I love oil of oregano.
I know a few people on my k9 kidney group give it to their dogs. I found this in the files:
Wild Oil of Oregano has become a popular treatment for candidiasis at human doses of 1 drop once or twice per day, building up to a dose of 1 drop 4 times per day, which is considered safe for long-term use.
Dogs dislike the taste and smell of oregano oil. For canine treatment, dilute full-strength oregano oil with coconut oil, then place a drop of the diluted oil in an empty 2-part gelatin capsule, which can be hidden in food. For dogs weighing 50-70 pounds, dilute ½ teaspoon oregano essential oil with ½ teaspoon coconut oil; for dogs weighing 25-35 pounds, use 1 teaspoon coconut oil; and for smaller dogs, use 1½ to 2 teaspoons coconut oil. Start with 1 drop of the diluted oil per day and gradually build up to 1 drop 4 times per day.
CANDIDA IN DOGS - Chinaroad Lowchens of Australia
I know the brand I buy is already diluted in olive oil. The directions above look like it may be for the undiluted.