Abstract
Background:
Free-roaming cats are a potential source of several infectious and parasitic diseases that can be easily transmitted to outdoor pet cats.

Aim:
The purpose of this study was to determine the prevalence and pattern of co-occurrence of causative agents of otitis externa and to identify associated risk factors in free-roaming cats living in the continental region of Croatia. In addition, we investigated the presence of Malassezia yeasts in the external ear canals of cats using mycology culture.

Methods:
Clinical assessment of otitis externa involved auricular and otoscopic examinations. Samples of cerumen and ear swabs were collected and analyzed via cytological examination and mycological culture.

Results:
The frequency of otitis externa in the population of free-roaming cats was 40.5% (30/74) based on the presence of Otodectes cynotis, Malassezia yeasts, cocci, rods, and/or neutrophils. Results revealed multiple diagnoses for the same ears and unevenly affected ears of the same cats. O. cynotis was detected in 25.7% (19/74) of the cats and was the primary cause of otitis in 63.3% (19/30) infected cats. Co-diagnosis of O. cynotis and Malassezia yeasts was common at both the ear (39.3%, 22/56 infected ears) and cat (40.0%, 12/30 infected cats) levels, while Malassezia was causing otitis in 30% (9/30) infected cats. Three or more diagnoses co-occurred in 15% of infected ears and 27% of infected cats. The clinical signs of otitis externa were absent in 8.9% (5/56) of infected ears, all affected by Malassezia alone or with O. cynotis. Malassezia yeasts were cultured in 83.3% (25/30) of the otitis cases, with heavy growth in 70% and M. pachydermatis as the predominant species in all cases.

Conclusion:
The high prevalence of otitis externa caused by O. cynotis and Malassezia yeasts in free-roaming cats in Croatia provides important insights into the health status of this cat population. Although otitis externa and its causative agents are frequently found in free-roaming cats, the actual prevalence of otitis externa and all associated risk factors have not been thoroughly assessed.

Key words: Free-roaming cats, Otitis externa, Clinical examination, Cytology, Mycology culture