(Lake Worth, FL, USA)
First, thank you for taking your time.
Our cat in question is a 1.5 year old, male domestic short haired inside only cat. This morning we noticed a red spot around his rear teat. We washed off and around the teat, as the fur appeared to be matted, and the cat did not appear to be uncomfortable. What remained is a partial red ring,about 3/4" wide, with no pus nor scabbing. The skin does not appear to be irritated, as the skin is pink and white inside the ring. There is no fur around the teat any longer, making the spot obvious. The teat itself appears pink and slightly larger than the others.
We just had his shots and vet check a little over a month ago, and all was fine. We also have a 7 year old, female Calico(Sasha) inside only cat, who also had her check up and is fine. She has no symtoms on her belly. Sasha is declawed but Milo is not.
Both of our cats are spayed/neutered, and enjoy sunning on the screened back patio, or warming up in the garage.
Our concern, is this the beginning of ring worm? Or is it something else.
It is impossible for me to know for sure what it is. Ringworm is generally circular and very flaky, crusty around the edges and the skin is red.
If he were older, I might be worried about mammary cancer, but at his age, I can't imagine that would be a concern.
That is not the most typical location for ringworm and he doesn't have a lot of risk factors for ringworm. He's indoors and showing no other lesions and your other kitty is fine.
It could just be some minor trauma. Cats, even indoor ones, can groom excessively in one location, can get caught on something, can get scrapes when they jump up or down,etc.
They also can get bug bites and stings. Bees, ticks, fleas, mosquitoes, all are capable of causing swelling and itchiness which in turn will make a cat lick the area resulting in hair loss.
Also, occasionally, another cat in the household will nurse on a nipple even though they are both older. Or is it possible that they were wrestling, playing and the other kitty accidentally bit or scratched him?
The only thing to do is watch it daily and see if the lesion improves and goes away or if it gets worse and others develop. I would suggest keeping it clean, but do not apply anything to it. If it's fungal, you don't want to put steroid cream on it. If it's an infection, you don't want to put steroid cream on it. If's it's infected, you want antibiotic ointment. Since you don't know what it is, you could do more harm than good by guessing.
Chances are good that it will go away by itself. However, if it doesn't go away soon, then, of course, a visit to the vet is in order.
Thank you for writing.