My vet quit offering Frontline Plus almost a year ago and started offering Certifect. I applied it to my Pomeranian and my son's Boykin Spaniel. My Pom didn't seem to have any problems at the time, but the Boykin ran through the house for 3 HOURS trying to rub it off. She finally calmed down and my husband went to work. When I came home from work, the Boykin was fine, but my Pom had urine all over him. I gave him a bath and he went to sleep on the couch beside me. He started having a seizure about an hour later and I called the vet. He didn't seem to think it was a seizure and sent me home. After the vet's office closed, he started having one seizure right after another and didn't stop. We took him to the emergency clinic with the Certifect box in hand. They bathed him again in detergent and put him on an IV all night to flush his system. I took him to my vet (the owner) the next morning and he told me not to use the Certifect anymore. I got a refund from the office and the vet contacted Merial. They said they hadn't heard of any problems. I googled Certifect and came up with several dogs with adverse reactions including seizures. Merial offered to pay my emergency clinic costs (over $500 and refund the med cost). I finally got the money this past Wednesday (the incident happened November 2, 2011). My vet no longer offers Certifect as there were multiple dogs in the practice with hair loss and other adverse reactions. So BUYER BEWARE!!!