Potagergirl. If it were me I would infuse garlic for 3 days into oil so it's not as strong, shaking it 2 times a day, then remove the garlic from oil and you can apply by hand or spray it on, along with keeping a small amount of garlic in their food occasionally. it gives of an odor not as noticeble to us but works well on my other animals to keep mites, ticks and fleas away
haven't tried this on my animals ,but I make a healing salve at home that helps people a lot and doesn't have anything that would hurt an animal in it, but takes about a week to infuse the oil.
1 tablespoon candula
1 tablespoon plaintain
1 tablespoon self heal
4 ounces olive oil
optional lavander either added for the 7 days with the others or 10 drops essential oil added when prepping the salve
put in oil and herbs in jar with lid and mix well at least 1 time a day on day 7 put through something to strain the herbs out and melt 3-4 ounces of beeswax slowly and adding in the infused oil , put in a coverable container and apply to affected area after cleaning
it will harden and you can add it back into more melting beeswax if it isn't your liking for consistency
only use this healing salve externally, and a little of this goes quite a ways