The Nutritional Requirements of Exercising Dogs. Richard C. Hill:
http://jn.nutrition.org/cgi/content/full/128/12/2686S
"In humans, high carbohydrate diets increase stamina because they increase muscle glycogen (Hultman et al. 1994). In dogs, however, high fat/low carbohydrate diets increase stamina. Beagles ran for 20 miles (140 min) when fed high fat (53-67% of energy) diets but became exhausted after only 15 miles (100 min) when fed a moderate fat (29% of energy) diet (Downey et al. 1980). A high fat/high protein diet containing no carbohydrate resulted in better performance and less evidence of exertional rhabdomyolysis when fed to sled dogs (Kronfeld 1973). A high carbohydrate (59% of energy) low fat (16% of energy) diet fed to sled dogs resulted in higher resting muscle glycogen concentrations compared with a high fat (62% of energy), low carbohydrate (14% of energy) diet, but glycogen was used more rapidly during a race; thus the final muscle glycogen concentration was unchanged (Reynolds et al. 1996).
In dogs, as in other species, fat oxidation provides most of the energy at low rates of energy expenditure (60% at 40% of maximal oxygen uptake; VO2 max)."
Optimal Nutrition for Athletic Performance, with Emphasison Fat Adaptation in Dogs and Horses. DAVID S. KRONFELD, PAMELA L. FERRANTE AND DOMINIQUE GRANDJEAN:
http://jn.nutrition.org/cgi/reprint/124/12_Suppl/2745S
"The nutritional strategy of carbohydrate loading risks a variety of abnormalities in dogs and horses. An alternative strategy of fat adaptation (the combination of fat feeding and training) was found to improve aerobic performance in dogs and horses and to spare glycogen utilization and reduce lactate accumulation." "Instead, horses and dogs experience digestive and metabolic limitations to high grain diets, which reflect their evolution on diets relatively low in soluble carbohydrates (Clarke et al.1990, Kronfeld 1973, Sprouse et al. 1987, White et al.1993)."
DIETARY METHODS FOR CANINE PERFORMANCE ENHANCEMENT
"Protein Dietary protein is also an important consideration for canine athletes. Current evidence indicates that aerobic training imposes an increased need for dietary protein in dogs. (Hammel, E. P. , et al.,Metabolic responses to exhaustive exercise in racing sled dogs fed diets containing medium, low and zero carbohydrate, Am. J. Clin. Nurr., 1976; 30: 409-418; Adkins, T. O., et al., Diet of racing sled dogs affects erythrocyte depression by stress, Can. Vet. J., 1982 ; 23: 260-263. ) In all animals, athletic conditioning results in adaptive physiological changes that facilitate efficient delivery of oxygen and nutrients to working muscles. These changes include increases in blood volume, red blood cell mass, capillary density, mitochondrial volume, and in the activity and total mass of metabolic enzymes. (Kronfcld, D. S., et al., Hematological and metabolic responses to training in racing sled dogs fed diets containing medium, low, or zero carbohydrate, Am. J. Clin. Nutr., 1977; 30: 419-430; QuerengaesseA. , et al., Blood changes during training and racing in sled dogs, J. Nutr., 1994 ; 2760S-2764S.) The increased tissue mass and requirement for gluconeogenic amino acids during exercise necessitate increased protein intake by working dogs. The protein content of the diet may also impact the capacity of the blood to oxygenate tissue and transport energy-containing nutrients needed by working muscles. (Kronfeld, D. S. , et al., supra.) Although the protein content of diets used in this study were within the range considered to be normal for healthy dogs, a slight reduction in protein content or amino acid availability may become significant during periods of increased physical activity."