Nicole, that's always scary when we see blood in our bully's stool. Has Loki been straining when he goes #2 ? You mentioned diarrhea, so straining may not be the case. Or has he been constipated? if it's bright red you tend to think more lower GI tract like hemorrhoidal, for instance. If it happens again, take a stool sample to the vets so they can have it analyzed. This actually happened to Finn a couple times last year but nothing was found and it resolved by itself. You may want to give him some extra pure pumpkin in his food to firm up the stool and to help him go if he is having some constipation.