I do a lot of herbal and homeopathic medicine with my dogs and have since adopted it for us too.
Garlic is known as nature's antibiotic. It's also great against viral stuff. If I think a dog is coming down with something, they get fresh shredded garlic on their food (1 clove a day). It's also purported to help repel fleas (but not ticks).
A soak of aspirin dissolved in tea can help with skin inflammations. NEVER use aspirin with cats.
NEVER give dogs onion - they quickly lead to hemolytic anemia.