The flash subsided, and Shelly suddenly found herself a bit lower in the chamber, but no worse for wear as far as she could tell. At least, she hadn't been reduced to blood spatter or lifeless flesh like her previous subjects.
* It worked! I'm alive! Thank quantum physics, I'm alive. But why did the machine reassemble me on all fours? *
As the seconds passed, Shelly had time to wonder why her vision wasn't clearing up and why the exit chamber was so smelly.
* My body odor wasn't that bad earlier, was it? And why is the dog smell suddenly so intense? *
You see, Shelly never did figure out why her teleportation experiments hadn't worked on living things. Any theologian or first-year philosophy student could have told her, but of course, Shelly wouldn't be caught dead rubbing shoulders with anyone from the humanities department. It was a rookie mistake, really: Shelly's contraption could collect and transmit molecules, but it had no mechanism for collecting the soul or ensuring the continuous conscious experience of its living subjects. What arrived in the exit chamber would be the same chemicals in the same proportions, but it would not be the same being. Previous animal testing had either failed entirely or "succeeded" in reassembling a lifeless corpse. In either case, the soul had already gone away into its afterlife when the body was vaporized. Shelly was just lucky that some kind of jinn or demon had not possessed the newly rematerialized body in order to wreak havoc on Earth.
This time, though, Shelly had used a dog. Dogs are different. Dogs, being loyal companion souls for the most part, are much more connected to the human world even in death. The ones that are pets often remain earthbound for quite some time to ensure their caretakers' well-being, which is why so many former dog owners report hearing their former pets late at night. Even the ones that are lab animals have a surprisingly resilient connection to their bodies and have survived (or been reanimated after) some unfortunately gruesome fringe medical experiments in the past. If Shelly had teleported the German shepherd by itself, it would have gone directly into its newly reconstituted body and become the first living creature to survive teleportation. But Shelly didn't quite manage to do that.
If Shelly had teleported herself alone, she would have survived teleportation as well, for a different reason. Since Shelly didn't believe in souls, she was much more psychologically dependent on her material existence than most people. And since she knew what the teleporter was for (unlike the rats and lizards she'd been testing it on) she knew where she expected to end up, so her soul could have found her new body quite easily there in the exit chamber. But Shelly didn't teleport herself alone. Instead, two bodies went in, two bodies came out, and two souls happened to get just a wee bit mixed up about which body was whose while floating through the astral realm.
Shelly looked to the side and saw herself standing uneasily on two legs with astonishment in her eyes. A few sniffs of the air confirmed that the blurry, color-drained figure was indeed Shelly's body--her old body. Shelly cried out from the shock her strange out-of-body experience, and shocked herself again when only deep barks came out. She twisted her head around instantly and saw a furry body stretching out behind her. She aimed her gaze down and saw the sturdy, padded paws she'd led the shepherd dog in on, and realized she could feel the pads against the floor. She lifted one of her back paws and set it back down in wonder. Behind the obvious dog legs that Shelly now controlled, was a shaggy shepherd tail that Shelly was even more unsettled to discover she controlled. It raised behind her and flexed in several directions of Shelly's choosing as she tested it out. Somehow it felt more satisfying to aim it down between her legs, as the realization sank in of what happened to her. A frantic look at the ominous fuzzy pouch in front of her tucked tail confirmed her worst fear: her fateful subject had been a male, so Shelly was now left with a dick and balls of her own, and not even the human kind either.
Shelly whimpered and looked back at the German shepherd was awkwardly adjusting to her original body. He had already discovered his new lady parts and staring down into the panties in awe. He stuck a finger down there and moaned in a surprisingly feminine human voice.
"I ... I can't believe I'm YOU now!" he said to Shelly, using human words for the first time. "When you got me out of the cage, I thought you wanted to do bad things to me like my old humans did. But you only wanted to give me your body? Or you wanted mine for some reason?"