I just found out today that for every batch of botulinum toxin created, tests are performed on laboratory mice. The test employed is the LD 50, that is the dose of botox that kills 50% of the mice it is given to. After the toxin is administered by a needle stick to the belly impaired vision, paralysis and respiratory arrest follow. Those that die suffocate. The process takes three or four days. The surviving mice are then euthanized. It is estimated that worldwide at least 600,000 mice die in the production of botox each year. In the European Union alone, tens of thousands of animals are estimated to be used in this testing per year. As the use of botox increases so does this number. Europe has a ban on animal testing for cosmetics but botox is considered a medical treatment so the ban does not apply. There currently is no other assay available or in use to determine botox strength and doseage in each batch of botox that is manufactured.
July 26, 2011 addendum:
Allergan (the manufacturer of Botox) spent $65 million on more than a decade of research that led to a new animal-free test, testing the effect of Botox on cells in a lab dish. The Food and Drug Administration approved the test in June 2011. Allergan estimates it will be able to reduce its animal testing by 95 percent over the next three years as countries outside the United States approve the new procedure as a replacement for the old LD50 test.