TL;DR: Ringworm is a contagious fungal skin infection that requires a non-emergency vet visit; capturing a photo of the circular hair loss early helps your vet provide an accurate diagnosis.
What is ringworm and what does it look like on my cat’s ear?
Despite its name, ringworm is not caused by a worm; it is a fungal infection of the skin, hair, and claws known as dermatophytosis. Common signs include:
- A classic circular patch of hair loss
- Scaly, red, or crusty skin
- Brittle or broken hair around the patch
- Rapid spread across the body if left untreated
Is ringworm a medical emergency for my cat?
The urgency level for a circular bald patch is Low. While not life-threatening, you should take the following actions:
- Schedule a routine appointment with your veterinarian within the next few days to begin treatment.
- Take precautions to prevent spread, as it is highly contagious to other pets and humans.
- Avoid emergency clinic visits as this condition does not require immediate intervention.
How does taking a photo of my cat’s ear help the vet?
Capturing a clear, high-resolution photo of your cat's ear is a vital tool for your veterinary team because:
- Fungal lesions can change appearance if the cat scratches them or secondary bacterial infections set in.
- A photo documented at the first sign of hair loss allows the vet to see the original shape and texture of the patch.
- Visual evidence helps differentiate ringworm from other conditions like ear mites, allergies, or stress-related over-grooming.
Clinical Context (Merck Veterinary Manual)
In cats, ringworm (dermatophytosis), most commonly caused by *Microsporum canis*, can present with variable clinical signs. Typical lesions consist of focal alopecia, scaling, and crusting, often located around the ears and face. However, cats can also have clinically inapparent infections and serve as a source of infection. While a Wood's lamp can suggest dermatophytosis, definitive diagnosis requires a DTM culture.
Chapter: Dermatology
Source: The Merck Veterinary Manual, 11th Edition (Page 874)