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Why is my dog's poop yellow after metronidazole for diarrhea?

Updated On September 23rd, 2025

Pet's info: Dog | Miniature Poodle | Female | spayed | 2 years and 11 months old | 10 lbs

Hello, my three-year-old Dog recently presented with bloody diarrhea. I took her to the vet that same day. The vet prescribed metronidazole 250 mg a day. Yesterday this was the color of her poop. Is this a normal side effect? Does it have anything to do with the medication? Is this an emergency?

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2 Answers

Most Helpful Answer

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Answered By Jennifer Summerfield, DVM CPDT-KA

Veterinarian, Certified Dog Trainer

Published on April 12th, 2020

I agree that this poop is quite a bright color yellow! This is not normally caused by metronidazole, so it's hard to say why it might be happening. Poop can sometimes be yellow or orange in color, and it may not mean anything in particular... so I wouldn't necessarily be concerned unless it stays this was for several days in a row, or she's having other symptoms of a problem. If she's still acting normal and this stool is improved vs. yesterday (which I'm assuming it is, since it definitely looks better than bloody diarrhea!) it should be okay to continue on her meds as prescribed by your vet, and monitor for the next few days. If her stool is not back to normal within the next 3-5 days, or if she develops other new symptoms in the meantime, then I would recommend having her rechecked by your veterinarian.

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Other Answers

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    Answered By Kevin Sanada, DVM

    Veterinarian

    Published on December 10th, 2017

    Yellow poop is generally not concerning and may indicate that he is recovering. Black or red poop is more concerning; especially if it's loose/watery and frequent. If the stools are starting to be more formed, then this will also be an indication that the treatment is working. I hope that helps and Toby gets better soon.

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