My grand pups had fleas real bad, they were given regular flea baths, given collars, house was bombed several times over summer, yard was treated and my daughter was very frustrated. I sent her Guardians choice and told her to try it, I use it fir my 3 dogs and have no issues. The dogs get excited when the see the jar, they live the taste and my daughter has not seen a flea in a year and a half. I have been using Guardians choice for about 3 years and my dogs are loving it as well