Garlic is okay for dogs in the right dosage. If you buy garlic formulated specifically for dogs and follow the directions, it is quite safe. Dosages too high can be toxic. My lab has been on it for 2 years now. Bug Off Garlic from springtimeinc.com.
I had been having trouble with ticks on my cocker spaniel. We started giving her one garlic pill everyday and we have not had any more tick issues. The only way she will take it is if I hide the pill in a small piece of banana. If the banana is too firm, she will break it and spit out the pill. So be sure it is a ripened banana.
EC: Read more about Garlic for Dogs here: https://www.earthclinic.com/pets/garlic_for_dogs.html