Tooth damage in captive orcas ( Orcinus orca )

摘要

Highlights ? Individual teeth in the mandible and maxilla of captive orca were scored for coronal wear, wear at or below the gum line, fractures, bore holes and missing. ? Dental damage was commonly observed across all captive whale cohorts, with damage beginning early in a whale’s captive life. ? Forty five percent of whales exhibited “moderate” mean mandibular coronal wear, and an additional 24% exhibited “major” to “extreme” wear. ? More than 61% of mandibular teeth 2 and 3, and 47% of mandibular tooth 4 exhibited evidence of having undergone the modified pulpotomy procedure. ? Conspecific aggression and oral stereotypies such as biting on hard tank surfaces likely contributed to the tooth pathology observed. Abstract Objectives Tooth damage as a result of oral stereotypies is evident in captive orca, yet little research on the topic exists. This study examines the associations between dental pathology, sex, facility, duration of captivity and other factors in captive orca. Design We evaluated mandibular and maxillary teeth from dental images of 29 captive orca owned by a US-based theme park. Each tooth was scored for coronal wear, wear at or below gum line and bore holes. Fractured and missing teeth were also noted. Summary statistics described the distribution and severity of pathologies; inferential statistics examined how pathologies differed between sexes, between wild-captured and captive-born orcas and between captive orca at four facilities. We also evaluated how dental pathology and duration of captivity were related. Results Approximately 24% of whales exhibited “major” to “extreme” mandibular coronal tooth wear, with coronal wear and wear at or below gum line highly correlated. More than 60% of mandibular teeth 2 and 3 exhibited fractures. Bore holes were observed primarily among anterior mandibular teeth, with more than 61% of teeth 2 and 3 bearing evidence of having been drilled. Four of five orca with the highest age-adjusted tooth pathology indices were captive-born. Conclusions Various dental pathologies were observed across all whales, with pathologies beginning at a young age. Oral stereotypies exhibited by captive orca contributed to the observed dental damage. By making dental and health records of captive whales publicly available, the theme park industry is uniquely positioned to provide further insight into dental pathology and resultant health consequences in captive orca.