Effect of distance traveled and speed of racing on body weight and serum enzyme activity of sled dogs competing in a long-distance race

Abstract

Objective - To determine the relationship of serum biochemical values and change in body weight with finishing status (retired from or finished the race), finishing order of a team, and distance traveled for dogs participating in a long-distance sled dog race. Animals - 262 of 848 dogs that participated in the 1995 Iditarod Trail sled dog race. Design - Prospective study. Procedure - Body weight was recorded for 261 dogs before the race and again when these dogs retired from or completed the race. Using a nonrandom convenience sample of participating dogs, blood samples were obtained from 151 dogs that retired from the race and 111 dogs that completed the race. Results - Serum biochemical indices of skeletal muscle damage were significantly higher in dogs retiring during the first 500 miles of the race than in dogs retiring in the last 638 miles or finishing the race. Serum sodium concentration was less than the reference range in a significantly greater proportion of dogs that retired from the race than of dogs that completed the race. There was little relationship between finishing order and serum biochemical values. Dogs completing the race lost a mean of 8.9% of body weight, and amount of weight lost was not related to finishing order. Clinical Implications - Results indicated that exertional rhabdomyolysis develops more often in dogs that retire during the initial 500 miles of a long-distance race, compared with dogs that complete the race. There is no detectable relationship between the speed with which the race is run (finishing order) and body weight loss or serum biochemical values.