Blood changes during training and racing in sled dogs.

Six male and six female Alaskan Huskies allocated three by three to two teams fed rations slightly different in protein/fat ratio (A, 29.2: 53.7%; B, 34.1: 48.5% of digestible energy) were studied for hematological and metabolic changes during a complete training and racing season (24 wk). Blood variables [packed cell volume (PCV), red blood cell count (RBC), mean corpuscular volume, hemoglobin, total plasma protein, free fatty acids, cholesterol, lactic acid, creatine phosphokinase (CPK), creatinine, alanine aminotransferase (ALT) and aspartate aminotransferase (AST)] and six minerals were determined before (at rest) and immediately after a test run of 9 km and then 10, 20 and 30 min later, at the beginning of training as well as 7, 20 and 24 wk later. Training and exercise both significantly influenced PCV, RBC, creatinine and ALT and exercise influenced CPK. Only negligible differences were found between the diets.