Impact of road transportation on physiological and oxidative stress biomarkers in puppies: Beneficial effect of melatonin

Abstract

Transportation stress is complex and can affect the welfare and health of animals. The study was aimed at investigating the impact of road transportation on puppies and the beneficial effects of melatonin supplementation. Fourteen (14) apparently healthy Nigerian indigenous breed of dogs (puppies) divided into two groups, group I (control) and group II (pretreated with Melatonin at 10 mg/kg) were transported by road during the hot-dry season. Vital parameters; respiratory rate (RR), pulse rate (PR) and rectal temperature (RT) were taken before, during and immediately after commencement of the journey. Blood sample was also collected from each puppy before and immediately after the journey, part of which was used to analyzed for some hematological parameters and oxidative biomarkers such as the concentration of malondialdehyde (MDA) and reduced glutathione (GSH) and the activities of superoxide dismutase (SOD) and catalase (CAT). The result revealed that road transportation caused moderate to severe stress on the puppies as observed with the discomfort index (DI) (27.75-34.64 ^oC). The dry-bulb temperature during the study period was 33.23 ± 0.13 ^oC, while the relative humidity was 73.85 ± 0.60%. The RT, PR and RR also increased significantly (p < 0.05) during and immediately after the transportation compared to before commencement of the transportation. The result further revealed that total leucocyte counts and Neutrophil:Lymphocyte ratio (NLR) were elevated immediately after the transportation. The MDA concentration was also significantly (P < 0.05) elevated immediately after the transportation compared to before commencement in the control group. The activities of SOD and CAT and the concentration of GSH was lowered immediately after the transportation compared to before commencement. Supplementation with melatonin before the transportation ameliorated the stress posed by road transportation on the puppies as can be observed in the lowering of the elevated RT, PR and RR, total leucocyte count, NLR and MDA concentration. Pretreated with melatonin also increased the depleted activities of SOD and CAT, and the concentration of GSH immediately after the transportation. The results showed that road transportation is stressful for puppies and supplementation with melatonin mitigated the stress posed on the puppies, probably through the ability of melatonin to scavenge reactive oxygen species generated during the transportation. The results further showed that melatonin may be used to enhance the welfare of puppies subjected to road transportation under adverse thermal conditions.

Keywords: Discomfort index; Melatonin; Oxidative stress; Physiological parameters; Puppies; Road transportation.