Some animals are kept specifically to provide blood, serum, and biological products for medical and research use, with welfare conditions that vary from well-managed to deeply problematic.
Animals used for blood and biological products occupy an under-scrutinised welfare space. Horseshoe crab bleeding causes stress and mortality in an animal whose sentience is uncertain but whose ecological role is vital. Mare bleeding for PMSG involves repeated blood collection from horses in welfare conditions that vary widely. Synthetic alternatives to LAL exist but are not yet universally adopted. Donkey farming for ejiao has caused population crashes and welfare concerns across Africa and Asia. These uses require the same welfare scrutiny applied to other animal product industries.