After a visit to a local rescue operation, a couple of my clients who had lost their elderly cat in January went home with not one, not two, but three new cats: Wynken, Blynken, and Nod. Wynken and Blynken were 6-month-old littermates originally from South Carolina. Nod was a 1-year-old from North Carolina. All three had been neutered and received basic vaccinations and medical care before their adoption. The trio arrived for their introductory appointment with me on a busy afternoon. Since we are working “no contact curbside drop-off,” the owners waited in their car while the cats came into my office. I phoned the owners multiple times during the visit to discuss various issues.
“Wynken and Blynken need some vaccinations,” I said, reviewing records from the rescue. “We should draw blood on all three to make sure none are carrying feline leukemia or immunodeficiency virus.” We did three full physical exams, drew three tubes of blood, gave several vaccines, ran three in-house blood tests, trimmed many toenails, packed up three fecal specimens to send to the lab, then called the owners one last time to book their next appointment. Phew! My assistant, Fawn, took the three carriers out, and we sent them on their way.
“Drat!” I said an hour later. “Senior moment! I totally forgot about Wynken’s ear.” The very first thing I had noticed when examining Wynken was a small scaly patch of hair loss on one ear. I had meant to address it after all the routine things were done, but by the end of the visit, it had slipped my mind. It was likely just a minor irritation or injury. No big deal. On the other hand, a hairless, scabby lesion on the ear of a young cat? Could be something much more problematic … and contagious.
Ringworm. It’s not a worm, it’s a fungus. There are many different types, but all together they’re called dermatophytes, and infection is called dermatophytosis. The fungus itself is ubiquitous in the environment. Spores of some species are often found in soil. Some animals can be carriers, having spores on their coats, but without any symptoms. The spores are very hardy, and can persist for months to years in the environment, lingering in gardens and houses, in kennels, cages, and pet carriers, on grooming tools, clippers, blankets, and combs and brushes. Both people and animals can be infected by contact with fungal spores.
It can take one to four weeks after exposure for skin lesions to appear. In people it usually presents as an itchy, red, scaly ring that looks as if a worm burrowed beneath the skin in a circle. Hence the misnomer “ringworm.” In cats and dogs, it often presents as dry, scaly patches … like the spot on Wynken’s ear. In young animals, ringworm is often mild and self-limiting, but some cases become serious, and a real headache to treat. I picked up the phone and called the owners yet again. “I’m so sorry,” I said. “I forgot to discuss the lesion on Wynken’s ear.”
In the past, the main way to definitively diagnose ringworm often involved inoculating a culture media with a few suspect hairs, waiting to see what grew, then identifying the species under the microscope. The test took a week or more. A new test now available, called a ringworm PCR test, looks for genetic material from the organism, and has a much faster turnaround time. Wynken’s dad brought her right back in. I plucked a few hairs and sent the sample off to the lab. Two days later, the diagnosis of ringworm was confirmed.
So what now? Since the three cats had already been living in close contact with one another, we decided to test Blynken and Nod immediately. Since neither had visible lesions, I collected hairs using a technique called a toothbrush sample, brushing each kitty from head to toe with a brand-new toothbrush right out of the package. I then cut off the head of each brush with all the fur still in the bristles, and sent them off in sterile containers for PCR tests.
Why do some animals get ringworm when exposed and others don’t? The fungus can’t infect intact skin. There has to be a point of entry — even simply micro-abrasions from fleas, grooming, or roughhousing. In most healthy adults, the immune system stops the fungus from growing, but young animals and children are more susceptible, as are the elderly and individuals who are stressed, in poor health, or immunosuppressed. Rescue kitties tend to be both young and stressed. Not surprisingly, Blynken and Nod both turned out to be positive, asymptomatic carriers.
Treatment is easier than it used to be. Since 2016, a liquid medication called Itrafungol has been FDA-approved to treat ringworm in cats. Cats are dosed twice daily in a specific protocol of “on a week, off a week” for three rotations. Biweekly medicated shampoos are often indicated. Occasionally we may also need the old-school total-body immersion in nasty-smelling lime sulfur dips, but usually we can avoid that. During treatment, owners must do extensive environmental control to prevent reinfection. Dust. Vacuum. Remove hair from everywhere. Disinfect surfaces, floors, carpets, fabric, and pet bedding.
The PCR test cannot be relied on as the sole method to monitor response to treatment, as it can’t differentiate dead genetic material from live. We may still need cultures for follow-up. Two negative tests two weeks apart are considered to confirm a cure. Wynken, Blynken, and Nod are only partway through their protocol. They are dealing with several concurrent challenges common in shelter or rescue kitties, including upper respiratory infection and intestinal parasites, but they are gradually improving. Their new family is doing everything possible to minimize stress and provide optimal care. From a very rocky start, these three have landed in a safe and loving place. “So shut your eyes while Mother sings/ Of wonderful sights that be/ And you shall see the beautiful things/ As you rock in the misty sea.”