Q: Is there a way to protect my dog from heartworms without paying for the yearly checkup and heartworm medicine?
A: Yours is an excellent question that touches on a legal issue about which most pet owners are wholly unaware.
The general answer is “yes.” As a consumer, you are able to purchase ectoparasite control products (topical) for both dogs and cats, over-the-counter (OTC) at most pet retail outlets. A product that comes to mind specifically is k9 Advantix II. The labeling on this product advises it “repels mosquitoes.”
As dirofalaria immitis (heartworm) is vectored (transmitted by) mosquitoes (different species of culicid mosquitoes — Culex spp., Aedes spp., Anopheles spp. — may act as a vector), theoretically this particular product may prevent heartworm. However, I must qualify here: I do not recommend, nor stock, nor sell any of the Bayer Animal Health ectoparasite control products. Thus, I cannot tell you with any amount of anecdotal experience that this particular OTC product prevents heartworm transmission and/or infection.
Furthermore, the core issue of your question is what is referred to as the “Veterinary-Client Patient Relationship”. The VCPR is recognized as a legal standing. By law, no veterinarian may prescribe any non-OTC drug to any patient they have not seen for a physical exam within the past 12 months. Therefore, the answer to the second part of your question is “no.”
However, if your dog is seen by his veterinarian and you purchase a 6-month supply of ectoparasite control at that visit, you may purchase an additional 6-month supply 6 months later, without the need for a physical exam of your dog by his veterinarian.