Changes in Rectal Temperature and Hematologic, Biochemical, Blood Gas, and Acid-base Values in Healthy Labrador Retrievers Before and After Strenuous Exercise

Objective: To measure changes in rectal temperature and hematologic, biochemical, blood gas, and acid-base values before and after exercise.

Animals: 14 healthy adult Labrador Retrievers.

Procedure: Dogs exercised continuously for 10 minutes by repeatedly retrieving a dummy thrown approximately 40 to 50 yards on land. The ambient temperature during each exercise period was recorded. Rectal temperature, pulse, and respiratory rate were measured; CBC and serum biochemical profile were determined; and arterial blood gas tensions, acid-base status, and plasma lactate and pyruvate concentrations were measured at rest and immediately after exercise. Rectal temperature, pulse, respiratory rate, and lactate and pyruvate concentrations were evaluated at intervals up to 120 minutes after exercise.

Results: Immediately after exercise, rectal temperature increased markedly; ambient temperature did not affect rectal temperature. Arterial blood pH and PaO2 were significantly increased after exercise, and PaCO2 and bicarbonate concentration were significantly decreased after exercise. Also, statistically, but not clinically, significant increases were observed in RBC, WBC, and segmented neutrophil counts; hemoglobin, total protein, and serum sodium and potassium concentrations; PCV; anion gap; and creatine kinase activity. Plasma lactate and pyruvate concentrations increased significantly after exercise, but there was no change in the lactate-to-pyruvate ratio.

Conclusion And Clinical Relevance: Reference values for healthy Laborador Retrievers during a standardized exercise protocol were established to compare data obtained from Laborador Retrievers with exercise intolerance and collapse. Important characteristics of lactate and pyruvate metabolism were documented that will enable more precise evaluation of exercise intolerance in this breed.