What is the ruling regarding excretions from animals that cannot be guarded against (i.e., not killed by death)?

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Animals that are not subject to the ruling of impurity upon death, specifically the cat and creatures smaller in creation, follow the ruling of humans: whatever is ruled impure for a human is impure for them, and whatever is ruled pure for a human is pure for them. The exception is semen; the semen of these creatures is impure because human semen is the beginning of human creation and is thus honored by being deemed pure, a status absent here. Creatures that lack flowing blood are pure in all their parts and excretions.