Malocclusion – Overgrown Teeth in Small Mammals

Malocclusion, the medical term for improper alignment of the teeth, is one of the most common veterinary problems seen in small mammals whose teeth continuously grow throughout their lives. Some species affected with malocclusion include rabbits, guinea pigs, hamsters, gerbils, rats, mice and chinchillas.

In the wild, most rodents and rabbits eat mainly nuts, seeds, grasses and low-growing shrubbery. The incisor teeth function to crop or shear plant material, and then the cheek teeth are used to grind the material before swallowing (similar to humans, who bite with the teeth in the front of their mouths and chew with the molars).

Unlike many other species, the teeth of these animals continually grow. The constant actions of cropping with the front teeth and chewing with the cheek teeth keep the teeth well aligned and provide constant and even wear on all the teeth, preventing overgrowth. Normal teeth, therefore, do not require trimming.

When malocclusion is present, the teeth continue to grow without being properly worn by the opposing teeth. The incisors can curl and twist, leaving the animal unable to pick up food. There are many predisposing factors, including heredity, diet and nutrition, injury to the tooth roots or face, and infection.

If the molar teeth are maloccluded, they can develop “points,” sharp edges that result from the uneven wear of the teeth. These points can cut into the inner cheeks and tongue. This is not only very painful, but also can lead to infection in these areas.

What to Watch For

Veterinary Care

Diagnostic Tests

Veterinary examination can usually identify incisor malocclusion. Your veterinarian may use an otoscope (the instrument usually used to look in the ears) or another type of speculum during the exam to look at the molar teeth.

Sedation may be required for complete evaluation of the molar teeth. Radiographs (x-rays) of the skull may be necessary to evaluate the tooth roots for infection, and to evaluate the nearby bones for signs of trauma or fractures. Sedation is required for diagnostic radiographs of the head region (even the most docile little critter will not stay still enough for the proper positioning for the required views).


heafor malocclusion involves trimming (“filing” or “clipping”) of the teeth. The incisors can usually be trimmed without the use of anesthesia. Anesthesia is almost always necessary for trimming of the molar teeth.

Antibiotics may be prescribed if infection is suspected, but are not routinely necessary if there is no suspicion of infection.

In severe cases, the incisor teeth can be surgically removed. This is a permanent procedure and must be discussed with your veterinarian.

Home Care

After your pet’s tooth trim, he may need soft food for one to three days as his mouth heals. Force-feeding or syringe feeding may be necessary.
Pets with a history of malocclusion are likely to need repeat tooth trimming. Some pets only need veterinary attention once or twice a year; others may need it as often as every six weeks. Most pets are somewhere in between these extremes.

Preventative Care

Feed your pet good quality pellets high in fiber. Fresh hay should be available at all times to encourage grinding of the back teeth. Stem hay is better than commercially packaged leaf or “hay cubes.”

Check your pet’s incisor teeth periodically since malocclusion is not cured but managed. Ask your veterinarian to check the incisor and molar teeth any time your pet gets examined. The molars should be checked at least once a year, but preferably twice a year.