Horseshoe Crabs and the Pharmaceutical Industry: Challenges and Alternatives - Project Report

Endotoxins are bacterial components that can cause systemic toxicity if they enter the mammalian blood stream. Testing for the presence of endotoxins is vital for the safe use of vaccines, injectable medicines, and medical devices in human and veterinary medicine. In North America and Europe the primary method for endotoxin testing is the Limulus Amebocyte Lysate (LAL) test. This utilises the coagulative properties of Atlantic horseshoe crab (Limulus polyphemus) blood to detect endotoxins, linking this immunologically unique and ancient species to the global supply chains of modern health and medicine. The development of the LAL test served as a replacement to previous methods of endotoxin testing which involved injecting samples into rabbits (the Rabbit Pyrogens Test) – a significant reduction in harm to animals.

However, procuring blood for this (regulatory mandated) testing involves capturing & bleeding over 500,000 crabs from wild populations each year. The continued use – and potential rise in use given increasing global demand for pharmaceuticals – of horseshoe crabs is prompting growing questions around welfare and sustainability. There are growing debates around Limulus’ sentience and capacity to suffer, with animal protection groups posing welfare and ethical questions. Whilst the crabs are returned, alive, to the sea following the collection of their blood, and some view the bleeding process as harmless, there are increasing discussions about the impact that capture and bleeding can have on crab health and mortality.

This report explores what a social science perspective might add to understanding the debates surrounding the use of horseshoe crabs in endotoxin testing. It draws on qualitative research with stakeholders, alongside documentary and policy analysis to examine the various perspectives, positions, and sides of debates about horseshoe crabs. This report attempts to represent the wide diversity of stakeholder perspectives about the biomedical use of horseshoe crabs in a balanced manner.

The two major themes responsible for the current contestation – the impact that the biomedical industry has, or does not have, on horseshoe crabs, and the current replaceability of horseshoe crabs within contemporary pharmaceutical processes – are discussed. Building on this, the report then discusses the role that ideas about animal welfare have traditionally played in shaping conversations about horseshoe crabs, examining why the biomedical use of Limulus has remained outside of, and resistant to, an engagement with the welfare concerns that underpin the social acceptability of the biomedical usage of other animals. Bringing conversations about horseshoe crabs into connection with wider discussions about animal welfare more broadly offers many opportunities for restructuring debates in helpful ways. Particularly, the 3Rs framework – the ambition to, where possible, replace, reduce, and refine the biomedical use of animals – emerges as a useful and appealing concept to a wide variety of the stakeholders involved in discussions about horseshoe crabs. As conversations about the biomedical use of horseshoe crabs are starting to change there is also a need for more openness and transparency. This is increasingly a staple of best practice within the broader biomedical industry, and greater openness here would afford an important opportunity to reassure publics and other stakeholders about the level of care involved in contemporary biomedical use of horseshoe crabs. The pharmaceutical reliance on horseshoe crabs is growing as a topic of public interest, without assurances and openness about humane care, it may be that public opinion shifts from an understanding of the (currently perceived) need to utilise horseshoe crabs in a care-full manner, to one that rejects this as a tolerable practice. With welfare potentially rising on the agenda, there are opportunities – and demands – for animal welfare organisations to become involved in, and help shape, future discussions about horseshoe crabs. 

This report is intended to be an overview of the topic. It is aimed at the multiple stakeholder and public audiences interested in the matter of horseshoe crabs and animal welfare. Additional scientific articles are in development in peer-reviewed academic journals and books, which will expand on the themes identified here.