I googled it for you, there is LAL which is a blood clotting agent (that exists only in the blood of horseshoe crabs) that reacts with the bacterial capsule which makes it important for vaccine safety tests. Alternatives do exist but ya know, money is more important to corporations than some animal's life.
I always thought it was about not getting sued for false advertising. Like some dentist would file a lawsuit because he wants money doesn't recommend that particular brand
USA centric thinking... The dentists anywhere else recommend the good stuff so you stay the fuck away from their clinic (they get paid all the same by the gov no matter how many they treat)
I googled it for you, there is LAL which is a blood clotting agent (that exists only in the blood of horseshoe crabs) that reacts with the bacterial capsule which makes it important for vaccine safety tests. Alternatives do exist but ya know, money is more important to corporations than some animal's life.