What Does Ringworm Look Like On A Dog?
QUICK ANSWER
Ringworm in dogs isn't a worm; it's a fungal infection. It typically appears as circular or irregular patches of hair loss with red, scaly, or crusty skin. It's contagious to other animals and humans, and treatment usually involves antifungal medication and environmental decontamination.
Despite the name, ringworm has nothing to do with worms. It's a fungal infection that affects the skin, fur, and sometimes nails. It's also contagious to humans, which makes identifying and treating it quickly especially important.
What does ringworm actually look like?
The classic presentation is one or more circular patches of hair loss with scaly, red, or crusty skin at the center. The edges of the patches may appear raised or inflamed. However, ringworm doesn't always look textbook. Some dogs show patchy hair loss without the classic ring shape, broken or brittle fur, darkened skin, or mild scaling that looks more like dandruff. Puppies, senior dogs, and immunocompromised dogs tend to show more obvious signs. Some dogs carry the fungus without showing any symptoms at all, which is why it can spread quietly through a household.
How does ringworm spread?
Ringworm fungi (most commonly Microsporum canis in dogs) spread through direct contact with an infected animal or through contaminated objects like bedding, brushes, collars, and furniture. The spores are hardy and can survive in the environment for months. It's zoonotic, meaning it can spread from dogs to cats to humans and back. The CDC lists ringworm as one of the most common zoonotic fungal infections. If your dog is diagnosed with ringworm, anyone in the household (human or animal) with skin changes should see a doctor or vet.
How is it diagnosed and treated?
Your vet can diagnose ringworm through a fungal culture (the gold standard), a Wood's lamp examination (some strains fluoresce under UV light, but not all), or microscopic examination of hair and skin samples. Treatment typically includes topical antifungal medication (medicated shampoos, creams, or dips), oral antifungal drugs for more widespread infections, and environmental decontamination. Treatment usually takes several weeks, and it's important to continue until your vet confirms the infection is fully cleared, not just when the skin looks better.
What about mange?
Mange is sometimes confused with ringworm because both cause hair loss and skin irritation, but they're completely different conditions. Mange is caused by mites (tiny parasites), not fungi. Demodectic mange causes patchy hair loss and is not contagious, while sarcoptic mange causes intense itching and is highly contagious. Your vet can distinguish between ringworm and mange through skin scrapings and fungal cultures. The treatments are different, so accurate diagnosis matters.
Ringworm looks alarming but is treatable with proper antifungal therapy. The biggest concerns are its contagious nature and the persistence of spores in the environment. If you suspect ringworm in your dog, get it confirmed by your vet so treatment can start promptly and you can take steps to protect the rest of your household.
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