Effect of dietary protein content and tryptophan supplementation on dominance aggression, territorial aggression, and hyperactivity in dogs.

OBJECTIVE: To evaluate the effect of high- and low-protein diets with or without tryptophan supplementation on behavior of dogs with dominance aggression, territorial aggression, and hyperactivity. DESIGN: Prospective crossover study. ANIMALS: 11 dogs with dominance aggression, 11 dogs with territorial aggression, and 11 dogs with hyperactivity. PROCEDURE: In each group, 4 diets were fed for 1 weeks each in random order with a transition period of not < 3 days between each diet. Two diets had low protein content (approximately 18%), and 2 diets had high protein content (approximately 30%). Two of the diets (1 low-protein and 1 high-protein) were supplemented with tryptophan. Owners scored their dog's behavior daily by use of customized behavioral score sheets. Mean weekly values of 5 behavioral measures and serum concentrations of serotonin and tryptophan were determined at the end of each dietary period. RESULTS: For dominance aggression, behavioral scores were highest in dogs fed unsupplemented high-protein rations. For territorial aggression, [corrected] tryptophan-supplemented low-protein diets were associated with significantly lower behavioral scores than low-protein diets without tryptophan supplements. CONCLUSIONS AND CLINICAL RELEVANCE: For dogs with dominance aggression, the addition of tryptophan to high-protein diets or change to a low-protein diet may reduce aggression. For dogs with territorial aggression, tryptophan supplementation of a low-protein diet may be helpful in reducing aggression.

Characterization and treatment of 20 canine dominance aggression cases.

This study was undertaken to characterize 20 cases of dominance aggression seen at Tufts University School of Veterinary Medicine and to investigate the efficacy of our non-confrontational behavior modification program for 8 weeks. The 20 cases included 18 pure breed and 2 mixed breed dogs. Thirteen of the dogs were male. The dogs' ages ranged from 7 to 84 months (mean 32.1 +/- 22.64 SE). There was no correlation between the severity of dominance aggression and the signalment of the dogs. At the conclusion of the eight week follow up period, 14 dogs (70%) were reported to have responded to the treatment to some degree. Six dogs did not demonstrate any noticeable reduction in aggressive behavior or became more aggressive. The results of the study is powerful evidence of the efficacy of the non-confrontational behavior modification program.