PetMeds® Missed Doses of Heartworm Medicine

Each spring many veterinary offices often get phone calls from anxious clients stating that they skipped their pets’ heartworm medication during the winter months, and are worried about starting their pets back on heartworm prevention without having their pet tested first. And while an annual to every other year heartworm test is certainly recommended, most pets can be routinely started back up on the monthly heartworm preventatives such as Heartgard or Iverhart without worry about safety or side effects. Heartwormpet meds can be restarted after several months of being missed, without worry about safety or side effects.

This decades long fear started when we used to use the old daily heartworm preventatives called filaribits. In those situations, it was critical that a pet be heartworm tested negative first, because there was the possibility of an acute severe reaction if a heartworm positive dog received filaribits. However, this is not the case with monthly preventatives, which in most cases are very safe to use, even in heartworm positive dogs. In fact, some veterinary cardiologists, may not approve the heartworm treatment drug (Immiticide) for a heartworm positive pet, but will on occasion prescribe monthly heartworm prevention in these pets as an acceptable alternative. With continuous use of Heartgard or Sentinel over 15 to 24 months, many pets can actually become heartworm negative.

Related Posts


  1. Wow, I didn’t know that heartgard could help lower heartworm treatment cost. Can you actually use it as a replacement for heartworm treatment? Thankfully, I don’t have to worry about this, since I already have all three of my dogs on heartgard, but I’m just curious. Thank you!

  2. Dr. Michael Dym, VMD veterinarianMarch 13, 2011 at 11:34 am

    Yes in many cases because of cost, age or sometimes risk to certain heavily infected or damaged older pets monthly heartguard over a period of 12 to 24 months can indeed treat and prevent further heartworm infestation although the approved method of immiticide is still preferable in treating active heartworm infection. Each case is different and should be evaluated by your veterinarian.

Leave a Comment