Diy Tick Killer For Dogs . Add witch hazel or vodka to fill almost to the top, leave a gap to be able to shake thoroughly. When used frequently, it's very effective at preventing fleas. DIY Flea & Tick Shampoo for Under 5 Homemade dog shampoo, Fleas from www.pinterest.com Carefully measure in 30 drops of geranium essential oil, 30 drops of cedarwood (virginian) essential oil, and 10 drops of garlic. I recommend using 15 drops of each oil in the diy tick repellent spray for dogs. Cover the pot and let the mixture steep.