This depends on where you live. In order for the heartworm microfilariae (baby worms) to survive in the mosquito, temperatures have to be over 67F for 2 weeks. This could be most of the year in the south. In the north, not as much of the year. Heartworm disease is truly a devastating disease – it causes permanent damage to the heart. However, heartworm preventatives are chemicals, and I’ve seen a dogs have reactions to any of the medications available, from vomiting, to seizures, to death from inflammatory bowel disease. While these reactions are uncommon, it still gives me reason to recommend we prevent during the transmission season, not year-round, unless we live where it is always warm.
What else can you do to protect against heartworms? Don’t take your dog outside at dusk and dawn, when mosquitoes are most active. Feed a meat-based, balanced diet appropriate for your dog’s needs so his or her immune system is strong and can fight off normal things.
Dr. Cathy Alinovi DVM
As a practicing veterinarian, Dr. Cathy treated 80% of what walked in the door — not with expensive prescriptions — but with adequate nutrition. Now retired from private practice, her commitment to pets hasn’t waned and she looks forward to impacting many more pet parents through her books, research, speaking and consulting work. Learn more at drcathyvet.com