Feline dermatophytosis typically presents a superficial dermatosis involving keratinized tissues. Clinical presentation can be highly variable, which may complicate diagnosis. 

Common Clinical Signs 

The most consistent feature is circular or multifocal alopecia with variable scaling. However, lesions are often asymmetrical and may not follow the classic “ringworm” pattern¹. 

Common findings include: 

• Patchy hair loss 

• Scaling and crusting 

• Erythema and hyperpigmentation 

• Seborrhea and follicular papules 

Lesions most frequently affect the face, ears, and muzzle^1,2. 

Pruritus and Lesion Variability 

Pruritus is typically minimal but may be variable. 

When present, self-trauma can alter lesion appearance and mimic other dermatological conditions such as pyotraumatic dermatitis or eosinophilic lesions². 

Atypical and Nodular Presentations 

Less common manifestations include: 

• Miliary dermatitis 

• Chin folliculitis 

• Onychomycosis 

• Pododermatitis 

Nodular forms such as kerion, pseudomycetoma, and mycetoma may also occur, presenting as subcutaneous nodules. 

Long-haired breeds, particularly Persian cats, and younger animals are more commonly affected^1,2. 

Challenges in Clinical Diagnosis 

Diagnosis based solely on clinical signs may lead to over- or under-diagnosis due to overlap with other dermatological conditions¹. 

A structured diagnostic approach is therefore recommended. 

Diagnostic Tools 

Multiple complementary tests may be required: 

Wood’s Lamp Examination 
A rapid, non-invasive screening tool that may show green fluorescence in M. canis infections. Results should be interpreted cautiously due to false positives/negatives². 

Dermoscopy 
Helps identify characteristic features such as comma hairs, aiding diagnosis^3,4,5. 

Direct Microscopy 
Allows rapid visualization of fungal elements in hair and scales, though sensitivity may be limited¹. 

Confirmatory Testing 

Fungal Culture 
Widely used and considered a reliable diagnostic method. It enables detection and identification of dermatophyte species². 

Polymerase Chain Reaction (PCR) 
Provides rapid detection of fungal DNA but may not distinguish active infection from carrier states¹. 

Histopathology 
Reserved for atypical or nodular cases. Special stains such as PAS and GMS may aid confirmation¹. 

Monitoring and Clinical Relevance 

Due to its zoonotic nature, timely diagnosis is important. 

Monitoring of treatment response typically includes: 

• Clinical improvement 

• Wood’s lamp findings 

• Fungal culture results 

Resolution is supported by the absence of lesions and negative diagnostic findings². 

Key Takeaway 

Feline dermatophytosis presents diverse and sometimes misleading clinical signs. 

Accurate diagnosis relies on a combination of clinical suspicion and appropriate use of diagnostic tools, enabling effective management and reduction of zoonotic risk. 

References  

1. Bajwa J. Feline dermatophytosis: Clinical features and diagnostic testing. The Canadian Veterinary Journal. 2020 Nov;61(11):1217. https://pmc.ncbi.nlm.nih.gov/articles/PMC7560770/pdf/cvj_11_1217.pdf  

2. Moriello KA, Coyner K, Paterson S, Mignon B. Diagnosis and treatment of dermatophytosis in dogs and cats. Clinical Consensus Guidelines of the World Association for Veterinary Dermatology. Veterinary dermatology. 2017 Jun;28(3):266-e68. https://doi.org/10.1111/vde.12440 

3. Scarampella F, Zanna G, Peano A, Fabbri E, Tosti A. Dermoscopic features in 12 cats with dermatophytosis and in 12 cats with self‐induced alopecia due to other causes: an observational descriptive study. Veterinary dermatology. 2015 Aug;26(4):282-e63. https://iris.unito.it/bitstream/2318/1529803/1/Dermoscopy_2015_preprint.pdf  

4. Zanna G, Auriemma E, Arrighi S, Attanasi A, Zini E, Scarampella F. Dermoscopic evaluation of skin in healthy cats. Veterinary dermatology. 2015 Feb;26(1):14-e4. https://www.zora.uzh.ch/server/api/core/bitstreams/b3d9a595-9737-43ec-b1f8-42ad9ef773a0/content  
5. Dong C, Angus J, Scarampella F, Neradilek M. Evaluation of dermoscopy in the diagnosis of naturally occurring dermatophytosis in cats. Veterinary dermatology. 2016 Aug;27(4):275-e65. https://www.academia.edu/download/90590292/201608faa01.pdf