Treating dental disease in rabbits

Dental disease in rabbits can be congenital or, more often, acquired

An increasing number of veterinarians are adding rabbit care to their practices. Photo courtesy Veronica Gventsadze
An increasing number of veterinarians are adding rabbit care to their practices.
Photos courtesy Veronica Gventsadze

Rabbits are gaining inroads into small animal practice. More “dog and cat veterinarians,” myself included, are taking on preventive care of this beloved pet species. Clients expect the same level of care for their rabbits as they do for dogs and cats; gone are the days when rabbits were seen only as an agricultural species.

As general practitioners, we have to provide effective treatment within our competence, and to know where this competence ends and the need for specialized treatment and referral begin.

Check those choppers

Rabbits can react to handling with extreme fear and stress, causing many of us to back off before an adequate physical examination is done. The part of the rabbit getting left out most often is its teeth. Their mouths are very narrow compared to our carnivore patients, and many rabbits will protest vehemently or chew nonstop when humans dare to push a scope into their mouths. Yet, the teeth are often the part of the rabbit most susceptible to disease leading to pain (hence inappetence and gut stasis), abscess formation, and injury to other parts of the body (eyes, nasal sinuses, nasolacrimal ducts).

A study led by Dr. Dan O’Neill, a senior lecturer in companion animal epidemiology at the Royal Veterinary College, looked at morbidity and mortality of 6,349 rabbits under primary veterinary care at 107 clinics in England. It was established oral disorders, including overgrown incisors, overgrown molars, and generalized dental disease, were prevalent in 10.9 percent of cases.

This might not seem very impressive until one considers the following: The study found anorexia, indicative of dental disease, was the second most common cause of death in rabbits, the first being myiasis.1 A rabbit whose pain from dental disease has reached a point where it can no longer eat, goes into gut stasis and quickly progresses beyond the point of no return if left untreated.

Dental disease in rabbits can be congenital or, more often, acquired. A common example of congenital dental disease is mandibular prognathism in dwarf breeds, especially rabbits under 1.5 kg, with resulting overgrowth and forward-pointing of lower incisors and curling inward of upper incisors.

Face it

In general, there is a strong correlation between the shape of a rabbit’s face and its likelihood of dental disease. The cuteness factor making short-faced rabbits, as well as dogs and cats, endearing to people, is responsible for a host of health problems in these animals. An online questionnaire was distributed by researchers in the U.K., which aimed to determine what type of rabbit people prefer.2

Based on 20,858 responses from around the globe, moderately brachycephalic rabbits were 2.84 times more popular than long-faced breeds, and extremely brachycephalic rabbits were 1.97 times more popular. It is, therefore, not surprising the most common breeds in the U.K. are miniature lops and Netherland dwarfs, which together comprise 53 percent of rabbits bred in the U.K. annually for online sales alone.3

To my knowledge, there is no reliable data on the relative popularity of rabbit breeds in the U.S. or Canada. The health problems associated with a short face in dogs, cats, rabbits, and horses have prompted 1,456 veterinarians worldwide to form the organization Vets Against Brachycephalism, whose goal is to change public opinion driving the demand for short-faced animals.

Acquired vs. congenital

Acquired dental disease is more common than congenital dental disease. It is most often due to inadequate wearing down of a rabbit’s constantly growing teeth. These rabbits do not have enough hay in their diet, or they do not eat enough of it. (See: What the Hay?) Another cause of acquired dental disease is trauma (usually from being dropped or hit) with damage to the jaw and resulting uneven wear of cheek teeth.

Dental care is an important topic to educate current and potential rabbit owners.
Dental care is an important topic to educate current and potential rabbit owners.

Incisors can get fractured longitudinally, which can cause damage or infection at the apex of the tooth. As a result, the tooth either stops growing altogether, or grows out deformed. This can also happen when incisors are trimmed using clippers instead of a dental burr.

The five steps of a dental exam on a rabbit are described by Krista Keller, DVM, DACZM, in a Lafeber Vet webinar.4 It might come as a surprise—and a relief—that in order to determine if a rabbit has problems associated with its cheek teeth, it is not necessary to look inside its mouth. This information is obtained from observing facial symmetry, palpating the face, sliding the mandible side to side with the mouth tightly shut, and evaluating the incisors. The exact nature of these problems is determined from an intraoral exam under sedation, and dental radiographs.

No matter how severe a rabbit’s dental disease, treating it must wait if the rabbit is weak from anorexia. Intravenous fluids, pain control, and assisted feeding are necessary to stabilize a weak patient and give it strength to withstand sedation (if only trimming is required) or general anesthesia (if extractions and/or abscess surgery are required).

Antibiotics

By now most general practitioners understand only a few antibiotics commonly used in small animal practice are safe for rabbits. There is an established tradition among general practitioners to rely on enrofloxacin (Baytril) to treat various infections in rabbits. However, despite its relative safety, Baytril and ciprofloxacin were shown to be effective in only 56 percent of dental abscess cases, while TMS, another “favorite” antibiotic for rabbits, targeted only seven percent of cases.

If it is not possible to run aerobic and anaerobic culture and sensitivity, the best empirical choices are oral chloramphenicol, injectable penicillin, or oral azithromycin.5 Antibiotics that are harmful if given orally, such as clindamycin, can be delivered in antibiotic-impregnated beads as long as the abscess does not communicate with the oral cavity.6

General practitioners who treat rabbits need a support network: like-minded colleagues seeing rabbits in the midst of “dog and cat” practice; mentors with specialization in exotics who can take on referral cases; and, most importantly, veterinary technicians/nurses, who are often the driving force behind the introduction of rabbit medicine into a practice. If you have such technicians/nurses working with you, treasure them like gold!

WHAT THE HAY?

Since most cases of acquired dental disease are caused by improper wearing down of teeth, long-stem fiber is essential. How can one get a rabbit to eat hay? First, a word about safety during the spread of rabbit hemorrhagic disease virus across North America. Since the virus can survive up to 90 days outside a host, hay that could potentially have been exposed to the virus either at the source or during transport, should be stored for three months before it is fed to an unvaccinated rabbit.

The quality of hay matters greatly. Good hay should be green, free of dust, and smell fresh. Variety is also important. Many rabbits will reject one type of hay only to chow down on another. Fresh grass, as well as berry and fruit tree branches, can be foraged and given to rabbits vaccinated against RHDV. Putting a bunch of dried herbs, such as parsley or mint, into the hay can give it a desirable scent.

However, the most powerful tool for teaching a rabbit to eat hay is the buddy system. Rabbits are social animals that take their cues from warren mates in the wild, and from their bonded companions as house pets. A hay-loving buddy, or even any rabbit within sight, can lead by example. Owners of multiple rabbits know how some animals will reject an offering from a human only to grab the same food from a buddy’s mouth. They trust each other more than they trust us, and who can blame them?

Veronica Gventsadze, MA, PhD, DVM, worked as a conference interpreter and a university professor of the humanities before gathering the courage to turn her love of science and animals into a profession. Upon graduating from Ontario Veterinary College (OVC) in 2008, she settled in British Columbia where she works in small animal private practice. Besides advocacy for rabbits, Dr. Gventsadze writes fiction incorporating lessons learned from animals. Gventsadze can be reached through her website https://veronica-gventsadze.com/contact.

References

  1. Morbidity and mortality of domestic rabbits (Oryctolagus cuniculus) under primary veterinary care in England. Dan G O’Neill, Hermien C Craven, David C Brodbelt, et al. Veterinary Record Volume 186, Issue 14. https://bvajournals.onlinelibrary.wiley.com/action/doSearch?ContribAuthorStored=Craven%2C+Hermien+C
  2. What Makes a Rabbit Cute? Preference for Rabbit Faces Differs according to Skull Morphology and Demographic Factors. By Naomi D. Harvey, James A. Oxley, Giuliana Miguel-Pacheco, Emma M. Gosling and Mark Farnworth. Animals 2019, 9(10), 728 https://www.mdpi.com/2076-2615/9/10/728
  3. The Status of Pet Rabbit Breeding and Online Sales in the UK: A Glimpse into an Otherwise Elusive Industry. By Emma M. Gosling, Jorge A. Vázquez-Diosdado and Naomi D. Harvey. Animals 2018, 8(11), 199. https://doi.org/10.3390/ani8110199
  4. https://lafeber.com/vet/rabbit-and-large-herbivorous-rodent-dental-disease/
  5. Periodontal Bacteria in Rabbit Mandibular and Maxillary Abscesses Kerin L. Tyrrell, Diane M. Citron, Jeffrey R. Jenkins, Ellie J. C. Goldstein, and Veterinary Study Group. Journal of Clinical Microbiology 2002 Mar; 40(3): 1044–1047. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC120222/
  6. https://www.dvm360.com/view/managing-dental-abscesses-rabbits-proceedings
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