DISEASE SUMMARY PAGE

Acquired Incisor Abnormalities in Rabbits

Normal rabbit incisors and peg teeth. Click here for full page view with caption Rabbit skull. Click here for full page view with caption Severely abnormal oblique inciors. Click here for full page view with caption Severe incisor malocclusion. Click here for full page view with caption Broken upper incisors and overgrown lower incisors. Click here for full page view with caption Hair mats from around overgrown incisors. Click here for full page view with caption Overgrown incisors requiring removal. Click here for full page view with caption Broken incisors. Click here for full page view with caption Molar and incisor deviation. Click here for full page view with caption Shortening incisors 1 of 4. Click here for full page view with caption Shortening incisors 2 of 4. Click here for full page view with caption Shortening incisors 3 of 4. Click here for full page view with caption Shortening incisors 4 of 4. Click here for full page view with caption Rabbit skull. Click here for full page view with caption

Summary Information
Diseases / List of Miscellaneous / Metabolic / Multifactorial Diseases / Disease summary
Alternative Names See also:
Disease Agents
  • Trauma:
    • Falling onto a hard surface, face first, leading to either tooth fracture or bone fracture. (B601.18.w18, Th16.1.w1, J60.6.w3)
    • Pulling on the bars of the cage (usually male rabbits). (Th16.1.w1, J60.6.w3)
    • Iatrogenic injury to the mandibular ramus during dental treatment. (B601.18.w18)
  • Infection of the tooth root allowing tooth movement. (J60.6.w3)
  • There may be an increased susceptibility to development of acquired incisor malocclusion in dwarf breeds, which have both the upper and lower jaw lengths reduced. (J213.6.w2)
  • Improper diet 
    • NOTE: It is generally agreed that incorrect diet plays a large part in the development of acquired dental disease (both acquired incisor abnormalities and acquired molar abnormalities) of rabbits, and that providing a correct diet (grass and other growing plants to graze, or hay and other green foods) can prevent development of most tooth abnormalities. However, there are a variety of different ways in which incorrect diets might affect tooth eruption. The following are the main suggestions: 
  • 1) Metabolic bone disease, due to inadequate dietary calcium, inappropriate dietary calcium:phosphorus ratio and vitamin D deficiency. (Th16.1.w1, J3.137.w8, J3.139.w7, J3.145.w8, J15.19.w3)

    • It has been observed that skull bone quality of pet rabbits with dental disease is much poorer than that of wild rabbits. (J3.137.w8)
    • Laboratory and commercial rabbits are fed a complete pelleted diet which is nutritionally adequate (they also generally have shorter life spans than pet rabbits which may live for 10 years); acquired dental disease is rare in these rabbits. (J3.137.w8)
    • Rabbit teeth grow constantly and rabbits need a constant supply of calcium. The minimum dietary calcium level required has been determined as 0.22% of feed for growth and 0.35 - 4.0% for maximal bone calcification (J284.26.w1); a level of 0.4% is the recommended minimum from the U.S. National Research Council (Nutrient Requirements of Rabbits, 1977). Another study of rabbits found a 10% increase in peak bone mineral density in the lumbar spine, as well as lower parathyroid hormone concentration and lower levels of biochemical markers of bone resorption and formation, when rabbits were fed a diet containing 1% rather than 0.5% calcium. (J519.29.w1)
    • Many pet rabbits are fed solely or mainly on feed mixes with various components including whole rolled grains, whole pulses, biscuit pieces and rabbit pellets. Many rabbits demonstrate food choice and fail to eat the pellets or grains. Many owners top up or replace the food, rather than waiting until all parts have been eaten. (J3.139.w7, J3.145.w8)
    • The vitamin and mineral supplement is usually contained in the pellets. Analysis of rabbit mixes from pet shops showed that, when the pellets and grains were removed (to mimic the diet as eaten), some of these diets had very low calcium levels (below recommended levels and even below the calculated minimum requirement); also, calcium:phosphorus ratios were reversed, e.g. 1:3 compared with the recommended 2:1. (J3.139.w7)
    • Additionally, many pet rabbits are kept solely or mainly indoors, particularly in winter, and do not have access to grass and other natural green foods, nor to sunlight, therefore cannot synthesise their own vitamin D (which would help with calcium absorption). While sun-dried hay does contain vitamin D, not all pet rabbits are given hay, and not all hay contains good levels of vitamin D. (J3.139.w7) Some pet rabbits, particularly those kept in hutches, have very low (even undetectable) plasma concentrations of 1,25-dihydroxycalciferol (vitamin D3). (J3.145.w8)
    • The low calcium, low vitamin D and reversed calcium: phosphorus ratio in the diet of some pet rabbits, could lead to metabolic bone disease. (J3.139.w7)
    • Loss of supporting alveolar bone may allow teeth to loosen in their sockets, allowing distorted growth. (J3.137.w8)
    • Secondary periodontal infection may allow further loosening of the teeth. (J3.137.w8)
  • Elongation of molars preventing proper occlusion and wear of incisors. 
    • Cheek tooth malocclusion and overgrowth may prevent normal incisor occlusion (by keeping the mandible and maxilla further apart than normal), and lead to malocclusion of the incisors. (B601.18.w18, J29.17.w1)
    • In summary:
      • Concentrate foods, providing nutrition in a lower volume and with less abrasive characteristics, reduces tooth wear compared to a diet of natural plant materials. (J29.17.w1, J60.6.w3)
      • The form of pellets and grain, compared with natural vegetation, may result in alterations to the forces during chewing, with the rabbit using a crushing rather than side-to-side jaw movement, which may alter tooth wear. (J213.6.w2, J60.6.w3)
    • See: Acquired Molar Abnormalities in Rabbits for details on alternative suggestions for the causes of molar elongation and changes in shape.
Infectious Agent(s) --
Non-infectious Agent(s) --
Physical Agent(s) --
General Description
Clinical signs
  • Obviously elongated, broken or deviating incisors, which look unsightly and may cause problems by e.g. catching on wire netting or water bottles.
    • The upper incisors curl within the mouth and the lower incisors protrude forward from the mouth.
    • Hair or food may be matted round the overgrown teeth. (J60.6.w3)
  • Difficulty in eating. (J60.6.w3)
    • Weight loss and emaciation may result from this. (J60.6.w3)
    • Note: many rabbits manage to eat well despite overgrown incisors. (B600.7.w7)
  • Lack of caecotrophy. (J60.6.w3)
  • Grooming problems, most commonly seen as perineal fur matting and soiling.
  • Soft tissue trauma, particularly to the upper lip and maxillary gums from the maxillary teeth, which may pierce the buccal or gingival mucosa; mucosal ulceration or abscess formation may occur.
  • Epiphora due to mucosal or bone pain (J29.17.w1), or associated with Dacrocystitis in Rabbits.
  • Note: there may be no obvious clinical signs. (J15.19.w3)
  • In Romerolagus diazi - Volcano rabbit at Jersey Zoo, difficulties in eating and grooming were noted in individuals with overgrown incisors (overgrowth associated with broken incisors). (J51.19.w1)

(B600.7.w7, J15.19.w3, J29.16.w5, J29.17.w1, J51.19.w1, J60.6.w3)

Diagnosis
  • Visual inspection. This can be carried out in the conscious rabbit. (J3.137.w8)
    • The incisors may be dull and look white (compared to shiny and cream to slightly yellow in normal rabbits), or become discoloured.
    • The normal vertical groove may be lost, and horizontal grooves may be evident.
    • Tooth enamel reduced or absent (normal in rabbits with hereditary mandibular prognaithism - see Congenital Incisor Abnormalities in Rabbits).
    • Upper incisors rotated outwards and overgrown.
    • Lower incisors deviated and overgrown.
    • Broken incisors.
      • May occur due to trauma.
      • Note: weakened, abnormal incisors are more prone to fracture. Poor quality teeth may break off below the gum line.
    • Lack of growth of incisors.
    • Note: it is important to inspect the molars also. This can be carried out in the conscious rabbit using an auroscope, and more thoroughly with the rabbit under anaesthesia.
      • Elongated incisors may prevent normal closure of the mouth, leading to failure of normal molar wear

    (J3.137.w8, J15.19.w3, J60.6.w3)

  • Radiological assessment (J15.19.w3)
    • This provides information about the tooth roots and the bones. (J15.19.w3)
    • A lateral view is usually the most informative. In a true lateral the mandibles are superimposed on one another; more information may be available if a slightly oblique view is obtained. (J15.19.w3)
    • Superimposition of the mandible over the maxillae makes interpretation of the dorsoventral view harder; it is important to get good, straight positioning for this view. (J15.19.w3)
    • Four views: lateral, right oblique, left oblique and vntro-dorsal provide optimum information; all four views can be achieved on a single small x-ray plate. (V.w125)
    • Fracture of the mandibular ramus or separation of the mandibular symphysis can be seen. (B601.18.w18)
    • For traumatic injuries, dental radiographic film may be positioned intraorally to allow detailed imaging of the incisors. (B602.34.w34)
    • Further information on radiography is provided in: Imaging in Lagomorph Diagnosis and Treatment - Radiography
Further Information

Note: dental disease involving tooth elongation appears to be rare in wild lagomorphs. (J29.17.w1)

Treatment

For incisor malocclusion: repeated shortening of the incisors or removal of the incisors. (J4.155.w7, J15.19.w3)

  • Incisor shortening (coronal reduction) using powered dental burrs or saws. (B601.18.w18, J15.19.w3, J60.6.w3)
    • This can be carried out in the conscious rabbit, or with the rabbit sedated or anaesthetised, which may allow better shaping of the incisors. (B601.18.w18, J15.19.w3)
    • If the rabbit is conscious it should be wrapped in a towel and held facing the person carrying out the procedure. (B601.18.w18)
    • The aim is to return the incisors to normal length and provide a normal chisel-shaped occlusal surface. (B601.18.w18)
    • Use an adapted syringe case or wooden tongue depressor to protect the soft tissues during the procedure. (B601.18.w18, J15.19.w3, J60.6.w3)
      • It is particularly important to protect the soft tissues if using a high-speed handpiece. (B601.18.w18)
    • Cool the teeth:
      • After use of powered equipment, cool the teeth using a cold wet swab. (J15.19.w3)
      • If a high-speed handpiece is used, water cooling is needed during use. (B601.18.w18)
      • Keep moving the burr from one area to another; do not concentrate on one location for too long at a time. (B601.18.w18)
      • If the teeth are not cooled with water during burring a sterile pulpitis or pulp necrosis may occur. (B600.7.w7)
    • High-speed handpieces allow faster trimming and shaping with minimal pressure on the tooth. Low-speed handpieces take longer to complete the same work, but are less likely to cause soft tissue injury or overheating of the teeth. (B601.18.w18)
    • If a cutting disc is used extra care is needed to avoid iatrogenic tissue damage. (B600.7.w7)
    • Avoid pulp exposure, remembering that in overgrown teeth the pulp chamber may extend much further into the visible (supragingival) crown than in normal teeth - e.g. 27 mm versus the normal 3 mm. (B601.18.w18)
    • Note: The procedure will have to be repeated periodically; if occlusion is restored, the time before trimming is next needed can be lengthened. (J15.19.w3, J60.6.w3)
  • Incisor trimming using nail clippers (J15.19.w3)
    • This is the traditional treatment for overlong rabbit incisors. (B600.7.w7, J60.6.w3)
    • This is not ideal but is cheap and quick. (J15.19.w3)
    • It is not possible to produce good tooth alignment or shaping of the occlusal surface. (B601.18.w18, J15.19.w3)
    • There is a risk of the tooth splitting when clipped, exposing the pulp cavity. (J15.19.w3, J60.6.w3)
    • It is common for incisors to fracture longitudinally if cut with clippers. (B601.18.w18)
    • Clipping may leave sharp edges on the teeth. (J15.19.w3)
    • This is painful for the rabbit. (J513.6.w3)
    • Forces applied during clipping may be painful for the rabbit and may damage the germinal tissues of the tooth. (B601.18.w18)
    • This procedure will have to be repeated every few weeks (J15.19.w3) every 2-3 weeks. (J513.6.w3)
    • If the teeth are clipped to short the pulp is exposed and may become infected. (J513.6.w3)
    • Eventually the crowns may stop growing and trimming will not be needed. (J15.19.w3)
    • Note: there may also be abnormalities of the cheek teeth. (J15.19.w3)
  • Surgical removal of the incisors (extraction) (B601.18.w18, J15.19.w3, J60.6.w3)
    • See: Extraction of the Incisors in Rabbits
    • Note:
      • Rabbits are able to eat adequately without their incisors, so long as hard foods (e.g. carrot, apple, broccoli) are chopped or grated. Food will be prehended with the lips. (B600.7.w7, J15.19.w3, J60.6.w3)
      • Rabbits are less able to groom without their incisors. (B600.7.w7)
      • Removing the maloccluded incisors will not prevent development of abnormalities of the cheek teeth. (J15.19.w3)
  • Partial vital pulpectomy and vital pulp therapy is needed if the pulp is exposed during treatment. (B601.18.w18)

Dietary and husbandry changes:

  • Improve the diet; it is recommended that rabbits should be fed mainly on fresh foodstuffs, 
  • Calcium supplementation to improve tooth and bone quality (J15.19.w3) if calcium deficiency has been confirmed in the rabbit. (V.w125)
  • Including more green food in the diet. (J3.137.w8)
  • Providing the rabbit with time outside in natural daylight. (B601.18.w18, J3.137.w8)
  • Preferably allow access to growing grass. (B601.18.w18)

Treatment of traumatic injuries. (B601.18.w18)

  • Appropriate analgesia: e.g. if there is pulp exposure or significant alveolar damage. (B602.34.w34a)
  • For fractured incisors without the pulp exposed:
    • Smooth the fractured tooth using a dental bur, so it does not irritate the soft tissues (B601.18.w18, B602.34.w34a, J213.6.w2) and, if possible, shorten the contralateral incisor to the same height. Shape the occlusal ends of the teeth to a normal chisel shape. (B601.18.w18)
    • Check the soft tissues for tooth fragments which will need removing. (J213.6.w2)
  • For fractured incisors with the pulp exposed - partial vital pulpectomy and vital pulp therapy: (B601.18.w18, B602.34.w34)
  • Monitor the teeth over several weeks; trimming of opposing teeth may be required until normal occlusion is restored. (B602.34.w34, J213.6.w2)
    • If normal regrowth does not occur, assess radiographically. (B602.34.w34a)
    • If normal occlusion is not restored, due to deformity, extraction of the tooth or periodic shortening and shaping is required (see above). (B602.34.w34a)
Prevention
In a study, it was noted that rabbits living in a garden or large enclosure (e.g. aviary) did not develop dental disease. (J8.42.w2)
  • Correct diet. (B601.18.w18, J15.19.w3)
    • Provide hay (and preferably grass in summer). This is an important part of the diet for pet rabbits. It provides (variable) vitamin D, fibre (essential for normal GIT function) and dental exercise which may encourage normal wear of the constantly-growing teeth.
    • Provide a balanced concentrate diet. as a small proportion of the total diet. 
      • If using a mix (which allows the rabbit to eat selectively), give a smaller amount to encourage the rabbit to eat all its ration (and to eat hay). Once the food has been given, it should not be topped up or replaced until all components have been eaten.
      • A complete pelleted or extruded diet may be given, although some rabbits will not eat pelleted diets.
    • Reduce feeding of energy-rich diets. (B601.18.w18)
    • Offer palatable green food daily.
      • Dandelion and clover are high in calcium. (J3.139.w7)
    • Alfalfa can be given (not all rabbits will eat this); this is high in calcium.
  • A vitamin and mineral supplement can be given for fussy eaters in which calcium deficiency has been diagnosed.
    • Nutrobal (Vetark Professional) contains 208 mg calcium per gram and may be used for rabbits with severe nutritional osteodystrophy.
    • Vionate (Shirleys) contains calcium at 94.5 mg/g.
    • Arkvits (Vetark Professional) contains calcium at 142 mg/g.
    • The supplement can be sprinkled onto preferred, easy-to eat soft foods such as bread or lettuce.
    • Note: Excessive supplementation may lead to development of urolithiasis. (J3.139.w7) See: Urolithiasis in Lagomorphs

    (J15.19.w3)

  • Provide access to the outside where the rabbit will have the option of basking in sun, particularly in summer, but preferably year-round. (B601.18.w18, J3.139.w7, J15.19.w3)
  • For further information on recommended feeding see Food and Feeding for Mammals - Nutritional Requirements and Diets Commonly Fed in Captivity
Associated Techniques
Host taxa groups /species
Disease Author Debra Bourne MA VetMB PhD MRCVS (V.w5)
Referees Molly Varga BVetMed DZooMed MRCVS (V.w125)

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