To characterize the skin-associated fungal microbiota (mycobiota) in dogs, and to evaluate the influence of body site, individual dog or health status on the distribution of fungi, next-generation sequencing was performed targeting the internal transcribed spacer region. A total of 10 dogs with no history of skin disease were sampled at 10 distinct body sites consisting of haired and mucosal skin, and 8 dogs with diagnosed skin allergies were sampled at six body sites commonly affected by allergic disease. Analysis of similarities revealed that body site was not an influencing factor on membership or structure of fungal communities in healthy skin; however, the mucosal sites were significantly reduced in fungal richness. The mycobiota from body sites in healthy dogs tended to be similar within a dog, which was visualized in principle coordinates analysis (PCoA) by clustering of all sites from one dog separate from other dogs. The mycobiota of allergic skin was significantly less rich than that of healthy skin, and all sites sampled clustered by health status in PCoA. Interestingly, the most abundant fungi present on canine skin, across all body sites and health statuses, were Alternaria and Cladosporium—two of the most common fungal allergens in human environmental allergies.

The skin of healthy cats appears to have a more diverse fungal microbiota compared to previous studies, and a fungal dysbiosis is noted in the skin of allergic cats. Future studies assessing the temporal stability of the skin microbiota in cats will be useful in determining whether the microbiota sequenced using NGS are colonizers or transient microbes.

BackgroundThe skin is inhabited by a multitude of microorganisms. An imbalance of these microorganisms is associated with disease, however, the causal relationship between skin microbiota and disease remains unknown. To describe the cutaneous bacterial microbiota of cats and determine whether bacterial dysbiosis occurs on the skin of allergic cats, the skin surfaces on various regions of 11 healthy cats and 10 allergic cats were sampled.Methodology/Principal findingsGenomic DNA was extracted from skin swabs and sequenced using primers that target the V4 region of the bacterial 16S rRNA. The bacterial sequences from healthy cats revealed that there are differences in species diversity and richness between body sites and different epithelial surfaces. Bacterial communities preferred body site niches in the healthy cats, however, the bacterial communities on allergic cat skin tended to be more unique to the individual cat. Overall, the number of bacterial species was not significantly different between the two health status groups, however, the abundances of these bacterial species were different between healthy and allergic skin. Staphylococcus, in addition to other taxa, was more abundant on allergic skin.Conclusions/SignificanceThis study reveals that there are more bacterial species inhabiting the skin of cats than previously thought and provide some evidence of an association between dysbiosis and skin disease.

Previous research revealed the feline skin bacterial microbiota to be site-specific and the fungal microbiota to be individual-specific. The effect of other factors, such as genotype and environment, have not yet been studied in cats, but have been shown to be potentially important in shaping the cutaneous microbiota of other animals. Therefore, the objectives of this study were to evaluate the effect of these factors on the bacterial and fungal microbiota of feline skin and oral cavity. The influence of genotype was assessed through the analysis of different cat breeds, and the influence of environment through comparison of indoor and outdoor cats. DNA was extracted from skin and oral swabs, and bacterial and fungal next-generation sequencing were performed. Analysis of the skin microbiota of different cat breeds revealed significant differences in alpha diversity, with Sphynx and Bengal cats having the most diverse communities. Many taxa were found to be differentially abundant between cat breeds, including Veillonellaceae and Malassezia spp. Outdoor environment exposure had considerable influence on beta diversity, especially in the oral cavity, and resulted in numerous differentially abundant taxa. Our findings indicate that the oral bacterial microbiota and both fungal and bacterial microbiota of feline skin are influenced by breed, and to a lesser degree, environment.

Identification of fungal organisms often poses a problem for pathologists because the histomorphology of some fungal organisms is not specific, fresh tissues may not be available, and isolation and identification in culture may take a long time. The purpose of this study was to validate the use of panfungal polymerase chain reaction (PCR) to identify fungal organisms from formalin-fixed paraffin-embedded (FFPE) tissues. Formalin-fixed paraffin-embedded curls were tested from 128 blocks containing canine, feline, equine, and bovine tissues with cutaneous, nasal, pulmonary, and systemic fungal infections, identified by the presence of fungi in histologic sections. Quantitative scoring of histologic sections identified rare (11.9%), occasional (17.5%), moderate (17.5%), or abundant (53.1%) fungal organisms. DNA was isolated from FFPE tissues and PCR was performed targeting the internal transcribed spacer 2 (ITS-2) region, a segment of noncoding DNA found in all eukaryotes. Polymerase chain reaction products were sequenced and identified at ≥97% identity match using the Basic Local Alignment Search Tool and the NCBI database of ITS sequences. Of the 128 blocks, 117 (91.4%) yielded PCR products and high-quality sequences were derived from 89 (69.5%). Sequence and histologic identifications matched in 79 blocks (61.7%). This assay was capable of providing genus- and species-level identification when histopathology could not and, thus, is a beneficial complementary tool for diagnosis of fungal diseases.

Background The pathogenesis and treatment of cutaneous malodour in dogs have not been investigated previously. Staphylococcus and Corynebacterium spp. are associated with human axillary malodour. Hypothesis Staphylococcus and Corynebacterium spp. are associated with cutaneous malodour in dogs, and treatment with a topical essential oil‐based product will improve malodour and reduce the abundance of odour‐causing bacteria. Animals Twenty seven bloodhound dogs from a south Texas boarding facility were enrolled in this study. Methods and materials Skin swabs were taken from the axilla and dorsum of 27 dogs at initiation of the study. Mean malodour scores were used to assign dogs to control or malodour groups. The malodourous dogs were randomly assigned to a treatment or placebo group, received four weekly topical applications of the spot‐on or placebo, and samples were recollected. Next‐generation sequencing (NGS) and real‐time quantitative PCR (qPCR) were performed on all swabs. Results Psychrobacter and Pseudomonas spp. were significantly more abundant (P < 0.001, P = 0.006; respectively), and overall bacterial diversity was reduced (P = 0.0384) on the skin of malodourous dogs. Staphylococcus and Corynebacterium spp. were not associated with malodour. The topical essential oil‐based product significantly (P = 0.0078) improved malodour in the treatment group and shifted their bacterial community structure. Conclusions and clinical importance A novel association of bacterial genera with malodour in bloodhound dogs, identified by NGS, highlights future targets for odour control. The topical treatment significantly reduced malodour. The interaction between the topical treatment and cutaneous microbiota should be further investigated and may be useful in other dermatological conditions involving microbiota.

Although Staphylococcus pseudintermedius is considered the major pathogen associated with superficial canine pyoderma, no study has investigated the entire bacterial community in these lesions with molecular techniques. The objectives of this study were to characterize the bacterial microbiota in two forms of superficial canine pyoderma lesions, superficial bacterial folliculitis (SBF) and epidermal collarette (EC), especially in terms of the staphylococcal community. Swabs from 12 SBF and 9 EC lesions were obtained from eight and six atopic dogs, respectively. Eight samples from the axilla and groin of four healthy dogs served as controls. DNA was extracted for 16S rRNA gene sequencing and quantitative polymerase chain reaction of Staphylococcus spp. and S. pseudintermedius. Healthy skin samples harbored significantly more diverse bacterial communities than pyoderma samples. Healthy samples had communities that were more similar to each other, and were distinct from pyoderma samples. Staphylococcus spp. abundance was increased in pyoderma samples, especially those from EC samples. Although determining species-level identities of staphylococcal sequences revealed many species, S. pseudintermedius was the primary staphylococcal species found in all sample types. As expected, there are many differences in the microbiota when comparing healthy and canine pyoderma lesions samples. These lesions do not seem to be associated with a change in the relative abundance of specific Staphylococcus species, but simply an overall increase in Staphylococcus spp. abundance. The results of this study provide a starting point for future studies investigating how antimicrobial treatments may further change the microbiota associated with these lesions.

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