Despite its name, ringworm is not a worm but a fungus, similar to athlete’s foot.
It produces infective ‘seeds’ called spores, which are quite hardy and are tricky to get rid of in the environment. They can live for years and it takes just one spore to cause an infection. However, only broken skin can be infected; a dog with healthy skin will not pick up a ringworm infection.
Ringworm can infect skin in all animals, including people as well as dogs, although infection in people is uncommon and it usually just causes one or two circular patches of red, irritated skin. It can sometimes be more severe in children, or people with a weakened immune system. If you think you have ringworm, see your doctor. Infection is more likely to occur if there is skin damage, such as a scratch or sore.
What does ringworm look like in dogs?
In dogs, ringworm has a number of different appearances, most often areas of hair loss with a crusty covering, or (rarely) may be asymptomatic. Patches of ringworm may look like a grey, scaly patch in some dogs, but more like a red lesion in others. You may see some hair loss or patches of broken hair. But lots of other (more common) skin conditions look very similar.
Young, elderly, or long-haired dogs are more commonly affected.
Generally, ringworm lesions appear on dogs’ paws, legs, head and ears, but they can appear on any part of the body.
Diagnosing ringworm in dogs
If you think your dog has ringworm, you will need to take them to the vet as they will need treatment to cure it and stop it from spreading to people and other pets in your family.
There are a few methods that vets use to diagnose ringworm. Your vet may use an ultraviolet lamp to look at your dog’s fur and skin. This is because some types of ringworm will show up under this type of light.
Your vet will most likely look at a sample of your dog’s fur under a microscope to see if they can spot the fungus. They might also take a sample from your dog’s skin and place it in a dish to see if it will grow under lab conditions. This is the most reliable test but it takes 10 days to give results.