Clinicomycological Evaluation and Therapeutic Management of Secondary Malassezia pachydermatis Dermatitis Associated with Generalized Demodicosis in Dog

Abstract

Aim: To describe the clinicomycological, cytological, antifungal susceptibility and therapeutic findings of secondary Malassezia pachydermatis dermatitis associated with generalised demodicosis in a Pug and to emphasise the importance of an integrated diagnostic and therapeutic approach. Presentation of case: An 8-year-old female Pug weighing 8.5 kg was presented with a 6-month history of generalised pruritus, alopecia, greasy seborrhoea, hyperpigmentation, lichenification and characteristic foul odour. Generalised demodicosis was diagnosed based on deep skin scrapings. Cutaneous cytology using Diff-Quik and New Methylene Blue staining revealed numerous budding yeast cells suggestive of Malassezia spp. Fungal culture followed by phenotypic characterisation confirmed the isolate as Malassezia pachydermatis, while antifungal susceptibility testing by the disc diffusion method supported the selection of itraconazole for systemic therapy. The dog was treated with an isoxazoline-based acaricide for generalised demodicosis, along with oral itraconazole and topical chlorhexidine–miconazole shampoo. Supportive treatment was also provided. The treatment resulted in the resolution of the cutaneous lesions and progressive hair regrowth, with complete clinical recovery. The dog was followed for one month after completion of treatment, during which no recurrence of dermatological lesions was observed. Discussion: Generalised demodicosis may predispose dogs to secondary Malassezia overgrowth through disruption of the skin barrier and alteration of local immune responses. A combination of parasitological, cytological and mycological investigations facilitates a definitive diagnosis, while antifungal susceptibility testing may assist in selecting appropriate therapy. Concurrent treatment of the underlying demodicosis and secondary Malassezia dermatitis is important for achieving clinical resolution and reducing the risk of recurrence. Conclusion: This case highlights the usefulness of integrated clinicomycological, parasitological and cytological investigations in the diagnosis and management of canine Malassezia dermatitis associated with generalised demodicosis. Early recognition and concurrent treatment of both conditions resulted in complete clinical resolution, with no recurrence observed during the one-month follow-up period.