Effects of Phytoncide Extracts on Antibacterial Activity, Immune Responses, and Stress in Dogs

Background and objective: Phytoncides are volatile and antibacterial organic compounds emitted by plants. In humans, these compounds are known to confer anti-bacterial, antioxidative, anti-inflammatory, immune-response-enhancing, and stress-reducing benefits. However, it remains largely unknown if phytoncides have parallel effects on dogs. Therefore, the aim of this study is to determine if phytoncides exhibit antibacterial activity, initiate an immune response, or alter stress hormone dynamics in dogs.Methods: Phytoncide extracts used in the study were obtained from Hinoki cypress (Chamaecyparis obtuse) and Korean red pine (Pinus densiflora). To examine the effectiveness of the extracts at initiating and sustaining anti-microbial activity in dogs, we conducted a disc diffusion experiment on bacteria that cause skin diseases in the dog. Furthermore, we evaluated the effects of phytoncides on the immune response and stress hormone levels of dogs by spraying the phytoncide extract on the skin of the beagle twice a day for eight weeks.Results: In this study, we investigated the effectiveness of phytoncides in eliminating bacteria cause skin infections in dogs. Our results confirm that mixed phytoncide extract was more effective than either phytoncide extract alone. After eight weeks, blood was collected from the common carotid artery of the beagle; we then measured the levels of immune response factors and cortisol. We found that with regards to the composition of white blood cells (WBCs), phytoncides significantly increased the proportion of lymphocytes and mononucleotides. They also increased the levels of immunoglobulin G and interferon-γ, while decreasing cortisol levels. Effects on several other immune markers were not significant.Conclusion: We suggest that mixed phytoncide extracts have antibacterial effects in dogs. Additionally, these compounds seem to enhance immunity and reduce stress in dogs.