Some argue, but...
As the co-moderator of an e-mail list on dog health and nutrition, I frequently see people allege that as long as you have a healthy dog, feed a raw diet, and do not over-vaccinate, your dog will not get heartworms. If only this were true! These measures may help to some degree, but they are not foolproof. The only way to know for sure that your dog is protected is to give heartworm preventatives.
Christie Keith, who lives in an area of Northern California where heartworm is relatively uncommon and has raised Scottish Deerhounds naturally for over 19 years, learned this the worst way.
â€œI went 16 years not using any form of allopathic preventative on my dogs. At the end of that 16-year period, on routine testing, I found that two of my dogs were heartworm-positive,â€ says Keith. â€œOne of the positive dogs was Raven, a Deerhound I bought from another breeder. She came to me at 17 weeks with bad ear infections and severe allergies, and no one could argue that Raven was healthy or had a normal immune system.
â€œIn contrast, my dog Bran was a third-generation, naturally reared dog of my own breeding. He was unvaccinated other than minimally for rabies. He was raw-fed. His mother and her mother were raw-fed and unvaccinated other than minimally for rabies. He was, by any definition available, extremely healthy and robust. He had never been sick a day in his life.â€
Christie successfully treated both her dogs, though Raven almost died of a pulmonary embolism during treatment. Bran became heartworm-free after months of using the â€œslow killâ€ method of heartworm treatment, with no sign of any adverse effects. Unfortunately, Bran died of acute renal failure not long after that. Necropsy results were inconclusive, showing that Bran had glomerulonephritis, but not why.
In her research to try to find the cause of her dogâ€™s death, Christie discovered that glomerulonephritis is a potential side effect of heartworm infection. Although she and her vets eventually came to the conclusion that Branâ€™s renal failure was caused by Lyme nephritis rather than heartworm disease, it was disturbing to realize that heartworms can affect more than the heart and lungs.
â€œI have no intention of ever living through what I lived through with Raven and Bran. I canâ€™t keep silent when I see people starting to believe that healthy animals donâ€™t get heartworm and that we can blithely forgo using preventatives if we donâ€™t overvaccinate and feed raw. Itâ€™s just not so. And itâ€™s not realistic to rely on the health and natural disease resistance of our dogs to protect them from a threat that they are exposed to frequently, as is the case in heartworm-endemic areas.
â€œNo creature is in a static state of health 24 hours a day, 7 days a week. If our dogs are frequently exposed to an infectious parasite, eventually they may well succumb to it, no matter how healthy they are normally.