The effect of daily oral probiotic and postbiotic supplementation on the canine skin microbiota: Insights from culture-dependent and long-read 16S rRNA gene sequencing methods.

Background: The effects of oral daily probiotic/postbiotic supplementation (ODPPS) on the skin microbiota of dogs have not been investigated previously.

Objectives: This prospective analytical cohort study describes the effect of ODPPS on the canine skin microbiota after 30-90 days of supplementation using culture-based and full-length 16S rRNA gene sequence analysis.

Animals: Twelve client-owned golden retrievers free of dermatological disease, living in the same environment.

Materials and methods: Skin (axillae and inguinal) swab samples were collected on Day (D)0. All dogs commenced ODPPS, and skin swab samples were taken from the same sites on D30 and D90. Swabs were cultured on sheep blood agar at 37°C for 24 h and bacterial colonies identified. DNA was extracted to obtain full-length 16S ribosomal RNA gene for microbiota profiling.

Results: Culture-dependent methods demonstrated reduced Staphylococcus pseudintermedius prevalence in inguinal tissue following ODPPS (p = 0.05). In the axillae, microbiota compositional differences were demonstrated at D90 compared to D0. A notable increase in beneficial skin-associated bacteria was observed in the axillae at D90 compared to D0, including Dubosiella newyorkensis (false discovery rate [FDR] p = 0.02) and Lactobacillus acidophilus (FDR p = 0.02). Higher bacterial genera diversity was observed on D90 of ODPPS.

Conclusions and clinical relevance: This study provides a comprehensive analysis of the canine skin microbiota using advanced long-read sequencing. The findings suggest that ODPPS could be a promising strategy for improving skin health by modulating the microbiota and reducing the risk of skin infections.