Bests & Worsts Reviews from Amazon

After placing Bayer Seresto Flea and Tick Collar on my extremely healthy 6-year-old indoor/outdoor cat, over three or four days he gradually became extremely lethargic, ultimately was in apparent pain (moving very slowly, arching back, turning often to new resting position). He soon found a new protected area under a table on the floor and just slept all day for a couple of days, as if instinctively preparing to die. He was unresponsive to my offers to pet him, barely lifting his head in response to my touch. Removed collar, did not put any other collar on him, and within two or three days he was his old rambunctious self. I'm out $100 for two collars - never did put the other one on the other cat. So it goes. Think twice before purchasing!