Ringworm in Cats: Causes, Signs & Treatment Guide

Ringworm (Dermatophytosis) is a fungal infection of the superficial skin layers, coat, and sometimes the claws. Despite the name, it is not caused by a worm — it is caused by a group of fungi known as dermatophytes.

Important: Ringworm is contagious to people and other animals. If you notice or suspect your cat has this condition, please call the hospital before your visit so that infection control measures can be prepared.

Signs to Watch For

• Circular patches of hair loss with broken or brittle hairs
• Scaling, skin flaking, or small papules in the affected areas
• Mild redness; itch varies — some cats show little to no itching
• Some cats are asymptomatic carriers — they carry fungal spores but appear normal

Causes: The most common causative fungi include Microsporum canis (most frequent), Microsporum gypseum, and Trichophyton spp. Routes of transmission include contact with an infected animal, contaminated hair or grooming tools, and fungal spores in the environment.

Diagnosis: Your vet will use Microscopy (examining hair and skin scales for hyphae and spores), Wood’s lamp (UV light; some strains fluoresce, but a negative result does not rule out infection), and Culture or PCR (to confirm and identify the causative fungus).

Treatment: Whole-body topical treatment (antifungal shampoo or rinse applied to the entire coat, not just the affected area); oral antifungal medication prescribed by your vet; environmental decontamination (collect shed hair and debris before disinfecting). Your vet will determine when it is safe to stop treatment.

Home Care: Isolate the affected cat from other pets and immunocompromised household members; wash hands immediately after handling the cat; do not share grooming tools; do not shave the cat at home — this can damage the skin and spread spores; collect shed hair before cleaning surfaces with a disinfectant solution.

Prognosis: Most cats recover fully, though treatment may take several weeks to months. If a family member develops a skin rash after the cat’s diagnosis, seek medical care and mention the exposure.

When to Seek Care: Lesions are spreading or weeping; the pet develops vomiting, lethargy, or loss of appetite while on medication.

Contact Thonglor Pet Hospital

Have questions about veterinary care for your pet in Thailand? Contact our team to ask about services, find a suitable branch or arrange an appointment.

If you need English-speaking assistance, please let us know when booking so we can confirm availability.

• Book an appointment: Schedule your visit

• Call us: +66 2 079 9999

• LINE: @jaothonglor

• Find a location: Explore our branches

For information about opening hours, treatment costs and preparing for your visit, see our Frequently Asked Questions.