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Ringworm Circus

July 4, 2010

Ringworm Fungus Infects Mangrove Kitten

White kitten glows purple under ultraviolet light, ringworm circle glows candy apple green

Candy Apple Green Glow of Ringworm Fungal Infection

Quick, Basic Ringworm Diagnosis

A tiny, short-haired white green-eyed kitten with a grey smudge on the top of her head toddled across the examination table and butted her head into my outstretched palm.  What a sweetie!

“I found her starving in the mangroves by the State Park,” said her new daddy.  “We call her Sissy.”

Sissy had fleas, earmites, a huge belly full of worms, and a round reddish-sore almost bald spot on the underside of her belly.  A quick turn out of the lights and turn on of an ultraviolet “UV”  Wood’s lamp, and a few seconds later, there was our answer.  Sissy glowed from a fungal infection.  50% of ringworm infections glow; 50% do not!

What is Ringworm?

Ringworm is a name for a group of  microscopic organisms in the fungus family, not actually a worm.  The pattern of infection on the skin starts at a center point and moves outward in a ring.  The line looks wormy and the ring gives it that name.  This stuff is everywhere in the environment, and most of the time our bodies fight it off successfully.

The very young, very old, infirm, or immunocompromised become easily infected with ringworm.  It is an equal-opportunity fungus.  People, cats, dogs, ferrets, sugar-gliders, hamsters, opossums, just about anybody can become infected.  A disease that will transmit between humans and animals is called zoonotic. Ringworm is a zoonotic disease.

Further Testing is Needed

Every pet parent asks, “If we know it’s ringworm, and the treatment is the same, why do we have to do another test to see which type it is?”

Everyone’s mind goes here!  The test is called a dermatophyte culture. The fancy doctor word for ringworm is dermatophyte.  (Saprophyte is a soil fungus, dermatophyte is a derm, or skin, … you get the idea.)  A nursing technician plucks infected furs from the ring edge of the freshest lesion and puts the sample on a special nutritional gel designed to feed and grow ringworm.  7-21 days later, the fungus grows.

Once the fungus grows, a microscopic examination reveals the fine architectural detail of the organism.  Depending upon the appearance and certain growth factors, a speciation is made.  The exact fungal organism species identified determines the length and strength of treatment.

The dermatophyte culture test takes one to three weeks, and the test can vary from US$25-100.  Many pet parents wonder why they have to spend that extra money.

Why Not Just Treat in Case of the Worst Scenario Anyway?

There are at least three good reasons not to just treat for the worst case scenario:

One- Treatment is expensive.  Itraconazole can run $400 per cat per month for 3 months or so.  Other fungal medications cost more or do not work!

Two-Prescription fungal medications tax the liver to process and eliminate them from the system.  They can cause liver damage, failure, or other serious side effects.

Three-Ringworm is zoonotic.  If people, children, grandparents are to be treated properly, the pet must be diagnosed properly.

Close up of candy apple green glow on kitten's infected fur

Ringworm Glow Close Up

Ringworm Treatment

Treatment for cats or dogs is similar.


Clean the house.  Clean the house. Clean the house.

You don’t need fancy antimicrobial soaps. Much recent research shows these soaps to be harmful to our planetary water supply.  The breakdown products of triclosan, for example, are poisoning the environment and the ingredient is illegal in many countries!

Clean up clutter, dust, furballs.  Use dilute bleach and water on bleachable surfaces.  Dilute bleach kills ringworm.  A capful of bleach in the laundry kills ringworm on the bedding.  Be careful to follow the bleach instructions on the product label and do not bleach any sensitive items that may ruin.

Next, clean the pet.  At the hospital, we use prescription shampoo and a prescription lime-sulfur dip product.  If you use this dip, follow the label instructions, wear gloves, goggles, and a water proof apron.  Do not get the lime-sulfur into your eyes or your pet’s eyes.  It causes a vicious corneal irritation called keratitis.  Usually, your veterinarian will prescribe dips once a week for many, many weeks.

New Ringworm Research:

Animal shelter researchers have found that investing in repeated weekly ringworm dermatophyte cultures may prove the resolution of the problem sooner than traditionally thought.  The additional investment in the testing might cause a kitten, for example, to become adoptable to the public many weeks sooner than if we used guesswork.  The shelter would save money in housing the little one, and the kitten could get a home during his or her primary stage of behavioral development called social bonding.

Important: Isolate the ringworm-infected pet(s) from non-infected pets.  This fungus spreads easily and you do not want to be culturing and treating a household full of people and pets!

Finally: follow your veterinarian’s advice regarding your particular situation.  VirtuaVet helps this story clarifies your misunderstandings and helps you feel like you’re on the right track.  Only your veterinarian can prescribe oral anti-fungal meds, check liver function, prescribe dosing and frequency intervals for the dips and for retesting.  And remember, half of ringworm does not glow, and many times ringworm is not in a ring!  Let your veterinarian test your pet.

Tru Take-Home Message

Clean, clean, clean, culture, culture, culture!

What if There are No Lesions?

Ah!  Yes!  A human in the house is diagnosed with ringworm and the physician asks you to have the pets checked to be certain they are not a reservoir of ringworm reinfecting the humans.

Your veterinarian can take a clean, new toothbrush and comb your pet’s whole body.  The samples go to the reference laboratory for a dermatophyte culture.

If you find any itchy, red spots on your skin or a family member’s skin, see your physician for a diagnosis.

Sissy Likes Her Dips!

Sissy actually loves taking baths.  Thank goodness, because she needs a lot of them!  Her ringworm does not glow anymore and we are waiting on the fungal dermatophyte culture results to see if she can stop the dips soon.

If your cat or kitten does not have ringworm, read about how Doc Truli diagnoses skin allergies and other skin problems.

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