I have been treating one cat with the topical apple cider vinegar to the cats coat as it has developed ringworm and has infected the other cat too. One will allow me to apply the other cat runs from me. So I mix a small dose with chicken broth and mix it with the wet food. It has been helping. Also, I made a separate solution to spray on the carpet area to ride of any parasites or fleas. Since it is not harmful and natural safe for pets.
I started using diluted ACV (1tbs per cup of water) on my 9 week old kitten for his ringworm 3 days ago. I can see it starting to clear up. With a dampened wash cloth and rub the solution into the infected spots and give him a "once over. " Seems to be working. I haven't gotten it yet, but I expect it.