Can Heartworm Preventatives be Given Late?

photo 2006 rikkis_refuge | more info (via: Wylio)Last night as I entered dreamland I was startled awake by a revelation: it was already the 5th...


London the houndphoto 2006 rikkis_refuge | more info (via: Wylio)
Last night as I entered dreamland I was startled awake by a revelation: it was already the 5th of the month and my pal Buster hadn’t yet received his Heartgard Plus.*

I, like many people, administer flea and heartworm medications on the first day of each month. That date generally makes it easier for me to remember the task. Obviously, however, first-of-month administration is not a guarantee — witness my experience from last night.

It turns out that many people have this experience. People often ask me what they should do if their dog’s Interceptor, Sentinel, or Heartgard Plus is a few days late.

My recommendation, if the medication is late by one week or less, is to do exactly what I did last night. I got up, gave Buster his medicine (which delighted him — he thinks it’s a treat), and went back to sleep without worrying at all. I will administer his next dose on schedule on May 1.

Monthly heartworm medications can be given one week late without causing any increased heartworm risk.

Many experts believe that the medications actually can be given two weeks late without leading to increased risk of infestation, but in my opinion that is pushing things just a bit. If your pet’s heartworm medication is more than one week late, I recommend that you contact your vet.

*Forgive me for sounding like a broken record, but I seriously feel pain every time I write the word Heartgard. A desire to create a brand is not, in my opinion, a valid reason to misspell the word guard.

3 thoughts on “Can Heartworm Preventatives be Given Late?”

  1. 1. Who writes this? I doubt your name is "Dogster" ("By Dogster, April 6, 2011.") 2. Do you ever answer people's questions? We shall see!

    By the way, if you have something important to ask regarding your dog (like the 2 comments already asked on here), this is NOT the place to ask it. You should be calling your vet and asking questions about situations that could potentially adversely affect your dog, not asking here. You should also notice that this article was posted in 2011, and you have asked important questions in 2021 and 2022. You don't know who this person is, if they're giving you valid information, or even if things have changed in the past 10/11 years! Ask your vet instead. Do it for your dog. They deserve better!

  2. I was considering letting my friend adopt my dog and we agreed to a trial yesterday, and today she announced that she was not going to order the heart guard medication from the vet where he already has a prescription waiting. Instead, she was going to order it to 800 pet meds and it will take approximately two weeks to mail them a prescription and to get the heartworm medicine back. In the meantime she does have medicine that she could cause it was prescribed for a larger dog, but she doesn’t want to do that. I would Love the back from a vet as to their Recommendations.

  3. Every time I give my dog Heartgard he has a horrible seizure within a week. Most times it’s just a few days. I hate giving him it. The vet say it’s better than getting heart worms. Can’t we find something that prevents heart worms but doesn’t cause seizures? Is that too much to ask ?

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