"Really? So, we both wanna spend the coming as females?" you reiterate with some surprise.
"Well, it is just for this one year, right? What guy hasn't been curious?" he comments with a wink. You smile and give a little shrug, then wince as the needle goes in. Within seconds, he's had he's shot too and the scientist has left the room. Before the door has even closed behind her, you're both sweating and your erections are tenting your gowns. You throw off the garments and reach for your needy members. But before either of you can get very far with pleasuring yourselves, your erect penises start to shrink. As they shrink, they become even more sensitive, causing you both to moan and pick up speed. Eventually, they stop dribbling precum as the whole closes at the ends. Your testicles get pulled up into your body with a pop, leaving your scrotums to get divided up into a pair of lip-like structures. Two new holes open up under your shrinking dicks, which have become your new clits. You just keep rubbing at them until you orgasm.
"Oh, man!" yells your change partner, panting and out of breath.
"Oh, WOMAN!" you pun, panting and laughing as well. You think you could go again. You're still sweating and almost too horny to think straight. Before you can go back to playing with yourself, though, you notice something funny about your new acquaintance's ears. They're pointed, and they look longer than the did before. In fact, their starting to develop something of a bend at the tips.
"Hey girl, you should check out your ears," you say with some interest. She reaches up to feel them, surprising herself when she finds they go up higher than she remembered. They grow out even longer and wider and flop over even as she is fumbling with them. Then they start growing black fur. A strange flattening feeling takes hold of your own ears, and she looks at you and laughs.
"You should check on yours, too!" she says. You reach up and, sure enough, you have your own flat, triangle ears that are starting to flop over as well. Before long you can even feel a certain amount of fuzz starting to grow in. Faraway sounds start getting louder and crisper until you can hear the other dogs outside for the first time.
"Hey, can you hear everything all of a sudden?" your partner asks.
"Yeah, pretty much. I guess these dog ears are gonna take some getting used to!" you answer. Then you catch a glimpse of red welts popping up along her chest breasts. "Hey, look!" you point them out to her. She looks down and starts patting over her new dog nipples. You look down at yourself and it doesn't take long for yours to grow in. In the midst of your horniness, their sensitivity is really turning you on. You reach back down to your vulva for another go. You close your eyes in ecstasy and let your tongue roll out, surprised by how flat and flexible it feels. Your acquaintance mumbles something about how silly you look with such a huge tongue, but its hard to catch all the exact words when she tries to talk with her own tongue hanging out like that. You just moan and go back to fondling your erogenous zones. A rhythmic drumbeat of joy starts pounding deep with in your soul before taking root in your lower back, and then it starts to spill out over your butt. Your eyes snap open at the sound of a painful yelp from your fellow volunteer.
"Don't pull on it," she advises, holding in her hands a shaggy black-and-white tail. You spin around just in time to see the last few centimeters of your own get covered up with an expanding patch of white fluff. (At least the first half of the tail fur seems to be black.) It's actually pretty fun to watch it wagging back and forth; you really are starting to remind yourself of an adorable collie. You soon reach out for the new appendage that you'll be carrying along behind you for a year. It actually takes you a few tries to catch it! When you finally manage, you look toward your fellow volunteer again, with a wide grin, holding your tail out beside you like some sort of trophy.
When you see her face, your eyes widen, your floppy ears perk up, and all you can do is point. Her nose is wide, her nostrils are wet, and her whole face has pushed forward, carrying her lips with it! It's not stopping either. Black fur sprouts on her cheeks even as you watch, with a white stripe down the bridge of her nose. She reaches for her developing muzzle flinches a bit when she finds the whiskers that have grown out on either side.
"Can you smell anything different?" you ask, watching her obvious dog nose taking shape.
"Roo have ro irea!" (You have no idea!) she tries to ask with her mouth shape and floppy tongue. "Hey! Holth ur traiw upf a ridl bwit. I warra tray rompm!" (Hey! Hold your tail up a little bit. I wanna try something!)
By the time you've pieced together what she was trying to say, she's already staring down at your raised tail, sniffing attentively through her black wet nose. She bends down and you can smell her moist warm breath directly on your anus! You yelp but instinctively stand still so she can sniff you. You soon notice a lot of interesting smells you hadn't detected before, either! For one thing, you can smell multiple dogs outside the room, and some of them are really turned on. For another, you can smell the half-formed collie behind you, and she smells as horny as you are! It looks like she will be the first friend you will have made as a dog, so a growing part of your mind wants to understand her scent better. You find yourself bending around to sniff under her tail, too, drinking in the aroma of happiness, curiosity and lust. While you are both still following each other's butts around in circles, something in your backs snaps and makes it really hard to stand anymore, even hunched over. You fall down onto your hands and feet, after which a loud clicking sound echoes through your sensitive ears. You look down and see that you have clawed paws where you once had hands, and you also see that your friend's black and white fur has now covered her whole body. You're both collies!