Hematologic, serum biochemical, and cortisol changes associated with anticipation of exercise and short duration high-intensity exercise in sled dogs.

Background: Many studies have demonstrated changes in clinicopathologic variables in response to exercise in athletic dogs. These changes have been attributed to the duration and intensity of exercise. However, inconsistencies in the timing of collection of resting blood samples can be a confounding variable when interpreting results.

Objectives: The objectives of this study were to determine whether hematologic and biochemical data in sled dogs are influenced by (1) anticipation of an exercise event or (2) short-duration high-intensity exercise.

Methods: Blood samples were collected into EDTA tubes and tubes without anticoagulant from sled dogs at rest, immediately before a 3-mile run (preexercise), and immediately after the run (postexercise). A CBC, biochemical profile (including electrolytes, glucose, proteins, creatinine, urea, enzymes, cholesterol, and total bilirubin), and serum cortisol concentration were measured using standard methods on automated analyzers.

Results: Significant increases in sodium, chloride, albumin, calcium, and cortisol concentration were observed in preexercise samples when compared with resting samples. Hyperglycemia and a further rise in serum cortisol concentration occurred immediately postexercise.

Conclusions: The results of this study indicate that anticipation of exercise affects several biochemical analytes, emphasizing the importance of appropriate timing of baseline blood samples. The pronounced hyperglycemia immediately after short-duration exercise may be a breed- or exercise-dependent phenomenon.