The last 50 years was characterized by a dramatic decrease in free-roaming cheetah populations and consequently the cheetah now appears on the IUCN Red List for Threatened Species. In order to save cheetahs from extinction, a number of projects were launched to breed cheetahs in captivity. Captive cheetahs, however, receive fundamentally different diets than their free-roaming counterparts, which necessitates feed supplementation to fulfill their unique dietary needs. The Hoedspruit Endangered Species Centre (HESC) is one such project aiming to breed captive cheetahs. At the HESC, a number of juvenile cubs were diagnosed with a form of relaxed carpal joints, namely metacarpal deformity of the front legs. Literature suggests that the condition is due to a magnesium deficiency, which is a consequence of an unbalanced diet. Supplementing magnesium to the diet of cheetahs can, however, affect the urinary system negatively: such as the formation of urolithiasis. V The aim of this study was to determine whether dietary magnesium supplementation in the diets of captive cheetahs will remedy metacarpal deformity and also to investigate the influence of magnesium supplementation on the formation of urolithiasis. The study was divided into two phases. Phase 1 was conducted to determine the influence of dietary magnesium supplementation on metacarpal deformity, identified in juvenile cheetahs at the HESC. To determine the degree of deformity, a leg deformity scoring system was developed. On a scale from 1-3, the cheetahs were scored twice to determine the Flexed Deformity Score (FDS) and Rotational Deformity Score (RDS) values before and after dietary magnesium supplementation. Phase 2 was conducted to determine the influence of magnesium supplementation on different physiological parameters that have an influence on the formation of urolithiasis. Phase 2 was divided into three periods. During each period, the cheetahs received a different diet. During period C, the experimental period, the cheetahs were divided into two groups. One group received a meat-only diet, whereas the other group received a meat-Mg diet. At the end of each of the three periods, blood- and urine samples were collected and analyzed to determine the concentration of minerals in the cheetah’s blood plasma and urine. Based on the FDS and RDS scores, a 25.5% response rate to dietary magnesium supplementation on rotational deformities was found, whereas a 60.8% response rate on flexural deformation was found. It is thus concluded that dietary supplementation of magnesium in juvenile cheetahs that experience metacarpal deformities, will remedy the deformity. By analyzing the changes of different blood- and urine parameters in the cheetahs it was observed that dietary magnesium supplementation do influence the formation of urolithiasis. The physiological state of the cheetahs can influence these parameters. The results obtained from the study can be utilized by nutritionists, veterinarians and institutions to enhance the health of captive cheetahs. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted