My dog had a really bad infection with black, wet discharge. I got the newest antibiotic ear medication from the vet and the infection returned a month later, just as awful.
I started one drop of MMS to 30 ml (1 ounce) filtered water. Would soak a cotton ball and put the ball in his ear and massage. I did this two times a day for two weeks then one a day for two weeks the every other day for a month to make sure it didn't return. That was two years ago. No recurrence.
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