This study compared the effects of feeding a high fat versus a high carbohydrate diet to Alaskan Husky dogs for 4 weeks before and during an 8 week conditioning programme. Blood samples were taken before and after aerobic bouts of exercise performed before and during the conditioning programme. These samples were analysed for serum concentrations of free fatty acids (FFA), triglycerides (TG), vitamin E, glucose and lipase. Results showed that dogs fed the high fat diet had higher post exercise FFA and TG values both before and after training. There were no significant differences in plasma vitamin E or in serum lipase activity between diet groups. It was concluded that feeding a high fat diet safely enhances the availability of local and peripheral lipid stores during exercise.