Preventive use of a topical anti-inflammatory glucocorticoid in atopic dogs without clinical sign of otitis does not affect ear canal microbiota and mycobiota.

BACKGROUND: Otitis externa is associated with a lack of bacterial/fungal diversity in atopic dermatitis. Clinical experience has shown that use of topical corticosteroids in the ear canal (EC) can prevent otitis. No data are available on the impact of this treatment on the EC microbiota. HYPOTHESIS/OBJECTIVES: To observe the bacterial/fungal diversity in the EC and the clinical effect of topical corticosteroids administered over a four week period in atopic dogs without active otitis. ANIMALS: Ten atopic dogs without active otitis. METHODS AND MATERIALS: Mometasone was applied in the right EC, while the left was used as control. A clinical and cytological evaluation of the EC was performed. Swabs of each EC were analysed using next-generation sequencing methods. RESULTS: At the beginning of the trial, variations in microbiota and mycobiota were observed between dogs and also within individuals. Statistically, no significant difference was observed in alpha and beta diversity between the treated and the untreated group over time. Clinically, right and left EC diversities were no different at Day (D)28 (P = 0.28). A significant difference was noted between D0 and D28 for the treated ears (P = 0.012) and not for the untreated ears (P = 0.63). No cytological evidence of microbes was found for treated ECs at D28. CONCLUSIONS AND CLINICAL RELEVANCE: These data suggest that the use of topical corticosteroids as proactive treatment is unlikely to increase the risk of secondary microbial overgrowth. The positive clinical effect of this proactive treatment seems to be supported through cytological and otoscopic improvement.

Feline maculopapular cutaneous mastocytosis: a retrospective study of 13 cases and proposal for a new classification.

CASE SERIES SUMMARY: Cutaneous mastocytosis is a disorder rarely reported in veterinary dermatology and usually described as 'urticaria pigmentosa'. This study aimed to evaluate the diagnosis, treatment and outcome of 13 affected cats, selected from the files of a private referral dermatology practice within a period of 14 years. Breeds of the affected individuals included Sphynx (n = 9), Devon Rex (n = 2) and Sphynx/Devon Rex crossbreeds (n = 2). Females (n = 9) were over-represented and the median duration of clinical signs prior to diagnosis was 8 months. The clinical presentation of these 13 cats was compared with cases reported in the veterinary literature and classified according to the current human consensus on cutaneous mastocytosis. Three clinical forms could be distinguished in cats: (1) large papular lesions and wheals, typically localised to the head, shoulders, ventral neck and axillae, and which may spontaneously resolve (termed polymorphic maculopapular cutaneous mastocytosis); (2) erythematous dermatitis, characterised by small maculopapular lesions often associated with crusts and with a poorer prognosis (termed monomorphic maculopapular cutaneous mastocytosis); and (3) more chronic dermatitis characterised by lichenification and hyperpigmentation, similar to the human condition 'urticaria pigmentosa' (termed pigmented maculopapular cutaneous mastocytosis). Histopathology was performed in eight cases and revealed a superficial-to-deep dermatitis characterised by infiltrates of mast cells and eosinophils. The response to various treatments, including antihistamines, steroids and ciclosporin, was variable. RELEVANCE AND NOVEL INFORMATION: This article reports 13 new cases of feline cutaneous mastocytosis, confirming the clinical presentation and apparent breed predisposition. The feline maculopapular cutaneous mastocytosis seems to be clinically very close to the human form. This study proposes a new classification system for the feline disease based on the current human consensus, clinical presentation and prognosis, with three different subforms: polymorphic maculopapular cutaneous mastocytosis with eventual spontaneous regression; monomorphic maculopapular cutaneous mastocytosis with chronic evolution; and pigmented maculopapular cutaneous mastocytosis.

Ear canal microbiota - a comparison between healthy dogs and atopic dogs without clinical signs of otitis externa.

BACKGROUND: The canine skin microbiota has been evaluated using relatively new microbiological techniques; studies have shown a difference in the composition of bacterial populations between healthy dogs and those with canine atopic dermatitis (cAD). However, little has been reported concerning the ear canal microbiota despite the fact that otitis externa is a common problem in dogs with cAD. HYPOTHESIS/OBJECTIVES: The study evaluated the ear canal microbiota of healthy dogs and atopic dogs without clinical signs of otitis. ANIMALS: Nine healthy privately owned dogs and 11 dogs with a diagnosis of cAD. METHODS AND MATERIALS: Ear swabs from the two groups were used for global bacterial DNA extraction. V1-V3 hypervariable 16S rDNA amplicon libraries were prepared for each sample and sequenced with MiSeq Illumina sequence (V3 kit). Taxonomical assignment and clustering were performed with Mothur using SILVA database. RESULTS: The ear canal microbiota showed changes in diversity similar to those reported for canine skin and seemed to be stable during the period of the study (28 days). Evidence of dysbiosis was observed in the atopic dogs, with increased abundance of Staphylococcus spp. and Ralstonia spp. (P < 0.05). Escherichia spp. also were found to be more abundant in healthy dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: This study demonstrated a shift in bacterial populations between allergic and healthy dogs. The observed results in the ear canal are similar to those reported on the skin and could explain the propensity of allergic dogs to develop bacterial otitis.