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My kitten has diarrhea. How quickly does metronidazole work?

Updated on September 23rd, 2025

Pet's info: Cat | Domestic Shorthair | Male | unneutered | 2 lbs

So I took my foster kitten to see our shelter vet today as he has had explosive diarrhea lately. She didnt seem interested in determining the cause and instead gave treatment for the symptoms; however, I expected this. She prescribed 0.6 ml of liquid metronidazole BID and 0.3 ml propectalen 2 to 3 times daily. He tested neg for parasites by the way. About how long will it take the metronidazole to work? I hope not long due to concern for dehydration. I am giving SQ fluids though.

2 Answers

Most Helpful Answer

Kevin Sanada, DVM

Answered By Kevin Sanada, DVM

Veterinarian

Published on May 30th, 2018

I wouldn't be too hard on the vet in this case, because shelter vets are quite used to treating these cases and metronidazole kills most of the offenders for causing diarrhea.

You are right to be concerned about dehydration and how quickly the treatment should work. In most cases the diarrhea will improve within a day of starting treatment. It may be 3-5 days before his stools are back to normal though. If the explosive diarrhea continues for longer than a day after starting treatment and/or the kitten seems to be very depressed/inactive, then it would be best to return him to the shelter. There are some cases that require hospitalization, but I can assure you that most are treated well at home with the prescribed protocol.

For now, I recommend following the veterinarians directions and calling the vet tomorrow if he seems to not be getting any better, or seems to be getting worse. Below is a link to an article about diarrhea in cats that may be helpful.

https://www.petcoach.co/article/most-common-causes-of-diarrhea-in-cats/

I hope that helps and the foster kitten gets better soon.
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Related Answers from Veterinarians

  • Answered By Kevin Sanada, DVM

    Veterinarian

    Published on September 11th, 2017

    It's good that the blood is gone, because it shows that some form of the infection was controlled. The runnier stool is not expected though and indicates that there may be some other cause of the diarrhea. Kittens tend to get a few different bugs (bacteria and parasites) at that age, so the Metronidazole may have cleared one infection, but didn't help the other.

    Runny stool is concerning for dehydration, so it's best if you can get him rechecked by the vet sometime soon. It's not an emergency, but he should be seen within the next day or two in order to keep him from getting dehydrated.

    I hope that helps and Fridge gets better soon.

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    1Pet Parents found this answer helpful

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