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Why is there fresh blood and dark clots in my dog's firm poop?

Updated on September 23rd, 2025

Pet's info: Dog | Mastiff | Male | unneutered | 150 lbs

I have a 1-yr old intact male Mastiff. He has firm stools with fresh blood and dark maroon/black blood clots on it, at the first part of the stool that comes out. My vet has checked his stool twice in the past month(he’s had blood in his stool for a month) for parasites and came back negative. He thinks he’s too young to have anything serious but what could this be? He’s been on flea meds and dewormer for months. Any ideas? He's also acting fine.

1 Answer

Most Helpful Answer

Jeffrey Milner

Answered By Jeffrey Milner

Veterinarian

Published on July 28th, 2017

Hi, sorry to hear about these problems with your pup. First I would consider changing his food onto something for a dog with a sensitive stomach and se if that helps at all. Blood in firm stool can indicate straining so it's possible the food has too much fiber in it and is making his stool too hard. You can try a prescription diet made by Hill's called ID which is for dogs with sensitive stomachs. Also, you might want to look into an abdominal ultrasound or endoscopy to check for Inflammatory bowel disease. I don't think X rays will show up with much, i would go straight to the ultrasound. If they see anything suspicious, during endoscopy they can take biopsies. But then again, if he's not bothered by it in any way and keep on weight with a good appetite, it may just be food related or something he will grow out of. I would monitor him for those signs and pursue more diagnostics if you see them. Good luck, I hope this helps!
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