Effects of a new dietary supplement on behavioural responses of dogs exposed to mild stressors

Abstract

Background & objectives: The effectiveness of a new dietary supplement (derived from fish hydrolysate and melon juice concentrate rich in superoxide dismutase) in reducing fear and stress-related behaviours in pet dogs was examined in a double-blind, placebo-controlled, randomized study.

Methods: 39 dogs were recruited after the owners had filled out a fear susceptibility index questionnaire. Over a 30-day period, one group of dogs received the supplement, and another group a placebo. Twelve behavioural variables were recorded in a series of four subtests (ST1-ST4) on days 0, 15 and 30. Saliva cortisol levels were measured before and after each set of STs.

Results: The dogs rated as more fearful displayed significantly higher cortisol values before the day 0 test session, were less active, spent less time playing with the experimenter, and approached the unfamiliar object less frequently. The owners did not correctly guess whether their dog had received the supplement or not. Behaviours of dogs were significantly different across the three sessions, with significant increases of stress-related behaviours (time spent in the door zone, number of interactions with the door, of whining, and of lip-licking). Conversely time spent with the experimenter increased, interactions and curiosity for the novel object and play with the experimenter decreased, presumably due to a habituation process. This suggests that the design of the four subtests session was relevant to test for mild stressors situations. Moreover, supplemented and placebo dogs responded differently to the three test sessions, indicating a supplement effect on dogs' behaviours and their adaptation to mild stressors situations.

Conclusion: The trial results suggested that the supplement facilitates activity and curiosity in a familiar environment, promotes dog-human interactions with an increased human familiarity, and tends to reduce subtle stress behaviours. Our results suggest that the supplement was effective in the context of mild stressors and habituation.

Keywords: cortisol; fear and stress behaviours; fish hydrolysate; mild stressors; pet dogs; superoxide dismutase.