Epidemiology of Traumatic Tusk Fractures of Managed Elephants in North America, South America, Europe, Asia and Australia

Josephine B Rose,Melissa A Fayette,Allison Woody,Rachel Lemont,David A Fagan,Jeffry S Proudfoot,Austin Leeds,Michelle R Bowman,Linda M Yang,James Oosterhuis

doi:10.3390/jzbg3010008

Abstract

Elephant tusk fractures are a management and medical challenge that can escalate into life-threatening complications. Here, an international survey was sent to elephant managers to understand the risk factors associated with tusk fractures since 2009, identifying best practices for reducing the incidence. Out of 459 elephants included in the survey, 85 elephants incurred at least one fracture. Though not statistically significant, descriptive statistics identified a trend for both Asian and African elephant males to be more likely to incur a fracture than females. Additionally, the first reported fracture occurred in males of both species approximately ten years earlier in age than females. The most common causes of fractures were conspecific interactions (44.6%), caught tusk in an enclosure or enrichment item (28.4%), and a strike by the elephant of a tusk with an object (12.2%). For social causes, unstable hierarchy (45.5%) and specific agonistic interactions (36.4%) were the most frequently cited fracture causes. Steel gates were associated with 23.8% of fractures caused by enclosure elements. Management changes including tusk trimming, enrichment, training, and re-arranging social groups were found to be important in reducing subsequent fractures, with odds ratios showing that a second tusk fracture was 6.37 times more likely to occur if no management changes occurred after the first fracture. Our data suggests that targeted management strategies in herds with maturing males, unstable social dynamics, and/or high-risk enclosure elements could reduce the frequency of tusk fractures.

Highlights

Information from the surveys was augmented with information provided through the AZA, European Association of Zoos and Aquaria (EAZA) and JAZA studbooks for both African and Asian elephants
A total of 220 institutions were contacted globally and 50 either completed the survey or reported to the authors that no tusk fractures had occurred within the study time frame, a 22.7% response rate
Incidence of tusk fractures were surveyed in 459 elephants living at 50 institutions (African, 76.127; Asian, 85.171; Table 1)

Summary

Introduction

The survival of Loxodonta and Elephas species continues to face challenges due to habitat loss, fragmentation and poaching [1,2]. Elephants under human care serve as important ambassadors to the survival of their species. A critical scientific approach has optimized elephant management recommendations in topics including exercise, musculoskeletal, metabolic, and reproductive health [3–6]. Elephant tusks are continuously growing maxillary incisors composed almost entirely of dentin uniquely arranged in a checkered pattern [7–10]. Defining characteristics of these modified teeth include their outward extension beyond the plane of the mouth [11] and comparatively low tensile strength ex vivo [12]. These traits logically would put them at a higher risk for tusk fractures.

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Conclusion