Influencing factors on the foot health of captive Asian elephants (Elephas maximus) in European zoos

Abstract

Pathological lesions of feet occur frequently in captive elephant populations. To improve foot health, it is important to identify risk factors associated with such pathologies. Several previous studies have analyzed potentially influencing factors but were limited, for example, by small sample sizes. This study analyzed the relationship between 87 independent variables and the foot health score of 204 Asian elephants (Elephas maximus) in European zoos using bivariate correlation, multivariable regression models, and principal component analysis (PCA). Correlation and regression tests revealed significant results for 30 different variables, mainly with small effect sizes. Only three variables were significant in more than one test: sex, time spent indoors, and time spent on hard ground, with lower scores (i.e. less or less severe pathological lesions) in females, and when less time is spent indoors or on hard ground. Due to small effect sizes and differing results of the statistical tests, it is difficult to determine which risk factors are most important. Instead, a holistic consideration appears more appropriate. A biplot of the PCA shows that factors representing more advanced husbandry conditions (e.g. large areas, high proportions of sand flooring) were associated with each other and with decreased foot scores, whereas indicators of more limited conditions (e.g. high proportions of hard ground, much time spent indoors) were also associated with each other but increased the foot score. In conclusion, instead of resulting from just one or two factors, reduced foot health might be an indicator of a generally poorer husbandry system.

What is the role of the studbook in zoo and aquarium research?

“…The primary role of studbooks is in managing the demography of populations, and identification of trends in population demographics may highlight emerging challenges, such as an aging population or poor breeding success (Faust et al, 2006). In elephants, for example, initial research on demographics and longevity (Clubb et al, 2008) highlighted points that sparked a much wider range of studies on reproduction (Clubb et al, 2008; Freeman et al, 2009) and health (Lewis et al, 2009; Wendler et al, 2020). This sustained research focus has resulted in measurable improvements in survivorship (Scherer et al, 2022).…”

The historical development of zoo elephant survivorship

“…Rather, a variety of specific improvements might act in concert. For example, Wendler et al (2020) showed that foot health in European Asian zoo elephants was not related to a single factor but to a series of factors corresponding to modern husbandry. These included larger indoor and outdoor enclosures, a higher proportion of the enclosure covered by sand, larger group sizes, more free choice for elephants whether they want to be outdoors or indoors, as well as larger keeper teams.…”

Air temperature and diet influence body composition and water turnover in zoo-living African elephants (Loxodonta africana)

“…Larger enclosures and more time spent outside and on naturalistic, soft surfaces (e.g. grass) were also correlated with better foot health, an area of particular concern for elephants [21][22][23].…”