Heartworm Preventatives with Snow on the Ground?! Why Minnesotans should use Heartworm Preventatives Year-Round

Minnesota is known for a couple of things: much of the year it’s cold & snowy, and our state bird *should* be the mosquito!

Heartworm disease is transmitted from an infected animal to another through a mosquito bite. This means trouble in the summer, but how can your pet get infected in the winter? The simple answer is mosquitoes are unpredictable. In the winter they can survive in your home. Their eggs can hatch earlier than anticipated in the spring and the adults can linger longer in the fall. We can’t guarantee our pets aren’t being exposed to mosquitoes at any given time.

The more alarming, and likely more common reason is inconsistency with giving heartworm preventatives. Contrary to popular belief, the monthly heartworm preventative you give does not protect your pet against any future infections. For example, if you give your heartworm preventative seasonally and give the last dose on November 1st, your pet will not be protected for any mosquito exposure in November.

Instead, preventatives work backwards to treat your pet for any heartworms they’ve already been exposed to before the worms can develop into adults. You read that right, the heartworm preventatives are actually deworming your pet of the infection they’ve already contracted. Therefore, the heartworm preventative given on November 1st, actually kills any microfilaria (immature heartworms), that have infected your pet in the previous 30 days.

Because of our erratic seasons in Minnesota and the complicated life cycle of the heartworm, the American Heartworm Society recommends giving a monthly heartworm preventative at least 3 months after the last mosquito. For us Minnesotans this may mean giving preventatives until March. However, that’s when temps warm up and those pesky mosquitoes begin to appear!

All in all, it’s best to give a monthly heartworm preventative year-round in Minnesota. When buying from a licensed veterinarian in bulk, you will receive exclusive discounts and a manufacturer guarantee. Unfortunately, the animal preventative medication industry is quite unregulated and a hot spot for counterfeit products. Guarantee you are spending your money wisely and, more importantly, protecting your pet by purchasing any pet preventative from a licensed veterinarian.