Effects of reduced mobility on trabecular bone density in captive big cats

Area of Science:

• Comparative anatomy
• Functional morphology
• Conservation biology

Background:

• Bone density and mass increase with mechanical loading.
• Wild animals are expected to have greater skeletal density than captive animals.
• Comparative studies often combine wild and captive specimens, necessitating understanding of captivity's effects.

Purpose of the Study:

• To compare trabecular bone volume fraction (BVF) between wild and captive felids.
• To investigate the impact of captivity on bone morphology in different limb bones.
• To assess the implications of these findings for conservation and comparative studies.

Main Methods:

• Comparison of trabecular bone volume fraction (BVF) in wild and captive felids (mountain lions, cheetahs, leopards, jaguars).
• Analysis focused on humerus and femur to assess location-specific effects.
• Calculation of humeral/femoral BVF ratio and its correlation with home range size in wild animals.

Main Results:

• Significantly greater BVF was observed in wild felids compared to captive ones.
• Captivity had a more pronounced effect on the humerus than the femur.
• A lower humeral/femoral BVF ratio in captive animals correlated positively with home range size in wild animals.

Conclusions:

• Captivity generally reduces bone volume fraction in the felid postcranial skeleton.
• Reduced forelimb loading in captive animals, potentially due to lack of predatory behavior, influences bone morphology.
• Findings necessitate caution when using combined skeletal specimens for studies and when reintroducing captive animals.