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My dog has black, tarry diarrhea and won't eat. Is it serious?

Updated on September 23rd, 2025

Pet's info: Dog | Mixed Breed | Male | unneutered | 9 years and 1 month old

My dog has black diarrhea that is like tar. He also won't eat, not even bread.

5 Answers

Most Helpful Answer

Answered By Andrea M. Brodie, DVM

Veterinarian

Published on February 15th, 2016

Black tar-like diarrhea is a sign of digessted blood and a serious condition that needs to be checked out by a veterinarian. This could be caused by ulcers, a tumor an injury to the upper airways with blood being swallowed, or an esphageal bleeding. Your dog needs to be seen by a veterinarian now, who will do blood tests, radiographs. Your dog may have to be hospitalised.

41Pet Parents found this answer helpful

Related Answers from Veterinarians

Answered By Dr. Massimo Orioles, DVM, Cert AVP, MRCVS
Veterinarian
Black tar diarrhea may be compatible with gastrointestinal hemorrhage, usually in the first part of the gastrointestinal system. Inappetence could be as well compatible with a gastrointestinal disease.

I would strongly recommend to take him to your veterinarian as soon as possible for a check up and more investigation performed to identify the underlying cause.

Your veterinarian may want to perform radiographs or ultrasound of the abdomen.
31Pet Parents found this answer helpful
Answered By Dr. Elizabeth
Veterinarian
Published on June 9th, 2019
Black tarry stool can indicate blood within the gastrointestinal system and this is serious. See this link about dog feces:
https://www.petcoach.co/article/the-real-scoop-what-is-your-dog-s-poop-telling-you/

I recommend to have Harley examined by a veterinarian today. It's best to play it safe. Best of luck.
1Pet Parents found this answer helpful
Answered By Dr. Elizabeth
Veterinarian
Published on June 26th, 2019
Rita needs to be examined today. Black stool can indicate bleeding in the gut which is very concerning. Here is a link about stool:
https://www.petcoach.co/article/the-real-scoop-what-is-your-dog-s-poop-telling-you/

Bring in a sample of fresh stool for examination. Best of luck.
1Pet Parents found this answer helpful
Answered By Tomasz Wnuk
Veterinarian
Published on May 13th, 2018
Yes, black poo is always a concern as it means that there is a bleeding in the small intestine or stomach. The bleeding could be from infection, which is commonly seen in UK, but it could be a sign of stomach or gut ulcer or even a tumour in the gut. Please, take Alfie to your vet to check him over and to run bloods to see how concerning is the bleed.
1Pet Parents found this answer helpful

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