How To Prevent And Treat Ringworm In Cats

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The probability that your cat has ringworm is quite high. As much as 90% of cats suspected to have ringworm actually have it. The infection is present in about 30% of cats suspected not to have it.


Cat ringworm can infect humans. The good news is that ringworm in cats is not only treatable but also a preventable cat disease.





What is ringworm?

Contrary to what the name might suggest, a fungus causes ringworm; not a worm. It got that name due to the appearance of the infection in humans; which is a red, circular, and raised marking on the skin.


Ringworm occurs in humans and all domesticated animal species. The fungus thrives in a warm and humid environment. It is prevalent in furry animals, such as cats, since the hairs interfere with routine grooming.


The fungus that causes ringworm belongs to the group of fungi called dermatophytes. That explains why the scientific name of the infection is dermatophytosis.

Some dermatophytes are species-specific – they only infect one species. Others, however, are zoonotic, meaning they spread between different species, including humans. Microsporum canis and Trichophyton mentagrophytes are the dermatophytes responsible for almost all cat ringworm infections. These two dermatophytes can infect humans and dogs.


How can your cat catch ringworm?

Cats catch ringworm when they get exposed to the spores of the fungus that causes the infection. That occurs when the cat comes in contact with an infected animal or human, and contaminated objects and surfaces. Air currents and dust also carry the spores since they are small. The spores can remain in their dormant state on furniture bedding, brushes, and combs for up to 18 months.


After the spores settle on the coat of the cat, they attach to the skin cells called keratinocytes and grow to cause the infection. The fungus thrives on the dead protein keratin, which supports the growth of fur and hair. As the fungus grows, the fur and skins become brittle and shed off together with thousands of spores.


However, not all contact with the fungus causes infection. The fungus might not survive the cat’s natural defense system, which includes sunbathing and grooming. The following cats are likely to catch ringworm;


  • Kittens: they have weaker immune systems
  • Long-haired cats, like the Himalayan cat: They are susceptible to the infection because the long hair easily gets matted compromising the removal of spores through grooming.
  • Older cats: They also have weaker immunes. Additionally, due to age, they are unable to groom themselves. As cats get older, the self-grooming practice becomes more difficult due to loss of flexibility.
  • Cats with immune disorders: Immunity naturally fights infections such as those caused by dermatophytes. However, cats with immune disorders such as FIV (feline immunodeficiency virus) are much more likely to get infected with ringworm.




Signs of ringworm in cats

Ringworm in cats has varied signs and symptoms. Some cats will manifest severe skin disease; others will have minor and less conspicuous lesions, while others will look completely normal.





However, a cat with one or more of the following signs and symptoms probably has ringworm:

  • Hair loss: As the fungus grows, it causes the weakening of hair follicles. Often, hair loss occurs in circular patches on the head, ears, and legs. The areas of hair loss are crusty and appear red.
  • Itchiness: Ringworm, even in humans, is not a particularly itchy infection. However, some cats have mild itchiness, while others will scratch to the extent of injuring themselves.
  • Redness of the cat’s skin (erythema)
  • Blackheads on the chin area.
  • Darkening of the skin (hyperpigmentation
  • Claw infection: Claws have Keratin, the protein dermatophytes feed on. Therefore, infection of the claws could be a sign of ringworm. The infection causes the claws to appear scaly and rough.
  • Overgrooming: Cats love self-grooming. However, the cat should not groom to the extent of hair loss. Such overgrooming could indicate the presence of ringworm infection.


Diagnosis of ringworm in cats

If you notice one or more of the signs and symptoms outlined above, take your cat to a vet. Note that, other infections and pests cause symptoms similar to ringworm. For example:

  • Mange and fleas cause itching and hair loss.
  • Allergies in some cats can cause skin irritation to the extent it appears red.


It is not safe to start ringworm treatment until you are 100% sure the fungus is the cause of the symptoms. A vet will conduct one or more of the following diagnostic procedures to confirm your cat has ringworm:


  • Wood’s lamp test: Wood’s lamp is a special light that makes fungus glow in a greenish color. The Wood’s lamp test is simple, non-intrusive, and probably the first test a vet will conduct. However, it is not accurate.
  • Other things, such as fibers, dead skin cells, and topical ointments, glow under the Wood’s lamp.
  • Only the M. canis dermatophyte species glows under the light.
  • The test only detects about 50% of M canis infections.
  • Therefore, your cat needs other tests to be sure it is ringworm infection.




  • Microsporum test: As mentioned earlier, one of the dermatophytes that cause ringworm is Microsporum canis. This fungus is visible under a microscope. When performing this test, first, the vet will stick a special clear tape on the infected area of the cat’s skin. Then, they will stain the tape with purple liquid. The purple stain makes the spores more visible under a microscope. The spores, if present, will appear like small ellipses with lines. Still, the spores can be challenging to see. As such, this test is only accurate in severe cases of ringworm.
  • Skin biopsy: A skin biopsy is a very accurate way of diagnosing ringworm. However, it is highly invasive as it involves clipping a tiny piece of the skin and sending it to a lab for analysis. The results come back after a few days.
  • Culture test: The culture method of diagnosis is non-invasive and highly accurate. The vet will take samples of the cat’s hair, and skin put them in a culture medium, and wait to see if the fungus will grow. Unfortunately, this ringworm diagnosis method can take over one week.
  • Polymer chain reaction test (PCR): This is a modern diagnosis method for ringworm that involves getting samples of the cat’s skin and fur. The technique is non-invasive and produces results faster than the culture test.


Ringworm is a zoonotic infection. Therefore, your vet is also likely to ask you if you have any ringworm-like lesions.


Treatment of cat ringworm

After the diagnosis, your vet can now treat your cat with medication to fight the fungal infection. The treatment is crucial to prevent the spread of the infection to other pets, children, and even adults.


Treatment plans vary, depending on the cat. However, they typically involve a combination of topical therapy, clipping the hair coat, oral drugs, and environmental decontamination. Therein lies a challenge – most cats are not used to regular baths, and they will object to oral medication. But, note that aggressive therapy is the best way to treat ringworm and prevent reinfection.


Hair coat clipping

Depending on the severity of the infection, it might not be necessary to cut the fur. However, ringworm often affects fur. It makes it brittle and fragile. The hair, together with fungal spores, shed off further and cause contamination of the environment. The shedding of fur increases the risk of spreading the infection and reinfection of the cat.





Cutting the infested fur minimizes continuous hair loss and enhances the penetration of topical treatment. Expert feline veterinarian, Arnold Plotnick, recommends the following hair clipping guidelines:


  • If the cat is short-haired and has five or more visible or inconspicuous ringworm spots, clip the entire hair coat.
  • If the cat is short-haired and has less than five visible or inconspicuous ringworm spots, clip the hair around the affected areas.
  • If the cat is long-haired, clip the entire coat even if the cat has less than five visible ringworm spots.


Topical therapy

If a cat tests positive for ringworm, it will receive some topical treatment. The topical treatments decrease the spread of the infection along the skin, eliminates lesions, scales, crusts, and spores. Therapy without topical treatment costs more and takes longer.


The most effective topical products used in cat ringworm treatment have miconazole. Veterinarians recommend topical shampoo as opposed to creams and ointments. Why? Creams and ointments are not only messy but also easily groomed off by the cat.


Generally, your vet will direct you to bathe the cat twice a week with the shampoo. They will also recommend you let the shampoo sit in the cat’s coat for at least 10 minutes. You could increase the effectiveness of the treatment therapy by applying a topical miconazole lotion on the affected area on the days you do not bathe the cat.


However, do not buy topical products off the shelf. Instead, use a product specially designed by a veterinarian. The topical therapy will last anywhere between several weeks and several months.




Oral antifungal medication

The foundation of ringworm treatment is an oral medication. Traditionally, these oral drugs contained griseofulvin. However, the compound has adverse side effects. Nowadays, these drugs have:

  • Ketoconazole
  • Itraconazole
  • Terbinafine

Vets prefer itraconazole as has fewer side effects. If any, the side effects will only be low appetite and vomiting.


Only use oral antifungal medication prepared by a veterinary compounding pharmacist. For effectiveness, these medications need to be in the right dosage. Also, an expert is likely to know to flavor the medicine to make it more appealing to your cat.


How long will a cat take to recover from ringworm?

With the proper administration of aggressive treatment, you will notice an improvement in 2 to 4 weeks. Your vet will reexamine the cat after four weeks of treatment, then weekly or bi-weekly after that. If Wood’s lamp test was positive in the initial exam, they would use it again to check for infected hairs. The vet will clip the infected hairs if there are any. Note that, presence of infected hairs could be proof you are having problems administering the topical therapy.


During the reexaminations, the vet will perform culture tests. The treatment will only be considered successful after two negative culture tests. However, you should continue treatment until three negative culture tests if you have more than one infected pet.

Prevention of ringworm

Contact with fungal spores is the only way to spread ringworm. Therefore, to prevent your cat from catching the infection:


Avoid contact with infected animals

Make sure it does not come in contact with other animals. Cats that live alone in homes are less likely to have ringworm. But stray cats and cats that live in multi-animal shelters are highly likely to have ringworm. If you have to bring another pet into your home, first put it in isolation and have a ringworm culture test done on it.


Environmental decontamination

Decontaminating your cat’s environment prevents both infection and reinfection. Decontamination is particularly necessary if the cat was previously infected. As mentioned earlier, fungal spores can remain dormant on surfaces for a long time.


The first step of decontamination is to restrict the infected cat to a single room that is easy to clean. Then, thoroughly clean all areas the cat had access to. The idea is to remove all infected hairs and fungal spores lying around. So, you should thoroughly vacuum clean furniture, floors, rugs, and carpets. After vacuuming, burn the vacuum bags, to ensure the spores die.


Use chemical disinfectants on surfaces you cannot vacuum. Disinfectants that are effective against fungus are hypochlorite and glutaraldehyde solutions. Also, you should assume all cat-related objects, including brushes, collars, bedding, and litterbox, are contaminated. You should either clean these items, using a chemical disinfectant, or throw them away.



As a caring cat owner, the health of your cat is a constant concern. For that reason, cat ringworm should worry you. It is not a terminal infection, but it will definitely deteriorate the health of your cat if not addressed. So, if you notice any skin and fur defects on your feline friend, take him or her to the veterinarian immediately. It might not be ringworm, but a healthy kitty should have healthy skin and an appealing hair coat.

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