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My dog missed heartworm medicine. Can I give another dose safely?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed Large (61lb +) | Female | spayed | 80 lbs

I can't remember whether or not I gave my dog her heartworm medication on April 27th, when it was due. I don't want to leave her susceptible to heartworm, but I also don't want to cause her to overdose.

2 Answers

Most Helpful Answer

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Answered By Angel Alvarado, LVT

Licensed Veterinary Technician

Published on May 5th, 2019

Most of the monthly oral preventatives have a wide safety margin. Heartgrad is very safe, so if that is the preventative you use, then a second dose will not be harmful. If you use a different medication, check with your veterinarian before giving another dose.

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    Answered By Angel Alvarado, LVT

    Licensed Veterinary Technician

    Published on December 27th, 2021

    Life happens, I am guilty of this myself! Do not worry, the likelihood of Aiko or your other dog(s) being harmed by the missed dose is very, very small. You can go ahead and administer the appropriate dose for each dog then carry on with the monthly schedule. Even if they already had a dose, a second dose will cause no harm as this medication has a very wide margin of safety. Consider creating a notification in your mobile phone as a reminder each month. You may also be able to register with the manufacturer to receive email reminders.

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