Water requirements of canine athletes during multi‐day exercise

BACKGROUND: Exercise increases water requirements, but there is little information regarding water loss in dogs performing multi‐day exercise OBJECTIVES: Quantify the daily water turnover of working dogs during multi‐day exercise and establish the suitability of SC administration of tracer to determine water turnover. ANIMALS: Fifteen privately owned Labrador retrievers trained for explosive detection duties and 16 privately owned Alaskan Huskies conditioned for mid‐distance racing. METHODS: All dogs received 0.3 g D(2)O/kg body weight by IV infusion, gavage, or SC injection before the start of a multi‐day exercise challenge. Explosive detection dogs conducted 5 days of simulated off‐leash explosive detection activity. Alaskan sled dogs completed a mid‐distance stage race totaling 222 km in 2 days. Total body water (TBW) and daily water turnover were calculated using both indicator dilution and elimination regression techniques. RESULTS: Total body water (% of body weight) varied from 60% ± 8.6% in minimally conditioned Labrador retrievers to 74% ± 4.5% in highly conditioned Labrador retrievers. Daily water turnover was as high as 45% of TBW during exercise in cold conditions. There was no effect of sex or speed on daily water turnover. There was good agreement between results calculated using the indicator dilution approach and those calculated using a semilog linear regression approach when indicator isotope was administered IV or SC. CONCLUSIONS AND CLINICAL IMPORTANCE: Water requirements are influenced primarily by the amount of work done. SC administration of isotope‐labeled water offers a simple and accurate alternative method for metabolic studies.