It’s a yeast infection. My dog has the same problem. Typically caused by food that includes grain. I have a boxer/pitbull with the same problem. I switched him to Evo, a high protein, grain free food and it didn’t cure. Then I put him on a completely raw diet (all raw chicken). He likes it and he’s been on it about 7 weeks but the ears are getting worse. People told me it would but I’m certainly hopeful it stops.
I cannot put ANYTHING in my dogs ears anymore; he’s completely jaded. Particularly for anything that stings and ACV WILL sting.
Raw is what we have our three yorkies on. The two girls have ear problems all the time even with raw. I have to watch what kind of chicken I buy. No enhanced - the sodium has to be low and WalMart chicken legs & thighs are enhanced. In fact, anything from Walmart has broth added. Adds weight. We feed our venison as well. They still have ear problems. :(