Dermatophytosis or ringworm in cats is a very common cutaneous pathology among felines, and although the name makes us think that it is a disease caused by some kind of worm and that the lesions are always ring-shaped, this is not the case. 

Don’t miss this interesting article on what it is and how to treat ringworm in cats.

What is Feline Ringworm?

Feline ringworm or feline dermatophytosis is a fungal disease. In 90% of cases, the fungus that causes this condition is Microsporum canis. This fungus feeds on the keratin of the animals’ skin, hair, and nails it parasitizes. Rarely, Trichophyton mentagrophytes is the causative agent of ringworm infections in cats.

It affects any cat breed, sex, and age, although it is more common in felines under one year. Both species of fungi are contagious to humans.

Symptoms of Ringworm in Cats

One of the characteristic symptoms of feline dermatophytosis is hair loss. Alopecia (hair loss) occurs when the fungal spores infect the hair shafts, causing an increase in the fragility of the infected hairs. The first areas affected are the head, ears, and paws. Because it is contagious, it spreads throughout the body.

Skin lesions tend to be circular, yet this form is not pathognomonic, and non-circular fungal lesions may exist.

Besides alopecia, other symptoms of ringworm include:

Appearance of wounds, yellowish crusts, and red, scaly skin.

Characteristic and peculiar odor.

Appearance of nodular areas called kerion.

Itching, constant scratching, licking, or nibbling of the affected areas.

Secondary bacterial infections.

Onychomycosis: Nail fungus. In this case, the nails will become weak, so that they will break and split. In some rare cases, this may be the only symptom.

What Causes Ringworm in Cats?

Transmission of ringworm occurs by:

Direct contact with the cat infected with the fungus.

Indirect contact. Spores of the fungus spread the disease and can remain dormant on combs, brushes, food bowls, furniture, bedding, carpets, or other surfaces for up to 18 months. Contact with contaminated objects or surfaces is another form of transmission.

Contact with ringworm fungus does not always result in infection. If the individual’s immune system is adequate, it will not allow the fungus to become established in the body, and disease will not occur. But, there are predisposing factors that will favor contagion and infection. These are:

A weak immune system (For example, cats under one year of age).

Malnutrition (Example: cats abandoned in the street).

Other diseases (Example: gastrointestinal parasites, Feline Immunodeficiency Virus -VIF-, Feline Leukemia Virus -VILeF-).

Stress (Example: abandoned kittens).

Poor hygienic conditions (For example, excess humidity, dirty environments, etc).

Ringworms in Cats (Treatment)

Dermatophytosis is a self-limiting skin disease. If the individual’s immune system functions well, the disease can “cure itself.” Yet, we recommend medical treatment because ringworm can take six to nine months or even longer to clear up. The goal of treating a sick animal is to shorten this time and thus prevent the spread to other animals and people.

The secret to a successful treatment is patience and perseverance since it lasts between four to six weeks. So, getting rid of ringworm is not a quick process.

In general, ringworm in cats treatment consists of several steps, and all are important:

Improve the predisposing factors already mentioned

Topical treatment: Use only when there are small and localized lesions in pregnant cats and kittens under three months of age. This treatment acts by deactivating the fungal spores, vital to avoid environmental contamination and contagion of other animals and people.

The first step in the topical treatment is to cut the hair surrounding the lesion, then clean it with some antiseptic solution (for example, iodine or chlorhexidine). And third, place the medication whose commercial presentation can be:




The antifungals used are Miconazole, Clotrimazole, and Terbinafine.

For creams and ointments, massage for five minutes to promote absorption and remove excess. In the case of shampoo baths, leave the shampoo for 10 minutes before rinsing.

Oral treatment: It is the most effective therapy against cat ringworm. It stops the reproduction of the fungus and its propagation. The products used at present are Itraconazole and Terbinafine. The disadvantage of this treatment is cats’ resistance to oral medication.

Decontamination of the environment and objects: Keep the environment as clean as possible and remove as many loose hairs as possible from the house. Use cleaning products such as bleach to deactivate the spores in the remaining loose hairs.

Treat until the animal has recovered and the culture is negative. Stopping the treatment too soon favors the reappearance of ringworm.

Work is underway to develop vaccines that will protect cats from developing the infection. Only a few European countries currently use vaccines containing various dermatophyte species (e.g., Microsporum canis and Trichophyton mentagrophytes). But, there are no conclusive studies on their protective effect.

How is Feline Ringworm Diagnosed?

Diagnosis will not be possible by clinical inspection alone. The veterinarian will perform several tests and ensure that no other systemic process is weakening the cat’s immune system.

Diagnostic tests for ringworm in cats are:

Wood’s light test is a quick test performed in the veterinarian’s office: We place this ultraviolet light illuminating the cat’s lesions. Turning off the office lights is essential, allowing the room to remain dark. The infected hairs will show a fluorescent apple-green coloration. The disadvantage of this test is that not all ringworm fungi respond to Wood’s light.

Microscopic examination (trichogram): Sample the hairs surrounding the lesion and observe them under the microscope for spores. The disadvantage is they are difficult to see.

Culture of the fungus: Collect hairs close to the lesion and those positive to Wood’s lamp and place them in culture media to check fungal growth. This laboratory test will provide information on the species of fungus responsible for the disease. Although fungal culture is a certain diagnosis, a disadvantage is fungi can take up to two to three weeks to start growing.

Polymerase Chain Reaction Test (PCR): This test looks for fungal DNA in affected hairs. This test is faster than a fungal culture since we get the results in one to three days. As it only looks for fungal DNA and does not discriminate between live or dead fungi, a disadvantage is that it is not useful once treatment has started. In these cases, fungal culture is better to determine when to stop medical therapy. Another disadvantage is the high cost.

If these tests show that the cat has a positive result for ringworm, all the animals that live in the same house should receive an examination, even if they do not show any symptoms.

How Long Does Ringworm Last in Cats?

Cats with ringworm will be contagious for about three weeks if they have received treatment. Otherwise, the infection may persist for three to six months or even longer.

Is Ringworm in Cats Contagious?

Yes, ringworm is a contagious fungus that affects cats and can spread to other animals, such as dogs and people (it is a zoonotic disease).

Kittens adopted from the street or shelters with malnutrition and poor hygiene are a primary source of infection. In these cases, we recommend the following preventive measures:

Quarantine: The kitten should remain isolated from other animals in the house. It should not come into contact with children and immunosuppressed people. Setting up a room where the kitten can stay until your veterinarian evaluates it is advisable.

Protect yourself: After handling the sick cat, wash your hands with soap and water and apply an antiseptic.

Disinfect and clean the house: Bleach is an excellent product that kills fungal spores in the environment. You can vacuum the floor and furniture to collect as much contaminated hair as possible. Clean all clothing that has been in contact with the sick animal, as well as blankets, beds, toys, food bowls, etc.

How Much Does it Cost to Treat Ringworm in Cats?

In the case of single, localized lesions of mild severity that respond to topical treatment, the total cost can be well under $100.

However, if the pet has many lesions, its general condition is poor, and it does not respond to medication, the cost can be much higher as it will need various diagnostic methods and complementary studies to check its general health and nutritional support.

Incubation Period for Ringworm in Cats

Are you wondering how long it takes cats to develop symptoms after exposure to fungi?  It needs two to four weeks to become visible in the infected animal. The incubation period ends when the first signs of the disease appear.

How to Treat Ringworms in Cats Without Going to the Vet

There are some home treatments for ringworm in cats. Yet, they may not solve the problem by themselves. Since we are facing a common zoonotic disease among cats, we recommend going to the veterinarian to check the case. And use these natural remedies to complement the medical treatment indicated by the professional.

Vinegar With Salt

Mix iodized salt with white or apple cider vinegar to make a paste. Apply the resulting paste on the affected areas of the skin. Leave it on for five minutes and remove. Repeat this procedure for at least three weeks.

Apple Cider Vinegar

It is a potent natural antibacterial and antifungal, a home remedy against many parasites and fungi. It is also analgesic and anti-inflammatory, promoting the healing of lesions caused by ringworm.

Apply vinegar on the lesions by adding five to 10 drops daily. It is essential to use pure organic apple cider vinegar.

Grapefruit Seed Extract

It has excellent antibacterial, antifungal, antiseptic, and antioxidant properties. For this reason, it is one of the most used natural remedies to combat different types of infectious processes, such as ringworm in cats.

Dilute grapefruit seed extract (do not use the essential oil) in water and apply it once or twice daily on the affected areas.

Coconut Oil

It is an excellent antibacterial, antifungal, and antiviral. We can use this remedy once a day, every three or four days.


We can supplement our cat’s diet with probiotics, which favor the immune system. There are specific commercial presentations for felines or, if unavailable, yogurt or kefir containing probiotics. Yogurt should be natural and sugar-free. As for kefir, there are different presentations, with milk and yogurt being the most common.

How Common is Ringworm in Cats?

As mentioned, ringworm in cats is a pathology veterinarians often see in the office. As it is a disease that manifests in immunosuppressed animals, it is more common to see clinical manifestations in kittens, malnourished cats, or cats with underlying diseases such as FIV or FIV.

It is essential to mention that healthy cats can carry ringworm fungus on their skin or fur without showing signs of disease. Thus, an immunosuppressed person can become infected, e.g., infants, children, older adults, and people with HIV.

If you suspect your cat may have ringworm, the best thing to do is visit the veterinarian to perform a fungal culture of the hairs.

As we have seen, cats transfer the fungus to humans, but can we infect cats? It is not possible. A person infected with the fungus can only infect another human being.


The veterinarian’s intervention is fundamental in controlling and preventing this disease. Due to its high zoonotic potential, there must be a rapid diagnosis of the infection in animals and appropriate treatment. It is the only way to limit the infestation of the environment and the contagion of other animals or humans.

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