RINGWORM IN CATS

Definition

Ringworm are cutaneous diseases that are due to the develoment of a filamentous fungus in the horny layer of the skin: hair, hair follicles, and claws. Ringworm is also called dermatomycosis. Several species of fungus can be involved, but more than 95 % of feline cases are due to Microsporum canis.

Contagiousness

Once present, 100 % of the cattery can get contaminated. Ringworms are highly contagious, because of the fungal spores that are the reproduction form of the fungus. These spores spread from one cat to another (or from cat to man), directly or through the environment: there may be up to 1000 spores per m3 of air, that are able to resist one year in the cattery !

Another reason to explain why the parasite spread over so quickly is: half of the cats would be asymptomatic carriers, which means that they do not show any clinical sign of ringworm even if they carry the parasite.

Diagnosis

Small and circular depilations are the classical ringworm lesions. The skin looks slightly red, with presence of greyish scales. These lesions extend progressively on the whole body, the nose and the ears… They heal spontaneously while new ones appear. Usually, the cat does not itch or very little.

These typical lesions are not so common. One says: “ if it looks like ringworm, it is probably not the case, but if it does not look like it, it could be… ”! It means you can also observe the following symptoms:

• general hair loss,
• miliary dermatitis with crusty papules on the body, the nose and around the eyes,
• excessive production of sebum (seborrhea), inducing itching,
• suppurative lesions, etc…

Ringworm develops mainly in kittens or young adults, but there are other predisposing factors:

• immuno-suppressing viral diseases, such as leukosis,
• anti-inflammatory treatments,
• chronical irritation of the skin (due to inadapted grooming products),
• genetic factors: persians seem to be especially receptive to ringworm.

No certitude can be got without performing complementary examinations.

Observation under Wood light
When exposed to this special light, the cat’s hair that carries Microsporum canis exhibit a greenish fluorescence, because of a pigment that is secreted by the filaments of the fungus. However, here are some examples of false negative results:

• the observator didn’t examine the cat against its fur, the lamp wasn’t hot enough
• only spores are present or another species that Microsporum canis is involved…

Direct microscopic examination of hair and scales

An experienced observator can find fungal spores and filaments. This examination must be performed to confirm or to precise the result of the previous observation.

Mycologic culture

A square of sterile carpet (or a tooth brush) is vigorously rubbed in the middle of a lesion, and the sampling is then put in a culture dish for 1 to 3 weeks.

In any case, a positive result confirms ringworm, but a negative one does not exclude it, because these examinations are not easy to realize.

Treatment

It must concern the affected cats, but also all the other cats of the cattery, that can be “ safe-carriers ”.

Local treatment

Long-haired cats are first shaved (at list in the injured areas), and their hair burnt, to avoid any further contamination. Massages are done with an antifungal lotion or shampoo: enilconazole (ImaveralND), miconazole (DaktarinND), chlorhexidine… To do 2-3 times per week until 1 month after complete clinical recovery.

Desinfection of the environment

To stop the contagion, it is advised to:

• vacuum-clean the cattery as often as possible
• to wash the cattery with bleach and if possible, with hot pressurized water
• to spread antifungal products all over, by fumigation or aspersion.

General treatment

Griseofulvine has been used for a long time. But this drug can have many side-effects: nervous diseases (in Persian, Siamese et Abyssin breeds mainly), digestive troubles… It must not be administered to pregnant queens. Soon, new oral products are now replacing the griseofulvine, formulated with: ketoconazole, itraconazole…

Conclusion

Getting rid of a ringworm in a cattery is time-consuming, difficult and expensive. But it has to be done. In case of setback, the reasons of the treatment failure must be investigated: protocole conducted in a wrong way, introduction of new carriers, immuno-depression in the animals… ? A very strict attitude has to be adopted to eliminate this parasite.

Donated by the Borg Cardona and Co. Ltd. visit Borg Cardona website