Oral microbiota populations of adult dogs consuming wet or dry foods

Abstract

Oral microbiota play a prominent role in canine periodontal disease and wet foods are often blamed for poor oral health, but canine oral microbial communities have been poorly studied. We aimed to determine differences in oral health measures, breath odor, and oral microbiota populations of dogs fed wet or dry food. Twelve adult dogs fed either a commercial dry (extruded) or commercial wet (canned) food for 6 wk were studied. Breath samples were measured for sulfur compounds, teeth were scored for plaque, calculus, and gingivitis by a blinded veterinary dentist, salivary pH was measured, and supragingival (SUP) and subgingival (SUB) plaque samples were collected for microbiota analysis. Plaque DNA was extracted and Illumina sequencing was conducted. Phylogenetic data were analyzed using the CosmosID bioinformatics platform and SAS 9.4, with P <0.05 being significant and P <0.10 being trends. Plaque coverage tended to be higher (P < 0.10) in dogs fed wet vs. dry food, but other oral health scores were not different. Dogs fed dry food had higher (P < 0.05) salivary pH and lower (P < 0.05) breath sulfur concentrations than those consuming wet food. Bacterial alpha diversity was higher in SUP than SUB samples, and a clear separation in beta diversity was observed between sample sites on principal coordinates analysis (PCoA) plots. In SUP samples, dogs fed wet food had a higher alpha diversity than dogs fed dry food, with PCoA plots showing a separation between wet and dry food. Relative abundances of Firmicutes, Synergistetes, and 10 bacterial genera were different (P < 0.05) in SUB samples of dogs fed wet vs. dry food. Relative abundances of Fusobacteria and over 20 bacterial genera were different (P < 0.05) in SUP samples of dogs fed wet vs. dry food. In general, oral health-associated bacterial taxa (Pasteurella, Capnocytophaga, Corynebacterium) were higher, while bacteria associated with poor oral health (Fretibacterium fastidiosum, Filifactor alocis, Treponema medium, Tannerella forsythia, Porphyromonas canoris, Porphyromonas gingivalis) were lower in dogs fed dry food. Such shifts in the oral microbiota may impact periodontal disease risk, but longer dietary intervention studies are required to confirm their role in the disease process. Our results suggest that dogs fed dry extruded foods have lower breath odor and tooth plaque buildup and an oral microbiota population more closely associated with oral health than dogs fed wet canned foods.

Keywords: canine health; next-generation sequencing; oral microbiome; periodontal disease.

Figure 1.

Salivary pH (a) and volatile sulfur concentrations (b) from healthy adult dogs consuming commercially available wet or dry food. Groups with different superscripts differ (P < 0.05).

Figure 2.

Bacterial alpha diversity indices of dogs consuming a commercially available wet or dry food as assessed by the Chao1 index (a and d), Simpson diversity index (b and e), and Shannon diversity index (c and f) in canine plaque samples (SUB, subgingival; SUP, supragingival). Groups with different superscripts differ (P < 0.05).

Figure 3.

Bacterial beta diversity indices of plaque samples (SUB, subgingival; SUP, supragingival) of dogs consuming a commercially available wet or dry food as assessed by the Jaccard index (a and c) or Bray–Curtis index (b and d).

Figure 4.

Linear discriminant analysis effect size (LEfSe) identified bacteria enriched in subgingival plaque samples of healthy adult dogs consuming commercially available wet or dry food [linear discriminant analysis (LDA) score ≥ 3].

Figure 5.

Linear discriminant analysis effect size (LEfSe) identified bacteria enriched in supragingival plaque samples of healthy adult dogs consuming commercially available wet or dry food [linear discriminant analysis (LDA) score ≥ 3].