Adding cider vinegar to drinking water discourages fleas from setting up home on dogs and cats. Start with just a few drops so that your pets get used to the taste, then build up a little, to a teaspoon per bowl for a small animal, to a tablespoon for a larger pet. Alternatively, dip your pet in a bath of cider vinegar and water. This is, apparently, suitable treatment for puppies that are too young for commercial chemical treatments. Avoid getting any vinegar in your pet’s eyes.