Avaliação otológica canina e sua relação com endocrinopatias: aspectos técnicos, micológicos e bacterianos

Abstract

Accurate assessment of canine otological microbiota is essential for proper diagnosis and management of otitis externa, one of the most common conditions in small animal practice. This thesis investigated technical, mycological, and bacterial aspects of canine otological microbiota, with emphasis on their relationship with endocrinopathies. Eighty dogs were evaluated, including 40 with hypothyroidism or hypercortisolism and 40 healthy controls, matched by age, sex, and breed. Animals underwent complete otological evaluation including otoscopy, auricular cytology, bacterial and fungal culture. For mycological analysis, hair samples were collected by manual traction or sterile vaginal cervical brush and inoculated in DTM medium for dermatophyte identification. Quantification of Malassezia spp. was performed by cytological evaluation, and bacterial samples were identified by MALDI-TOF, subjected to antimicrobial susceptibility testing using the VITEK system, biofilm formation capacity assessment by crystal violet method followed by microbiological counting of the sessile form, and ultrastructural analysis by scanning electron microscopy. Additionally, commercial and compounded propolis-based products were tested for antibiofilm efficacy. The prevalence of Malassezia spp. was significantly higher in endocrinopathic dogs (37.5%) compared to controls (10.0%; p<0.01), with dogs with otological malasseziosis presenting a 5.4-fold higher risk of being endocrinopathic (OR = 5.40; 95% CI: 1.60-18.20). Positive fungal culture for dermatophytes was identified exclusively in endocrinopathic dogs (5.0%). Different Staphylococcus strains were isolated, with all S. pseudintermedius strains demonstrating biofilm formation capacity (BFI>1.10) and variable antimicrobial resistance profiles. Results demonstrate strong association between endocrinopathies and opportunistic fungal infections, emphasizing the importance of endocrine investigation in recurrent otitis cases, and highlight the role of bacterial biofilms in persistence of otological infections.