Serum biochemical changes in dogs competing in a long-distance sled race.

Fifty-five blood samples were collected from 28 dogs competing in the 1991 Yukon Quest International Sled-Dog Race to examine race-induced changes in serum biochemical values. Blood was collected after a 36-hour mandatory rest at the midpoint of the race, and again at 2 subsequent checkpoints. The mean speed of dogs between checkpoints was approximately 4.5 mph. There were no significant increases in PCV, or in serum total protein, sodium, or creatinine concentrations during the race. Mean serum potassium concentration decreased significantly (P < 0.05) from 4.8 +/- 0.4 to 4.4 +/- 0.3 to 3.9 +/- 0.3 mEq/L, as did the serum triglyceride concentration (138 +/- 52, 88 +/- 25, 81 +/- 16 mg/dl). Plasma cortisol concentration did not change significantly. Increases in the mean serum activity of creatine kinase (167, 420, 344 U/L), and aspartate aminotransferase (55, 79, 62 U/L) during the race were significant (P < 0.05). Participation in a long-distance sled race was associated with mild changes in routinely measured serum biochemical values in dogs.