I have horses. Recently they got rain rot. This is a bacterial, not fungal infection. I have used fungicides in the past for another rain rot infection my mare got 7 years ago. I bathed her every day with topical fungicides and betadines and it took months and months and she lost all her hair. When she got it back recently (as well as her mother), I wasn't going through the fungicide route yet again.
I did research online and decided to literally pour apple cider vinegar onto where she broke out (yes it burns, but it dries out the many sores). Take a stiff brush and scrub the infected areas. Do NOT share the brushes! In 4 days, "yes", 4 days, the mares were remarkably better and were no longer hurting or sore. Two days later all the lesions and scabs were gone!
That was a week ago. Now, every few days, I spray some ACV on the areas just to keep it at bay. It also softens their hair.
It literally cleared up the rain rot in 6 days, not weeks, not months!