Effects of dietary protein and fat concentrations on hormonal and oxidative blood stress biomarkers in guide dogs during training

We compared the effects of different feeding strategies on hormonal and oxidative stress biomarkers in guide dogs during specialized training programs. Eight neutered adult dogs belonging to the Labrador retriever breed were divided during the training work into two homogeneous groups for sex (2 males, 2 females), age (17 months ! 1), initial body weight (26.3 kg ! 1), and BCS (4.5 of 9 ! 0.11) and fed two commercial diets with different concentration of energetic nutrients. One diet was a performance diet (HPF) characterized by low-carbohydrate/high-protein and fat content (29:39:19% as-fed) and the other a normal maintenance diet (LPF), characterized by high-carbohydrate/low-protein and fat content (50:24:12% as-fed). The trial lasted 84 days. At days 0, 28, 56, and 84, 180 min before the training work (T0) and immediately after (T1) and after 120 min (T2), blood adrenocorticotrophic hormone (ACTH), cortisol, d-ROMS (reactive oxygen metabolitesederived compounds), and BAP (biological antioxidant potential) were evaluated. Lactate was measured at T0 and T1. The statistical model included the effects of diet (HPF vs. LPF), time (from day 0 to day 84, end of the trial), and exercise (T0, T1, and T2) and their interaction. ACTH (P 0.002) and cortisol (P 0.013) showed higher values in the HPF than in the LPF group; there were no signi!cant differences observed for lactate. Time showed no signi!cant difference for any hormones or blood lactate. Exercise signi!cantly (P < 0.001) in"uenced ACTH and cortisol concentrations, showing higher values at T1 than T0 and T2, and with lactate higher (P < 0.0001) at T1 than T0. Diet did not in"uence biomarkers of oxidative stress. Time did signi!cantly (P < 0.05) in"uence BAP results but not d-ROMs. Exercise had no effect on BAP results, but d-ROMs were higher at T0 than T2 (P 0.001). There was no interaction effect. The pituitary-adrenal (HPA) axis response and the oxidative stress indices could represent an objective method to identify optimal dietary protocols for creating a successful guide dog during the early training period.