PSIX-2 Skin microbial compositions differ among dog body sites and are affected by dietary probiotics

Abstract The study aimed to characterize the skin microbiota across four distinct body sites and investigate the impact of dietary probiotics on the skin microbiota of healthy adult dogs. Healthy adult dogs [n = 60; mean age = 6.2 ± 2.8 yr; mean body weight (BW) = 13.1 ± 4.0 kg] were randomly assigned into three treatment groups and fed for 60 d: a control kibble diet (CON; n = 20; 29.0% crude protein, 10.1% crude fat, 9.9% crude fiber, 7.1% ash, as-fed), CON supplemented with Bifidobacterium longum 548 (CON-B; n = 20), or CON supplemented with Bifidobacterium longum 548 and Lactobacillus rhamnosus 451 (CON-B-L; n = 20). All dogs were individually housed in a temperature- and humidity-controlled research facility. Protocols were approved by the facility’s Institutional Animal Care and Use Committee before the study. On d 60, skin swab samples were collected from the dorsal lumbar area, right axilla, right groin, and right ear concave pinnae of each dog using sterile swabs. These samples were placed into bead tubes and stored at -20°C until analysis. DNA extraction from skin swab samples was followed by sequencing the V4 region of 16S rRNA using Illumina sequencing on a MiSiq. Sequence data were processed through QIIME 2.0, and statistical analysis was performed using R 4.3.1. to test differences between body sites and diets, with a significance threshold set at P < 0.05. The predominant bacterial phyla observed across all body sites were Actinobacteria (40 ± 21.7%), Firmicutes (31.2 ± 17.9 %), Proteobacteria (17.9 ± 13.3%), and Bacteroidetes (6.6 ± 6.1%). Additionally, Acidobacteria, Gemmatimonadetes, and Verrucomicrobia were exclusive to the groin region. Considering data from all body sites, diets affected relative abundances of phyla and genera in dogs. At phylum level, dogs fed the CON-B diet displayed greater (P < 0.05) relative abundance of Actinobacteria compared with those on the CON diet. The CON-B diet also resulted in a greater (P < 0.05) relative abundance of Firmicutes than dogs on either the CON or CON-B-L diets. At genus level, dogs on the CON-B diet showed significantly greater (P < 0.05) relative abundance of Clostridium, Clostridiaceae unclassified, and Lachnospiraceae unclassified compared with the other diet groups. Dogs on the CON diet displayed a greater (P < 0.05) relative abundance of Dietzia compared with those on probiotic-supplemented diets. These findings underscore the variation in skin microbial composition across distinct body sites, contributing valuable data to limited information available on the skin microbiota of dogs. Moreover, consumption of probiotic influenced the skin microbial compositions in dogs, which warrant further studies to elucidate the relationship between probiotics, skin microbiota, and skin health in dogs.