Abstract
Little is known about physiological factors that affect the sense of olfaction in dogs. The objectives of this study were to describe the canine nasal and oral microbiota in detection dogs. We sought to determine the bacterial composition of the nasal and oral microbiota of a diverse population of detection canines. Nasal and oral swabs were collected from healthy dogs (n = 81) from four locations—Alabama, Georgia, California, and Texas. Nasal and oral swabs were also collected from a second cohort of detection canines belonging to three different detection job categories: explosive detection dogs (SP-E; n = 22), patrol and narcotics detection dogs (P-NDD; n = 15), and vapor wake dogs (VWD-E; n = 9). To understand if the nasal and oral microbiota of detection canines were variable, sample collection was repeated after 7 weeks in a subset of dogs. DNA was extracted from the swabs and used for 454-pyrosequencing of the16S rRNA genes. Nasal samples had a significantly lower diversity than oral samples (P<0.01). Actinobacteria and Proteobacteria were higher in nasal samples, while Bacteroidetes, Firmicutes, Fusobacteria, and Tenericutes were higher in oral samples. Bacterial diversity was not significantly different based on the detection job. No significant difference in beta diversity was observed in the nasal samples based on the detection job. In oral samples, however, ANOSIM suggested a significant difference in bacterial communities based on job category albeit with a small effect size (R = 0.1079, P = 0.02). Analysis of the composition of bacterial communities using LEfSe showed that within the nasal samples, Cardiobacterium and Riemerella were higher in VWD-E dogs, and Sphingobacterium was higher in the P-NDD group. In the oral samples Enterococcus and Capnocytophaga were higher in the P-NDD group. Gemella and Aggregatibacter were higher in S-PE, and Pigmentiphaga, Chryseobacterium, Parabacteroides amongst others were higher within the VWD-E group. Our initial data also shows that there is a temporal variation in alpha diversity in nasal samples in detection canines.
Highlights
It is estimated that the olfactory perception of dogs is about 10,000 times more sensitive than that of man [1]
We report further characterization of the nasal and oral microbiota of dogs from different geographic locations using generation sequencing
The results show that the nasal and oral microbiota is distinct and unique in bacterial diversity and community structure
Summary
It is estimated that the olfactory perception of dogs is about 10,000 times more sensitive than that of man [1]. Studies have shown that the microbiota can have an impact on health, immune homeostasis, nutrient status [3] and the cognitive function [4] of the host. The majority of those studies have focused on the microbiota of the gastrointestinal tract; there is sufficient evidence suggesting that the microbiota associated with skin [5] and the oral cavity [6] has crucial health implications on the host [5, 7, 8]. Jenkins et al reported that the oral administration of metronidazole altered the detection ability of explosive detection dogs [14]. These findings suggest that microbial communities could influence host physiology and behavior. A potentially unfavorable outcome, especially in the case of military working detection dogs, would be if transportation of detection dogs to different locations could alter their nasal and oral microbiota, and thereby affect their olfactory detection skills
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