"...To use blood for transfusion purposes, even in the case of an animal, would be improper. The Bible is very clear in showing that blood should not be eaten..." Watchtower 1964 2/15 p.127
Watchtower's main argument against transfusion is that eating blood and transfusing blood are the same thing - you are "consuming" it either way. Why does Watchtower think this should apply to animals, since eating other animals, including the blood, is a way of life in the animal kingdom (as illustrated by compound complex's cat and mouse story above).
Not eating blood only applies to humans. I can't see a shred of logic to prohibiting transfusion for animals.