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What to Do If You Missed a Heartworm Dose

Did you miss a dose of heartworm prevention medicine?

Don't panic! Here's what to do if you missed a dose.

If you've missed a dose of heartworm prevention medicine, there are several things you need to take into consideration before starting your pet back on heartworm preventatives.

However, in the case that your pet has never been on heartworm prevention it's important that you learn how to get started right away. Heartworm disease has been reported in all 50 states year-round. Monthly heartworm preventatives can help your pet avoid this potentially deadly disease.

Why is it important to never a miss a heartworm dose?

The American Heartworm Society has recommended year-round heartworm protection, without missing a dose. A missed heartworm pill leaves your pet exposed to becoming infected, which can happen even in winter. Making monthly heartworm medication part of your pet's health care regimen makes it easier to remember. Of course, mistakes happen and sometimes pet parents forget a dose. However, it may help you to remember if you consider that:

  • Heartworm disease is deadly...but preventable.
  • Heartworm disease has been documented in all 50 states throughout the year.
  • Heartworm infection can cause varying degrees of heart and lung pathology in dogs and cats.
  • Heartworm disease can lead to various symptoms from exercise intolerance, coughing, possible heart failure, vomiting, lethargy, abdominal distention, and in some cases, scarily enough, sudden death.
Do I need to get my pet tested immediately if I missed a heartworm dose?

Many times pet parents are given inappropriate information by both their friends and maybe even some veterinarians. It is not necessary to have a pet immediately tested for heartworms if they have missed one month of heartworm medicine. The reason for this is because it takes at least 6 months for a pet to become heartworm-positive if he or she is bitten by mosquitoes carrying heartworms. This means that even if your pet has become infected during the time that you missed a heartworm dose, test results would not show as positive until 6 months after the initial infection.

What if the dose is just a few days late?

Most of the monthly heartworm medicines have a safety factor of at least 15 days of protection if a dose is missed. This means that if you're just a week or two late, your pet is likely still within that window of protection and would be unlikely to become infected during that time. In this case, it would be fine to just resume giving your pet heartworm prevention medication as usual.

What if my pet has missed a month of heartworm prevention?

The simplest answer to those who miss a month of heartworm prevention is to give the dose immediately and restart the monthly preventative schedule. At the time of an annual or semi-annual exam, a routine blood heartworm test is recommended, along with a complete wellness exam and/or vaccinations and other laboratory testing if appropriate. While pet parents are encouraged to maintain their monthly heartworm preventative scheduling, accidentally missing a dose will not be a health risk or harmful to their pets in these isolated circumstances.

If missing a dose isn't harmful, why can't I give my pet heartworm prevention when I want?

Pet parents shouldn't pick and choose their own schedule of monthly heartworm medication administration. Irregular use of many medicines such as prescribed antibiotics and/or parasitic medication may be associated with the development of resistant strains of parasites. It is hard to predict when heartworm transmission season ends or begins in many areas of the country. In fact, heartworm-carrying mosquitoes have been seen even in colder months in some areas of the country.

Being a responsible pet parent means consistently giving your pet proper health care, nutrition and love. Neglecting to protect your pet from heartworms unnecessarily exposes him or her to a deadly yet preventable disease.

Interested in more commonly asked questions about heartworm disease? Check out our heartworm disease FAQs resource.

Max's Tip

Innovations in heartworm and flea prevention can make it easier than ever to protect your pet against multiple parasites at once! Read our article covering combination heartworm & flea preventatives.

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