Your Rabbit's Teeth
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Rabbits’ teeth are part of a complex digestive system that promotes efficient assimilation of plant materials that are indigestible to many other species. The front teeth include four sharp, chisel-like incisors: two on the top and two on the bottom. Behind the upper front teeth are two smaller peg incisors. When a rabbit is at rest, the bottom incisors nestle between the peg incisors and the upper front teeth.
There are twenty-two premolars and molars, often called cheek teeth when referred to as a group. Their deep grooves create ridges that are perfect for breaking down fibrous plant materials. In a healthy rabbit, the cheek teeth come into contact only during the chewing process.
Dr. Angela M. Lennox, editor of Rabbit and Rodent Dentistry Handbook, coauthor of Clinical Radiology of Exotic Companion Mammals, and past president of the Association of Exotic Mammal Veterinarians, explains the function and growth of the teeth:
Rabbits use their incisors to slice food, and the tongue moves the food into the mouth. The molars, moving in a lateral arc, grind the food on one side of the jaw at a time.
One of the most important features of the teeth is that they are open rooted, meaning they grow continuously throughout the rabbit’s lifetime. Teeth in healthy rabbits are properly worn down by the ingestion of silicate-containing [abrasive] plant materials.
It’s important for a rabbit’s teeth to retain their proper length, shape, and alignment. When tooth wear is decreased or abnormal, the risk of dental problems increases.
(The teeth have long crowns instead of true roots, but for ease of communication the word “roots” is used in this article.)
Some Common Dental Problems
Fracture
Fractures are serious injuries that can lead to other problems, including damage to roots (and resulting abnormal tooth growth) and abscesses. Incisors may fracture during a fall or when a rabbit sustains some other head injury. When teeth are overgrown, they are more prone to fracture.
In addition, a tooth may fracture during improper dental treatment. Dr. Lennox, who teaches rabbit dentistry and surgery at various veterinary conferences throughout the US, says:
It’s recommended that specialized dental equipment be used to examine and treat disorders in rabbits, including high-speed dental burrs to shorten and shape the teeth. Simply clipping overgrown teeth with nail clippers or rongeurs carries a high risk of tooth fracture and abscess, does not allow teeth to be restored to normal shape, and does not address underlying issues such as infection.
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Malocclusion
Malocclusion (misalignment) of the incisors is a noticeable problem. Molar malocclusion generally isn’t noticed until a rabbit begins to exhibit signs of distress or the rabbit is brought in for incisor treatment.
In Rabbit and Rodent Dentistry Handbook, Dr. Vittorio Capello indicates that the most common causes of dental disease are congenital (hereditary), traumatic injury, change in jaw formation, primary malocclusion of the cheek teeth, and metabolic bone disease. All but genetic disorders are commonly referred to as acquired dental disease (ADD).
Keep in mind that incisor overgrowth affects proper working of the jaw, thus impacting the health of the cheek teeth (and vice versa). If your rabbit has incisor problems, it is important to have cheek teeth checked regularly because changes to molar alignment, shape, and growth will likely not be visible in the early stages.
Spurs and Spikes
When cheek teeth are not wearing evenly, they will form spurs or spikes that can, in turn, lacerate the tongue, cheeks, and other soft mouth tissue. Though it may seem that a tiny, sharp point on a tooth cannot cause serious problems, the opposite is true. As a rabbit tries to avoid use of a particular tooth, abnormal pressure may be put on other teeth and the uneven wear becomes even greater. In addition, an abscess may form in the soft tissue.
Abscess
Facial abscesses are most commonly caused by dental disease. Because abscesses are serious and often difficult to treat, it’s important to consult with an experienced vet.
Signs of Dental Disorders
Though dental problems are common, rabbits generally exhibit subtle signs so it’s incumbent upon caregivers to note changes to behavior. Sometimes a rabbit may seem picky about food or less active. Other signs include dropping food, drooling, eating or drinking less, bad breath, reduced grooming behavior, and accumulation of caecotrophs around the anus.
Greater evidence of a problem includes ocular (eye) discharge, hunching and/or grinding the teeth in pain, lethargy, refusal to drink, anorexia/weight loss, and swelling on the face.
Diagnosis and Treatment
Dental disorders can generally be successfully treated when the problem is identified in the early stage. Dr. Lennox offers this:
Proper diagnosis is enhanced with specialized dental examination tools (mouth gags and speculums), radiographs of the skull to see the position of the teeth and roots, and in some cases with an endoscopic examination of the mouth. Sedation is required for thorough examination of the cheek teeth.
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When the incisors are maloccluded, repeated trips to the vet for trimming and reshaping (including the anesthesia) can be stressful for the rabbit. Extraction is sometimes the best choice, especially when regular trimmings will be required for the rabbit’s lifetime (rabbits do well without incisors; see below). Other reasons for incisor extraction include fracture, endodontic disease, and facial abscess. This major surgery should be discussed in detail with a veterinarian experienced in rabbit dentistry.
Regarding molar malocclusion, Dr. Lennox advises:
When problems involve the cheek teeth, use of specialized dental equipment for rabbits is recommended to bring the teeth back to normal shape and size. Extraction of loose or abscessed teeth is also important.
Other Medical Treatment
Teeth problems can be very painful, necessitating the administration of analgesics (pain medication). If infection is present, an antibiotic will likely be prescribed prior to any surgery as well as after the procedure.
While at the animal hospital, rabbits are generally monitored carefully. Fluids and syringe feeding may be necessary.
Euthanasia
Euthanasia is generally not necessary for dental disorders that are caught in the early stages. However, when it’s obvious that the rabbit’s quality of life is becoming compromised and treatment is not likely to help, euthanasia may be the most loving option.
Home Care
Aftercare for dentistry will vary, based on the severity of the disorder and the dental procedures. The home-care regimen may include administration of pain medication, antibiotics, subcutaneous fluids, and syringe-fed food.
Within hours of surgical recovery, the bunny can (generally) be expected to start eating on his or her own. However, it’s important to remain alert to signs of gastrointestinal hypomotility (slowdown) and take appropriate action.
Rabbits without their incisors use their lips and tongue to pick up food, moving it to the back of the mouth to be ground by the molars. It’s helpful for caregivers to tear leafy greens into small pieces. Since a rabbit uses the front teeth to pull dead hair from the body, it’s also recommended that caregivers provide grooming assistance.
When a rabbit is treated for a molar condition, especially surgery, the veterinarian can be expected to outline a home-care regimen.
Prevention of Dental Disorders
Unfortunately, it’s unclear what causes acquired dental disease in all rabbits, but diet is considered an important factor. Because caregivers are in control of the diet, this aspect of rabbit care is emphasized. Dr. Lennox shares this:
Studies on wild European rabbits (from which our domestic rabbits descended) show the diet is composed of very coarse fibrous plant materials that are high in silicates, which promote the normal wearing of teeth. The closest we have to that is grass hay.
Some hay may be vitamin and mineral deficient (depending on soil conditions, harvesting, storage, and packaging), thus emphasizing the need for feeding a variety of quality grass hays.
Processed pellets were developed for rabbits in production or going to slaughter to minimize mess and optimize growth and pelt development. This obviously is not the goal for companion rabbits. However, due to variances in hay quality, it may be beneficial to feed a limited amount of pellets, based on the weight of the rabbit. The pellets should be grass-hay-based and of high quality (e.g., not containing soy, grains, seeds, dried beans, or pieces of fruit).
Leafy greens are vitamin-rich but should be fed in measured amounts so that the rabbit does not forgo eating hay.
If it is unsafe for your rabbit to browse the yard, pick and offer some grass shoots, clover, or other chemical-free, rabbit-safe plants. Plants found in the natural environment are generally more fibrous than are purchased greens. As Dr. Lennox advises above, don’t over-feed the greens.
In Conclusion
Rabbits are marvelously constructed to get the most nutrient value from low-energy foods. In addition to providing regular vet care, help keep your bunny’s teeth healthy by giving him or her safe things to chew on. These include untreated grass mats and willow baskets, cardboard boxes and tubes, and unsprayed apple branches. Provide unlimited grass hay, which not only helps wear the teeth evenly but also acts as an important digestive aid.
Warm thanks to Dr. Angela Lennox for contributing to this article.
References
Capello, Vittorio with Gracis, Margherita; Lennox, Angela M. Ed., Rabbit and Rodent Dentistry Handbook. Zoological Education Network
Capello, Vittorio and Lennox, Angela M, Clinical Radiology of Exotic Companion Mammals. Wiley-Blackwell
Harcourt-Brown, Frances, Textbook of Rabbit Medicine. Butterworth-Heinemann
Meredith, Anna and Flecknell, Paul, Eds., BSAVA Manual of Rabbit Medicine and Surgery. British Small Animal Veterinary Association
Quesenberry, Katherine E. and Carpenter, James W., Eds., Ferrets, Rabbits, and Rodents. Saunders
This article was first published in Issue 9, Autumn/Winter 2009/10, of Bunny Mad (“The magazine for bunny mad people!”), a United Kingdom publication. www.bunnycreations.co.uk. Used with permission.