I have recently read a number of things against proheart 6 unfortunatly I am not feeling to well.I was in an accident this past fri and I was just dropping in to check on everyone for a minute.I really can't remember the pro's and con's but I think there were some health risks try checking it out online before you give it to your babies.I use interceptor and have for a while.My daughter used heartguard but switched due to the possibility that her dog got whip worms and ours were safe from the interceptor.They are all scary to me along with the vaccines but some are very neccessary so I try and research and use those with the least side effects.Good luck.I am sorry I can't be more specific tonight.
Laurie