Dodgy guts prior to dosing?

[Lunar Loops]

This may seem like a stange question, but how many other test subjects out there experience the feeling of wanting to evacuate their bowels BEFORE partaking of the party particulars? My yak has noticed a need to go to the toilet before he doses, especially when he is heading out of the lab environment for the night. We are not talking full blown diarrhoea here, but the need for a sitting evacuation (usually more than one) before leaving the lab and dosing in an outside environment.

It's almost like the yak's body is somehow sensing what is about to be ingested and saying 'whoaaaa there my hairy friend, do you really want to introduce that foreign substance into my system for the purposes of observation?'

Either that or the yak is just rather fussy where he s(H)its, but if that were the case he would surely experience the same symptoms prior to leaving the lab on any occasion.

Just curious and apologies for the nature of the question.