Get Your Dog Care Questions Answered by Experts
Hello. I'm sorry for the long wait.
It's not too uncommon for dogs to develop a stress colitis after anesthesia. This could lead to the bloody diarrhea you are seeing. I would ideally get him started on a round of Metronidazole. This is an antibiotic and also an anti-inflammatory in the gut. It should get this resolved fairly quickly.
I hope this helps, let me know if you have any other questions.