886 S Pine St, PO Box 277

Grantsburg, WI 54840

Phone: (715) 463-2536

1(800) 924-0588

140 Evergreen Square SW

Pine City, MN 55063

Phone: (320) 629-7474

It's Winter… Does My Pet Still Need Heartworm Prevention?


When winter arrives, one question that comes up is whether or not pets need to remain on heartworm preventative medicine. The fact remains: if you want to protect your pet from one of the most fatal and painful diseases, your pet should stay on heartworm prevention all winter long. But why?

Why Is Heartworm Prevention Just As Important In Winter?

Vacation Can Bring Fresh Threats

Do you plan on bringing your pet with you when you travel? If you’re planning to head for a warmer region, your pet may be exposed to mosquitoes and the threat of heartworms. 

Mosquitoes Can Hatch On Warm Winter Days

While our winters can be quite brutal, you can never predict when the weather will begin to warm or if we will have a warmer day. Mosquito larvae begin to hatch when the temperature reaches 50-degrees. This means that on a mild winter day, your pet becomes vulnerable to heartworms. 

Furthermore, mosquitoes lay their eggs in areas that may be protected from colder temperatures. Standing water in nearby garages, sheds, or porches may be a breeding ground for mosquitos. These chilly insects will hatch and seek out a warmer location, such as a house.

Heartworm Medication Continues to Kill Existing Larvae During Winter

If your pet contracted heartworm larvae in the fall, the medication you administer the following month kills those larvae. When you skip a month (or longer) it gives the larvae the opportunity to grow and develop into adult heartworms. From there, heartworm medication does not kill adult heartworms.

Heartworm Disease Is Fatal But 100% Preventable

Most importantly, you do not want to put your pet at risk of contracting heartworms, no matter the circumstances.

Heartworms grow and reproduce in your pet’s circulatory and respiratory systems, making it harder and harder to breathe over time. As they grow, they put additional strain on your pet’s heart and lungs, often damaging the connections and structures of these vital organs. When left untreated, a pet’s body cannot sustain itself while harboring heartworms.

Can’t My Pet Just Be Treated Should They Get Heartworms?

While there is a treatment for heartworm positive dogs, it is a complicated procedure that can be quite painful for dogs and expensive for their owners. The treatment usually consists of two treatments, four weeks apart. During this treatment, dogs receive an injection of melarsomine which kills adult heartworms, but the danger doesn’t end there. After dying the heartworms do not just disappear. Their bodies remain cycling through the dogs’ circulatory system, slowly breaking apart. These fragments can lodge in blood vessels, continuing to cause destruction. Under some circumstances, they can even cause heart failure. This is why dogs must remain on bed rest during the two months of heartworm treatment.

Even after treatment, many dogs will continue to suffer from the side effects of the initial infection due to permanent damage caused by heartworm.

There is no treatment for heartworms in cats.

Protect Your Pet’s Heart and Life

We urge pet parents to continue to protect their pets’ hearts all year long. When it comes to heartworm disease, you do not want to risk your pet’s health and life. If you have questions regarding your pet’s heartworm medication or you’re ready for a refill, we’re here to help. Schedule an appointment or order your pet’s medication online.

Photo Credit: Pexels.

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