End of Experiment 1

21 05 2015

The final part of Maria’s cage height study ended last week. Mink had access to an enriched compartment whose ceiling was progressively raised or lowered every 2-3 weeks to see if that’d affect how much time they spent there. No idea what’s in the data yet.

The end of this experiment meant killing all the animals save those Andrea’s keeping on for another month. We do this because we don’t want to move animals from our large enriched cages to small farm ones (that’s what’d happen if they just went back to farm stock), and because we want to take responsibility for and control their deaths so that they are as humane as they can be. Over the years we’ve refined the killing method, balancing three things: MSU’s desire to use CO2 (rather than the super-effective CO used on farms) for human safety; our strong desire not to expose conscious mink to it because it’s so aversive to them; and new rules about using anaesthetics like isoflourane (which, mis-used — not that we ever did this — can irritate animals’ eyes and be nasty for humans). All went very smoothly this time, though it’s always a sombre process. Maria’s summary:

So sad. But killing went better than last time. Having two separate chambers, the first one for the anaesthetic, and then a second for the CO2, really helped. Only two or three mink (out of 27) urinated while in the anaesthesia chamber; no-one ever shrieked (what mink do when threatened); and no-one ever attempted to escape. Before the anaesthetic knocked them out, they just didn’t seem particularly upset to be there: our ideal.

The vets were with us all day, and very nice too: very good about caring. They are going to officially train us to use the vaporizer in June (it’s easy), so that next time they’ll just help us set up and then they’ll just come back for the equipment at the end of the day.