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Some Interesting Notes on Rabbit Teeth

Here is an Etherbun post from a few years ago from Mary Cotter who summarizes a vet dentist’s observations on rabbit teeth:

Last week at NAVC David Crossley (who is a renowned veterinary dentist, working on his Ph.D. right now) gave a very informative talk on rabbit teeth. A lot of the points he made are worth summarizing here. Some of this will be brief quotes from his paper in the proceedings of the conference – anyone interested can order the entire proceedings (covering all species) for around $45 from NAVC.

1) Because rabbits’ upper and lower molars do not "match" (there are different numbers of upper and lower molars, and the upper and lower molars are different sizes), "abnormalities of a tooth in one jaw may affect up to three teeth [!] in the opposite jaw."

2) It is largely the silicate content of grass that helps to abrade down molar length, and rabbits should chew primarily grass for several hours per day. Chewing less abrasive foodstuffs can result in molar overgrowth. Even some wild rabbits who have access to more lush vegetation (higher in energy and lower in silicate content – typical of most vegetables as far as I know) can start to show a minor degree of molar overgrowth.

3) Side-to-side chewing motion is required for a rabbit to chew grass, but mostly up-and-down motion to chew pellets, grains, etc. It is the side to side motion that prevents molar spurs from forming. Because the lower dental arcade is somewhat narrower than the upper, up-and-down motion will permit the formation of molar spurs fairly readily.

4) Teeth in the lower jaw grow faster than teeth in the upper jaw, so spurs and other abnormalities are seen more readily in the lower teeth.

5) "Once any dental problem progresses to a stage which affects the efficiency of chewing, affected rabbits tend to alter their eating habits, increasingly searching out higher energy foods. Owners frequently notice the change and increase the supply of this type of food. Unfortunately this further reduces tooth wear and may result in serious dietary imbalances and caries development. Any reduction in jaw function has a dramatic effect on the bone, particularly around areas of stress such as muscle insertions."

6) Because of their blunted head shape, dwarf rabbits’ incisors often do not function normally, which can result in not only overgrown incisors, but also problems with molars. In larger breeds, incisor malocclusion is more often the **result** of overgrown (over-long) molars.

7) "Any rabbit that does not wear its teeth sufficiently will end up with its mouth held open by elongated cheek and/or incisor teeth. This interferes with chewing, and once established the problem tends to self perpetuate." Crossley made the point that the chewing of fresh grass probably tends to abrade the teeth even better than the chewing of hay. Needless to say, however, in many areas of the USA, chewing grass outdoors will expose the rabbit to life-threatening diseases such as Baylisascaris, West Nile virus, etc. etc. – so hay may be the overall best choice for those who don’t have protected "grazing land" for their house rabbits. In any case, the overall thrust of his lecture was this: Feed your rabbit low-energy, high-silicate vegetation that will require hours (literally) of chewing. The way to keep your bunny's GI tract healthy turns out also to be the way to keep his teeth healthy.