I live in Wisconsin at the tippy top right on the peninsula on Lake Superior. October-March it is below 60 degrees everyday (Dec-Feb it's commonly negative in temperature), but we do get the occasional "heat stroke" in October or March where it spikes to 60, sometimes 80 degrees for a day. I've had Gutie on heartworm medication every month, but my vet has suggested that Gutie doesn't need it when it gets below 40 degrees. She suggested that I just administer Pyrantel for those cold months for hookworms/roundworms since there are no mosquitoes to pass along heartworms. It also saves me $ if I do that (and it's in liquid form which is much easier to get Gutie to take it). May-October I would have him on full prevention. The vet said an annual screening for heartworm when he comes in for his annual shots should be enough?
What are you thoughts? I don't want to ever put my dog at risk, but I do trust my vet.