The LD50 Test
Invented in 1927 by J.W. Trevan. The protocol: administer escalating doses of a substance to groups of animals until half die. A standard test uses 60-100 animals. Death is the measured endpoint. The dose at which 50% die becomes the LD50 value.
The OECD began replacing the classical LD50 in the 1980s-1990s with alternatives using fewer animals (Fixed Dose Procedure, Acute Toxic Class Method, Up-and-Down Procedure). Despite decades of phase-out language, approximately 11,500 LD50-type procedures were still recorded in UK data for 2023.
The Draize Test
Developed in the 1940s by John Draize at the FDA. Place 0.1 mL of test substance into the eye of a conscious, restrained animal. Observe for up to 72 hours. Score opacity, swelling, discharge, and tissue damage. Historically performed on rabbits but dogs have also been used.
Criticized on both welfare and scientific grounds: animals are not sedated during application, results are subjective and scorer-dependent, and interspecies extrapolation is unreliable.
Can identify severe irritants. Cannot yet fully replace in vivo testing for moderate irritants.
The Smoking Beagles (1967-1970)
From 1967 to 1970, Dr. Oscar Auerbach conducted smoking experiments on beagles at the Veterans Administration Hospital in East Orange, New Jersey. 86 beagles were first devocalized, then fitted with tracheotomy tubes through which cigarette smoke was delivered directly into their lungs.
In 1975, reporter Mary Beith conducted an undercover investigation at a UK laboratory conducting similar experiments. The resulting images — devocalized beagles with tubes protruding from their throats — became one of the most recognizable symbols of animal experimentation and triggered massive public outcry.
The Tobacco Institute dismissed the results, arguing animal models don't prove human causation — while simultaneously arguing human epidemiological data was insufficient. Both positions served the same purpose.