Abstract
A 3-year-old wild-caught Indochinese tiger (Panthera tigris corbetti) was diagnosed with suspected fractures of all four canines and several molars when examined during crating for transport to the United States from Malaysia. This animal was imported to increase the genetic variability of this critically endangered, small population managed species in captivity. On examination during quarantine at the San Diego Zoo, the dental abnormalities were more extensive than expected and involved almost all teeth in all quadrants. Supernumerary, malpositioned, malformed, abscessed, and fractured teeth, retained and deformed tooth buds, retained and impacted primary and deciduous canines, and chronic mandibular and maxillary osteomyelitis were identified on spiral computed tomography (CT) images of the head. The goal of treatment was to resolve chronic localized dental infection and the risk of bacteremia. Four staged surgeries were successfully performed over a period of 2 months, one quadrant at a time, to extract all teeth other than the incisors and three molars which were not associated with areas of suspected osteomyelitis. Risks associated with these procedures included the development of pathologic fractures of the mandibles or maxillae during the operative or postoperative period. The CT images were consulted preoperatively and intraoperatively to guide the surgical extractions.2 The extensive extraction sites were sutured closed after filling with absorbable gelatin sponges (Gelfoam, Pharmacia & Upjohn Co., Kalamazoo, MI, USA) and a synthetic bone graft particulate (Consil Orthopedic Bioglass, Nutramax Laboratories, Inc., Edgewood, MD, USA) designed to improve the rate of osseous growth while being resorbed and replaced with bone during the healing process.4 The animal was also placed on treatment with clindamycin at 12 mg/kg PO SID (clindamycin hydrocholoride capsules, Ohm Laboratories, Inc., North Brunswick, NJ, USA) for a total of 7 months. Meloxicam (0.09 mg/kg PO SID; Metacam, Boehringer Ingelheim Vetmedica, Inc., St. Joseph, MO, USA) was administered for clinically effective postoperative analgesia. Although two suture abscesses requiring minor debridement and resuturing were identified on recheck examination, no significant anesthetic, operative, or postoperative complications occurred, and the animal tolerated the procedures well.
A recheck spiral CT scan of the head performed 4 weeks after the final surgery revealed no evidence of fractures or active infection. Husbandry modifications, including the exclusion of bone from the diet and the exclusion of chewable enrichment items (fire hose, tire), were made during the course of treatment. The majority of these items were reintroduced to the animal without complication beginning 4.5 months postoperatively. The paucity of remaining teeth is not expected to be problematic for this captive animal, and the long-term prognosis for this individual is excellent. A follow-up CT scan is scheduled for November 2005, 1 year after the final surgery. This case highlights the value of both advanced diagnostics and collaboration with outside specialists in diagnosing and successfully managing certain complex cases.
Dental disease, often secondary to cage biting or other trauma, is common in captive carnivores.7 Each of the individual dental abnormalities diagnosed in this animal has been described in humans as well as domestic and exotic animals. However, it is unusual to find such a multitude of severe dental problems in one individual. Details on this animal’s early medical history are sparse and the etiology in this case remains uncertain. However, it is plausible that genetic, developmental, nutritional, and/or environmental factors may have contributed to the severity and extent of this animal’s dental disease. The gross abnormalities of the canine teeth resemble those described in three other large exotic cats which were attributed to trauma.3 Multiple dental abnormalities attributed to canine distemper infection have been described in a dog, but this is not well documented.1 In the case of this tiger, selected extracted teeth were examined histologically. Pulp necrosis and suppurative pulpitis were confirmed in a molar that had evidence of pulp gas on CT scan. Osteomyelitis could not be confirmed histologically; however, only small amounts of bone were available for examination. A fracture with repair by bone and cementum was identified in a canine tooth. Multiple teeth showed evidence of hypercementosis and multifocal ectopic aggregates of dentin, suggestive of cemento-osseous dysplasia as described in humans. Because this tiger is intended for breeding, the dental development of any offspring will need to be carefully monitored to determine if any of these dental abnormalities are heritable. With early diagnosis and intervention, impacted teeth can often be successfully managed with surgery to allow for full eruption and normal occlusion.5,6
Literature Cited
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4. Nutramax Laboratories. Consil Orthopedic Bioglass product insert, 2004.
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