Why your dog needs heartworm prevention all year long
One of the most common questions asked by animal guardians is whether monthly heartworm medication needs to be given year round, even in the colder winter months. While heartworm disease is transmitted by mosquitoes, there have been increasingly warmer winter months in recent years which has led to the appearance of mosquitoes even in colder months. However, in order for mosquitoes to transmit the infectious larval stages of heartworms through a bite, the average ambient temperature typically has to be 65 degrees or higher for 30 consecutive days, even in the winter months.
My late professor and well-respected veterinary cardiologist and first president of the American Heartworm Society, David Knight, spoke and wrote about this idea quite often. Most of the heartworm prevention medications also contain other ingredients that help control and prevent intestinal parasites, which can be seen any time of year; therefore, it is still recommended by most veterinarians to administer monthly heartworm medications year-round, even in the cooler climates, as many of these intestinal parasites are what are called zoonotic diseases, meaning that they may be transmitted to people. Additionally, while rates of heartworm infection can vary from year to year, heartworm disease has been diagnosed in all 50 states. The American Heartworm Society (AHS) recommends a year-round heartworm prevention program, even in regions where winters are cold, as well as in dry desert states with “few” mosquitoes.
Most pets tolerate monthly heartworm oral medications quite well, with only rarely some sensitive dogs reacting to some of the stronger combination oral preparations. In those circumstances, I have found that the topical preparation, Revolution, is often well-tolerated by even the most sensitive of animals. While holistic clients may seek our herbal alternatives such as quassia bark or black walnut, these have not been studied for long term safety; therefore it is recommended to administer heartworm medication to pets year round with an approved prescription product.