The influence of diet on behavior is well established in other species, but its role in canine behavior is less understood. A 2009 thesis by Wouter H. Hendriks and colleagues investigated whether diet composition, particularly fibre type and tryptophan supplementation, could affect dogs’ feeding motivation, activity, and stress-related behavior.
Two in vitro fermentation studies were first conducted to evaluate the microbial activity of different fibrous ingredients in the canine gastrointestinal tract. Based on these results, two diets differing in fibre fermentability were formulated and tested in dogs. The high-fermentable fibre diet produced more short-chain fatty acids and was associated with reduced feeding motivation six hours after meals, as well as lower activity levels in home kennels, compared to the low-fermentable fibre diet. However, secretion of satiety-related hormones did not differ between diets, suggesting that mechanisms beyond hormonal signaling contributed to sustained satiety.
The researchers also tested dietary supplementation with tryptophan, the amino acid precursor of serotonin, in mildly anxious pet dogs. Despite significant increases in plasma tryptophan concentrations and improved tryptophan-to-amino acid ratios, neither owner reports nor controlled behavioral tests revealed notable changes in dogs’ anxiety or stress resilience after eight weeks of supplementation.
Overall, the findings indicate that fibre fermentability can influence feeding-related behaviors, such as motivation to eat and activity levels, but tryptophan supplementation had no measurable behavioral benefits in privately-owned dogs. These results underscore the complexity of the relationship between nutrition and canine behavior, highlighting that some dietary modifications may subtly influence motivation without altering core stress or anxiety responses.
Source: Hendriks, W. H., Verstegen, M., & Bosch, G., 2009. Can diet composition affect behaviour in dogs? : food for thought.
