You can try adding an 1/8 tsp of Miralax to his food if the blood is from straining. Doodles always tended to be constipated and pumpkin only worked for a short time. He now gets a 1/4 tsp of miralax twice a day (I started with the 1/8 tsp). If his stools start to get too soft I just skip a dose or cut back a little.