I used the flea prevention drops on my cat Seymour. He started to freak out running everywhere, erratic breathing, and clawing his fur. I called the emergency vets office and they had me use dawn dish soap to cleanse the area and I brought him in. They cleaned the area and said to not use those drops. Seymour lost a huge patch of fur on the back of his neck. Never again will I ever use these products.