Effects of Fuel Type for Muscle Metabolism on Exercise Thermoregulation in Dogs
	Used with permission from Allsorts' Dog Pictures

Thermoregulatory efficiency is a function of the rate of total body heat production and heat dissipation.  It is reflected in body temperature and is under control of thermoregulatory centers in the hypothalamus (Greenleaf et al. 1995).  Thermoregulatory efficiency in dogs increases with exercise duration (Kruk at al. 1987).  Increased plasma ion concentrations affect thermoregulatory centers in the brain that influence exercise thermoregulation.  Elevated plasma osmolality in dogs is associated with higher rectal temperatures during exercise (Greenleaf et al. 1995).  Body temperature during exercise and thermoregulatory efficiency can be influenced by the availability of carbohydrates and free fatty acids for energy metabolism in working muscles.  Increased availability of carbohydrates for use in energy metabolism in muscles causes substantial changes in the exercise thermoregulation of dogs.  Minor changes in exercise thermoregulation in dogs are caused by increased availability of free fatty acids for energy metabolism (Kruk et al. 1987).
 

Glucose: Infusion of glucose into the cephalic vein during exercise caused the following in dogs:

• Lower rate of increase in rectal temperature (Greenleaf et al. 1995).
• Lower rate of increase in muscle temperature.
• Lower rectal and muscle temperatures after exercise.
• Slightly decreased cardiac frequency during exercise.
• Lower levels of oxygen uptake.
• Higher thermoregulatory efficiency.
• Elevated serum insulin concentrations.
• Elevated lactic acid concentrations.
• Diminished plasma free fatty acid and glycerol levels.

Free Fatty Acid: Consumption of soy bean oil four hours before exercise and injection of heparin immediately before exercise to increase free fatty acid levels in the blood had the following effects on dogs:

• Increased cardiac frequency during exercise.
• Higher levels of oxygen uptake.
• Lower thermoregulatory efficiency.
• Elevated lactic acid concentrations (Kruk et al. 1987).

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