This terrifying experiment involved researchers applying VX (a nerve agent) to the backs of a number of guinea pigs in order to see how well a chemical worked in stopping the effects of VX. The chemical, BChE, is known as a bioscavenger which is something that can bind to a nerve agent to stop it from working.
Animals used and number
32 guinea pigs – in two different types of experiment
What happened to the animals?
- On arrival, they had devices implanted to record their temperatures and signs of recovery, etc.
- Days later, surgery was performed to insert a cannula either into an artery or vein in the neck, depending on what was going to happen to the guinea pigs next. (A cannula allows access to blood vessels so that substances can be given or blood samples taken.)
- In ‘most cases’, it was then at least 5 days before the guinea pigs were poisoned with VX.
- Eight animals were used to study how VX reacts in the body.
- 24 guinea pigs were used in the BChE studies. The cannula in these guinea pigs left their bodies between their shoulder blades. They were permanently ‘tethered’ after surgery. (Tethering involves the animal being permanently connected to a pump, via tubing.)
- VX was made at Porton Down and applied to a clipped area on the guinea pig, in front of their cannula, towards their heads.
- The animals were given a dose of VX which was higher than that required to kill them.
- Once obvious signs of poisoning were seen, the guinea pigs received an injection of three drugs into their thigh.
- The animals were then split into four groups and given more drugs, at different times, or none.
- The animals were observed, continuously, for 8 hours after dosing and at ‘regular intervals’ for up to 2 days.
How did they suffer?
- The guinea pigs were observed and given a score for signs of poisoning and their temperature. The higher the score, the worse the condition of the animal. A score of 31 meant the animal was dead. The descriptions of the scores given to the animals are truly chilling:
o Substantial incapacitation – no meaningful voluntary movement – 9 points
o Moderate incapacitation – loss of function of hind legs, but still mobile – 6 points
o Gasping – 3 points
o Continuous tremor – 2 points
o Production of tears – 2 points
o Visible production of saliva – 2 points
o Writhing – 1 point
o Chewing – often rapid with no food in mouth – 1 point
- Animals were killed at the end of the study or when their body temperature was too low or they had lost a quarter of their bodyweight more than a day after being poisoned.
- Dead animals were dissected.
Species differences between those animals and humans
Repetition or parallel work in humans
Developed in the UK in the early 1950s, it is thought that VX was used in the 1980s during the Iran-Iraq war.
Reference for paper: Mann, T.M et al (2017) ‘Bioscavenger is effective as a delayed therapeutic intervention following percutaneous VX poisoning in the guinea-pig’, Toxicology Letters, doi: 10.1016/j.toxlet.2017.11.029