Dental Disorders in Rabbits

Jan 21, 2013 by

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Dental problems in rabbits can be complex and result in serious conditions. This article addresses the most common issues, including signs of dental disorders; pain management (analgesia); diagnosis, treatment, and home care of dental problems, including malocclusion of incisors and of molars; euthanasia; and prevention of dental disorders.

INTRODUCTION

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 on the peg incisors, behind the lower edge of 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, who teaches rabbit dentistry and surgery at Purdue University and at veterinary conferences throughout the US and is the editor of Rabbit and Rodent Dentistry Handbook, 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 grow continuously throughout the rabbit’s lifetime. Teeth in healthy rabbits are properly worn down by the ingestion of rough 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.

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
  • Metabolic bone disease

All but genetic disorders are commonly referred to as acquired dental disease. Some researchers are focusing on the role of calcium metabolism in the development of dental disease. Dr. Lennox advises that at the present time there is much that remains unknown about calcium metabolism in rabbits; thus, this article does not address metabolic bone disease.

Dental problems can be very serious and may result in health issues from which it is difficult for a rabbit to recover. For example, overgrowth of molars can lead to obstruction of nasal passages, or the elongated apexes may cause blockage in the nasolacrimal duct. Reference the section below on prevention of dental disorders for information on ways to help your rabbit maintain healthy teeth.

Note: Rabbit teeth do not have true anatomical “roots.” That portion of the tooth is therefore referred to as an “apex,” the term used in this article.

SIGNS OF DENTAL DISORDERS

Though dental problems are common, our little prey companions often mask the condition so as not to appear vulnerable. Thus, it’s incumbent upon caregivers to note changes to behavior and appearance, including:

  • Pickiness about food or sudden change in food preferences
  • Dropping food
  • Drooling
  • Wet fur or matting on face and forelimbs
  • Eating or drinking less, with corresponding change in fecal output
  • Change in weight
  • Bad breath
  • Reduced activity
  • Reduced grooming behavior
  • Poor coat condition and loss of fur
  • Accumulation of cecotropes around the anus

Greater evidence of a problem includes:

  • Ocular (eye) discharge
  • Pain (e.g., hunched posture, grinding the teeth)
  • Lethargy
  • Refusal to drink
  • Anorexia/weight loss
  • Swelling on the face

It’s important to note that the clinical signs listed for dental disease are non-specific – they may be indicative of some other health problem. In addition, signs can sometimes be attributable to something other than a medical condition. For example, pickiness about food may be related to its quality or to a change in diet. Reduced activity may be a response to unfamiliar visitors. Anything that stresses a rabbit can alter behavior. Observing the variables that affect your rabbit makes it easier to detect problems before they become serious.

PAIN MANAGEMENT (ANALGESIA)

As previously noted, dental disorders often cause discomfort and pain, which in turn can cause severe stress in rabbits. In addition, dental procedures require the use of pain medication.

Dr. Teresa Bradley Bays, author and lecturer on exotic animal species, including rabbits, offers advice on the use of analgesics:

Analgesics should be provided immediately if pain is detected or if the rabbit patient is experiencing any illness or trauma that would be painful in other species, including humans. Pain medication should be administered by the veterinarian before proceeding with diagnostics and any other treatments.

 

Pain medicine should also be provided before surgery (to prevent wind-up pain), during surgery, and after surgery, as well as for recovery at home. A multimodal approach – where a combination of analgesic types are used – creates a synergistic effect that decreases the dose of each individual medication while providing better pain control.

COMMON DENTAL PROBLEMS: DIAGNOSIS AND TREATMENT

Introduction

Rabbit dentistry is complex, primarily because the teeth grow continuously. In addition, the mouth cavity is small, with cheek folds. 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 in some cases with an endoscopic examination of the mouth. Sedation is required for thorough examination of the cheek teeth.

It’s important to obtain veterinarian care for all dental disorders. If a condition is left untended, serious problems result and the rabbit suffers a painful condition, which eventually becomes life-threatening.

Abscesses

Facial abscesses are most commonly associated with dental disease. Because they are serious and often difficult to treat, it’s important to consult with an experienced veterinarian.

Fractures

Fractures are serious injuries that can lead to other problems, including damage to apexes (and resulting abnormal tooth growth) as well as 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 adds:

To examine and treat disorders in rabbits, it’s recommended that specialized dental equipment be used, including high-speed dental burrs to shorten and shape the teeth. Simply clipping overgrown teeth with nail clippers or rongeurs carries 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 or disease of the molars.

 

It should be remembered that most disease of the incisors is secondary to disease of the molars.

Malocclusions

Malocclusion (misalignment) of the incisors is a noticeable problem. Sometimes the veterinarian may suggest that a rabbit’s front teeth be extracted. Dr. Lennox explains:

For rabbits with congenital jaw malformation and malalignment of the incisors without disease of the molars, frequent trimming of incisors often becomes necessary. For these rabbits, the best option may be extraction of the incisors. Rabbits do not require incisors to eat hay and pellets and usually do very well after extraction. Incisor extraction is a routine procedure for an experienced rabbit veterinarian [see below].

Molar malocclusion generally isn’t noticed until a rabbit begins to exhibit signs of distress or the rabbit is brought in for incisor treatment. 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 it is unlikely that changes to molar alignment, shape, and growth will be visible in the early stages.

More detailed information about malocclusion of both incisors and cheek teeth is included below.

Spurs and Spikes

When cheek teeth are not wearing evenly, they form spurs or spikes that can lacerate the rabbit’s tongue, cheeks, and other soft mouth tissue. Though it may seem that a tiny, sharp point on a tooth would not cause serious problems, the opposite is true. As a rabbit tries to avoid use of a particular tooth, abnormal pressure is put on other teeth and the uneven wear becomes even greater. In addition, an abscess may form in the soft tissue.

Remember that a rabbit’s teeth are continuously growing. Therefore, the abnormal pressure of misaligned teeth on the other teeth is cause for discomfort. Additionally, the avoidance of one or more teeth can change the way a rabbit’s jaw normally rotates when eating food. Thus, what may seem like a small problem has the potential of negatively affecting the entire mouth (e.g., other teeth, muscles, ligaments).

Reference the information about fractures (above) for treatment of spurs and spikes.

MALOCCLUSION OF INCISORS: DIAGNOSIS, TREATMENT, PROGNOSIS, AND HOME CARE

Overview

Rabbits use their incisors to grip and slice their food as well as groom their bodies. When incisors are maloccluded (misaligned), repeated trips to the veterinarian for trimming and reshaping (including the anesthesia) can be stressful for the rabbit. Therefore, the decision to remove the incisors depends in part on the condition of the teeth and on how often they need to be trimmed.

If incisor malocclusion is congenital (hereditary), it can be assumed that the teeth will need trimming every four to six weeks throughout the bunny’s life and, as previously stated, extraction may be the best option. Other reasons for incisor extraction include fracture, endodontic disease, and facial abscess. (Rabbits do well without incisors; see the Home Care information below.)

This major surgery should be discussed in detail with a veterinarian experienced in rabbit dentistry. It’s important that the entire tooth (including pulp tissue) be removed, but even with the most skilled surgeon there is a slight chance that teeth will grow back.

Tooth extractions in rabbits are major surgery, so the health of the rabbit is a serious consideration. If there is an infection, the veterinarian will probably prescribe a round of antibiotics before extracting the teeth. Caregivers should also be aware that obese or older rabbits are a higher surgical risk.

When a rabbit is not healthy enough to undergo surgery, the preferred method of maintaining incisors is with a high-speed, water-cooled burr, with a guard to prevent mouth injury. It may be necessary to sedate the rabbit to protect from movement injuries to the mouth and tongue.

Diagnostic Procedures

Because incisor misalignment is often accompanied by cheek teeth malocclusion, a full dental exam is often performed using anesthesia, a rabbit mouth speculum, cheek spreaders, and radiographs (X-rays).

Post-Surgical Procedures

Following surgery, the veterinarian should assure that the extracted teeth were removed in entirety. This is done both by examination of the teeth and by comparing pre- and post-surgical skull radiographs. If any apex or pulp tissue remains, there may be steps that can be taken to prevent the teeth from growing back or developing an abscess.

The wound should be flushed, antibiotics will reduce the risk of infection, and post-surgical analgesics will help manage the pain. Additionally, fluids may be administered and the rabbit syringe-fed.

Home Care of a Rabbit with Incisor Extraction

Aftercare for incisor extraction will vary, based on the severity of the disorder and the dental procedures. Discomfort may cause stress and a resulting gastrointestinal disorder. The veterinarian may prescribe a home-care regimen that includes administration of the following:

  • Antibiotic
  • Analgesic (pain medication)
  • Subcutaneous fluids
  • Syringe-feeding throughout the day (i.e., not one large feeding)
  • Anti-gas medicine and possibly gastrointestinal (GI) motility stimulants to help thwart GI hypomotility/stasis (slowdown and shutdown, respectively)

Within hours of surgical recovery, the bunny can be expected to start eating on his or her own. However, it’s important to remain alert to signs of GI hypomotility/stasis and take immediate and appropriate action.

Rabbits without their incisors use their lips and tongue to pick up food and move it to the back of their mouth, where it’s ground by the molars. To help prevent additional dental problems, veterinarians recommend a diet high in fiber (grass hay). To compensate for the lack of incisors, caregivers can help their bunnies to eat by tearing leafy green vegetables into rabbit-sized bites.

Since a rabbit uses the front teeth to pull dead hair from the body, the bunny will need grooming assistance from the human caregiver.

MALOCCLUSION OF MOLARS: DIAGNOSIS, TREATMENT, PROGNOSIS, AND HOME CARE

Overview

According to Dr. Angela Lennox, there are two leading theories for the cause of acquired dental disease of the molars: inappropriate wear from improper diet and metabolic bone disease.

When any irregular growth occurs, all cheek teeth are affected. Abnormal wear and growth necessarily result, affecting the entire mouth, including the musculature. The normal workings of a rabbit’s jaw require all the teeth to be properly formed and in alignment.

Severe dental disease from any cause can lead to the most severe complication: dental abscesses and resulting bone infection (osteomyelitis).

Diagnostic Procedures

Some of the steps that a veterinarian may take to assess the molars include:

  • Administering anesthesia to allow for complete examination and to reduce stress in the rabbit (if the rabbit’s overall health permits)
  • Gently feeling along the jaw for signs of swelling or tenderness
  • Removing any food from the teeth and checking for infection
  • Using a small speculum to see inside the small, narrow mouth cavity
  • Taking radiographs of the entire skull (several views) to see the extent of apex elongation and any abscess formation

Comparing the radiographs with those of a rabbit without dental problems will help determine the severity of the condition; however, there are some considerations with this. Dr. Bradley Bays notes that multiple views are necessary and that some caution is warranted in radiograph interpretation. She explains:

Standard skull radiographs may show some malocclusion of cheek teeth, but it’s difficult to discern the full extent of malocclusion due to superimposition of the right and left arcades. This can be overcome by taking a number of special radiographic views, in particular, oblique views where the skull is slightly rotated.

 

Surgical Procedures and Related Treatment

Unless a molar is loose or there is an infection, molar extraction is not recommended due to the arrangement and function of a rabbit’s teeth. If surgery is not necessary, 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. Success of the correction is judged visually and by post-procedure radiographs. Simply reducing teeth down to the gum level may not be appropriate.

When major surgery to extract the molars proves necessary, it’s best if the rabbit is in basically good health and at a desired weight. Discuss with the veterinarian the long-term prognosis. The after-care can be extensive, additional surgeries may be required, and periodic dental exams, often under anesthesia, will certainly be necessary.

If there is an abscess, extracting the entire pus pocket (as a solid mass) is key to containment of the bacteria. The surgery can result in extensive bone loss because the affected bone and surrounding tissue have to be removed to prevent bacteria spread; this surgical cutting away is often referred to as debriding or excising. In addition, there may be more than one abscess.

A culture and sensitivity test will help determine the cause of the infection as well as the correct antibiotic. It is likely that the rabbit will require both systemic and local medication. There are several recognized methods of administering antibiotics locally, including powder and beads; manuka honey has been used with success in some difficult cases. In addition, whether to close the wound or leave it open for possible additional treatment as well as flushing are serious considerations.

Post-Surgical Procedures and Prognosis for Recovery

Depending on the level of the caregiver’s expertise, the rabbit may have to remain in the hospital to ensure proper care. Whether at home or hospitalized, watching for signs of digestive problems is very important. Following extraction, treatment will likely include:

  • Subcutaneous fluids
  • Syringe-feeding (after the rabbit has stabilized)
  • Analgesic (pain medication)
  • Antibiotic
  • Wound care, including flushing and filling
  • Medication to support the gastrointestinal system, if needed

Though there is an extremely high rate of abscess recurrence (not necessarily in the same area), the prognosis for recovery will be better if the pus is extracted in entirety, with both the contaminated bone and surrounding tissue surgically excised. Appropriate after-care must also be administered.

The prognosis is poor if a total extraction and bone removal are not possible. In such case, the rabbit will be more comfortable with the abscess removed, but the difficult decision regarding euthanasia will arise if the abscess returns.

Home Care of a Rabbit with Molar Extraction

Molar extraction is a very painful surgery and the rabbit will require an intensive home-care regimen outlined by the surgeon, most likely including:

  • Analgesic (pain medication)
  • Antibiotic
  • Wound flushing
  • Syringe-feeding
  • Treatment for GI hypomotility, if necessary

Because the antibiotics will probably be administered for at least a month, digestive upset is possible, given that the normal balance of flora in the gut may be affected. Some veterinarians may prescribe probiotics for rabbits on antibiotics for extended periods of time; the efficacy of presently available probiotics is currently unknown.

Once the rabbit is eating normally, a high-fiber diet helps maintain health. Though the elimination of unhealthy treats can be done immediately, a change in the type and amount of food should be accomplished slowly – especially if the rabbit is not eating the proper quantities of grass hay and leafy greens – to prevent life-threatening hepatic lipidosis (reference “Liver (Hepatic) Disease in Rabbits”).

Following molar extraction, it’s critical that caregivers adhere to the surgeon’s instructions. Without the necessary commitment to that care, including regular dental rechecks, the rabbit’s chances for recovery are poor.

EUTHANASIA

Euthanasia is not needed 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.

PREVENTION OF DENTAL DISORDERS

Diet

Unfortunately, it’s unclear what causes acquired dental disease in all rabbits, but diet is considered an important factor. The way in which foods can affect dental wear has already been noted in this article. Basically, when a diet lacks sufficient fiber, the teeth grow faster than they are worn down, resulting in uneven and unusual length, misalignment (malocclusion), food impaction, abnormal curvature, sharp points (spurs/spikes), loose molars, apexes that invade surrounding tissue, and other problems.

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), which emphasizes the need for feeding a variety of quality grass hays.

 

Research emphasizes the need for hay in a rabbit’s diet, not only for healthy teeth but also for proper function of the digestive system. However, due to variances in hay quality, it’s usually recommended that processed pellets be fed in limited amounts, based on the weight and overall condition of the rabbit. The pellets should be grass-hay-based and of high quality (e.g., not containing soy, dried beans, grains, seeds, or pieces of fruit).

 

Caregivers should remember that pellets are higher in caloric density, meaning that rabbits who eat pellets are quickly satiated. When allowed to free-feed or to eat too many pellets, rabbits don’t browse hay in the amounts needed. It may be useful for caregivers to remember that pellets were developed for rabbits in production (breeding industry) or going to slaughter (meat industry) to minimize mess and to optimize fast growth and pelt development. This obviously is not the goal for our companion rabbits.

 

Leafy vegetable greens are important to a rabbit’s diet because they are vitamin-rich; however, greens should be fed in measured amounts so that the rabbit does not forgo eating hay.

Regarding processed pellets as part of the diet, Dr. Bradley Bays advises further:

Processed food pellets are too small and soft to wear teeth down properly. In addition to needing less chewing time, pellets cause the rabbit to chew in an up-and-down motion rather than the natural side-to-side motion that keeps the teeth ground down. Research shows that poor diet – which includes overfeeding of pellets – can lead to improper molar wear, which, in turn, increases the incidence of acquired dental disease.

 

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, including those that look succulent, are generally more fibrous than purchased greens.

Reference the various articles and FAQ sheets on this website for additional information about diet, including recommended vegetables as well as treats. Each rabbit is unique, and some breeds seem more prone to dental problems than others. Individualizing your bunny’s diet, based on age, weight, health, and activity level will help ensure his or her well-being.

Traumatic Injury and Changes in Jaw Formation

Traumatic injury and changes in jaw formation are two additional causes of dental disease. To the extent possible, human guardians ensure their rabbits’ safety against such trauma. But seemingly small “injuries” can occur, and they have the potential for changing jaw formation and negatively affecting teeth alignment. For example, a caged rabbit who pulls or chews on the metal enclosure can suffer damage because the action can change teeth alignment, and even a slight change can have significant impact. Providing more play and runaround time may reduce the rabbit’s frustration at being caged and stop the behavior.

Though caregivers may not want to cage their rabbits, there are times when it may be unsafe for them to roam the house. Alternatives to caging include playpens, perhaps joined together to create a larger space, or a baby gate to restrict the bunnies to a particular area of the home.

CONCLUSION

Rabbits are marvelously constructed to get the most nutrient value from low-energy foods. In addition to providing regular medical care, help keep your bunny’s teeth healthy by giving him or her safe things to chew on. These might include untreated willow baskets, cardboard boxes, and unsprayed apple branches. Provide unlimited grass hay, which not only helps wear the teeth evenly but also acts as an important digestive aid. (Reference “Disorders of the Cecum of the Rabbit” for more information about the important function that hay serves.)

Caregivers may want to consider supplementing their rabbit’s care with alternative therapies, some of which are addressed in separate articles posted on this website. There are times when combining the expertise of both standard and alternative treatments offers the best supportive care.

When researching complementary treatments, be aware of training and qualification requirements and give careful consideration to the health, nature, and needs of your rabbit. Be clear and realistic about your expectations and goals for treatment, which should prioritize your rabbit’s comfort and quality of life.

 

by Marie Mead with Teresa Bradley Bays, DVM, CVA, DABVP (ECM), and Angela Lennox, DVM, Dipl ABVP (Avian)

Copyright © 2013 by Marie Mead. Used by permission. All rights reserved. Portions of this article appeared in “Your Rabbit’s Teeth,” Bunny Mad (UK), Issue 9, Autumn/Winter 2009/10.

I wish to extend my sincere gratitude to Dr. Teresa Bradley Bays and Dr. Angela Lennox for sharing their expertise in this article. Warm thanks also to Cheryl Abbott, Sandi Ackerman, Heidi Anderson, Dr. Susan Brown, Dr. Stephanie Crispin, Nancy and Gary McConville, and Karen Witzke for their review of and suggestions for this article.  – Marie Mead

Marie Mead has been involved in various capacities with animal rescue, advocacy, and education for over twenty years. She has made a home with special-needs rabbits and other animals, all of them rescues. Author (with collaborator Nancy LaRoche) of Rabbits: Gentle Hearts, Valiant Spirits – Inspirational Stories of Rescue, Triumph, and Joy, Marie has also written rabbit-related stories and articles for other publications. Additional writings have covered topics such as aging and the environment.

Teresa Bradley Bays, DVM, CVA, DABVP (Exotic Companion Mammal Specialist) practices in Missouri at the Belton Animal Clinic and Exotic Care Center. She is the author of numerous articles and book chapters on exotic animals and is the senior editor and coauthor of Exotic Pet Behavior: Birds, Reptiles, and Small Mammals. Dr. Bradley Bays speaks nationally and internationally on exotic animal medicine and surgery. She is also actively involved with community service as veterinarian for HELP Humane, veterinarian for an animal facility at a domestic violence shelter, and founder and coordinator of the Pajamas for Foster Kids Program (www.beltonanimal.com for additional information).

Angela Lennox, DVM, Dipl ABVP (Avian) is a 1989 graduate of Purdue University and has practiced exotic animal medicine exclusively since 1991; she is the owner of Avian & Exotic Animal Clinic of Indianapolis (Indiana). As adjunct professor at Purdue University, she teaches both veterinary and veterinary technician students. Dr. Lennox is the author of numerous professional articles, coauthor of Clinical Radiology of Exotic Companion Animals, and editor of Rabbit and Rodent Dentistry Handbook. She is past president of the Association of Exotic Mammal Veterinarians and has lectured extensively both nationally and internationally. She currently lives near Indianapolis with her husband of more than 20 years and four daughters. www.exoticvetclinic.com

BIBLIOGRAPHY   

My sincere thanks to the veterinarians named in this article for sharing their expertise during personal interviews and in subsequent feedback. In addition to House Rabbit Handbook: How to Live with an Urban Rabbit, the following list of publications, although by no means comprehensive, may assist those who desire additional research.

  • BSAVA Manual of Rabbit Medicine and Surgery. Anna Meredith and Paul Flecknell (Eds.)
  • Clinical Radiology of Exotic Companion Mammals. Vittorio Capello and Angela Lennox
  • Color Atlas of Small Animal Anatomy: The Essentials. Thomas O. McCracken and Robert A. Kainer with David Carlson
  • Exotic DVM (journal)
  • Exotic Pet Behavior: Birds, Reptiles, and Small Mammals. TeresaBradleyBays, Teresa Lightfoot, and Jorg Mayer
  • Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery. Katherine E. Quesenberry and James W. Carpenter
  • The 5-Minute Veterinary Consult: Ferret and Rabbit. Barbara L. Oglesbee
  • Journal of Exotic Pet Medicine
  • Notes on Rabbit Internal Medicine. Richard A. Saunders and Ron Rees Davies
  • Rabbit and Rodent Dentistry Handbook. Vittorio Capello with Margherita Gracis
  • Rabbit Medicine & Surgery. Emma Keeble and Anna Meredith
  • Textbook of Rabbit Medicine. Frances Harcourt-Brown