Does black pudding have blood in it?

Definietly. All meat or meat products when raw contain blood. Meat is simiply the muscle of an animal, and offal are simply the organs of an animal. And even when an animal is killed, blood remains in its body parts. Even when you fully cook meat blood will remain, most may have left during the cooking process, however some may have simply dried into the cooked meat during the heating process. Blood is often considered the most tasty part of meat. People who eat their steak medium rare do so because it is more 'juicy' this juiciness is in fact the blood of the steak.