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My new rescue dog has diarrhea with red mucus. What should I do?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed | Male | neutered | 3 years old | 14 lbs

I recently adopted a rescue dog. The first day home he barely ate. Day 2, he started to eat a little. Day 3 he has diarreha dark and once with red jam looking mucus. A few hours later it was a peanut butter brown. He is eating more. Note he is on meds for anxiety daily. Should I be concerned or wait until he gets settled in.

2 Answers

Most Helpful Answer

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Answered By Dr. Elizabeth

Veterinarian

Published on January 23rd, 2019

With these pups, there is always a potential for parasites or bacterial overgrowth to cause the symptoms. I would recommend to get Parks in for an exam and to have the stool checked for parasites. That is usually a good sign if you don’t see any more blood, which is what I’m concerned you were seeing in the stool. It’s better to be safe and also to make sure he doesn’t have any parasites to spread to his new human family. There are other causes for blood in the stool as well and these can vary from a new diet to internal organ damage. The first step is to rule out the most common things. I hope this is helpful and please feel free to post any additional questions.

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    Answered By Makenzie Kurth, DVM

    Veterinarian

    Published on June 11th, 2018

    Thanks for using Petco Pet Education Center, formerly Petcoach. And thanks for rescuing Cosmo! If he is eating and bright and happy, the following applies: Diarrhea with blood is a hallmark of colitis (inflammation of the colon). It is usually caused by rapid change in diet, eating something naughty (getting into trash/something outside), or stress (boarding, change in routine or household). Cosmo likely had two of those three so I am not surprised at all that this happened. The good news is that the amount of blood is almost never a concern. Now, if he is lethargic, there is vomiting, or the diarrhea seems to be pure blood, that is a different story and Cosmo should see the vet ASAP. Best of luck to you and the new addition!

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