Histoplasmosis and multicentric lymphoma in a Nubian goat.

Following treatment for pneumonia, a 1-y-old female Nubian goat was presented because of a persistent fever for 3 mo and peripheral lymphadenopathy for 1 mo. Cytology and histology of the superficial cervical and prefemoral lymph nodes demonstrated a moderate-to-marked "left-shifted" lymphoid population, suggestive of lymphoma, and extremely rare extracellular, 2-4 µm, oval, basophilic yeast, consistent with Histoplasma capsulatum. On immunohistochemistry, >95% of the lymphocytes demonstrated positive cytoplasmic and membranous immunoreactivity for CD3. Histoplasma spp. urine antigen and serum antibody testing were positive and negative, respectively. Panfungal PCR and sequencing of DNA extracted from scrolls of formalin-fixed, paraffin-embedded tissue yielded matches to H. capsulatum with 99-100% identity. Given the poor prognosis and persistent pyrexia, the animal was euthanized. Postmortem examination confirmed concurrent multicentric, intermediate-size, T-cell, lymphoblastic lymphoma and histoplasmosis; lesions consistent with intestinal coccidiosis and suspected pulmonary Rhodococcus equi were also noted. Although dimorphic fungi have been described previously in goats, lesions of Histoplasma spp. had not been documented in this species, to our knowledge. Given the low disease burden, it is suspected that the lymphoma was primary, leading to an immunocompromised state and development of secondary, opportunistic infections.

Follicular choristoma in the third eyelid of an eclectus parrot (Eclectus roratus).

CASE DESCRIPTION: A 1-year-old male eclectus parrot (Eclectus roratus) with a 3- to 4-month history of blepharospasm in the right eye was referred to a veterinary medical teaching hospital for further evaluation. Conventional medical treatments had been ineffective. The referring avian specialist had plucked a suspected ectopic feather from the right eye 6 weeks prior to the referral evaluation. CLINICAL FINDINGS: The parrot was sedated, and ophthalmic examination of the right eye with slit-lamp biomicroscopy revealed a 3 × 2 × 2-mm raised vascular mass with a focally pigmented center associated with the temporal aspect of the leading edge of the third eyelid. No abnormalities were detected in the left eye. TREATMENT AND OUTCOME: The parrot was anesthetized, and the right eye mass was excised and submitted for histologic examination. Histologically, there was a single pigmented feather follicle bulb surrounded by multiple discrete lymphoid follicles and moderate lymphoplasmacytic inflammation within the substantia propria of the third eyelid conjunctiva. The histologically normal feather follicle in an abnormal location classified the lesion as a choristoma. Nine months after surgery, the parrot had no signs of ocular discomfort and no overt regrowth of the feather follicle. CLINICAL RELEVANCE: For the eclectus parrot of this report, a lesion caused by normal differentiation of an ectopic feather follicle in the right third eyelid was successfully treated. A third eyelid choristoma appears to be a hitherto unreported pathological finding in avian species. Although rare, the presence of a choristoma should be considered as a differential diagnosis for birds with blepharospasm.

Gastrointestinal pythiosis with concurrent presumptive gastrointestinal basidiobolomycosis in a Boxer dog.

A 2-year-old female spayed Boxer dog was presented for a 1-month history of progressive hemorrhagic diarrhea with tenesmus and weight loss despite trial courses of antibiotics and diet change. Abdominal ultrasound revealed severe, focal thickening, and loss of normal architecture of the colonic wall with abdominal lymphadenomegaly. Dry-mount fecal cytology, performed on several consecutive days, consistently revealed numerous, round, 16-20 µm structures with basophilic, granular content, and a thin cell wall. Transmission electron microscopy identified these structures as fungi. Culture, polymerase chain reaction (PCR), and sequencing of the internal transcribed spacer, D1/D2 regions, and DNA-directed RNA polymerase II core subunit (RPB2) confirmed the presence of Basidiobolus microsporus in the feces. Biopsies collected via ileocolonoscopy revealed marked, multifocal, chronic, neutrophilic, and eosinophilic ileitis and colitis with ulceration, granulation tissue, and intralesional hyphae (identified with Gomori methenamine silver stain). A Pythium enzyme-linked immunosorbent assay and Pythium-specific PCR performed on the formalin-fixed paraffin-embedded biopsy specimens were positive while Basidiobolus-specific PCR was negative, thus confirming a diagnosis of pythiosis. This report describes a fatal case of colonic and intestinal pythiosis with the presence of fecal Basidiobolus sp. spores, suggestive of concurrent gastrointestinal basidiobolomycosis.

Correlating Gastrointestinal Histopathologic Changes to Clinical Disease Activity in Dogs With Idiopathic Inflammatory Bowel Disease.

Prior studies have failed to detect a convincing association between histologic lesions of inflammation and clinical activity in dogs with inflammatory bowel disease (IBD). We hypothesized that use of a simplified histopathologic scoring system would improve the consistency of interpretation among pathologists when describing histologic lesions of gastrointestinal inflammation. Our aim was to evaluate the correlation of histopathologic changes to clinical activity in dogs with IBD using this new system. Forty-two dogs with IBD and 19 healthy control dogs were enrolled in this retrospective study. Endoscopic biopsies from the stomach, duodenum, ileum, and colon were independently scored by 8 pathologists. Clinical disease activity was scored using the Canine Inflammatory Bowel Disease Activity Index (CIBDAI) or the Canine Chronic Enteropathy Clinical Activity Index (CCECAI), depending on the individual study center. Summative histopathological scores and clinical activity were calculated for each tissue (stomach, duodenum, ileum, and colon) and each tissue histologic score (inflammatory/morphologic feature). The correlation between CCECAI/CIBDAI and summative histopathologic score was significant ( P < .05) for duodenum ( r = 0.42) and colon ( r = 0.33). In evaluating the relationship between histopathologic scores and clinical activity, significant ( P < .05) correlations were observed for crypt dilation ( r = 0.42), lamina propria (LP) lymphocytes ( r = 0.40), LP neutrophils ( r = 0.45), mucosal fibrosis ( r = 0.47), lacteal dilation ( r = 0.39), and villus stunting ( r = 0.43). Compared to earlier grading schemes, the simplified scoring system shows improved utility in correlating histopathologic features (both summative histology scores and select histologic scores) to IBD clinical activity.

Novel Poxvirus in Proliferative Lesions of Wild Rodents in East Central Texas, USA.

Northern pygmy mice from 2 localities in East Central Texas, USA, had proliferative epidermal lesions on the tail and feet. Electron microscopy of lesion tissue revealed poxvirus. Phylogenetic analyses indicated the virus differed 35% from its closest relatives, the Chordopoxvirinae. Future research is needed to determine whether this virus could affect human health.

Association of fecal calprotectin concentrations with disease severity, response to treatment, and other biomarkers in dogs with chronic inflammatory enteropathies.

BACKGROUND: Calprotectin is a marker of inflammation, but its clinical utility in dogs with chronic inflammatory enteropathies (CIE) is unknown. OBJECTIVE: Evaluation of fecal calprotectin in dogs with biopsy-confirmed CIE. ANIMALS: 127 dogs. METHODS: Prospective case-control study. Dogs were assigned a canine chronic enteropathy clinical activity index (CCECAI) score, and histologic lesions severity was assessed. Fecal calprotectin, fecal S100A12, and serum C-reactive protein (CRP) were measured. Food- or antibiotic-responsive cases (FRE/ARE, n = 13) were distinguished from steroid-/immunosuppressant-responsive or -refractory cases (SRE/IRE, n = 20). Clinical response to treatment in SRE/IRE dogs was classified as complete remission (CR), partial response (PR), or no response (NR). RESULTS: Fecal calprotectin correlated with CCECAI (ρ = 0.27, P = .0065) and fecal S100A12 (ρ = 0.90, P < .0001), some inflammatory criteria, and cumulative inflammation scores, but not serum CRP (ρ = 0.16, P = .12). Dogs with SRE/IRE had higher fecal calprotectin concentrations (median: 2.0 µg/g) than FRE/ARE dogs (median: 1.4 µg/g), and within the SRE/IRE group, dogs with PR/NR had higher fecal calprotectin (median: 37.0 µg/g) than dogs with CR (median: 1.6 µg/g). However, both differences did not reach statistical significance (both P = .10). A fecal calprotectin ≥15.2 µg/g separated both groups with 80% sensitivity (95% confidence interval [95%CI]: 28%-100%) and 75% specificity (95%CI: 43%-95%). CONCLUSIONS AND CLINICAL IMPORTANCE: Fecal calprotectin could be a useful surrogate marker of disease severity in dogs with CIE, but larger longitudinal studies are needed to evaluate its utility in predicting the response to treatment.

Analysis of Bacterial and Fungal Nucleic Acid in Canine Sterile Granulomatous and Pyogranulomatous Dermatitis and Panniculitis.

Next generation sequencing (NGS) studies are revealing a diverse microbiota on the skin of dogs. The skin microbiota of canine sterile granulomatous and pyogranulomatous dermatitis (SGPD) has yet to be investigated using NGS techniques. NGS targeting the 16S rRNA and ITS-1 region of bacterial and fungal DNA, respectively, were used to investigate if bacterial and fungal DNA were associated with skin lesions in cases of canine SGPD. The study included 20 formalin-fixed paraffin-embedded (FFPE) skin samples and 12 fresh samples from SGPD-affected dogs, and 10 FFPE and 10 fresh samples from healthy dogs. DNA was extracted from deep dermis and panniculus, and microbial DNA was amplified using primers targeting the bacterial 16S rRNA V1-V3 and fungal ITS-1 regions. The amplified DNA was utilized for NGS on an Illumina MiSeq instrument. The sequences were processed using QIIME. No differences in fungal or bacterial alpha diversity were observed between the SGPD and control samples. Beta diversity analysis demonstrated differences in the bacterial communities between SGPD and control, but not in the fungal communities. Compared to controls, the family Erysipelotrichaceae and genus Staphylococcus were significantly more abundant in the SGPD FFPE samples, and genus Corynebacterium were more abundant in fresh samples. The bacteria found to be more abundant in SGPD are common inhabitants of skin surfaces, and likely secondary contaminants in SGPD cases. This study provides additional evidence that SGPD lesions are likely sterile.

The feline skin microbiota: The bacteria inhabiting the skin of healthy and allergic cats.

BACKGROUND: The 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 FINDINGS: Genomic 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/SIGNIFICANCE: This 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.

Granulomatous Inflammatory Response to a Microchip Implanted in a Dog for Eight Years.

An 8 yr old neutered male springer spaniel dog was referred to Texas A&M University, College of Veterinary Medicine for a large, firm, fixed mass, located in the dorsal cervical tissue. The dog was otherwise healthy and had undergone microchip implantation approximately 8 yr prior. Radiographs, ultrasound, and microchip scanner confirmed the presence of a microchip within the mass. The microchip and associated mass were surgically excised, and histopathologic examination revealed granulomatous inflammation surrounding a cracked microchip. This case represents the first report of a granulomatous inflammatory response to a microchip 8 yr after implantation in a dog and highlights an important differential diagnosis.

Panfungal Polymerase Chain Reaction for Identification of Fungal Pathogens in Formalin-Fixed Animal Tissues.

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.

Atypical cutaneous cryptococcosis in four cats in the USA.

BACKGROUND: Cryptococcosis is an uncommon fungal infection in humans and mammals. Occasionally, cryptococcosis manifests as cutaneous lesions, either as an extension of nasal disease or as stand alone lesions unassociated with the nose. Histologically, these lesions are typically characterized by abundant organisms with mild granulomatous dermatitis. Herein, four feline cases of atypical cutaneous cryptococcal infections are described. METHODS: Skin punch biopsies from four client owned cats were submitted for histological evaluation between 2006 and 2015. Histological examination, including histochemical stains, was performed in all cases. Immunohistochemical stains and PCR were performed in three of four cases. Fungal culture was performed in two cases and transmission electron microscopy was performed in one case. RESULTS: Grossly, the cutaneous lesions were papular to nodular with occasional ulceration and were located predominantly on the trunk. Histological examination revealed severe granulomatous to pyogranulomatous and eosinophilic dermatitis with rare, capsule-deficient yeasts. Immunohistochemistry, PCR and fungal culture confirmed Cryptococcus spp. to be the aetiological agent in these cases. CONCLUSIONS AND CLINICAL IMPORTANCE: In cutaneous lesions, capsule-deficient strains of Cryptococcus spp. may induce a severe inflammatory response with rare intralesional organisms that may not be readily identified on routine haematoxylin and eosin stained slides. Special stains with careful examination and ancillary tests (PCR, immunohistochemistry, fungal culture or antigen testing) should be performed when pyogranulomatous and eosinophilic dermatitis is encountered without an identifiable cause.

Characterization of the cutaneous mycobiota in healthy and allergic cats using next generation sequencing.

BACKGROUND: Next generation sequencing (NGS) studies have demonstrated a diverse skin-associated microbiota and microbial dysbiosis associated with atopic dermatitis in people and in dogs. The skin of cats has yet to be investigated using NGS techniques. HYPOTHESIS/OBJECTIVES: We hypothesized that the fungal microbiota of healthy feline skin would be similar to that of dogs, with a predominance of environmental fungi, and that fungal dysbiosis would be present on the skin of allergic cats. ANIMALS: Eleven healthy cats and nine cats diagnosed with one or more cutaneous hypersensitivity disorders, including flea bite, food-induced and nonflea nonfood-induced hypersensitivity. METHODS: Healthy cats were sampled at twelve body sites and allergic cats at six sites. DNA was isolated and Illumina sequencing was performed targeting the internal transcribed spacer region of fungi. Sequences were processed using the bioinformatics software QIIME. RESULTS: The most abundant fungal sequences from the skin of all cats were classified as Cladosporium and Alternaria. The mucosal sites, including nostril, conjunctiva and reproductive tracts, had the fewest number of fungi, whereas the pre-aural space had the most. Allergic feline skin had significantly greater amounts of Agaricomycetes and Sordariomycetes, and significantly less Epicoccum compared to healthy feline skin. CONCLUSIONS: 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.

Ochronosis-like condition in a cat.

BACKGROUND: Endogenous ochronosis is caused by a defect in the enzyme homogentisate 1,2-dioxygenase (HGD), which results in abnormal pigment deposition in the skin and urine abnormalities. Ochronosis previously has not been described histologically or ultrastructurally in a domestic animal species. HYPOTHESIS/OBJECTIVES: To describe the clinical, histopathological and ultrastructural findings in a case of aberrant pigmentation in a cat with features that resemble ochronosis. ANIMAL: A 5-year-old, spayed female Domestic short hair cat presented with multiple black cutaneous plaques on the face and progressive lethargy. The cat's urine turned brown when exposed to air. The familial history of the cat was unknown. METHODS: Clinical examination; histopathology, electron microscopy and mass/energy dispersive X-ray spectroscopy of tissues. RESULTS: Septic peritonitis and additional pigment in the spleen, intestine and lymph node were found at postmortem examination. The pigment was determined to be an organic compound and had a similar histological appearance, staining properties, ultrastructure and composition to ochronotic pigment. No mutations were found in exons 3, 6, 8 and 13 of the HGD gene in the cat. CONCLUSIONS AND CLINICAL IMPORTANCE: To the best of the authors' knowledge, this is the first report of a condition resembling ochronosis in a domestic animal species that has been evaluated with histopathology and advanced imaging techniques. It provides an additional differential in cases of aberrant pigmentation in cats.

Congenital dystrophic epidermolysis bullosa (DEB) in Sprague Dawley rats: a case series.

BACKGROUND: Epidermolysis bullosa is a rare skin disease caused by defects in the basement membrane and/or other dermoepidermal junction components. HYPOTHESIS/OBJECTIVES: We describe a series of spontaneous cases of dystrophic epidermolysis bullosa (DEB) in a colony of Sprague Dawley rats investigated with histopathology, transmission electron microscopy (TEM) and inheritance pattern. ANIMALS: Four, 4-day-old pups from a litter of Sprague Dawley rats developed blistering, haemorrhagic skin lesions and were euthanized. Age-matched controls from the same litter were normal. Several months later two more litters presented with identical findings. All three litters had the same sire, suggesting a genetic component. METHODS: Skin from affected and control animals was evaluated histologically and with TEM. Unaffected sibling pairs from affected litters were bred in order to potentially reproduce the disease and determine the mode of inheritance. RESULTS: Histologically, there was significant dermoepidermal clefting below the basement membrane with variable amounts of haemorrhage and cellular debris within the clefts. Ultrastructurally, clefting occurred below the basement membrane with an intact lamina densa and normal hemidesmosomes. Anchoring filaments were strikingly absent. Litters produced from phenotypically unaffected sibling pairs resulted in a total of four more litters with approximately a quarter of pups affected. CONCLUSIONS AND CLINICAL IMPORTANCE: Based on the gross lesions, histopathological features and TEM determination of separation below the lamina densa and lack of normal anchoring fibrils, these cases are most consistent with DEB. This is the first report of naturally occurring, localized and reproducible recessive DEB in Sprague Dawley rats.

Serum and fecal canine α1-proteinase inhibitor concentrations reflect the severity of intestinal crypt abscesses and/or lacteal dilation in dogs.

Gastrointestinal (GI) protein loss, due to lymphangiectasia or chronic inflammation, can be challenging to diagnose. This study evaluated the diagnostic accuracy of serum and fecal canine α1-proteinase inhibitor (cα1PI) concentrations to detect crypt abscesses and/or lacteal dilation in dogs. Serum and fecal cα1PI concentrations were measured in 120 dogs undergoing GI tissue biopsies, and were compared between dogs with and without crypt abscesses/lacteal dilation. Sensitivity and specificity were calculated for dichotomous outcomes. Serial serum cα1PI concentrations were also evaluated in 12 healthy corticosteroid-treated dogs. Serum cα1PI and albumin concentrations were significantly lower in dogs with crypt abscesses and/or lacteal dilation than in those without (both P <0.001), and more severe lesions were associated with lower serum cα1PI concentrations, higher 3 days-mean fecal cα1PI concentrations, and lower serum/fecal cα1PI ratios. Serum and fecal cα1PI, and their ratios, distinguished dogs with moderate or severe GI crypt abscesses/lacteal dilation from dogs with only mild or none such lesions with moderate sensitivity (56-92%) and specificity (67-81%). Serum cα1PI concentrations increased during corticosteroid administration. We conclude that serum and fecal α1PI concentrations reflect the severity of intestinal crypt abscesses/lacteal dilation in dogs. Due to its specificity for the GI tract, measurement of fecal cα1PI appears to be superior to serum cα1PI for diagnosing GI protein loss in dogs. In addition, the serum/fecal cα1PI ratio has an improved accuracy in hypoalbuminemic dogs, but serum cα1PI concentrations should be carefully interpreted in corticosteroid-treated dogs.

What is living on your dog's skin? Characterization of the canine cutaneous mycobiota and fungal dysbiosis in canine allergic dermatitis.

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.

Presentation, treatment, and outcome of squamous cell carcinoma in the perineal region of 9 goats.

Nine goats were treated for squamous cell carcinoma (SCC) of the perineal and/or tail region. This case series is the first detailed description of clinical presentation and treatment of caprine SCC in North America and characterizes the potential risk factors and outcomes.

Présentation, traitement et issue du carcinome squameux dans la région périanale chez 9 chèvres. Neuf chèvres ont été traitées pour le carcinome squameux (CS) de la région périanale et/ou de la queue. Cette série de cas est la première description détaillée de la présentation clinique et du traitement du CS caprin en Amérique du Nord et caractérise les facteurs de risque et les issues potentielles.(Traduit par Isabelle Vallières).

Fecal and urinary N-methylhistamine concentrations in dogs with chronic gastrointestinal disease.

Due to their ability to release inflammatory mediators, such as histamine, mast cells are potentially important in gastrointestinal disease. The purpose of this study was to measure N-methylhistamine (NMH), a histamine metabolite, in fecal and urine samples from dogs with chronic gastrointestinal disease. Fecal and urinary NMH concentrations were compared between dogs with chronic gastrointestinal disease and control dogs, and/or to control ranges. Correlation between fecal and urinary NMH concentrations, serum C-reactive protein (CRP) concentration, the clinical disease activity index (CCECAI), and gastrointestinal mucosal mast cell numbers (where available) in dogs with gastrointestinal disease was evaluated. Seven of 16 dogs with gastrointestinal disease had increased urinary or fecal NMH concentrations, but there was no correlation between NMH concentrations and the CCECAI or mucosal mast cells numbers. Urinary NMH concentrations were positively associated with histological grading and serum CRP concentrations. The lack of correlation between NMH concentrations and the CCECAI suggests that NMH may not be a good marker for clinical disease activity in dogs as determined by the CCECAI. Based on their association with severity of intestinal mucosal inflammation, urinary NMH concentrations may potentially have clinical utility as a marker of intestinal inflammation in certain groups of dogs with chronic gastrointestinal disease, but future studies in a larger number of dogs are necessary to further characterize the role of mast cell-mediated inflammation in dogs with chronic gastrointestinal disease.

The skin microbiome in healthy and allergic dogs.

BACKGROUND: Changes in the microbial populations on the skin of animals have traditionally been evaluated using conventional microbiology techniques. The sequencing of bacterial 16S rRNA genes has revealed that the human skin is inhabited by a highly diverse and variable microbiome that had previously not been demonstrated by culture-based methods. The goals of this study were to describe the microbiome inhabiting different areas of the canine skin, and to compare the skin microbiome of healthy and allergic dogs. METHODOLOGY/PRINCIPAL FINDINGS: DNA extracted from superficial skin swabs from healthy (n = 12) and allergic dogs (n = 6) from different regions of haired skin and mucosal surfaces were used for 454-pyrosequencing of the 16S rRNA gene. Principal coordinates analysis revealed clustering for the different skin sites across all dogs, with some mucosal sites and the perianal regions clustering separately from the haired skin sites. The rarefaction analysis revealed high individual variability between samples collected from healthy dogs and between the different skin sites. Higher species richness and microbial diversity were observed in the samples from haired skin when compared to mucosal surfaces or mucocutaneous junctions. In all examined regions, the most abundant phylum and family identified in the different regions of skin and mucosal surfaces were Proteobacteria and Oxalobacteriaceae. The skin of allergic dogs had lower species richness when compared to the healthy dogs. The allergic dogs had lower proportions of the Betaproteobacteria Ralstonia spp. when compared to the healthy dogs. CONCLUSIONS/SIGNIFICANCE: The study demonstrates that the skin of dogs is inhabited by much more rich and diverse microbial communities than previously thought using culture-based methods. Our sequence data reveal high individual variability between samples collected from different patients. Differences in species richness was also seen between healthy and allergic dogs, with allergic dogs having lower species richness when compared to healthy dogs.