Diarrhea with blood indicates that your dog suffers from inflammation of the large bowel, known as colitis. Below are the most common causes for colitis in dogs this age. Please click on the links below for more information on these diseases. Should you seek a one on one consultation with a licensed veterinarian, please visit our Ask the Vet page where you can submit a question 7 days a week, 24 hours a day:
Please bear in mind that diarrhea and blood in the stool at this age has the potential to be attributable to clotting disorders or even cancer. It is also possible that any number of underlying systemic diseases, not just disease of the gut, could also lead to diarrhea with blood secondarily. As such, a veterinary visit with a full diagnostic work-up is advisable for your pet.