Jenny knew she had only moments before Thomas returned and she's be put to sleep, unable to save herself from whatever sick fate they were planning. Gathering her limbs under her and trying not to think too much about how to move, she pushed up from the floor, her back end rising first followed quickly by her front. Thankfully, her hind and forelegs seemed to be the same length and she found herself standing with her spine horizontally level to the floor.
"Magnificent!" Randall exclaimed, seeming to be frozen as he gaped at her new form in awe.
Jenny wasted no time, flexing her wings as wide as the tiny room would allow, trying to appear as large as possible as she whipped her head around to glare at her twisted creator. Opening her curved beak she let forth a piercing SKREEEEE and advanced on the man, forcing him to back up into the corner as she swiped with one paw, claws extended.
Snapped from his exultant reverie, Randall's eyes suddenly flashed with fear before the huge beast Jenny had become. He cowered down, throwing his arms over his head and curling into a ball before her anger. With another sharp SKEEEE, Jenny wheeled and barreled for the door, collapsing her wings in hopes of fitting through the portal. Luckily she had picked up speed as she sprung from her powerful equine hindquarters, her paws giving her traction as she shot for the gap, because suddenly Thomas filled the doorway as he raced back to subdue her, not knowing she was up and on the attack.
She collided with him, her momentum and superior weight and power bowling the man over, the tranq gun spinning from his grasp and sliding across the lab floor. Jenny didn't give him or it a second glance, pivoting to head for the stairs, her only route of escape.
"THOMAS!" Randall yelled from the back room, apparently having regained his composure. "Get up! After her!! We can't let her reach the outside!"
Jenny glanced over her shoulder as she reached the stairs only to see him appear in the door over the dazed Thomas, who was attempting to roll to his hands and knees.
"You'll never make it outside, my dear! Your new form is too big, the stairs too small! Come back and I promise, we won't drug you! What will you do if you escape?! You're a freak! Not even a pure animal to blend into the world! Stop now and I'll even let you help to choose your fate!