“Observation of Subject 001 has revealed the perfect opportunity of acquisition. The subject is fond of alcohol, making frequent trips to the local bar to consume daiquiris mixed with vodka. After acquiring the necessary research funds I generously bribed the bartender to spike her next drink with a powerful sedative. “
A tall black-furred weasel finished typing and closed his laptop as he stared out across the street from the coffee hut he was using as a base of operations. “Perfect,” he muttered as his mark, a lovely curvy vixen, wearing a rather revealing dress, stumbled out of the front door of the bar. Through careful watching he knew the red fox would pass by this location shortly, even with the added effect from the sedative. That was why he took the precaution of purchasing the small building, that and it’s close approximation to his goal. “Just on time,” he muttered as he scurried to the front door. Just as he opened the tinted glass door, his target collapsed right in front of him. The weasel looked around before grabbing the vulpine and dragging her inside. He quickly closed the door and latched it before hefting the 140 pound fox over his shoulders. He manhandled her behind the counter, huffing as her heels caught on the floor several times.
Once there, he lifted his newly acquired subject onto a trolley bed, strapping her limbs and head down before he wheeled her out the back through the loading door into a van. He slammed the door closed and drove off to his research lab.
***
“Subject 001 is more magnificent up close. Her body is that of a typical Vulpes Vulpes female. Approximate height: Five feet and eleven inches. Weight: 140 pounds. Distinguishing feature: Lack of fur, skin, and muscle around the face and extends to the entire skull. This somehow does not impede vital functions like breathing, eating or hearing. Her exposed skull is adorned with a full mane of fur and a pair of fully functional ears.”
The scientist looked up from the research notes he was typing to find his test subject was stirring. The all too familiar groan and confused noises as the drug’s effects finally started to weaken made the weasel grin. A sedated subject was nice, but a live and fully aware one was even better. The next few days were going to be so much fun.
***
Ivy woke up slowly, first feeling the cold steel of metal pressing against her back, then the heat of bright surgical lamps on her body. She cracked open her eyes and blinked at the harsh glare. "What..."
Her words cut short as she felt something sliding into her throat, her eyes widened at the sudden sensation. (What the fuck?) Then she realized what it was: a straw. She gulped and coughed, but her stomach instantly felt queasy as she saw another one appear and she choked again.
"Drink this," a voice said from beside her, Ivy looked over and saw a white coat-clad weasel holding a glass of water to her lips. "Slowly."
Ivy did as she was told, taking tiny sips, letting the cool water ease her dry throat. The weasel nodded when she'd finished and then turned to his table of tools. The vixen tested her bounds, pulling up with her wrists and ankles. The tight leather cuffs held fast and Ivy observed the busy scientist as he sorted through various instruments. Some of the mad doctor's tools looked like they would better belong in a medieval dungeon. She saw a long needle, some kind of device resembling a pair of pliers, and a series of sharp looking blades. He also had a tray of unidentifiable liquids in bottles .
"Ah, yes, now you're awake," the weasel said cheerily, turning back to his latest obsession, in his right paw he held a pair of surgical scissors.
"What's that for?" Ivy asked with not a drop of fear in her glowing eyes. In fact she exuded curiosity, wondering what the bold little weasel had in store. The pair of sharp blades glinted under the bright lights as the weasel started to cut through the fabric of her dress.
"For your outfit," he said casually while continuing to slice through her clothes. When the material fell away, exposing naked vixen fur once more, Ivy huffed.
"You know how much that dress cost me?" She pouted as the weasel tossed the scraps and made short work of the vixen's black lace panties. They too dropped aside as if they were paper. With no warning, the weasel grabbed each of her legs, spreading them apart just enough to let him get closer to her most sensitive areas. "HEY! Give a girl a warning first!" Ivy moaned as the weasel not so gently probed her wet snatch.
After a minute's assessment, the weasel turned back to his tray leaving Ivy frustrated, horny, and sore. "That's all?" You could have just done that at the bar," Ivy pouted as the weasel ignored her. She watched as he turned back to his notes and scribbled a few things down before returning. He quickly pulled on a pair of surgical gloves and got to work.
"EPPP!" Ivy whimpered softly as her clit was poked with something cold and sharp. The feeling was quickly followed by the sensation of something viscous being pumped into her cli, sending shivers straight up and down her spine. "Hhhmph mmmmppphhhnnngggg...ahhhhh..." Ivy mewled as wave after waves of bliss washed over her. As the orgasm subsided, she heard the weasel speak to her, though she couldn't make out any specific words. Through the moments of spine arching and orgasmic bliss Ivy was dimly aware of the doctor taking verbal notes.
***
"Subject 001 seems to respond well to the initial dose of Cellular DNA Resequencing Serum. First response was a post injection period of sexual arousal followed by a complete black out. Subsequent doses have failed to reproduce the observed effects. The test subject's clit has grown from 10 millimeters to a staggering 60 centimeters. Its vulva and internal sexual functions have grown out into a large set of male testicles and slightly furred scrotum.
Both appear typically Vulpus-Vulpus in shape and function. Further gene editing is required via updated formula."
***
Ivy let out a pant, losing count of how many times her increasingly enlarging sex was poked and pumped full of fluids, whimpering as the doctor approached. "Please, let me cum!" Ivy let out a whine louder, her large bits swollen and bobbing as the weasel shoved a fresh syringe directly into the knot.
"Soon," the doctor muttered, leaving Ivy huffing in need as a fresh dose was pumped into her male bits. Ivy let out a gasp and heated moan as her bits started to change before her eyes. The pointed tip of her obscenely large bone swelled out to the flat flair of a horse cock. The shaft of the appendage grew thicker, the fat knot melding into the flesh to form the ring. The cock throbbed and pulsed as it continued growing ever larger and more erect. The reddish flesh darkened till it was a pitch-black in color.
By the time it finished changing , several inches of the tip was buried between the vixen's bust. Ivy gave an appreciative sigh as her new cock twitched and jerked before falling still, fat globs of pre staining her breasts and neck fur.
"Now we shall see about getting those eggs to grow," She heard the weasel say as he stabbed both of her nuts with an IV drip.
Ivy sighed loudly and relaxed against the table top, waiting for whatever the doc had planned for her to start. Though the drugs seemed to have dulled her perception somewhat, the vixen was acutely aware of every time he was touching her, and surprisingly she enjoyed it. The mystery of the weasel's end game was so much more entertaining than picking up a cheap date at the bar. ~I wish my paws were free to touch my new cock~ the exasperated vixen thought to herself, when she got an idea. ~ Maybe if I?~ Ivy wiggled and gave her lower extremities a thrust. The movement was slight but seemed to be magnified as her cock slipped farther between her breasts.
The ebony tip came right into reach as she stuck out her tongue. Ivy ran her taste buds along the slick head and smiled as it tasted sweet. It reminded her of chocolate ice cream. She licked deeper, savoring the rich flavor before moving trying to thrust more. Her swollen testicles plopped around as she managed to get her tongue into her cock slit. Ivy tried to hump against the tabletop but it wasn't working. Instead the weasel moved toward her and pressed his hands on her hips.
"No please! Don't move them," Ivy begged, but the weasel ignored her pleas and began massaging her inner thighs. Ivy whimpered, denied release once again as the doctor inspected the latest changes. In a surprise twist Ivy let out a howl as the weasel started to stroke her shaft. "Fuck yes!" She howled as the small mustelid worked her engorged member. "Ooooh fuck yeah, give it to me harder! Oh, God damn!" She yelled out in lust as the weasel's fingers dug deep into her softening sack, squeezing tightly. With the long denial finally near ending the horse cocked vixen's body shuddered as her orgasm exploded.
A gush of warm liquid shot from her enlarged cock spraying across her chest and face. Ivy's eyes rolled back in her head as the last drops left her, dribbling from her mouth. The weasel was quick to scoop up a generous sample of the vixen seed before slipping off to conduct his tests. Ivy was spent and exhausted, yet strangely satisfied as she slumped against the table, catching her breath.
***
"Another partial success. Subject 001's genitalia now conform to project guidelines. We must continue however, the Mitochondrial DNA is still vulpine. Extensive testing has shown that the spermatogenesis process is highly unstable. It may be possible to change the resulting sperm by introducing foreign dna. Father testing is required."
***
Ivy watched as the weasel stepped back to observe the results of his handiwork. His eyes were squinted tight as he seemed to be lost in thought. Whimpering as the need to orgasm was building in her again, Ivy called out. "What if you drain all my cum?" She offered, the bulk of the weasel's verbal noteage too complex for her horny brain, but she did grasp the basic idea. The doctor quizzically looked at her  before getting excited.
"Yes, that might work. Why didn't I see that?" Ivy's tail wagged as the male flittered about the lab gathering various things before standing above her. "You promise to behave if I remove you from the table?" He asked.
"Yes yes!" Ivy begged to be free as her restraints were quickly released. She dimly heard the doc warn about something but she was too excited to pay attention. She swung her legs to the floor and stood up, only to collapse as her leg muscles atrophied during her long captivity. Whimpering she accepted help from the surprisingly strong mustelid into a wheelchair. Her horse cock nestled tight against her groin as she was wheeled to a different part of the lab. This area looked more like a stable as she was parked in a stall. There was a large metal plate bolted to the wall. A single steel cable hung next to her, attached to the center of the plate.
"I can understand why you would want to keep me bound, but surely this is a bit excessive." She whined as the doctor brought over a large machine. The main bulk of it was a larger canister, connected to that by a clear hose was a large cylinder. Ivy let out a huff as the weasel fondled her. It didn't take much to get the monster horse cock hardening once more. “Hah…. ah… ahh….” Ivy gasped as the tip of her member was inserted into the cylinder. The inside was silky smooth and it started to squeeze and pulse as the weasel switched the machine on. "Oh gods! This feels amazing! What is it doing?! How does it feel so good! Mnnn... oohh... ahhhh.. fffuuuuckkkk..." Ivy groaned in delight as the milking device took hold, sucking her cock dry. The weasel left to set up the next part of the experiment letting the machine drain the subject dry.
Ivy twitched and shuddered as the umpteenth orgasm hit her. Her balls jiggled as she thrashed about, her past five being dry. Just as she felt another wave start to build, the machine was suddenly still and silent. Curious, the vixen opened her eyes and stared at a fat cock head that wasn't her own. She gulped , helpless as the weasel guided it to her own cock. The grinning weasel made the tips kiss before the fox felt as her cock stretched, the slit widening to engulf the other cock. She closed her eyes, the bliss of her cock swallowing the stallion's cock above her he was almost too much to bare.
The feral horse whinnied as it began fucking the Ivy's thick meat, its huge cock pumping into the vixen until their combined cocks looked like one. Their two bodies slapped wetly together as they fucked, each one desperate in their own way. For Ivy this was the most mind blowing experience she ever had, while for the horse it was the last chance to pass on his seed before he was retired from the herd. It didn't take long, the tightness around the stallion's cock made the old horse extra sensitive as he shot his seed deep into the strange vixen below. The dumb animal didn't care that it wasn't a mare, a hole was a hole to be fucked. Ivy's eyes widened as she felt the sudden gush of horse fluids flood into her prostate and flow into her balls.
"Oh fuck!" Ivy cried out loud as her toes curled, her whole body trembling. She knew it wouldn't take long before the rush wore off and then she'd really feel drained, but the feeling of the stallion's hot semen filling her cock and balls was pure heaven. She decided right there on the spot, whatever the weasel wanted to do to her was perfectly fine by her.
***
"Seminal Override was a complete success! All traces of the subject's original DNA has been replaced with that of the stallions. Already several mares have been inseminated with the stallion's replacement. All pregnancies show no sign of complications. Subject 001 has adjusted to their new life, even willingly undergoing limb replacement. Both arms and legs have been outfitted with the latest in feral prosthetics, for ease of milking.
Subject 002 has been located and with funding further refinement of the Stallion Retirement Extension can proceed"
The weasel smiled as he closed his laptop and walked out of the lap, barely glancing over at 001 as the machines kept her placated and pumping valuable racehorse seed as he turned off the lights.