Sent my dogs to a dog sitter using the rover app while we were at church youth camp and they came home with fleas. I went to the store where I was recommended to buy Harts Ultraguard Pro on my animals. I have a 6 year old malinois that is 60 lbs and a 7 month old GSD at 70 lbs. I followed the directions to a “T” and my GSD is just fine (so far). My malinois however, has severe hives, scabbing along the spine, and now walking along the walls to keep balance. SO MAD RIGHT NOW.