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Dog vomiting, diarrhea, shaking after restarting Trifexis. Vet needed?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed Large (61lb +) | Female | spayed | 2 years and 1 month old | 75 lbs

My dog has been taking Trifexis since she was a puppy, we moved and we had trouble finding a vet when she was out so she skipped a month. We just recently started her back on usual dose but she is having a hard time. She’s constantly vomiting, having uncontrable diarrhea, and she shakes and itches every once in a while. I need to know if this is super serious or if it will pass over. I don’t mind spending the money at the very if I need too but I also don’t want to pay 200 dollars if don’t.

1 Answer

Most Helpful Answer

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Answered By Dr. Heidi DVM, CVA, CCRT, CVTP, CVSMT, CVCH

Veterinarian, Certified Veterinary Acupuncturist, Certified Canine Rehabilitation Practitioner

Published on February 23rd, 2018

While we certainly can see GI upset with heartworm preventatives, it would be very usual for a dog to have the severity of the signs that you are describing (especially when she had previously not had any problems with it), so I would recommend having your vet examine Cookie to see what they think is going on. At the very least, it sounds like she needs some medication to stop the vomiting and diarrhea. Good luck! I hope that was helpful and that Cookie feels better soon. Thanks for using Petco Pet Education Center, formerly Petcoach.

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1Pet Parents found this answer helpful

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