Soon he started to feel the first changes. It was like his body was burning. Probably without the gas, he would be in pain now, but it felt... fine? First, he noticed his tail growing, new bones started to grow, extending his spine. He looked at the screens where he could see his body from different perspectives. "Pill is starting to work, relax and enjoy the change." the woman says through the speaker.
Relax? In few moments he'll be a horse! He already had a stub of his tail. He tries to grab it, but his fingers felt stiff. Index finger started to grow, while rest were shortening. Right, hooves. He didn't expect them to change that fast. He couldn't also use his hand to cover his privates, as soon it was like he had just one finger per hand.
His hands were required somewhere else, as he felt some cracks in his back and hip. Standing upright suddenly felt uncomfortable. The change was really faster than he expected, he falls forward on his elbows and knees. His feet were starting to change too, making them temporarily useless. He could feel every bony in his body changing. Growing. His neck started to grow, he could move his head much more than before. Speaking of head, it also started to change. His throat feels weird, he tries to cough, but some weird noises came out of his mouth. Even if his face wasn't changed, his vocal cords were.
As his chest barreled, he felt it touching the ground. His hooves were ready so he tries to stand on them, it felt like standing on the tips of his fingers. Damn, the change was arousing, but... he had a feeling that something wasn't right. Finally, he stood on all fours properly and looks back at his body. His vision was getting poorer and wider, giving him a headache. The mist also starts to smell differently, he couldn't describe it, it was like his senses changed completely. A soft white coat started to grow all over his body. His face finished changing. He looks into the screens to see he is a complete horse.
"Okay, Mr. Adam, your change is done. Please stay there and wait" the voice in the speaker says. Adam tries to calm down his breath.