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My dog ate Tri-Heart Plus heartworm medicine. Is it safe for her?

Updated on September 23rd, 2025

Pet's info: Dog | Mixed Breed | Female | spayed | 1 year and 1 month old

My 13mo old 10 lb. shorkie just ate 6 tablets of Tri-Heart Plus for dogs up to 25 lbs.I haven't been able to locate a vet that is open this time of n.

4 Answers

Most Helpful Answer

Dr. Melanie, BVSc MS

Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on June 23rd, 2016

You did exactly the right thing by calling around to vets to ask for help right away. It's always best to check when you aren't sure, and are worried about your pet. The Triheart dose that we give dogs for heart worms has very small doses of the two medications that are in it. Ivermectin is one of the medications that is in the Tri heart. The dose is 68 micrograms. Veterinarians use this medication also to treat dogs with skin mites and use a dose over 100 times the dose in one heart worm preventive tablet. Therefore, even if she would have eaten two or three boxes of the Triheart she should be very safe and there is not any risk of an overdose of the ivermectin. The other medication is called pyrantel pamoate which is used for deworming of intestinal parasites. This medication has a very large safety margin also, and can be given at 10-20 times the normal dose without any risks of toxicity. Therefore, just like with the ivermectin in the Triheart Plus, I would not expect any potential side effects either. These potential side effects could include an upset stomach, mild diarrhea, and/or vomiting. Monitor her for those side effects, and bring her into your vet in the morning if you are still concerned.
Vote Icon51Pet Parents found this answer helpful

Related Answers from Veterinarians

  • Answered By Andrea M. Brodie, DVM

    Veterinarian

    The TriHeart dose that vets give dogs for heart worms contains a very low dose of Ivermectin and pyrantel pamoate and at the dose your dog ate the TriHeart, there is extremely little chance that she will get overdosed. Both medications have a very large safety margin and I would not expect any potential side effects

    Since she ate a large amount of chews she may get an upset stomach, although this is unlikely also. Watch for mild diarrhea or vomiting, just in case.

    Vote Icon

    30Pet Parents found this answer helpful

  • Answered By Dr. Melanie, BVSc MS

    Veterinarian

    Published on April 17th, 2019

    No need to be concerned! Heartgard is a very safe medication, and toxicity is only seen if the dog is given an excessive amount of the medication, like 10-20 times the recommended amount. Barry Allen will be fine.

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    1Pet Parents found this answer helpful

  • Answered By David Elbeze, DVM, MRCVS

    Veterinarian

    Published on December 8th, 2016

    The amount of Ivermectin, which is the potentially toxic ingredient, is still very low in those tablets, you should not see any signs of toxicity even after the ingestion of a double dose.

    Just in case, here are the signs you should be aware of, if you see any of those you should take him to the vet right away:

    depression, ataxia, tremors, drooling, paresis, recumbency, excitability, stupor, coma

    Vote Icon

    2Pet Parents found this answer helpful

Smart Picks for Smart Questions

Health & Wellness
My dog ate Tri Heart Plus. How long until it's out? Side effects?
Side effects that could be caused by this type of intoxication are mainly gastrointestinal like vomiting and diarrhoea. If that is the cases, start feeding with a bland diet based on boiled chicken and rice in small portion every 6 hours for the following 48hours. Then gradually reintroduce the normal diet over 5 days. I would definitively recommend a veterinary check up if you notice persisting diarrhoea, vomiting, lethargy or inappetence. Unfortunately these medications are designed to last for long time in the body as they are usually due once a month (so it will take approximately one month to be completely out).
Updated on September 23rd, 2025
Health & Wellness
My dog might have eaten an extra Trifexis pill. What should I do?
Hi there. Trifexis has a very wide margin of safety (a dog could eat an entire box and not have any serious issues, in most cases), so it's unlikely that this will cause any problems. The most likely side effect would be vomiting or GI upset, in the first day or two after taking the meds. If she's acting normal so far, you probably won't see any issues at all. It's fine for her to continue with her normal daily routine as far as eating, exercising, etc.
Updated on September 23rd, 2025
Vet Q & A
My dog ate too many Heartgard Plus pills. Should I call the vet?
Heartgard Plus has a very high margin of safety, so I would not expect this to cause any serious problems. I would recommend monitoring her for the next day or two to make sure that she's acting normal, but otherwise you shouldn't need to do anything different :) You can go ahead and give her next dose on April 15th as scheduled.
Updated on September 23rd, 2025
Health & Wellness
My dog accidentally got a double dose of Trifexis. Is she safe?
This medication contains a combination of Spinosad and Milbemycin. Milbemycin can be used safely in dogs for heartworm prevention but has other uses as well, and can be given at a dose two to four times the normal dose that we use for heartworm prevention, so I would not worry at all about a higher then normal dose of that medication. Spinosad is used for flea prevention and is a relatively safe drug. The most common side effects seen with its use include a decreased appetite, vomiting, diarrhea, lethargy and rarely, in dogs with a low seizure threshold, possible seizures. Studies on research dogs showed no long term effects on dogs that were given TEN times the recommended dose. Side effects that were seen at that high dose included nausea, vomiting, a decrease in appetite and some diarrhea. She will probably be OK but all you can do at this stage is monitor her for any signs of toxicity. If any are noticed she needs to see a vet immediately.
Updated on September 23rd, 2025
Medications
My dog accidentally got an extra dose of heartworm medicine?
If it was Heartgard, there is no cause for concern. It is an extremely safe product and very difficult to overdose. If it was a different preparation of ivermectin, a double dose may not be cause for concern unless your dog is sensitive to it or carries the MDR1 gene. Typically, a non sensitive dog requires dosing around 2000mcg/kg before clinical signs become apparent. See your vet for an exam as soon as you can if you are concerned. Bring the container of ivermectin with you. Treatment for ivermectin toxicity is supportive in nature. Monitor for vomiting, excess salivation, ataxia (wobbly gait), dilated pupils or tremors.
Updated on September 23rd, 2025
Health & Wellness
My dog ate extra Heartgard. Is he safe? Will the heartworm medicine work?
Hello, thank you for using PetCoach. I understand your concern but Max should be just fine. It does not appear that he got an overdose. If he was a breed with a known sensitivity to Ivermectin I would be more worried (herding dogs, collie breeds, etc). Here is a link to Ivermectin toxicity so you can know what to watch for but I don't think he will have any issues. Usually they will present with neurological symptoms. As always, if you are worried you should take him to your vet for an exam. ( http://www.pethealthnetwork.com/dog-health/dog-diseases-conditions-a-z/ivermectin-toxicity-dogs ) The treatment will still be effective. Don't worry about that! Hope this helps. Best wishes. If you have more questions please feel free to post again.
Updated on September 23rd, 2025
Medications
My dog vomited after Trifexis heartworm medicine. Is she safe now?
If Grace has been entirely normal since the episode of vomiting I don't think you have anything to worry about. Of course, continue to monitor for any signs of ill health like vomiting, diarrhea, lethargy, or inappetance. Thanks for using Petco Pet Education Center, formerly Petcoach and best wishes to you and Grace!
Updated on September 23rd, 2025

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