Efficacy of a diet containing caseinate hydrolysate on signs of stress in dogs

The purpose of this randomized, double blind, placebo-controlled trial was to evaluate 3 the efficacy of a diet containing caseinate hydrolysate (CH) on signs of stress in 2 4 groups of dogs (defined as Anxious and Non-anxious) using physiological (serum 5 cortisol and lysozyme, N:L ratios and heart rate) and behavioral parameters. 6 From an initial group of 40 female Beagle dogs, ranging in age from 10 months to 4 7 years (mean = 1.47 years; SD = 0.53) belonging to a dog colony, 32 were selected for 8 this study according to their level of anxiety. A group of 16 Anxious dogs and a group 9 of 16 Non-anxious dogs were identified. 10 A baseline period, aimed to obtain reference values of investigated parameters, 11 preceded the experimental phase. Both groups (Anxious and Non-anxious) were divided 12 into a treatment group, which received the diet containing CH, and a control group 13 which received a placebo diet (PD). Anxious CH and PD groups were balanced for 14 anxiety level. Each dog was evaluated 3 times a day at 4 weeks intervals (T1-T2-T3). 15 Each evaluation lasted 2 days and involved a Reactivity Evaluation Form (REF), a 16 blood sampling, heart rate recording and a 10 min behavioral video recording. Results 17 from REF scores showed that while at T1 Anxious dogs had significantly higher scores 18 (Mann-Whitney test: P<0.001) compared to Non-anxious dogs, no difference was found 19 between Anxious dogs fed with CH diet and Non-anxious fed with PD or CH diet at T3. 20 Behavioral observations evidenced some signs of improvement in Anxious dog fed with 21 CH diet. Cortisol level significantly decreased in Anxious dogs fed with CH diet 22 (Friedman test: P<0.05). Individual differences in physiological measures of stress 23 responses may have contributed to the large variability, making interpretation of these 24 measures difficult. These results suggest that CH may be used as a functional ingredient 25 alleviating stress in dogs.