Why does my dog have blood in his poop?

Original Question: For the past 2 months our dog has been having bloody diarrhea with mucus. We have gone to the vet several times where they have completed X-rays, fecal samples and both were negative - they also gave him a de-wormer. Medicine has also been prescribed for nausea, vomiting and diarrhea and they have changed his diet twice. He sometimes responds well to his medicine with a normal stool but after a couple of days he is back to a bloody diarrhea and mucus. The vet has also changed his diet twice to i/D Digestive Care Dog Food and now he is on Gastrointestinal Royal Canin Dog Food but nothing has worked. What do we do next and what could be causing this? - Kristian

Dec 26, 2018

Hi Kristian,

Thanks for your question.

These symptoms can be caused by many different disease states in the body. The bottom line is that you and your veterinarian have not confirmed the diagnosis yet. The tests you mention are very limited in their ability to diagnose many of the possible causes. You have only looked for the presence of parasites with the fecal test and any structural abnormalities with the radiographs. These are very specific diagnostic tools that have the potential of detecting a limited range of possible causes.

Here is what I would recommend you speak with your veterinarian about:

Perform general wellness blood work and urine testing to evaluate whether your dog is demonstrating an infectious reaction, organ dysfunction, inflammatory reaction, electrolyte problem, protein-losing condition, etc. This will also help you assess how his body is coping with this ongoing diarrhea. He may be dehydrated or malnourished which this has the potential of confirming. This type of broad testing is an early step and it allows a diagnostician to focus on an area of the body if there is an abnormality. It can help direct a veterinarian as to what diagnostic step would be next and potentially most valuable.
Consider performing a fecal culture to see if there is a particularly uncommon or resistant bacterial infection causing this.
Consider discussing the value of a treatment that is aimed at solving colitis specifically. I would name this medication but my license does not allow it. I want you to know I don’t like mentioning this option because I would highly recommend confirming a diagnosis before implementing a treatment. If you would want to continue along this line you could consider a probiotic as well. But again, you have already tried a treatment and it isn’t working so I strongly suggest you focus on diagnosing the condition.
Consider performing an ultrasound which is much more valuable than an X-ray for finding a structural abnormality.
Discuss with your veterinarian the value of an intestinal biopsy.

These tests should bring you a lot closer to a confirmed diagnosis. I think in order to address this you’ll need an actual diagnosis before you initiate another treatment based on an assumptive diagnosis.