Symptoms and Treatment of Ringworm in Dogs

Symptoms and Treatment of Ringworm in Dogs

If you’ve owned a dog for a few years (or have children), you’ve probably heard the term “ringworm.” This is the common name used by pet owners and parents for a particularly nasty and contagious fungal infection of the hair, skin, or nails.

Ringworm isn’t actually caused by a worm; the name comes from the raised, inflamed ring of skin that often surrounds infected areas. Don’t let the name fool you—there are no worms to be found in a case of ringworm. Because ringworm can be transferred from dogs to humans (and to any other domesticated animal), it’s critical that you familiarize yourself with its symptoms and treatment options.

Spotting ringworm on your dog or cat early will ensure you’re able to address the problem before it spreads to other members of your household. Completely removing ringworm fungi from your environment is a monumental task that is only simplified by early detection.

Identifying a Ringworm Infection

Ringworm can form on a pet’s face, ears, paws, or any other part of his body. The first sign is usually fur loss on a small, irritated circle of skin. Left untreated, these lesions grow and fester. It’s possible that the middle area will re-grow brittle, easily broken hairs while the outer ring continues to get larger and more inflamed. Ringworm infections are not always circular and often appear on multiple parts of the body at once. If you suspect your dog or cat has ringworm, be sure to check him from head to toe to ensure you’ve spotted all affected areas. Ringworm infections are not necessarily itchy.  Your dog might not even notice the lesion, depending on how it manifests. In fact, some dogs can carry ringworm and pass it to other dogs and animals without ever showing symptoms. However, it is not uncommon for dogs to develop secondary bacterial infections in ringworm afflicted areas which then inspire obsessive licking and scratching—both this infection and the core fungal infection will need to be treated to get your dog back to perfect health.

What ringworm in dogs looks like.

What ringworm in dogs looks like.

Causes of Ringworm

Ringworm is caused by dermatophytes fungi (the actually name of the condition is dermatophytosis). This fungi is pretty much impossible to avoid; spores can be picked up from soil or from other animals in a dog’s environment. Ringworm spores can even be transferred on a brush or via your carpet. If your dog is regularly outside, visits dog parks, or goes to daycare, he is at risk of developing ringworm. Even a quick trip to the vet could end up in a ringworm outbreak, though veterinarians do take steps to ensure their office environment is sterile and safe for the animals that enter.

Ringworm Treatment Diagnosis

The first step in treating ringworm is, as with many conditions, acquiring an official diagnosis from your vet. Many skin infections have similar symptoms and treating your dog for ringworm won’t do you much good if he has mites or some other cause for his skin problems. Your pets may be asymptomatic. Their ringworm may not show, causing them to be unwitting carriers and allowing them to infect other pets. Sometimes ringworm is only suspected when another condition the animal has suppresses their over all immune system.  Circular, bare spots on the skin suggest ringworm, but these round patches can also show as result of allergies, sarcoptic mange, and various other conditions. A vet can perform several different tests to positively identify a spot is ringworm infection and to identify which fungal species caused it. (There are 3 main fungi that cause 95% of the ringworm cases in pets.)  These tests include:

  • examining hair samples under a magnifying lens with an ultraviolet light (the Woods test);
  • a microscopic exam with stained samples; and
  • culture tests, which are time consuming and involve lab diagnoses and confirmation.


Once you have an official diagnosis, treatment can begin. The only way to cure ringworm is to kill the fungi that cause it via medicated baths (and, occasionally, oral antibiotics). It’s not necessary to rely on highly toxic solutions; certain all-natural treatments have demonstrated the ability to kill ringworm fungi just as well as the harsh stuff, with no side-effects. When treating longer-haired dogs, you may want to trim the hair shorter, though shaving the dog’s hair is not recommended as it could nick his skin, introducing infection. It’s not possible to prevent your dog from getting ringworm from an unknown source, but it is possible to prevent the infection from spreading to other animals by quarantining your infected pup and conducting a thorough cleaning of your home, car, and any other place he has been since becoming infected. If your vet reaches a ringworm diagnosis with your pup, she will provide you with advice regarding limiting the infection to one animal. In some cases you may need to discard the dog’s bedding, toys, and other equipment. All animals in your home will likely need several medicated baths to ensure the problem is completely eradicated.

Luckily, ringworm infections are not too difficult to handle and pose no long-term health risk to your pups or family if caught early. The biggest risk is re-infection from an environment or animal that hasn’t been treated correctly. Infected animals are contagious for a few weeks, even during treatment. If your dog has no ongoing health problems and you follow your treatment protocols, he’ll be ringworm free and back to normal in no time at all.


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