Using frozen/cooked frozen blood in black pudding I am having a hell of a time trying to track down blood in the US for black pudding. None of our local processors can provide it, several butchers are claiming it's illegal to sell (not true, but you have to be licensed at the abbatoire). I haven't been able to find a place that will sell dried pigs blood over the internet AND can ship.

The only option I've found so far is frozen pig blood from a local meat plant (they do NOT sell fresh, only frozen), or a small asian market (they ONLY sell coagulated pig blood that has been cooked).

Can these be used interchangably or is it an absolute requirement that the blood be fresh?
The frozen blood (once it is thawed) would be the better option.  I would not consider the cooked and coagulated product to be interchangeable with the thawed product.