My babies had a bad reaction to this product. My boy started walking sideways and with a limp as if he had a wooden leg (back, right leg). My girl was lethargic, kept trying to lick it off and slept more than usual. Neither wanted to eat, drink water or play. They were not behaving normally after I applied the Vectra
I washed them to give them some relieve and took them to the vet. The vet administered a Benedryl shot to both of them and told me to keep an eye on them for 48 hours and if they did not improve to call him.
Well, it didn't improve so I called the vet and took them back to the hospital. The vet told me to give them a bath that evening and another in the morning to wash off the med. I did that and 4 days later, it's getting better but my babies are still not 100%.
I'm going back to Frontline (the better of two evils)

Until I figure out how to get my babies off drugs while keeping them safe at the same time (a difficult balancing act)

I cringe every time I have to give drugs to my trusting little angels.