Characterizing the 25-Hydroxyvitamin D Status of Two Populations of Free-Ranging Eastern Box Turtles (Terrapene carolina carolina)
Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, IL, USA
Vitamin D is a circulating hormone that is a component of homeostatic mechanisms, including bone development, growth, neuromuscular function, reproduction, cardiovascular health, and immune function. In humans, adequate levels of vitamin D have been shown to decrease the risk of developing different conditions, including diabetes, muscular dystrophy, hypertension, and inflammatory bowel disease. Vitamin D status may be important in animals that are being affected by infectious diseases such as ranavirus and Mycoplasma, since vitamin D can play a significant role in immune function. In omnivorous reptiles such as the eastern box turtle, vitamin D may be acquired through the diet, or through photobiochemical synthesis secondary to UVB radiation. This study measured vitamin D status in 60 individuals from two well-studied populations of eastern box turtles in Illinois (n=24) and Tennessee (n=36). Vitamin D concentrations in plasma were not significantly different between Illinois (mean: 117.5 nmol/L) and Tennessee (mean: 98.7 nmol/L) (p=0.129) populations. Similarly, there were no differences between age class (p=0.533) or sex (p=0.532). There was a significant correlation between UV at the time of capture and vitamin D concentrations (R=0.301, p=0.030). Vitamin D was not correlated with total calcium (R=0.018, p=0.89) or Ca:P ratio (R=0.025, p=0.85). Data obtained can be used to improve the care of captive and free-ranging turtles, as well as better characterize the health of wild populations.