“Healthy Teeth Means Healthy Bunny- Chew on these tips for top dental care."
By Margaret Wissman, DVM, DABVP

Anyone who has a dog or cat probably knows that dental care is very important. Companion animal veterinarians routinely explain to owners how necessary it is to have their pets’ teeth brushed periodically at home and, once plaque and tarter accumulate, the pet should undergo routine dental prophylaxis (cleaning) on a regular schedule (usually under general anesthesia, as it is difficult to get pets to cooperate to rinse and spit!)

Have you ever wondered why you haven’t been asked to brush your rabbit’s teeth or have dental cleanings performed? This is because rabbits possess a completely different type of tooth than those belonging to cats and dogs.

Dogs and cats, like their owners, start out with baby teeth, also called “deciduous teeth” because they fall out. They are replaced by permanent teeth that should then last the life of the pet or person. These teeth must last for the life of the pet, which is why dental care is so important.

A rabbit’s teeth continue to grow throughout its life, so they are constantly being worn down and renewed. This type of tooth is called “open-rooted,” meaning that it continually grows. For this reason, a rabbit’s teeth do not need to be brushed
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Lay of the Jaw
Let’s look at the rabbit’s oral anatomy to understand what is important about rabbit oral hygiene.
On each side of the mouth, rabbits have two upper and one lower incisor, three upper and two lower premolars and three upper and lower molars. Rabbit teeth are curved, and the incisors near the front of both the upper and lower jaws are modified to form a chisel-like cutting organ. (Unlike cats and dogs, rabbits don’t have canine teeth, the long pointy teeth.)

The incisors are permanently sharp from gnawing. Enamel is only present on the front surface of the teeth, and the back surface is composed of dentin, which is softer than enamel. For this reason, the front surface wears down more slowly than that of the back.

The space between the incisors and the cheek teeth where no teeth are present is called the diastema. (To give you a visual, Madonna has a diastema gap between her front teeth).

Malocclusion and overgrowth occurs most often with the front incisors, which can grow 10 to 12 centimeters per year throughout the rabbit’s life. A second set of incisors that are located behind the upper-front incisors may also overgrow. The premolars and molars are called “cheek teeth” and can also overgrow from malocclusion.
The muscles of the jaw extend both forward and backward. The mandible (lower jaw) moves forward, backward and vertically, but less so from side to side because of the unique anatomy of the rabbit’s temporomandibular joint (TMJ), which is longitudinally elongated and therefore restricts lateral movement.

Tailor Made
Rabbit teeth and oral muscles are perfectly designed for consuming the necessary roughage that should constitute the bulk of the rabbit’s diet, mainly hay. While wild rabbits prefer to seek out and eat tender shoots and succulent plant parts as the major portion of the diet, domesticated rabbits are also highly adaptable to a high-roughage diet.

I’m sure you have noticed that your pet rabbit spends a lot of time eating and chewing. These actions keep the teeth properly worn down, as long as the rabbit’s teeth are in proper alignment. Rabbits chew their food thoroughly with highly organized tongue movements and up to 120 jaw movements per minute. That’s a lot of chewing!

Rabbits should not be offered unlimited pellets, even if they are the kind of pellets that are lower in calcium, such as timothy hay. Overfeeding pellets tends to promote obesity and chronically soft stools. However, iff pellets are too restricted, this may lead to fur-pulling and gnawing at inappropriate items, such as carpeting, furniture, shoes, books, or even electrical wires. Check with your vet for the correct pellet proportion to feed your rabbit.

Boredom and destructive behavior can be avoided by providing the rabbit with timothy hay, fresh grasses, and appropriate vegetables. It is also a good idea to offer your pet suitable items for chewing and gnawing, such as safe wood and chew toys designed for rabbits.

Good Teeth gone Bad
So, what can go wrong with rabbit teeth? The most common problem is tooth overgrowth from poor alignment, also called malocclusion. The causes of malocclusion are usually multi factorial and can include infections, as well as genetic and traumatic causes. The chewing action of the rabbit is both vertical and horizontal , which provides a grinding action that keeps the occlusal (the opposing surfaces of the teeth that meet normally) surfaces evenly worn. If the mandible is too short or too narrow, this will result in the misalignment of the teeth.

Once teeth are misaligned, they no longer grind down correctly. Misalignment of a single tooth is often the result of an infection in a tooth root or from trauma to the tooth. If one tooth becomes misaligned, it can throw off the entire bite, or it might just affect the opposing tooth.

Malocclusion of the incisors is most common in the smaller or dwarf breeds of rabbit. It usually will be apparent early on, when the owner notices that the front teeth are overgrown. If this is not discovered in time, a rabbit with malocclusion may suffer weight loss or more severe problems due to the inability to consume adequate quantities of food. If a rabbit is unable to eat for any length of time, it may quickly develop a very serious condition called hepatic lipidosis, which can be fatal.
Malocclusion may also occur in the cheek teeth (premolars or molars). Since these teeth are in the back of the mouth and very tricky to see, problems occurring in these teeth are more difficult to diagnose. The only abnormality that an owner of a rabbit with molar malocclusion may notice is weight loss or the inability to eat.

An alert and healthy rabbit that appears interested in food and acts hungry but will not eat often might have molar malocclusion. Another sign of molar malocclusion is if the rabbit begins to eat food and then droops the food from its mouth. If the cheek teeth overgrow, points that pinch or abrade the cheek tissue or tongue may develop, thus making eating very painful.

Check with the Vet
Whenever a rabbit is presented for a physical examination, a thorough oral examination that includes a look at the incisors and cheek teeth should also be performed. While it is quite simple for a veterinarian (and owner) to see the incisors, as they are front and center, special tools are required to get a good look at the cheek teeth. An otoscope, small vaginal speculum or fiber-optics endoscope my be necessary to clearly see the back teeth, because the mouth of the rabbit does not open very wide. Some rabbits do not tolerate this examination without struggling, and these patients may require sedation or general anesthesia in order to see he cheek teeth.

Solutions to Malocclusion
If teeth are overgrowing due to malocclusion, it is possible to trim long incisors with a dental drill or side-nosed cutters. Never trim your rabbit’s teeth with nail trimmers, which would likely split the tooth longitudinally. A split tooth is predisposed to infection of the root. Nail trimmers may also leave a cut tooth with ragged surfaces. Because the teeth of the rabbit aren’t structured like yours or mine, cutting them is not painful, as long as the tooth isn’t split down to the root.

It is possible to cut the incisors of most rabbits without any sedation or anesthesia. Using side-nosed cutters, a rabbit-savvy vet can teach an owner how to rim teeth at home, although the owner needs to be aware of the risk of splitting a tooth. This would need to be discussed and agreed upon by both the owner and veterinarian.
The best way to trim incisors is with a high-speed dental drill, operated by a rabbit-savvy vet. However, this procedure does require sedation or general anesthesia due to the risk of injuring the tongue or fragile oral tissue should the patient move during the procedure. Either way the teeth are trimmed, it is usually necessary to trim the incisors every four to eight weeks.

Malocclusion of the cheek teeth, once diagnosed, requires tranquilization or general anesthesia for corrective dentistry. The sharp, overgrown edges can and do cause very painful punctures and laceration of the tongue or inside of the cheek (also called “buccal mucosa”). A dental drill or tool used for cutting bone is necessary to correct overgrown cheek teeth.

Trimming the cheek teeth properly can be very difficult, because it requires working in the small oral cavity while trying to prevent injury to the gums, tongue, or mucous membrane. As with overgrown incisors, the cheek teeth that are overgrowing must be trimmed periodically, usually every four to eight weeks.

When to extract
While it is possible to rim overgrown teeth periodically, which can be very stressful to the rabbit, it is recommended that the maloccluded teeth be permanently extracted. It is a good idea to first radiograph (X-ray) jaws and teeth to uncover any abnormalities prior to extracting teeth.

If malocclusion has occurred as a result of a tooth root abscess, antibiotics should be administered prior to performing the procedure. Teeth are extracted under general anesthesia. Lower incisors are removed first, then the apposing to incisor is also removed. (If one were left, with no tooth to grind against it, it would surely overgrow.) Cheek teeth are much more difficult to extract.

It’s possible for a tooth to regenerate if a portion of it breaks off, leaving a broken piece of tooth root in the jaw. It often takes about six to eight weeks for a new tooth to erupt. If this occurs, removal can again be attempted once the tooth has grown to a size suitable for excision. Sometimes, if the root is damaged, the tooth may grow back at an unusual angle or in an unusual shape.

After surgery to extract teeth, open sockets are flushed with antiseptic, or the roots may be cultured if bacterial infection is suspected. Antibiotics are usually administered after extraction, and this may be based on the results of bacterial culture and sensitivity.

If there is infection in the tooth root or there is an abscess, antibiotics may need to be administered for six to eight weeks after excision. Since this can be quite painful, pain medication is usually prescribed for up to five days after the procedure.

Home Hygiene
For a healthy rabbit with good occlusion of the teeth, there is very little that the rabbit owner needs to do in the way of oral hygiene. Provide your rabbit with hay, in addition to pellets, and also offer appropriate wood or other rabbit toys for your pet to chew on. Chewing helps to keep the teeth properly aligned and ground down. If you notice that your bunny chews on the cage wire or food bowls, it might be in need of something more appropriate on which to direct its chewing behavior.

Examine your rabbit’s teeth and oral cavity during your periodic grooming sessions, and make note of any overgrown teeth or abnormal bumps in the mouth area. Pay attention to your rabbit’s eating habits, and bring your bunny in to see your rabbit vet if you notice a change in food consumption or if you notice any slobbering, drooling or food falling from its mouth.

Take your pet in for routine periodic checkups that include a thorough examination of the oral cavity, and you will be doing all that you can to ensure good oral hygiene in your bunny.

For more information on buying and caring for pet rabbits, stop by the store and pick up the 2005 annual issue of Rabbits USA!