[OwnedByJezebel]

Very interesting.

I read recently that some heartworms have become resistant to the preventative treatments. Possible link? Do any of these apply?

1. The Heartguard isn't working as well because of the development of resistant heartworms (although the article states that they knew of the problem over 10 years ago, so I doubt that is the case). Or,
2. Maybe the partially effective Heartguard allowed only the strongest strains to survive, resulting in the outgrowth of the resistant strain. Or,
3. Maybe there aren't any resistant new heartworm strains, but the possibility was put out there as an excuse for the failure of the Heartguard. Or,
4. Maybe there is Heartguard failure and there are new resistant strains of heartworm, but there is no connection.

I just wonder. And I'm glad that I use Sentinel. I've given it to 5 dogs without any problem, they've tolerated without incident.