Serum chemistry and electrolyte alterations in sled dogs before and after a 1600 km race: dietary sodium and hyponatraemia

Abstract

Sled dogs are known to develop numerous serum biochemical changes due to endurance exercise. Previous studies have suggested that mild hyponatraemia and hypokalaemia can develop during endurance racing. The aim of the present study was to determine if serum biochemical alterations are similar to previous reports, and if electrolyte alterations are still present with present feeding practices utilised by mushers. Serum chemistries were obtained from 26 Alaskan Huskies belonging to 3 different teams, before and after a 1600 km race. Meals and snacks were analysed via calculation to determine daily macronutrient and electrolyte intake. Numerous biochemical alterations were observed including significant differences in serum total protein, albumin, globulin, aspartate aminotransferase, creatine kinase, TAG, NEFA and urea nitrogen (P < 0·05). Serum electrolyte status revealed a mild, yet significant decrease in serum sodium (P = 0·002); and serum potassium was not significantly different (P = 0·566). Further examination of the sodium intake across the three teams revealed two teams with an average daily intake of approximately 8·5 g/dog/d (700 mg/4184 kJ) and the other team consuming 11·1 g/dog/d (1200 mg/4184 kJ). Regression analysis shows a significant modest positive correlation between serum sodium decrease and sodium intake per metabolic body weight of the dogs, as well as a modest positive correlation between sodium intake and serum potassium implicating the renin–angiotensin aldosterone system as a major factor involved in sodium and potassium homoeostasis. These findings suggest that consumption of approximately 0·9 g/kg0·75 (1·2 g/4184 kJ) of sodium per d may prevent exercise-induced decreases in sodium and potassium.

The Effects of Varying Concentrations of Dietary Protein and Fat on Blood Gas, Hematologic Serum Chemistry, and Body Temperature Before and After Exercise in Labrador Retrievers

“…This is consistent with observations in other exercise models where dogs being fed a high-fat diet tended to have lower serum lactate ( 17 ). Consistent with the metabolic demands of exertion in the well-conditioned endurance athlete ( 4 , 18 ), serum non-esterified fatty acid concentration was significantly different immediately post-exercise relative to pre-exercise values, and gradually recovered toward pre-exercise values during the ensuing 20 min of recovery for all groups.…”

Evaluation of Three Hydration Strategies in Detection Dogs Working in a Hot Environment

“…Although these dogs were not performing endurance activity, there are not studies of fractional sodium excretion in moderate exercise. The significantly reduced sodium in sled dogs following 10 days of endurance racing ( 16 , 17 ) raises the possibility of increased sodium loss with prolonged exertion. In one study ( 16 ), arginine vasopressin (AVP) was decreased at 2 h after completing the race.…”

“…In that study, fractional excretion of sodium was decreased post-race, however the authors hypothesized that there was increased urinary sodium loss from activation of the renin–angiotensin–aldosterone system and increased muscle catabolism leading to increased urea filtration ( 16 ). In one study of sled dogs, sodium supplementation was associated with improved sodium homeostasis ( 17 ). Dogs in all groups had an increase in fractional excretion of sodium over the working day, but maintained their blood sodium concentrations.…”

“…Most studies of working or hunting dogs have shown small or no electrolyte changes following exercise ( 4 , 14 , 15 ). In one study of sled dogs, sodium was significantly decreased following 10 days of endurance racing ( 16 , 17 ). Because dogs do not sweat, any electrolyte loss would be through saliva or urine.…”

The Effects of Exercise on Serum Chemistry, Non-Esterified Fatty Acid, Insulin and Glucagon Dynamics during a 400 Meter Sprint in Racing Greyhounds

“…A single Greyhound study has shown a rise in free fatty acids which can be partially attributed to hemoconcentration as well as increased lipolysis [8]. Changes in non-esterified fatty acid (NEFA) concentrations have been reported to increase or decrease depending on duration of running, with sprinting activities showing some discrepancy regarding increases and decreases due to exercise [8] [13] [16].…”