Feline Dermatophytosis (most commonly Microsporum canis)
Also known as: Dermatophytosis
⚠ Emergency Warning Signs
Not an emergency condition in itself, though widespread lesions with signs of significant secondary infection warrant a prompt (not urgent-emergency) vet visit.
Overview
Despite the name, ringworm is a fungal skin infection, not a worm. It's highly contagious between cats, to other animals, and to people, which makes prompt identification and appropriate hygiene precautions important alongside treating the cat itself.
Symptoms
- Circular patches of hair loss
- Scaly or crusty skin
- Itching
Causes
Infection with a dermatophyte fungus, most commonly Microsporum canis in cats. Despite the name, ringworm is a fungal infection (most commonly Microsporum canis in cats specifically), not caused by any actual worm — the fungus infects the outer layer of skin, hair, and claws, and is genuinely one of the more contagious skin conditions between animals and, notably, to humans as well (a real zoonotic consideration worth taking seriously in a household with an infected cat).
Risk Factors
Kittens, senior cats, and cats with a suppressed immune system are more susceptible; multi-cat environments, shelters, and catteries see higher rates due to close contact.
Transmission
Direct contact with an infected animal or contaminated objects (bedding, grooming tools, furniture); fungal spores can persist in the environment for a long time, which is why environmental decontamination matters as much as treating the cat.
Incubation Period
Typically 1-3 weeks from exposure to visible lesions.
Disease Stages & Progression
Starts as small, often circular patches of hair loss and scaling, which can spread to multiple sites, especially on the face, ears, and paws, if untreated.
Early Warning Signs
Small, roughly circular patches of hair loss, sometimes with a scaly or crusty appearance, most often first noticed on the face, ears, or front legs.
Advanced Symptoms
Multiple spreading lesions, more widespread hair loss, and occasionally secondary bacterial skin infection from scratching.
Diagnostic Methods
A Wood's lamp exam can screen for some (not all) strains that fluoresce, but definitive diagnosis is by fungal culture or PCR testing of hair/skin samples — Wood's lamp alone is not reliable enough to rule ringworm in or out on its own. A fungal culture is the gold-standard diagnostic test, though it can take 1-2 weeks to produce a result; a Wood's lamp (UV light) examination can provide a faster, same-visit screening tool, though it only reliably fluoresces for some ringworm-causing fungal strains and a negative Wood's lamp result doesn't rule out infection — a genuinely important limitation to understand, since relying on Wood's lamp alone can miss a real infection.
Veterinary Examination Process
Examination of the coat and skin under a Wood's lamp as an initial screen, followed by sample collection (hair pluck/skin scraping) for fungal culture or PCR.
Recommended Lab Tests
Fungal culture (definitive but can take 1-3 weeks to result) and/or PCR testing (faster turnaround) of hair and skin samples.
Diagnostic Imaging
Not applicable.
Blood Test Indicators
Not typically used for diagnosis.
Biopsy / Histopathology
Occasionally used in atypical or difficult-to-diagnose cases.
Differential Diagnoses
Other causes of hair loss and skin lesions — flea allergy dermatitis, bacterial skin infection, mange, food or environmental allergy — fungal culture/PCR distinguishes ringworm from these.
Home Monitoring Guidance
Watching for new lesions on your cat and on any other pets or household members, and following your vet's environmental decontamination instructions closely since reinfection from a contaminated environment is common if this step is skipped.
Veterinary Treatment Options
Combination of topical antifungal treatment (medicated shampoos/dips), oral antifungal medication for more extensive cases, and thorough environmental decontamination (vacuuming, washing bedding, disinfecting surfaces) since spores persist in the environment. Treatment combines oral antifungal medication (for more significant or widespread infections) with topical antifungal treatment (medicated shampoos or dips) and environmental decontamination — this last part is genuinely as important as treating the cat itself, since ringworm spores are notably hardy and can persist in the environment (bedding, carpet, furniture) for months, meaning reinfection from a contaminated environment is a real risk if decontamination is skipped or incomplete.
Surgery Requirements
Not applicable.
Recovery Timeline
Typically several weeks to a couple of months of combined treatment; cure is usually confirmed with repeat negative fungal cultures rather than just visual improvement, since the fungus can still be present after lesions look better.
Possible Complications
Spread to other pets and to people in the household (ringworm is zoonotic); secondary bacterial skin infection from scratching.
Long-Term Management
Not typically a long-term condition once properly treated and confirmed clear by follow-up testing; environmental decontamination reduces the risk of reinfection.
Prevention
Isolating and promptly treating any newly acquired or shelter-sourced cat before introducing them to other pets, and good hygiene (washing hands after handling an affected animal, disinfecting shared spaces). Thorough environmental cleaning (vacuuming frequently, washing bedding in hot water, using appropriate disinfectants effective against fungal spores specifically) alongside isolating a newly-diagnosed cat from other pets and people (particularly immunocompromised household members, young children, and the elderly, who are at higher risk of contracting ringworm from an infected cat) during treatment are the key prevention and containment measures.
Vaccination Availability
Not applicable — no vaccine is used for prevention in typical pet cat care.
Prognosis
Excellent — ringworm is very treatable, though it can take patience given the multi-week treatment and confirmation-testing timeline.
References
WSAVA dermatology guidelines; International Society for Companion Animal Infectious Diseases (ISCAID) dermatophytosis guidelines.
Medications Used
- Topical antifungal shampoos/dips (e.g., lime sulfur, miconazole-based products)
- Oral antifungal medication (e.g., itraconazole, terbinafine) for more widespread infections
Estimated Treatment Cost by Country
| Country | Estimated Cost Range | Notes |
|---|---|---|
| IN | 800–4,000 INR | |
| US | 80–400 USD | |
| UK | 60–300 GBP | |
| AU | 100–500 AUD | |
| JP | 6,000–30,000 JPY | |
| DE | 60–300 EUR | |
| BR | 150–700 BRL |
Frequently Asked Questions
Can I catch ringworm from my cat?
Yes — ringworm is zoonotic and can spread to people, especially children, the elderly, or anyone with a weakened immune system; wash your hands after handling an affected cat and see a doctor if you develop a similar skin lesion.
Does 'ringworm' mean my cat has worms?
No — it's a fungal infection, not a parasitic worm; the name comes from the classic circular appearance of the skin lesions.
How do I know if my cat is actually cured?
Visual improvement of the skin isn't enough on its own — your vet will typically want a repeat negative fungal culture to confirm the infection is truly cleared before you stop precautions.
Do I need to throw away all my cat's bedding?
Not necessarily throw away, but thorough washing/disinfecting (or discarding items that can't be adequately cleaned) is an important part of treatment, since fungal spores can persist in the environment and cause reinfection.
Can my other pets catch it?
Yes, other cats, dogs, and even some other species can be infected — isolating the affected cat during treatment is usually recommended in a multi-pet household.