Locally-Owned in Oakdale and St. Paul, Minnesota

Heartworm Prevention: Mosquitoes are Coming!

heartworm disease, heartworm prevention, pet health, pet wellness, pets, pet parents, Minnesota pets, Animal Emergency & Referral Center of Minnesota

It’s easier to prevent heartworm disease than to treat the life-threatening heart and lung disease that can follow. To learn more about Heartworm disease, please talk to your family veterinarian, read our Heartworm Disease blog, or visit the American Heartworm Society.

How do we prevent Heartworm disease?
Regular preventative medication and Heartworm disease screening.

How do you use heartworm prevention? 
The majority of products are monthly pills or topical medications that kill the young stages (larvae) of adult heartworms. They work retroactively. For example, the dose that you give in April is aimed at killing larvae that have been transmitted in March. This is different from flea and tick preventatives that work proactively by preventing infestation of fleas and ticks for the month after you apply a topical preventative.

Some examples of active ingredients in heartworm preventatives include:

  • Ivermectin: Heartgard ®, Tri-Heart ®, Iverhart ®, HeartShield ®
  • Milbemycin Oxime: Sentinel ®, Interceptor ®, Trifexis ®
  • Moxidectin: Advantage Multi ®
  • Selamectin: Revolution ®, Paradyne ®

What if I can’t remember to give a monthly medication? 
If a once-monthly medication is just too difficult to remember to give, there is another option. ProHeart6 ® is an injectable, long-acting dose of moxidectin heartworm preventative for dogs. This injection is administered by a family veterinarian and designed to prevent heartworm infection for 6 months.

How many months do I need to give my pet his/her preventative medications?
The American Heartworm Society recommends:

  • Dogs: YEAR-ROUND use of heartworm preventative medications and annual testing.
  • Cats: For cats living in a heartworm risk area, YEAR-ROUND use of heartworm preventative medications is safe and effective. Indoor-only cats may also be at risk since mosquitoes can get inside the home. Speak with your family veterinarian about heartworm testing (not as simple as testing in dogs) and heartworm prevention for cats in very low-risk heartworm regions.

How do I know if I live in a high-risk or low-risk area? 

The American Heartworm Society map below shows data acquired from 2013-2016 on specific numbers of heartworm positive cases by region. Visit their website for more maps and information.

The Companion Animal Parasite Council map below shows data acquired from dogs tested in 2016 for Heartworm disease in the United States by two major laboratories. Visit their website to view Heartworm disease data from years past or even different parasites (i.e. tick-transmitted, intestinal parasites) of your interest.

Why do I need to give preventative medications year-round? 
Weather patterns are always changing, especially in Minnesota. Sometimes we have later winters or earlier summers. Giving heartworm preventatives only in the typical summer months would provide insufficient protection for your pet.

Also, heartworm preventatives often contain additional products that serve as intestinal parasite deworming. This is essential for households with children, elderly, and immunocompromised people since pets can transmit intestinal parasites to people.

Do I need a prescription for heartworm preventative? 
Yes. The Food and Drug Administration (FDA) has labeled all heartworm prevention medications to be used and/or prescribed by a veterinarian.

Do I really need to test every year?
Yes. Preventatives are excellent, but they’re not always 100% effective at prevention. In addition, some parasites are developing resistance to anti-parasite drugs. There is ongoing research into this topic, but we know that inappropriate use of anti-parasitic drugs (just like the inappropriate use of antibiotics) can worsen resistance problems. Experts recommend year-round use of heartworm preventatives, rather than partial year administration. 

There’s an added benefit to annual testing – tick-transmitted disease screening for dogs. Many commercially available heartworm tests for dogs also include exposure to the most common type of tick-transmitted diseases (Lyme, Anaplasma, and Ehrlichia).

heartworm disease, heartworm prevention, pet health, pet wellness, pets, pet parents, Minnesota pets, Animal Emergency & Referral Center of Minnesota

If you have any questions about Heartworm disease or heartworm prevention, we encourage you to consult with your family veterinarian. We hope your pets have a healthy spring and summer!




  • This field is for validation purposes and should be left unchanged.
Oakdale St. Paul Text Us