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Dental Problems in Rabbits and Rodents

Pet Tales
by Barry B. Burtis D.V.M

Dental Problems in Rabbits and Rodents

February is Pet Dental Health Month. Veterinarians take the opportunity to remind pet owners that, as we do, pets require dental care. Rabbits and rodents are common pets and they have some special considerations when it comes to their dental health.

To best understand rabbit and rodent dental problems, it is necessary to know a bit about normal teeth in these animals.

Rabbits are principally grazers. They feed on grasses and other short plants. Their teeth are designed to slice off the vegetation and then grind it for proper digestion. Rabbits have two incisors (teeth at the front of the mouth) on each side of the upper jaw - rodents have only one. The second incisor tooth is quite small and may be missing in some rabbits. The large incisors on the upper and lower jaw normally wear in a chisel pattern. The premolars and molars or cheek teeth in rabbits are arranged in parallel rows on either side of the mouth growing from the upper and lower jaw. In rabbits, all the teeth grow and erupt throughout their life. Unlike rodents, rabbits do not regularly gnaw. Food is gathered into the mouth, the incisors chop it into manageable pieces and the cheek teeth grind it with side to side chewing action. Tooth wear occurs from the abrasive effect of the food eaten. Normally, the rate of tooth growth and eruption matches the rate of wear.

Rodents have four continuously growing incisor teeth. These teeth - two in the upper jaw and two in the lower - are used for gnawing. Gnawing is accomplished by an up and down and front to back chewing action. There is considerable variation in the cheek teeth of different rodent animals. The rat, mouse and hamster have a few small, short, cheek teeth. They develop roots, stop growing and stop erupting once the teeth on the upper and lower jaws meet and oppose one another when chewing. These animals normally eat foods that have high energy content and little abrasive action. Rodent species such as the guinea pig and chinchilla have rootless cheek teeth that continue growing and erupting throughout their life. These animals eat tough, low energy, abrasive food. Like rabbits, growth and eruption match the rate of wear in normal circumstances.

Dental disease can be a common problem for pet rabbits and rodents. Tooth overgrowth is one of the problems that may require treatment by a veterinarian. Accurate trimming of overgrown incisors requires the use of a high speed dental drill or a fine-taper fissure bur in a low speed dental handpiece. Sedation or general anesthesia is generally preferred for these procedures. However, the reshaping of these teeth can be done, without causing pain, in wide awake animals, with minimal restraint, if they are used to handling. Using other means to trim incisors that have overgrown may cause splits along the length of the tooth or injure the growing tissue at the base of the tooth thus affecting future tooth growth.  If animals require trimming of spikes or overgrowth of cheek teeth, general anesthesia is required.

The best treatment for these problems is to try and prevent them in the first place. Careful management of the pet's diet and environment is the best way to do this. Many species of rodents spend much of their spare time gnawing. To prevent incisor overgrowth, they must be provided with a suitable medium to do this. Rabbits, on the other hand, do not require such materials. Rabbits and rodents, if given a choice, will eat more concentrated energy sources first. This may result in dietary deficiencies or imbalances. It may also mean that they do not need to chew their food as much and these foods may have much less abrasive action than more natural ones. Therefore limit concentrates and provide lots of grass or hay for rabbits, guinea pigs and chinchillas. Exposure to sunlight, activating Vitamin D, can also help improve bone and tooth structure.

Development of incisor and cheek tooth overgrowth in dwarf  rabbits may be associated with the changes that have occurred in jaw structure as a result of their breeding. With these genetic influences, in mind, it may be important to choose individuals as pets, whose ancestors have had healthy teeth.