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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

Answered By Dr. Elizabeth
Veterinarian
Published on January 23rd, 2019
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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