How many teeth does a rabbit have

Veterinary technicians play a vital role in educating rabbit owners about prevention and early detection, as well as assisting veterinarians with diagnosing and treating dental disease.

July 1, 2017 | 

The laterolateral view often yields the most valuable information regarding dental disease.1,7 The incisor teeth, cheek teeth, and supporting structures are easily evaluated for malocclusions.1,7 The appearance of the bone surrounding the teeth may also be assessed.1,6 The dorsoventral view is particularly helpful for evaluating the palatal and buccal margins of the cheek teeth and the zygomatic bone.1,7 Oblique projections of the skull are useful for separating individual cheek teeth of the mandible and maxilla, which are directly superimposed in laterolateral views.1 In 2009, Boehmer and Crossley introduced the use of anatomic reference lines when evaluating dental radiographs (BOX 2).1,7

BOX 2 Boehmer and Crossley Radiographic Anatomic Reference Lines1,7

A black line (A) extends from the tip of the nasal bone to the occipital protuberance. The roots of anatomically normal maxillary cheek teeth will not extend past this line. The white line extends the height of the tympanic bulla. A second black line (B) runs parallel to the first, extending from the rostral end of the hard palate to one-third of the height of the tympanic bulla. The occlusal surface of the cheek teeth will appear to match this line in healthy rabbits. A yellow line (C) highlights the mandibular cortical bone. The roots of anatomically normal mandibular cheek teeth will not extend past this line.

A black line (A) extends from the lateral margin of the mandibular incisors to the medial margin of the mandibular ramus on the same side. Another black line (B) extends from the lateral margin of the mandibular incisors to the lateral wall of the tympanic bulla on the opposite side. Cheek teeth should not extend outside of these reference lines. Two yellow lines (C) highlight the medial cortex of the mandible, which should appear straight, smooth, and symmetric.

A black line (A) extends from the lateral margin of the mandibular incisors to the medial margin of the mandibular ramus on the same side. Another black line (B) extends from the lateral margin of the mandibular incisors to the lateral wall of the tympanic bulla on the opposite side. Cheek teeth should not extend outside of these reference lines. Two yellow lines (C) highlight the medial cortex of the mandible, which should appear straight, smooth, and symmetric.

Computed tomography (CT) is becoming a widely accepted alternative to dental radiography in specialty and academic facilities.1,2 CT allows 3-dimensional reconstruction of the skull, viewing of finer detail than can be seen on radiographs, and isolation of areas or teeth of interest.1 CT is especially advantageous for evaluating intranasal structures, surrounding soft tissue structures, abscesses, and neoplasia.1

Treatment of Dental Disease in Rabbits

Treatment of dental disease consists of returning teeth to their normal length, restoring normal occlusion, extracting diseased teeth, and treating associated abscesses.

Crown Height Reduction

Crown height reduction can often be curative in the beginning stages of dental disease when accompanied by diet correction and other preventive measures.1–3 However, in cases of moderate to severe dental disease, crown height reduction procedures will need to be performed repeatedly.1-3 Overgrown incisors or cheek teeth should be trimmed using a dental bur or trimming forceps (FIGURE 6A) designed specifically for crown reduction.1-3 Nail trimmers, rongeurs, and other manual cutting tools should never be used to perform crown height reduction.2,3 Root damage, tooth fractures or splinters, and abnormal regrowth are likely to occur when using improper equipment.2,3 Crown reduction performed without sedation or anesthesia is difficult and often done blindly, resulting in missed sharp points or spurs and injury to the gums, cheeks, or tongue.1-3 Rabbits with moderate to severe dental disease should be anesthetized, allowing crown reduction and reshaping to be performed with a low-speed dental bur while protecting soft tissues with bur guards and dental spatulas.1–3 (FIGURE 6B)

FIGURE 6. Common dentistry equipment. A. Molar cutters. B. Spatulas. C. Tabletop mouth gag. D. Mouth gag and cheek dilators. E. Dental handpiece and cheek guard. F. Dental burs. G. Incisor luxator.

Tooth Extractions

Tooth extraction with the patient under general anesthesia is indicated for any tooth that is loose, infected/abscessed, fractured, or severely maloccluded.2 Extractions can be performed intraorally or extraorally, depending on the difficulty of the extraction based on the accessibility of the diseased tooth and the size of the patient.2 Tabletop mouth-gag positioners, oral speculums, cheek dilators, spatulas, a low- to high-speed dental handpiece with a cheek guard, dental burs, and Crossley incisor and molar luxators are specialized equipment used to assist in positioning and tooth extraction (FIGURE 6).2,6 Analgesia and nutritional support must be provided after surgery to any patient undergoing a tooth extraction procedure.6

Treatment of Abscesses

Abscesses on a rabbit’s head or jaw are often associated with the periapical area of an infected incisor or cheek tooth.1 In rabbits, mandibular abscesses are more common than maxillary abscesses.1 Often, abscesses present as palpable masses. Occasionally, an abscess is detectable only on radiography or CT.1 Treating a rabbit with an abscess can be difficult because the pus has a remarkably thick-to-solid consistency.1 Primary treatment of an abscess is to remove the cause, which is 1 or more infected teeth.1 Further treatment of the abscess varies by veterinarian preference but may include repeated lancing and flushing of the abscess, systemic antibiotics, complete surgical excision of the abscess, and antibiotic bead impregnation.1,3 Analgesia and nutritional support may be indicated in patients that have an abscess.1

Prevention of Dental Disease in Rabbits

Proper nutrition and husbandry are essential for the prevention of dental disease. Rabbit owners should be instructed to feed unlimited high-fiber foods.3,5 Grass, a good-quality timothy hay, and fibrous, green, leafy vegetables are favorable foods that are high in fiber and encourage the grinding motions of the jaw that benefit attrition of the teeth.7 Rabbits require a diet that provides enough calcium for sufficient mineralization of their continually growing teeth and surrounding bone structures, but not so much calcium that urinary tract disease is a risk.5 The ideal amount of dietary calcium for a rabbit is 0.5% to 1.0%.5

Barn-dried hay may not contain as much vitamin D as sun-dried hays.5 Alfalfa hay is very high in calcium.7 It is a good choice for rapidly growing young rabbits but should not be fed as a sole source of hay for adult rabbits.5 If possible, rabbits should be allowed to graze outside on a variety of grasses and weeds while basking in the sun, which helps prevent a vitamin D deficiency.5

Pellets are not a necessary part of a rabbit’s diet. If pellets are fed, they should be timothy hay based, not alfalfa based.5 Pellets require a less desirable chewing motion of the jaw, not the grinding motion required for fibrous grasses and hays.5 Mixed-cereal foods are also not recommended because it is impossible to prevent rabbits from selectively feeding.5

In addition to proper nutrition practices, owners can be educated about acquiring their pet rabbits from breeding stock without a history of dental disease in their lineage. Growing rabbits are especially susceptible to congenital malocclusions and metabolic bone disease if fed inappropriate, low-calcium food items early in life.5

Conclusion

Dental disease is profoundly common in pet rabbits. Although it cannot be prevented in all pet rabbits, feeding a high-fiber diet and providing objects to encourage chewing are positive preventive practices. Annual physical examinations of pet rabbits assist in early detection of dental disease. Veterinary technicians play a critical role in educating rabbit owners about early clinical signs of dental disease, as well as diagnostic modalities and treatment options for a pet rabbit with suspected dental disease.

Pain Assessment in Small Mammals Sarah Kolb, RVT, VTS (Clinical Practice–Exotic Companion Animals)

Recognizing and assessing pain in small mammals can be challenging. As prey species, small mammals mask signs of illness and injury, especially when in an unfamiliar environment. The International Association for the Study of Pain (IASP) describes pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage.”1 Lichtenberger and Ko indicate any “animal should be assumed to be experiencing pain in any condition expected to produce pain in human beings.”2 Therefore, when working with a patient, it is reasonable to ask yourself, “Would this illness or procedure cause me to feel pain?” If your answer is yes, then it is likely the illness or procedure will also cause the animal pain.

History and husbandry information about the patient should be obtained from the owner using open-ended questioning techniques upon arrival at the veterinary clinic. Since the patient will most likely be masking any signs of illness or discomfort, information obtained from the owner about how the animal has been acting in its normal environment will be helpful. The interview process also allows time for the animal to become accustomed to the veterinary clinic setting. Observation of the patient during the interview or in a quiet room before handling may reveal signs of pain or discomfort. If a small mammal is unable to mask clinical signs of pain and discomfort, it should be considered severely debilitated.

Assessing pain in small mammals can be a difficult task, but it is not impossible. There is no one objective way to tell if a small mammal is feeling pain, as individual animals display different clinical signs. These signs may include anorexia, lethargy, lameness, reduced grooming, abnormal vocalizations, aggression when usually docile, or any deviation from normal behavior.3 Many small mammals in pain hide under bedding or substrate. They also segregate themselves from their cage mates, positioning themselves on opposite ends of their enclosure. An increase in the frequency and depth of respirations or rapid, shallow breathing is also a sign of distress. Bruxism, a loud tooth grinding, is a common clinical sign of pain in small mammals. The animal may be less active or even completely immobile. It may display a hunched posture, arch its back, or press its abdomen to the floor.3

Various species and individuals have different pain responses and pain tolerance.4 Rats have a harderian gland that secretes red, porphyrin tears when they are ill or stressed, giving the appearance of bleeding eyes. Guinea pigs and rodents may display piloerection. Guinea pigs, which normally give high-pitched squeals when handled, also tend to be quiet during handling while painful. Ferrets are reluctant to curl up while resting and commonly squint their eyes. Other animals, frequently rodents, spend more time than normal curled up and may have bulging eyes. Overgrooming, chewing at the location of pain, and self-mutilation are observed in small mammals, most commonly in rodents and sugar gliders.

Appropriate multimodal analgesia techniques can and should be used in small mammals. The veterinary technician oath states, “I solemnly dedicate myself to aiding animals and society by providing excellent care and services for animals, by alleviating animal suffering, and promoting public health.”5 Veterinary technicians play an integral role in recognizing pain in patients and act as patient advocates to alleviate pain and suffering in all animals.

References

1. Merskey H, Bogduk N, eds. IASP Taxonomy. International Association for the Study of Pain. iasp-pain.org/Taxonomy#Pain. Accessed October 2016.
2. Lichtenberger M, Ko J. Anesthesia and analgesia for small mammals and birds. Vet Clin Exotic Anim Pract 2007;(10):293-315. doi:10.1016/j.cvex.2006.12.002
3. Pollock C. Pain management in small mammals. LafeberVet; April 23, 2011. lafeber.com/vet/pain-management-in-small-mammals. Accessed October 2016.
4. Manicinelli E. Recognising and managing pain in small mammals and exotics. Vet Times November 1, 2011. vettimes.co.uk/article/recognising-and-managing-pain-in-small-mammals-and-exotics/. Accessed October 2016.
5. The Veterinary Technician’s Oath. Oklahoma Veterinary Technician Association. okvta.org/veterinary-technicians-oath.html. Accessed October 2016.

References

1. Boehmer E. Dentistry in Rabbits and Rodents, West Sussex, UK: Wiley Blackwell, 2015.
2. Lennox A. Diagnosis and treatment of dental disease in pet rabbits. J Exotic Pet Med 2008;17(2):107-113.
3. Brown S. Rabbit dental disease. VeterinaryPartner.com. 2001. VeterinaryPartner.com/Content.plx?P=A&A=472. Accessed October 2016.
4. O’Malley B. Clinical Anatomy and Physiology of Exotic Species, St. Louis, MO: Elsevier Saunders; 2005.
5. Harcourt-Brown F. Textbook of Rabbit Medicine, Woburn, MA: Reed Educational and Professional Publishing; 2002.
6. Harcourt-Brown F. The progressive syndrome of acquired dental disease in rabbits. J Exotic Pet Med 2007;16(3):146-157.
7. Boehmer E, Crossley D. Objective interpretation of dental disease in rabbits, guinea pigs and chinchillas. Use of anatomical reference lines. Tierarztliche Praxis 2009;37:250-260.
8. Lavin LM. Radiography in Veterinary Technology. 3rd ed. Philadelphia, PA: Elsevier; 2003.