Anyone ever have their dog break out in hives after applying flea meds such as Advantage or Frontline? I have used Advantage on Dixie since summer of 2007 (only when needed, not necessarily monthly during flea season) with no problems that I noticed. I applied it Thursday after I saw a flea on Grace. About 24 hours later she broke out in hives that I ended up having to have treated at the after-hours vet. Then Sunday night it happened again - back to the doggy ER we go. Other than her rabies vaccine on the 22nd, nothing has changed. Could it be the Advantage? Thoughts?