My lab is about 70 pounds and very healthy. After using the Sargaents Gold "new formula"??? flea and tick treatment on her she became very aggitated, constantly running with her hind quarters down and trying to bite. This dog is the most passive dog in the world and after talking with my son he told me to keep washing her with mild soap and lots of water. After doing this 5 times she is finally a little better but still not 100%. I will never use this product again and encourage others to beware of this product. I guess we cannot affort to save a few dollars by using a lesser brand when we are actually harming our beloved pets!!! I am lucky, she didn't die and is recovering - thank god!!!