Quote Originally Posted by Spiritwind
Its late, so maybe that is why I'm not following this post, since I am tired and about to go to bed.. but i'm not sure what this had to do with the question?

Also, just kind of an extra bit of info.. even though heartgard is supposed to be safe at the normal recommended doses, you will find very FEW collie people that will used heartgard in non MDR-1 tested dogs. There have been a few Collie people who have claimed their dogs reacted to normal heartgard doeses as well... even though the study shows its supposed to be safe.
I was responding to the comments about breeders with pregnant collies and heartworm preventative use.

Heartgard has about a 1.1% reaction rate regardless of breed. Not all animals do well with all medications, heartworm preventative or otherwise.

All I know is we use Heartgard Pluls or Tri-Heart Plus alot where I work including with collies and I've only ever seen one dog, in 7 years, have an actual reaction to them and it was a shepard/lab mix as I recall. We've had dogs of all breeds on different heartworm preventatives while pregnant and never seen a problem either. I suppose that could be coincidental but that's an awfully high percentage just to be coincidental to me considering the number of patients we have on those meds.