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There are nystatin oral rinses...but it is hard to get a dog to take these.
Ketaconazole is an antifungal not antibiotic...so you should see an improvement rather quickly if it is thrush.DR.V
It is still pretty early to expect all lesions to be gone. I would imagine another 5-7 days and the lesions should be gone...but you obviously keep the dog on the medication until your vet tells you to stop.
Good Luck...and I am glad you are seeing results.