Cat Carriers & Ringworm

Longhaired cats are prone to carrying ringworm.

Ringworm--scientifically referred to as dermatophytosis--is an aggressive skin condition carried by longhaired cats in particular, although any cat can be affected. It causes patchy hair loss, intensely itchy skin and sometimes open sores. Untreated ringworm quickly spreads to affect other pets and people and is very difficult to eradicate. Once infected with ringworm, a cat should always be considered a carrier.

What is Ringworm?

Check your cat's skin for ringworm frequently.

Ringworm has no connection with worms; it's an aggressive fungal infection affecting the top skin layers. Its name comes from the characteristic ring pattern of hair loss and lesions that commonly develop in animal sufferers. Ringworm is usually caused by the dermatophyte "microsporum canis" although other dermatophytes can also be responsible. Because ringworm is zoonotic--transferring to both other animals and people--any cat suspected of carrying ringworm should be immediately seen by a veterinarian.

Signs

There are some common ringworm signs. Cats often show patchy hair loss, sometimes developing in the characteristic ring pattern. Hair breaks off at the shaft leaving a short stubble. Cat carriers may have itchy skin, scratch persistently and be obsessed with grooming. More advanced ringworm causes open sores known as lesions, which might be circular with a definite outer ring and a contrasting center, sometimes oozing. However, some cat carriers are just a little itchy and don't show either hair loss or lesions.

Diagnosis

Grooming tools carry and spread ringworm.

Diagnosis by a veterinarian involves several stages. A trained eye can often diagnose superficially by observing the nature of hair loss or lesions, but other veterinary tests confirm diagnosis. A Wood's lamp--giving off ultra-violet light--is often a first-check method; skin carrying ringworm may fluoresce under UV light, but not all affected skin behaves this way. A vet also will take skin and hair samples for microscopy and cultures. Culture involves placing hairs and skin debris into a specially prepared culture solution, then incubating it in a laboratory to see whether the relevant dermatophyte develops.

Treatment

Cat treatment requires a combined approach of anti-fungal skin baths with veterinary shampoo and medications taken internally. Historically, treatment of ringworm involved tablets containing griseofulvin, but this has been discontinued for use in cats as of 2010. The most effective systemic treatment is an orally administered liquid containing itraconazole, available against prescription. Treatment and baths continue for several weeks. The cat must retest negative, using the culture method. Anti-fungal creams can also be obtained from a vet and used additionally on the worst lesions. Other pets should also be bathed as a precaution.

Living With Carriers

Once a cat is diagnosed with ringworm, always consider the cat a carrier of the disease even after gaining a final negative test result. It is very difficult to eradicate ringworm from either an animal or the environment, but effective cleaning will prevent further outbreaks. Spores are prolific, so treat soft furnishings by aggressive, frequent vacuuming and dispose of affected pet bedding. Disperse veterinary disinfectant through the home using a large garden spray; ask your veterinarian for a product recommendation. Thoroughly disinfect grooming equipment and never use these tools on other pets. Wash hands with handwash containing chlorhexidine after cat-handling.

References

• Feline Advisory Bureau: Tackling Ringworm in Cats
• Marvista Vet: Ringworm FAQs

Resources

• National Health Service Choices: Ringworm
• Directors of Health Promotion and Education: Ringworm