D. E. Larsen, DVM
The exam room was crowded with Rose, her two boys, and the cat. The cat was a rough-looking little gray tabby female who looked like she had just come off the street.
“Good morning, Rose,” I said. “I don’t think we have seen you before.”
“We just moved here from Florida,” Rose said. “I have been a nurse in the Navy and just transferred to the Navy Reserves.”
“That must have been quite a move,” I said. “Are you pretty well settled in at this point?”
“Yes, and we like it here,” Rose said. “And the boys found this cat out in the field, and it has made itself at home. I just wanted to get her shots and probably deworm her. Maybe you can tell if she has been spayed yet. I don’t think we are ready for a litter of kittens just yet.”
“Let’s look her over a little,” I said. “It looks like she has probably been out in that field for some time. She is a little thin and rough around the edges.”
With Rose’s concern about the cat being spayed, I picked her up to palpate her abdomen before doing an exam.
“I don’t think I need to look for a scar from a spay surgery,” I said. “This little cat is already carrying a little surprise package of four kittens in the hopper.”
“Oh, great,” Rose said. “Can we just leave her here and have you do everything.”
“We can probably do that. This is an early pregnancy,” I said as I continued to look over the cat.
And then, I noticed a patch of dry, scaly skin on her right temple.
“I think we better get the black light and look this cat over a bit,” I said.
“A black light. Do you think she has ringworm?” Rose asked.
“This is a pretty suspicious-looking skin lesion on her face,” I said as I slipped out of the exam room to grab the black light.
“Okay, boys, we are going to turn the lights out for a couple of minutes,” I said. “Are you okay with that?”
Rose’s boys looked around six or seven and were probably well past the age of being afraid of the dark. But I had learned not to surprise little kids by switching the lights off without telling them what was going to happen.
“These boys are big enough that this will be an adventure,” Rose said.
I turned off the light in the exam room and switched on the black light to allow it to warm up. We stood in the dark. I kept a hand on the cat so she wouldn’t get lost.
“We’ll stand here for a moment, so our eyes adjust, and then we’ll look at this cat with this special light,” I explained to the boys.
After a couple of minutes, I pointed the black light at the boys so they could see the change of color of their tee shirts. Then I turned my attention to the skin lesion on the cat.
The lesion on the cat’s temple glowed green. There were many broken hair shafts in the very green lesion. I pointed these out to Rose.
“You can see how the individual hair shafts are broken, and they glow green under the black light,” I said. “This lesion is ringworm. I will do a skin scraping to make sure there are fungal spores. We can culture it if you like, but we will start treatment right away.”
“Do you think a culture is necessary?” Rose asked.
“No, when the black light exam and the skin scraping leaves no questions, I consider a culture to be elective,” I said. “This lesion will be mostly resolved by the time we get culture results.”
I turned on the lights and started to collect items to do a skin scraping when Rose grabbed one of her boys and turned his back toward me.
“Will you look at this with your black light?” Rose asked.
This boy had a half-dollar-sized skin lesion on the back of his head. His hair was cut short, so there was no problem seeing the lesion.
“Rose, I can’t look at your son,” I said. “But you know, I will get this scraping from the cat, and it will take me several minutes to look at it under the microscope. I will leave the blacklight here while I am out of the exam room looking at this sample under the microscope.”
I collected the skin scraping and left the blacklight, plugged in, and turned on, setting on the counter.
“This will take me several minutes,” I said as I started out the door. “You need to keep this door closed, so the cat doesn’t escape.”
The hair shafts on the skin scraping were covered with fungal spores. There was no question about the diagnosis of this cat. I busied myself to give Rose enough time with the black light.
“Rose, there is no question on the diagnosis of the cat,” I said. “That skin lesion is a ringworm lesion. With her pregnancy, we will make an exception and hold on to her for a spay. We will get her vaccinated and dewormed. We will give her a bath with some anti-fungal shampoo and get her started on both oral and topical medication to get that ringworm under control. We will probably need her for two or three days.”
“What should I do with these boys?” Rose said. “They both glowed just like that cat.”
“If they would like, we can give them both a bath in the tub in the back. We could do it at the same time we do the cat and use an anti-fungal shampoo.”
“No way,” both boys said in unison.
“You need to talk with a doctor, or at least, a pharmacist,” I said. “You want to get this stuff under control before it spreads.”
Everything turned out okay. We spay the cat, and the ringworm resolved. Rose and the boys visited the local doctor, something they needed to do anyway, and the lesions on the boys resolved with proper treatment.
Over the years, multiple cats were blamed for ringworm on kids. Sometimes, I believe that was the case. But I was never convinced about the asymptomatic carrier state for cats. I cultured many cats without lesions and never found a single cat that cultured positive when they had no visible lesions.
Photo by Piers Olphin from Pexels