Pet Ringworm Facts


When people think of ringworm infections, they generally assume it is referring to an actual worm in the skin. This is actually incorrect, it is not a worm, but a parasitic fungus that causes an infection on the skin by feeding off of keratin, which is in hair, skin, and nails and on dead skin and hair cells. Its name comes from the scaly, raised, ring-shaped brown or red mark on the skin that it causes. The ring was once thought to be a worm, hence the inaccurate name.

It would be more accurate to call it dermatophytosis, which means “plants that feed on skin.” It can be found anywhere on the body, although it prefers places that are hidden, dark and moist. On humans, it is sometimes called something different when it is on different parts of the body. For instance, athlete’s foot is a form of ringworm, as is jock itch. While ringworm is very curable, it is also frustrating to experience, highly contagious, and is occasionally stubborn when treated. Some treatments can take months.


The ringworm most people are familiar with are the kinds that affect mammals, from cats and dogs to chinchillas, ferrets, hamster, guinea pigs, and yes, even humans. Ringworm is zoonotic, which means that you can catch it from your pets and your pets can catch it from you.

Cat Ringworm with ringworm sores on faceThe two dermatophytes to be most worried about are Microsporum canis (the most common form of ringworm as well as the most common skin condition in cats), Microsporum gypseum (mostly affects dogs and cats that dig into contaminated soil), and Trichophyton mentagrophytes (affects mammals which have been exposed to rodents or rodents’ burrows). After having ringworm once, you or your pets will eventually become immune unless the animal is immuno-suppressed, but it can take months after contracting the fungus.

Ringworm cannot get through a normal layer of skin, but it can penetrate a wound or any opening on the body. Since the fungi is extremely hardy, it can last for up to eighteen months on skin without dying, and it will usually enter the body at one point through a wound or mouth, eyes, or nose. Ringworm is also extremely prevalent, so it can be contracted just about anywhere.

Sometimes the animals that pass on the disease show no signs of ringworm because they are already immune to it and are simply a carrier. Some animals that contract the fungus never show symptoms and simply become a carrier as well, while others do show symptoms. Most animals will eventually cure themselves after a few months without any external help. However, when symptoms are persistent or the ringworm area becomes infected or if the symptoms persist for more than a few months, it is important to seek medical attention for your pet.


There are several signs to look for when you make sure you or your pets have ringworm. It differs between species:

  • Animals and humans that are more prone to disease or whose immune system is suppressed are prone to contracting ringworm: the young and the elderly, HIV positive or FHIV positive, stressed animals and people.
  • If you deal with stray animals or if your pet is an outdoor pet, you have a higher risk of contracting ringworm.
  • Following interaction with the fungus, symptoms can appear in ten to twelve days.
  • Look for a growing scaly bump that appears slightly raised at the edges. It can either be reddish or brownish, with lighter skin in the middle and can first appear like a bug bite or even a particularly bad pimple. It may itch a little, a lot, or not at all. The characteristic ring is mostly found on humans, but odds are that if you get it, your pets have it or will contract it.
  • If your pet scratches itself often and there are no signs of fleas, your pet may have the initial symptoms of ringworm. Ringworm is not always itchy in animals either, so that is not a definite sign.
  • In furry animals, the animal will usually have missing fur in the infected area. As the flesh heals, the interior may grow darker fur while the outside becomes reddish and inflamed as the ringworm spreads. The hair there will be broken off. Its shape will not always be that of a ring, so do not depend on shape to determine the cause.
  • Cats tend to have several ringworm sites all over their bodies. Kittens show these signs of ringworms if they have been raised in colonies, so be vigilant with any pet store or shelter pet.
  • Cats also tend to be the ones most likely to contract it, with rodents then dogs the next likely candidates.
  • Dogs usually only show one lesion, like most humans, although sometimes more lesions appear. Inflammation is an atypical canine symptom.
  • These symptoms are rare, but sometimes there are nodules with draining tracts or ulcers.
  • If you know that a dog or cat has had ringworm before but has no external symptoms, it may be a carrier, so check for signs on your other pets.
  • The common areas to check are in the face, ears, tail, and paws.
  • When the flesh is infected, it can appear crusty.
  • There is no definite set of symptoms to look for – in some animals, the hair loss is minimal and there is no scratching. In others, however, the lesions appear quite alarming, like scaly red sores, and the itch can be unbearable. The open sores can also get infected like any open wound.
  • An ultraviolet light, called a Wood’s lamp, held near the fur can show where the broken hairs are, because they glow green in the light. Other materials on the skin can cause the greenish glow, so the test is not conclusive (it only diagnoses about 50 percent of ringworm cases), but it is a good first step.
  • Microscopic inspection of broken hairs or skin cells can confirm a diagnosis. The fungi are notoriously hard to see, so this is not a common diagnostic tool for ringworm.
  • A fungal culture wherein broken hairs or skin cells are put in a special culture medium that enhance fungal growth and discourages bacterial growth in order to see whether fungal spores grow over the course of approximately ten days, although it can take up to three weeks for a conclusive culture. The culture will turn a reddish color and show a cotton-like fungal growth. This diagnostic test is fully conclusive and can even indicate which kind of ringworm is affecting the pets. The test also indicates whether the pet is a carrier, which is why it is a routine test during some veterinarian check-ups.
  • On occasion when the ringworm symptoms are atypical, the diagnosis can only come from a biopsy. Similar pet skin conditions like demodex, mange, or skin allergies can show ringworm-like symptoms.


In some cases, the ringworm may be defeated by the immune system, and the animal will simply be a carrier. However, treatment is encouraged in order to shorten the window during which the fungus can be spread. There are several ways to treat an animal or pet who has contracted ringworm.

  • Isolate the animal suffering with ringworm so that any other pets do not contract it as well. You may clean your other pets with Medicated Pet Wash in order to prevent spreading.
  • Clip or shave around the affected area in order to help prevent it from spreading. For long-haired animals, this may lead to a full-body shave.
  • Wear gloves when you are attended to the ringworm area on your affected pet.
  • Clean the affected area with Medicated Pet Wash. Scrub well.
  • Ringworm sores should be treated with Sulfinex Cream.
  • Use Healing & Protection Spray to treat broken skin, once the Sulfinex is applied.
  • Vacuum the house and change the bag every time.
  • Treat all linens that the animal uses with Disinfectant Spray or Xtreme Cleen.
  • Wash out other items like kennels and litter boxes with Disinfectant Spray or Xtreme Cleen.
  • Ringworm spores may be killed by exposure to direct sunlight (which is why it usually stays in the darker places on the body) so you can put your pets’ objects out in the sun in order to combat the lingering ringworm fungus.
  • Watch your pet to make sure that the ringworm is not spreading or getting worse.
  • All of these treatments must not cease until cultures show the ringworm is gone.


20 percent of households have this infection, although only 3.3 percent of human cases of ringworm were contracted from their pets, since humans have their own kinds of ringworms as well.

However, once there is a pet with ringworm in the household, you are 30 to 70 percent more likely to contract it yourself or have it spread to other members of your family (human and pets), although that is no guarantee that you will contract it from your pet. However, one of your pets may have ringworm without the symptoms or may simply be a carrier. And since ringworm is more likely to affect those with weaker or less developed immune systems, your children are at higher risk.

While it is impossible to fully prevent contraction of ringworm, because it can thrive in almost every environment, there are a few things that you can do to try and lessen the odds of you and your pets getting ringworm:

  • When you interact with pets other than your own, be sure to wash your hands thoroughly and wash your clothes, especially if you have been to a shelter or pet store. Use Disinfectant Spray on hard surfaces, and Xtreme Cleen on fabrics. An effective solution of Xtreme Cleen is 2 ounces to 1 gallon of water.
  • Regularly wash your pets with Medicated Pet Wash.
  • Regularly groom your pet. Since ringworm likes dead skin and hair cells, it is important to get rid of that extra hair. Vacuum often if your animal is a shedder, and spray vacuum brushes with Disinfectant Spray.
  • If you have your pets groomed by professionals, make sure that they clean their clippers and other grooming supplies after every session.
  • Keep your animals, particularly your cats, indoors.
  • Do not accept used bedding, linens, toys, animal-type sports equipment, animal clothing, or litter boxes from other pet homes. Always get new items in order to assure cleanliness and that the items were not used by a carrier.
  • Get new pets from individual households where there is less chance that the animal contracted ringworm from another animal or from a contaminated environment.
  • If you are part of a multi-cat home, especially if one or more of those cats go outdoors, you are at higher risk, so be sure to observe your cats carefully.
  • Regularly check your pets for symptoms of ringworm. The earlier it is discovered, the earlier it can be treated.