"NO-HAAAAW, PL-HEEEE-HAAAAW LET ME-HEEEEE GO!"
Your cries go ignored as they grab you by the ears and drag you painfully across the wooden deck with such force and expert ease. You can't even find the time nor the balance to struggle, before getting tossed unceremoniously into one of the stalls. You get up unsteadily on two hindlegs, kneeling and begging to the guards who just locked the door behind you and left. Your hooves smashing futilely against a wooden surface meant to handle an animal as strong as you will become.
"Haw don't wan-HAW-HEE-HAW donk-Hee-Haw! Haw-HEEEEE-HAAAW!"
Your tattered clothes feels tighter with each bray, ripping slowly at the seams by an ever expanding body. Your center of mass shifts, causing you to lose balance and fall onto all fours. Your joints crack ominously as they stretch your limbs and spine into a four-legged stance. You paw desperately after your vanishing humanity, as fur and pelt overtakes your body completely.
"N-HAAAW! HAAAAAAW-HEEEEE HAAAAW! HEEEEEE-HAAAW!!!"
At that last bray, you're done for. Indistinguishable from a regular donkey, just like the rest of the victims. Ready for whatever fate these people had in mind for you.