Hmmmm; always wondered about those "Rx: Required" drugs you can buy over the 'net...

I used an application of Frontline Plus on both Cinder & Smokey last year when Cinder developed a tummy rash and a lot of itching. NO problems with either one of them. Can't remember the "Application Instructions", though. I wonder if you got "too much" in one place on his back?

I also think there are different "strengths" - depending on weight... Was the package marked with the right weight bracket for Mr Binx?

I'd suggest you ask the Vet before trying another application! *IF* he really is alergic to one of the ingredients - he *might have an worse reaction if given it again.