Ringworm in Cats: Everything You Need to Know

Ringworm is a contagious skin condition caused by a fungus (dermatophyte), which lives on hair and in the hair follicles of cats and other animals.

The fungus can be transmitted directly between animals or through indirect contact via surfaces and objects contaminated with hair, dust or skin deposits from infected animals. The fungus’ spores are contagious for over eighteen months and when fighting the disease, thorough cleaning of the cat’s environment is very important for the treatment to be successful.

The fungal organisms that can cause ringworm in cats are Trichophyton mentagrophytes and Microsporum canis, and more rarely other types of ringworm fungi. People can also be infected, and then get reddened skin rashes that can be itchy. Infection can also be transmitted to rabbits, dogs and guinea pigs, etc.


Infection with T. mentagrophytes usually causes symptoms in all cats, while M. canis mainly causes visible symptoms in young cats and impaired individuals. The incubation period, ie the time between the time of infection until the cat has visible symptoms, varies between four days and four weeks.

Typical skin changes, in the form of spotty hair loss, broken hairs and flaky skin, are seen primarily on the head, neck, back and extremities, but can be found all over the body. The skin may become red and frizzy, and some cats may itch, especially if the ringworm rash paves the way for a secondary bacterial infection. Claw detachment sometimes occurs.


The diagnosis is made by detecting the ringworm fungus, either by the organism being visible in hair or skin scrapes using a microscope, or by culturing on a special culture medium. The fungus is slow-growing, which is why it takes about two weeks to get an answer from a crop. Some ringworm species are fluorescent and become visible when the cat is illuminated with ultraviolet light.

If the fungus is not detected in the cat at the first opportunity, it may be necessary to repeat the sampling after a couple of weeks to be able to safely rule out infection.

Treatment and prognosis

Ringworm infection can heal on its own in about three months. It is therefore not always necessary to treat adults and otherwise healthy cats that do not pose a risk of infection to other animals. In most cases, and especially when a larger group of cats is affected, such as a cattery, however, you choose to fight the infection. This should be done as early as possible so as not to risk the infection becoming permanent in the cat group. The treatment is supplemented with thorough cleaning and disinfection to prevent re-infection.

Ringworm is treated with antifungal or antifungal agents, fungicides / antifungals, which are given in tablet form in the mouth. It is often also combined with shampooing with medical shampoo.

The veterinarian designs a tailored plan for treatment and cleaning for a group of cats. The drug treatment is usually effective against the ringworm fungus, but the prognosis for getting rid of the infection completely depends largely on how well you have managed to eradicate the infection from the environment.


Avoid buying ringworm infection when planning to buy breeding animals. New cats should always be kept in quarantine for the first two to four weeks so that any infections can be detected before the other cats are affected.

Avoid using equipment (such as a brush or transport cage) used by other cats. If this can not be avoided, the equipment should first be thoroughly cleaned and disinfected.

There has been a ringworm vaccine for cats available in countries like Sweden, but it is now deregistered.

The effect of the vaccine has been debated.

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