How old is your dog and what does it eat... do yo vaccinate annually - use HW/spot on prevention?
check his teeth, if there is no inflammation around, or tartar - then look systemically at what you are putting into or on the dog as well as what you may need to boost the immune system
abx aren't always the answer, certainly not long term fine to fight acute infection, but treat from the inside out - especially if it is auto-immune condition
He is your friend, your partner, your defender, your dog. You are his life, his love, his leader. He will be yours, faithful and true, to the last beat of his heart. You owe it to him to be worthy of such devotion. - Unknown