Dogs can experience hematochezia, too. Usually for them, it is not a sign of cancer. It could be anything from sudden changes in food to trying to pass a sharp object they ate. In my dog’s case, the bloody stools were caused by worms.
I was walking my dog in the park, and I had to scoop up his feces and dispose of them properly. This is when I noticed the blood.
I took him to the vet right away, fearing some deadly condition was to blame. I was so happy to learn that he only had hookworms. She gave him a dewormer, and I bought some medicine to prevent the worms from returning.