I use Revolution for Puppies and Kittens. That includes the heartworm prevenative. My 5 lb. Rosie is very sensitive to flea meds and heartworm meds and she has gotten along just fine with the puppy Revolution. Good luck.
__________________ Joanne  Eli  Chipper Eva  Snowboy Rosie(R.I.P. 1996-July 29, 2013) Cocoa(R.I.P 1998-April 26, 2012): |