What are you cleaning them for? Just normal maintenance or are you trying to treat something like yeast or a bacterial infection? Most large petstores have ear cleaner (and depending on the store more than one) and you can even find some products that help with problems. If you are just doing routine cleaning, otc ones are fine. I have a Catahoula that has chronic yeast in one ear (floppy eared dog thing). I used the vet stuff in the beginning and followed their instructions exactly and the expensive stuff didn't ever get rid of it completely. Now I use an otc one and while it doesn't get rid of it either, keeps it controlled enough to keep him comfortable for much less.