I have been using Interceptor for my heartworm preventitive since I have had my dog. Just tried to re-order from the vet and they said Novartis has quit making it for a while due to some quality control issues. Supposedly, what's on the market now is o.k., but the vet says they can't get any for a while. Novartis keeps pushing back the date they are supposed to start making it again. I was just curious what is another good option to Interceptor? Never had any problems with it, but start wondering when QC issues arise. Vet is recommending Iverhart (spelling??). Anybody had any issues with it?