Ringworm in Cats
Ringworm is often seen in cats, even indoor cats. But despite the name, it doesn’t involve any worms. Ringworm is a fungal infection that can affect the skin, fur, and claws. It can cause crusty and bald patches and itchiness. Left untreated, it can spread across the body and cause open sores, especially in animals with weak immune systems. Cats can pick it up from other animals that have ringworm, as well as from the environment where an infected animal has been. Not only can cats spread it among themselves, but it is also contagious to other animals and humans.
Fortunately, even though this disease is highly contagious, it is also very treatable.
What Is Ringworm?
Ringworm is a fungal infection that affects many different species of animals. It’s also referred to as dermatophytosis. In cats, about 98% of ringworm cases are caused by the easily transmitted fungus Microsporum canis.1 The fungi feed on keratin in the fur, skin, and nails. Ringworm gets its name from the red, ring-shaped rash that it sometimes causes. However, some infected cats only have very minor symptoms.2
Symptoms of Ringworm in Cats
Ringworm symptoms range from very mild to severe. They commonly show up on the head, tail, and feet of cats but can affect other body parts as well.
Red rings on the skin
Scaly or flaky skin
Lesions and sores
ringworm lesion on cat’s front paw
Red Rings on the Skin
Cats don’t always have the classic ring-shaped infected area, but it is possible. The circular area will typically lose its fur, and the skin will appear rough and scaly.
In addition to the circular spots of hair loss, ringworm also can cause irregular patches of hair loss throughout the body.
Scaly or Flaky Skin
Ringworm can cause scaly or flaky skin with or without hair loss. The coat might simply look like it has a lot of dandruff.
Lesions and Sores
Besides the red rings, more irregular raised lesions can occur throughout the body. Also, in more severe cases, cats can have relatively large lesions and open sores.
Not all bumps and lesions that come with ringworm are itchy, but they can be. Itching in a specific area sometimes can help owners find a ringworm case in its early stages.
When ringworm affects nails, they can take on a rough, pitted appearance. Eventually, they can look scaly and deformed.
Causes of Ringworm
Cats can carry the fungal spores of ringworm and show symptoms of the disease, or they might not show any symptoms at all. Either way, spores can spread to other cats quite easily. The common causes are:
Direct contact from touching another animal that has ringworm
Indirect contact from touching the bedding, food and water dishes, toys, and other items that a carrier or infected pet has touched
Exposure doesn’t always result in a case of ringworm. Animals with weak immune systems, as well as those with skin sensitivities, are especially prone to ringworm.1
Diagnosing Ringworm in Cats
To confirm that your cat has ringworm and not another type of hair or skin issue, your vet might perform tests for a diagnosis, including:
Wood’s lamp: A special black light called a Wood’s lamp causes the fungus to glow a yellowish-green color.3 It’s a simple and noninvasive test to perform, but it’s not always accurate. The lamp can make other things glow, including dead skin cells, topical ointments, and other fibers, so it’s just one test used for evaluation.
Microscope: Your vet can look for fungal spores under a microscope. A piece of clear tape placed on the lesion will pick up cells that can then be stained. A special purple stain will cause the ringworm spores, which look like small ellipses with lines, to be visible under a microscope. However, the spores can still be hard to see even with this test.
Culture: One of the most accurate ways to diagnose ringworm is to take samples of your cat’s fur and skin and place them on a special culture medium to see whether the fungus will grow.2 It’s a slow method that can take weeks for results.
Biopsy: A skin biopsy is the most invasive way to diagnose ringworm, but it’s also very accurate. This method involves cutting out a piece of skin and sending it to a lab for microscopic analysis. It can take several days to get results.
PCR: The newest method to detect ringworm is through a noninvasive polymer chain reaction test, more commonly referred to as a PCR. Like the culture test, the PCR test uses skin and hair but can detect ringworm in only a few days.
These different tests will verify that your cat has ringworm. Your vet will then be able to treat the fungal infection with appropriate medication. Your vet might also ask whether you have any lesions or other skin abnormalities similar to your cat’s, as you’ve likely been exposed to the fungus.
Ringworm lesions can look similar to other issues, which is why it might be necessary for your veterinarian to run more than one test. For example, fleas and mange can cause hair loss and itching. Plus, some cats will lick their fur off and irritate their skin until it’s red due to allergies or stress and anxiety. A misdiagnosis can mean your cat will be given the wrong kind of medication.
Ringworm microsporum stained purple
Alastair Macewen / Getty Images
If your veterinarian has diagnosed your cat with ringworm, they’ll likely prescribe an antifungal medication to treat the infection. Itraconazole is a frequently used medication for pets with ringworm.4 Sometimes topical ointments are used to treat ringworm in conjunction with oral treatments.3 By using both oral and topical treatment regimens, you’ll kill both the spores on the skin and suppress the infection in the cat systemically.
Finally, if you have a cat with ringworm, you’ll need to treat your home environment to kill any spores. Use a diluted bleach solution on surfaces after your general cleaning routine. It can be helpful to restrict your cat to a small, easy-to-clean area until it is no longer infected.2
Prognosis for Cats With Ringworm
Most cats recover from ringworm infections, though it can take some time. In general, the lesions can take more than a week before they show improvement from treatment. Also, inadequate treatment or stopping treatment too soon can cause a relapse. After a course of treatment, your vet might perform another test to make sure the ringworm has cleared up and your pet is no longer contagious. Until you know this, minimize contact between your pet and any other people and pets in the house, and keep its area sanitary.5
How to Prevent Ringworm
Ringworm is highly contagious, but it’s also preventable if the appropriate steps are taken. Washing your hands before and after handling your pet is the easiest way to decrease the likelihood of you or your cat becoming infected with ringworm. Aside from that, don’t let your cat play with cats that don’t live within your household. Maintain a sanitary living environment for you and your cat. And if you have ringworm, refrain from touching your cat until your doctor has determined that you’re free of the infection.
Is Ringworm Contagious to Other Animals?
Ringworm in cats is contagious to other animals. They’ll either acquire it from direct or indirect contact with the infected animal. Ringworm can live for up to 18 months in the environment on items such as brushes, pet beds, furniture, carpeting, and bowls.6 So if you have an infected animal or suspect a case, immediately separate its items from any other pets you have.
Is It Contagious to Humans?
Ringworm is a zoonotic disease, which means it can spread from an animal to a human. A ringworm infection in a person typically occurs after a person has touched an infected or carrier cat. But it can also occur after simply handling items that were used by an infected cat. Immune-compromised individuals are more prone to contracting ringworm. Hand-washing and maintaining sanitary conditions can help to prevent the spread.