K 17 is the internal test label for Thalidomide. Between 1955 and 1957 K 17 was tested on animals. Tests over several weeks were exclusively done on rodents. However when it comes to organ development and metabolism, the bodies of cats and dogs are more similar to the human body. K 17 was tested on cats, dogs, horses, pigs and donkeys – but only by vets who were doing those tests for veterinarian purposes.
Other tests on animals were done by a company in the US (by Smith, Kline & French in Philadelphia who was initially interested in buying a licence from Grünenthal for Thalidomide, but the deal never happened). All the animals that were tested with K 17 tolerated the substance without any side effects.
Most striking discovery: even very high dosages of K 17 did not cause the death of any tested animals. However, according to the indictment, scientists at Grünenthal by no means should have come to the conclusion that K 17 therefore wouldn’t cause any damage to human life. None of the tests that were done on animals provided an explanation about how K 17 works: about WHY the new substance had a sedative and tranquillizing effect. Also, tests over several generations were not done at all.
Source: Anklageschrift (indictment) from 1967, today archived at the National Archives of North Rhine-Westphalia in Duisburg, Germany (Rheinland Division, Gerichte Rep. 139, No. 1–396), p. 45ff.