Ringworm in Cats: Causes, Treatment and Prevention

Reviewed by Dr. Ameer Hamza, DVM

Despite its name, ringworm is not caused by a worm. It is a fungal skin infection caused by dermatophyte fungi — most commonly Microsporum canis in cats — that infects the skin, hair, and nails. It is one of the more challenging feline skin conditions to manage, not because it is dangerous to cats but because it is highly contagious (including to humans and dogs), environmentally persistent, and requires sustained treatment over weeks to eliminate. This guide covers everything from recognising the signs to eliminating it from your home.

What Is Ringworm and What Causes It?

Dermatophytosis (ringworm) is caused by fungi of the genera Microsporum, Trichophyton, and Epidermophyton. In cats, Microsporum canis is responsible for approximately 98% of cases. The fungus infects keratinised tissue — the outer layer of the skin and the hair shaft — and derives nutrition from keratin. The infection spreads through direct contact with infected animals, contact with infected shed hair and skin cells in the environment, and through contaminated objects. The fungal spores are highly environmentally resilient and can remain infectious for over a year in household environments, which is why environmental decontamination is as important as treating the cat.

Signs in Cats

The classic presentation is one or more circular patches of hair loss with a scaling, crusted margin. Hairs at the edges of the lesion are often broken and stubby. The underlying skin may be reddened or thickened. Common locations include the face (particularly around the ears and muzzle), forelimbs, and paws. However, the presentation in cats is variable — some cats have extensive irregular hair loss rather than neat circles; some have scaling without obvious hair loss; and a significant proportion of infected cats (particularly longhaired cats) are subclinical carriers — they carry and shed the fungus without showing obvious lesions. These carriers are an important source of spread in multi-cat households and catteries. Diagnosis should be confirmed by a vet — skin scraping for microscopic examination, Wood's lamp examination (approximately 50% of M. canis infections fluoresce bright green under UV light), and fungal culture are the diagnostic options.

Treatment Protocol

Topical treatment is applied directly to affected areas and used as a whole-body shampoo or rinse to reduce environmental shedding. Miconazole, ketoconazole, and chlorhexidine-based antifungal shampoos are effective when used consistently 2–3 times weekly. Apply antifungal cream directly to visible lesions. Clip the hair around lesions to improve topical penetration — do this carefully in a contained area and dispose of the hair directly into a sealed bag to avoid spreading spores. Systemic antifungal medication — most commonly itraconazole — is necessary for widespread infection and accelerates the elimination of active fungal replication throughout the body. Your vet will prescribe the appropriate dose and duration based on your cat's weight and infection severity. Duration: treatment should continue for a minimum of 6 weeks and until two consecutive negative fungal culture results (taken 2 weeks apart) confirm elimination. Early cessation is the primary cause of recurrence.

Protecting Your Family

Because ringworm is zoonotic, infected cats should be handled with precautions. Wash hands thoroughly after any contact with the infected cat or their environment. Avoid letting the cat sleep in your bed until the infection is cleared. Children, elderly people, and immunocompromised individuals should minimise direct contact with the infected cat during treatment. If a family member develops a red, itchy, ring-shaped skin lesion, consult a doctor — human ringworm is easily treated with topical antifungal cream but should be diagnosed and treated promptly.

Frequently Asked Questions

What does ringworm look like on a cat?

Circular or irregular patches of hair loss with scaling and broken hair stubs. Face, ears, and forelimbs most commonly. Some cats are symptomless carriers.

Is it contagious to humans and other pets?

Yes — ringworm is zoonotic and spreads to humans, dogs, and other cats. Handle infected cats with precautions and wash hands thoroughly after contact.

How is it treated?

Antifungal shampoos plus systemic itraconazole, for a minimum of 6 weeks. Continue until two negative fungal culture results. Environmental decontamination is essential alongside treatment.

How do I clean my home?

Vacuum thoroughly, wash bedding at 60°C+, wipe hard surfaces with dilute bleach (1:10). Spores survive 12–24 months — continued cleaning throughout the treatment period is critical.

How long does it take to clear?

6–12 weeks with appropriate treatment. Never stop early — confirm elimination with two consecutive negative cultures. Multi-cat households take longer due to reinfection risk.

For a full overview of cat skin health and care, see the complete cat care guide.

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Disclaimer: This article is for educational purposes only. Ringworm in cats requires veterinary diagnosis and treatment. If a family member develops suspicious skin lesions, consult a doctor promptly.