Occurrence of Malassezia Otitis Externa in Dogs Presented at a Veterinary Clinical Complex, Jabalpur

Introduction

Otitis externa is one of the most frequently encountered disorders in small animal clinical practice and is characterized by inflammation of the external ear canal and its associated structures. The condition is considered multifactorial, involving primary, predisposing, perpetuating, and secondary factors, and is often associated with chronic pathological changes of the ear canal in affected dogs (Crespo et al., 2002) [3] . Among fungal pathogens, Malassezia species, particularly Malassezia pachydermatis, are recognized as important opportunistic yeasts associated with canine otitis externa (Crespo et al., 2002) [3] . Malassezia yeasts are common commensals of the skin and ear canal of warm-blooded vertebrates and may become pathogenic when changes occur in the host or the local ear canal environment. Increased humidity, excessive sebum production, allergic skin disease, endocrine disorders, and impaired host immunity can promote yeast proliferation and lead to clinical disease (Theelen et al., 2018) [14] . Members of the genus Malassezia are lipiddependent yeasts belonging to the family Malasseziaceae, order Malasseziales, and phylum Basidiomycota. At present, 18 species have been identified based on molecular and physiological characteristics (Laniri, 2022; Diaz et al., 2024) [4,10] . Unlike most Malassezia species, M. pachydermatis can grow on Sabouraud Dextrose Agar due to its ability to utilize lipid fractions present in the peptone component of the medium (Cabanes et al., 2014; Ilahi et al., 2017; Hobi et al., 2022) [1,7,8] . Epidemiological studies have reported considerable variation in the occurrence of Malassezia otitis in dogs depending on geographical location, climate, breed composition, and diagnostic methods employed. Understanding the occurrence pattern of Malassezia otitis in relation to age, breed, and sex is essential for identifying susceptible populations and improving clinical management strategies. Molecular confirmation of M. pachydermatis also provides reliable species identification and contributes to epidemiological surveillance (Diaz et al., 2024) [4] . The present investigation was therefore undertaken to determine the occurrence of Malassezia otitis externa in dogs presented to a veterinary clinical complex in central India and to evaluate its distribution according to age, breed, and sex, along with molecular confirmation of M. pachydermatis isolates.

Materials and Methods

Study location and duration

The study was conducted in the Department of Veterinary Medicine, College of Veterinary Science and Animal Husbandry, Nanaji Deshmukh Veterinary Science University, Jabalpur, Madhya Pradesh, India. The investigation was carried out over a period of six months from December 2025 to May 2026.

Selection of animals

Dogs presented to the Veterinary Clinical Complex (VCC), Jabalpur during the study period were screened for otitis externa irrespective of age, breed, or sex. Animals were classified as suspected cases based on history, clinical signs, and otoscopic examination. Information regarding age, breed, sex, and duration of illness was recorded for each dog using a structured questionnaire.

Video-otoscopic examination

The external ear canal was examined using a video otoscope (Global Technology Solutions LLC., Janakpuri, New Delhi) to assess erythema, cerumen accumulation, discharge, inflammation, and other lesions associated with otitis externa.

Sample collection and cytological examination

Aural exudate was collected from the junction of the vertical and horizontal ear canals using sterile cotton-tipped swabs. The swab material was rolled onto clean glass slides, stained with a modified stain, and examined under oil immersion (100×). Slides were assessed for the presence of yeast cells, bacteria, and inflammatory cells using a semi-quantitative scoring method. Acetate tape impression smears were prepared from affected skin lesions by gently pressing transparent acetate tape onto the lesion and mounting it on a glass slide. The stained preparations were examined microscopically for the characteristic footprint-shaped budding yeast cells of Malassezia spp.

DNA extraction

Representative cytologically positive samples were subjected to molecular confirmation. Genomic DNA was extracted using the QIAamp DNA Mini Kit (Catalog No. 51304) according to the manufacturer's protocol. Ear swab samples were lysed with Proteinase K and extraction buffers, followed by ethanol precipitation, spin-column purification, washing, and elution of DNA in Buffer AE.

PCR amplification

Molecular identification of Malassezia pachydermatis was performed using primers targeting the 26S rDNA region as described by Taha et al. (2011) [13] . [13] PCR was carried out in a final reaction volume of 25 µL. Amplification was performed in a thermal cycler under standardized conditions for the 26S rDNA gene. Agarose gel electrophoresis PCR products (10 µL) were resolved on 1% agarose gel containing ethidium bromide in 0.5× TAE buffer.

Electrophoresis was performed at 70 V for 90 min alongside a 100 bp DNA ladder, and amplified products were visualized under a UV transilluminator.

Statistical analysis

Occurrence data were analyzed using the Chi-square (χ²) test to determine the association of Malassezia otitis externa with age, breed, and sex. Statistical analysis was performed using R software (R Core Team, 2013), SPSS, or equivalent statistical software, and differences were considered significant at p < 0.05.

Result and Discussion Overall occurrence of Malassezia induced otitis externa in dogs

The total number of dogs examined and screened at VCC Jabalpur were 2479 from January to May 2026. Among these the overall occurrence of dermatological lesions was These observations are in close similarity with those of Walia et al. (2025) [15] who reported an overall incidence of otitis in dogs as 3.67% (89/2420) in contrast with Petrov et al. (2013) [11] who reported the 25% prevalence of Malassezia Pachydermatis.

The observed variations in the results may be assigned to several factors, including differences in sample size, geographical location and management practices adopted by dog owners across different studies. Variations in these factors may contribute to variance in the findings, as differences in environmental conditions and study populations can influence the revealed outcomes.

Age wise occurrence of Malassezia otitis externa in dogs

The age-wise occurrence of Malassezia otitis externa was screened in a total of 140 dogs having dermatological lesions. [6] and Seetha et al. (2018) [12] [9] who reported higher incidence of Malassezia dermatitis in Beagle in contrast with Giaro et al. (2006) reported that Poodles were the most commonly breed affected by M. pachydermatis associated with otitis.

Acknowledgement

AcknowledgementsThe authors acknowledge the Department of Veterinary Medicine and the Veterinary Clinical Complex, College of Veterinary Science and Animal Husbandry, Nanaji Deshmukh Veterinary Science University, Jabalpur, Madhya Pradesh, India, for providing the facilities required for conducting the study. Disclaimer (Artificial Intelligence)Author(s) hereby declares that no generative AI technologies such as Large Language Models (ChatGPT, COPILOT, etc) and text-to-image generators have been used during writing or editing of this manuscript.

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