclusion. This type of malocclusion can sometimes be cured through burring the teeth (normally the incisors) at regular intervals, with appropriate instruments, until they grow correctly again. This may take several months, and often, despite this repeated treatment, it is not possible to solve the problem completely.

What is selective feeding?

Selective feeding is a big problem with rabbits and many owners are still unaware of it.

Rabbits that are housed indoors and fed mainly on mixed cereal food, with limited access to vegetables or grass, will pick only the pieces that they like most, leaving the rest of it.

It is therefore imperative that if you feed a muesli type dried food you do not re-fill your rabbits bowl up until all the food has gone, and consider swapping your rabbit onto an extruded nugget type food to prevent selective feeding.

Wild rabbits that have unrestricted access to grazing and browsing, or even pet rabbits that consume a varied diet based on hay, grass and vegetables, are less likely to develop dental disease, when compared to those rabbits that are allowed to selectively feed on their low fibre mixed cereal ration.

What are the signs of dental disease?

Rabbits may just suffer from malocclusion of the incisor teeth, in which case burring the teeth as and when is necessary, in many cases, is sufficient to manage the problem. Never allow anyone to clip your rabbit's teeth with nail clippers or any other type of clipper. The pressure that is put onto the tooth during clipping is likely to crack and split the tooth down to the root; this can potentially result in a tooth root infection, which can be very difficult to treat.

Overgrown incisors are a hindrance to many rabbits and, in the majority of cases, they are better off having them surgically removed. Rabbits adapt perfectly well to having no incisors, as they begin to use their lips to hold and pick up their food. Consult your vet if you are considering having this done.

Molar and premolar malocclusion is more complicated. Often a rabbit may begin with incisor malocclusion and, as the jaw is pushed out of alignment, the molars and premolars will overgrow as a consequence.

Common clinical signs in cases of dental disease include reduced appetite (the rabbit goes off certain foods, sometimes hard foods, sometimes softer ones), may salivate profusely and have a wet chin, or matted fur, at the front paws where they have been wiping their mouth. Weight loss may occur if the problem develops slowly and the rabbit may become depressed. Discharge from the eyes may be evident when elongation of the upper tooth roots is responsible for impinging on and blocking the nasolacrimal ducts. The upper tooth roots can, in severe cases, even grow into the eye sockets. If you feel along your rabbits lower jaw you may fee bumps due to teeth overgrowing into the bone.

How will my vet diagnose dental disease?

Radiography of the skull is recommended in any case of suspected dental disease, in order to assess the status of all the tooth roots which can be overgrown or distorted. The x-ray will also allow assessment of bone involvement and will show how extensive the problem is. The nasolacrimal ducts can also be evaluated at the same time.

Can my rabbit be treated?

Rabbits with dental disease affecting the cheek teeth require general anaesthesia, often on a regular basis, in order to appropriately assess the teeth, remove any sharps edges and restore a more normal occlusal plane. This may need repeating as often as monthly for the rest of the rabbit's life, so it is also a serious financial commitment for the owner. The welfare of the rabbit has to be, in any of these situations, of primary concern.

In more advanced cases surgery may be necessary to remove cheek teeth if they are not stable in their socket, or if they are infected. Your rabbit may be referred to a more specialised 'rabbit vet' for this type of surgery.

What about abscesses?

Facial abscesses are common in rabbits and may be associated with bony structures in the skull. Abscesses often carry a poor prognosis since it can be impossible to surgically remove and completely clear the infection. Systemic antibiotics are often ineffective, especially if not combined with surgery, in reaching the site of infection due to the poor blood supply.

Surgery is the only available option in many of these cases. Beads containing antibiotics can be implanted into the infected site during the surgical procedure which slowly release antibiotics directly to the abscess over a period of time. Many vets also apply manuka honey locally over the abscess site following a surgical procedure, this is due to the good antibacterial properties of this natural product.

If, with appropriate treatment, your rabbit is pain free or its pain can be managed successfully, and has a good quality of life, they will live perfectly happily for many months or years, however, if the rabbit's quality of life, at any point, cannot be maintained, then euthanasia is the kindest option.

Conclusion

Dental disease in rabbits is a complicated and often preventable problem. Always ensure you feed your rabbit a good diet to try and prevent problems arising. If you are concerned about your rabbit's teeth, consult your vet as soon as possible.

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