I was recently inspired by   JhonnyRebel 's piece "Ponygirls", and ended up writing a short story on the topic. I've broken it up into short chapters (about 4400-5000 words), and decided to make those my first posts here.
This is Part 1, at 4349 words. More coming soon!
Part 1
Part 2
Part 3
Part 4
Part 5
Part 6
Part 7
Master List of Chapters

This story features a pair of bondage-loving anthro racehorses getting picked up on the side of the road by a generous stranger, and goes from there. It's set in a possible future world, where bioengineering allows the creation of whole new species, including anthros.
Technically speaking, those anthros all have the same legal rights as humans; however, there are a few secret labs still cloning and genetically engineering anthros and training them to be pets or servants, and other anthros that want to be dominated by someone. There are laws permitting human-anthro partnerships of various degrees of kink, and agencies to make sure nobody's rights get violated.
These chapters will contain a good dose of ponyplay, rubber, and similar fun--enjoy!

This is a very early draft, and I would appreciate any and all feedback you have after reading. If you want to see more of my writing and works, check out my DeviantArt gallery, which tends to have general audiences content instead of mature pieces like this.

Not sure what more to say. Credit to   JhonnyRebel for the original image, which I used for the preview with a bit of cropping to make it square. Definitely go see the original! https://www.furaffinity.net/view/26041079/

Pasting the story below, sans formatting, in case the doc is giving people problems or they just don't want to download it

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A sleek car pulled up along the side of the road, coasting gracefully to a stop as its electric motors turned kinetic energy back into electricity. It stopped well short of the two figures there at the edge where pavement gave way to grass and then forest, and turned perpendicular to them, its nose toward the trees. A few moments of silence passed, broken only by birdsong and the occasional whoosh of another car or truck zooming past. The cabin area of the car turned transparent, showing the single occupant as he gathered a few things from inside the passenger compartment. The door opened, first outwards and then sliding forwards on a rail and extending arm until it was alongside the front wheel of the vehicle. The car’s occupant disembarked, smiling to the two onlookers and then moving back to the trunk of his vehicle to get a few other things. He was a young man, about five foot eight and wiry, with a tousled mess of black hair. He wore utilitarian clothes with plenty of pockets, a belt pouch and multitools strapped at his waist, and a pair of sturdy hiking shoes on his feet. Having retrieved all he needed to, he closed the trunk and set about unrolling a picnic blanket over the grass. The two figures watched, still keeping their distance and not saying a word. One of them stood up from the hefty looking case that had been put to use as a chair.
The man sat down on the blanket, facing more towards the road than those watching him, though he did smile and wave in their direction to show he had seen them. “I won’t hurt you. It’s okay,” he said, balancing soft, soothing tones with enough volume that those words would carry across the distance. Two pairs of ears pricked, the two figures looked at each other, and then tentatively walked forwards. “That’s it, good, it’s alright, nothing to worry about,” the man said, and then turned so that he could only see the approaching duo out of the corner of his eye, not that he looked much. He started humming, listening to the birds and buzz of insects enjoying the warm afternoon. There weren’t many vehicles on this stretch of road, so the sound of approaching steps also stood out. He looked up when those steps came to a stop a short ways to his right.
“Well hello, and what are a pair of fine horses like you doing all the way out here?” He asked, still smiling and keeping his mannerisms non-threatening. The two figures were equine, after a fashion; both were anthropomorphic, standing more than eight feet tall on their two legs. Their legs, heads, and tails were all horse, while their torsos and arms were humanoid. Bioengineered beings like that were common enough, but the attire of these two mares was where things got interesting. They were identically clad in skintight translucent bodysuits of some latex-like material that covered everything up to their necks. Over top of this, working from the ground up, they had sleek boots, part rubber, part leather, that laced up all the way to mid-thigh; the boots included sturdy no-slip horsehoes, and a series of straps and cuffs around the pastern and cannon. From there, one mare had a harness of straps around her hips and backside, along with a leather piece between her legs. The other just had the crotch piece. They both had leather corsets around their middles, with a number of straps and metal attachment rings. Attached to the tops of the corsets were a series of straps that wound around the horses’ latex-coated breasts and connected to a leather collar around their necks, which again had numerous metal rings where a leash could be fixed. They wore elbow-length fingerless gloves of the same black latex material as their boots. Their off-white manes were wrapped into waist-length ponytails, and their actual tails were likewise wrapped at the bases. Finally, they were bridled, webs of leather straps encircling their heads to hold metal bits in their mouths.
The two of them blinked; one started to speak but then thought better of it and just champed at her bit, fidgeting a little and scuffing her hooves on the ground. The man stood up, moving slowly and facing away from the horses until he was on his feet, like he would if they were ordinary horses and he didn’t want to spook them. Turning, he looked the two over, taking in the details. They were both paint horses, chocolate brown fur marked here and there with white patches that showed through the latex base of their outfits. Their muzzle and blaze markings, as well as manes and tails, were cream white. Traces of dirt, mud, and forest debris clung to those long white plumes of hair and the rubberized outfits. Both horses had their hands free, but hadn’t taken off their bridles. “Good horses, you’re good girls, aren’t you?” He said, and the two of them simultaneously stomped their right hooves once in affirmation, still looking at him, their ears upright and attentive. He held out his hands to them, gently, and the mares obliged him, first one and then the other leaning in to nuzzle him and breathe his scent. He traced his hands along their equine faces, feeling how hot and flushed they were, the faint dampness of sweat in their fur. They both sighed in gentle pleasure as he stroked their manes and ears. One of them, the one with extra straps around her backside, also had two earrings in her right ear. “Good girls, good,” the man soothed, and gently grabbed each of the horses by the bridle. “Kneel down.”
The movements were simultaneous, beautifully choreographed and rehearsed, as both horses went down to their left knee on the grass, hands gently resting on their raised right knees. The man smiled again, praising the two horses and softly patting their manes. From there, he removed the bits, leaving the two of them haltered but with their mouths free. He set the metal pieces aside on his picnic blanket, and looked into the horses’ mouths, checking to make sure they didn’t have any bridle sores. They were in good shape, and made no protest to his examinations, waiting patiently with mouths open, then closing their mouths and licking to get used to the absence of metal over their tongues when he was done. “Good girls. I’m Sierra—who are you two?” He asked.
“Number 88,” said the one with earrings, while her twin said “Number 90, sir.” They both had similar voices—a bit shy, unused to speaking, and slightly raspy from dehydration.
“88 and 90,” Sierra nodded, accepting those numerical designations as their names, at least for now. “You two look a bit lost, and dehydrated. And, unless I miss my guess, you rather enjoy a bit of bondage. Put your hands behind your backs, I’m going to tie your wrists.”
“Yes sir,” the two said in unison, crossing their wrists behind them with no hesitation. Sierra moved around the two horses, humming softly so that they could keep track of him by sound. Both horses kept their heads pointed forwards as he walked around them, though they did follow him with one ear, and 90 glanced sideways at him before returning her focus in the direction of the parked car. Neither one protested as their wrists were tied together with a length of paracord—90 even tried to lean her hindquarters against Sierra’s hands as he bound her.
“Someone’s frisky, hm?” Sierra said, tracing a hand along 90’s arm. She shivered and nodded, her ears dipping as she blushed. “Well, maybe I’ll do something about that later, since you’ve been such a good horse,” Sierra said, walking back to the front of the horses, and holding up another length of rope as he tied it into a Y, then affixed a carabiner to each end. The horses watched, and then lifted their chins so that he could hook the carabiners to their halters. “Stand up,” he said, giving a tug on then central part of the Y, so that both horses felt the pull. They stood with the same rehearsed grace as they had knelt, even with their hands tied behind them, and then followed Sierra over to his car, where he retrieved two water bottles from a backpack, then a collapsing bucket and small cooking pot. He emptied one water bottle into each receptacle, then held the bucket and pot out to the horses. “Drink as much as you want,” he said, and both horses immediately buried their muzzles in the offered containers, slurping noisily and only occasionally coming up for air. When they had drunk all they could get out of the relatively small containers and were still clearly thirsty, Sierra led them over to the picnic blanket and had them kneel down again, then poured the remaining water into their mouths.
“Thank you,” 88 gasped out as soon as she had swallowed.
“We haven’t had any…” 90 started, and then stopped herself, hanging her head and shifting in discomfort.
“You’re welcome,” Sierra said, and then, noticing 90’s abashed and worried expression, added “you are both free to speak, in case you have been trained to keep quiet.”
The two of them nodded, 90 looking relieved as she did. “We haven’t had any water for almost two days,” she said. “That was when we escaped.”
“Escaped?” Sierra asked, one eyebrow quirking slightly. “Sit down, make yourselves comfortable. I want to hear how you came to be on the side of the road and hitchhiking, and about this escape.”
The two horses took a moment to adjust themselves, evidently unfamiliar with being told to get comfortable. 88 ended up placing both legs underneath her, sitting back on them, while 90 sat more like an oversized dog, squirming her hips against the ground some.
“I can take those bindings off you, if you want,” Sierra said, nodding to the paracord still around the horses’ wrists. With how obedient and docile the two of them seemed, he had thought they might enjoy a little extra bondage, but with the mention of them escaping from somewhere he wasn’t as sure.
The two of them glanced at each other, then looked back to him and shook their heads. “We prefer being…well restrained,” 88 said, pulling against the cords around her wrists and closing her eyes for a moment in a blissful expression.
“We escaped from the hippodrome because we don’t like racing,” 90 explained, also evidently enjoying her improvised handcuffs. “Constant stress, almost no time outside—and unnnf, always in chastity!” She groaned, squirming a little more insistently against the ground.
“I see. But you do like being bridled, restrained, and…” He debated his phrasing for a moment. “Cared for by someone?” He settled on as a fairly mild way to put it.
Both horses moaned with longing and nodded. “Oooh, yes, yes please,” 88 said.
“Would you be our Master?” 90 asked, looking hopeful.
“I’ll admit, the idea fascinates me,” Sierra replied, stroking one hand idly along his chin while his other hand played with the loose end of the rope he had attached to the horses’ halters. “What would that entail? What sort of master do you want—and what are you willing to do for him?”
Both horses moaned again, and 88 joined her twin in gyrating her hips, latex and leather squeaking together as she moved. “If you care for us, love us, and let us go outside and enjoy the fresh air and pasture every now and then? Master, we’ll do anything you want,” 88 said.
90 nodded her enthusiastic agreement. “Use us and care for us like horses. Put us to work, ride us, put us to sleep tied up in our stables…” She hesitated a moment, her hips falling still but tail swishing behind her. “Or—in your bed, if we’re really good, and you want us?” She suggested, and then shivered and hung her head a little.
“And what if I want to race you?” Sierra asked. “You said you didn’t like racing, but if I decide that’s what a matched team of horses is good for?”
The two shuddered a little, and 88 was the one who spoke up: “We’ll obey our master, whatever he wants,” she said, though she looked scared to say it. “Racing at the hippodrome was—not enjoyable. But if you want it, we’ll race for you, we’ll do our best.”
90 bit her lip, but nodded agreement again. “You harness us up and put the whip to work, we’ll run. Just, please let us rest between races, and have time outside. And I know that we’re supposed to save all our energy for the races, but if we do well—can we get our chastity belts off and get some relief? Please?” She implored.
“I don’t think I’ll make you race,” Sierra said, to relieved sighs from both horses. “So, those chastity belts—If I take them off, who would you be comfortable having sex with? Me, other humans, other horses, yourselves, sex toys…?”
“Anyone master says,” the two chorused at once. “We’re trained as escorts and breeding mares,” 88 added.
“Not that we’ve gotten to do either in way too long,” 90 muttered, and huffed out an exasperated breath. “I can’t even remember the last time I was bent over for a stallion.”
“Alright, so, how about this—If I take the role of your master, I’ll make sure that you get time outside, as well as a good diet and adequate hydration,” Sierra said, gathering his thoughts on the matter as he went. “I’ll work you, like horses, and make sure you get plenty of exercise. You’ll be kept restrained and outfitted at my choosing, and as you enjoy. Are you familiar with the concept of safe words and signals?”
Both horses looked at each other, then back at him and shook their heads. “This all sounds wonderful,” 90 said “But I have no idea what you mean by safe words.”
“It’s something that all bondage lovers should practice,” Sierra said. “A safe word is something you say to tell your master that you have been pushed too far out of your comfort zone. It is an emergency signal that means it’s time to stop whatever is happening and get you back to okay. Safe signals are the same idea for when you can’t vocalize, for whatever reason. Understand?”
From the confusion in their faces, it was clear that they didn’t. “But—if you’re our Master, you can do whatever you want with us, even if we’re uncomfortable,” 88 said.
Sierra shook his head. “Safe signals are a way to warn if there is an emergency. If you can’t breathe, for example, or you’re scared and don’t want to continue, or you’re injured. I don’t care what you were trained back where you came from, safe signals are necessary, and they save lives. Any dominant who doesn’t teach the use of safe signals, and respect their use as an inviolate emergency stop, should never be allowed to exert their will over anyone else. So, if I take you in, I’m going to follow that rule. How about—if you say ‘pine’, or make three rapid sounds—grunts, banging on something, anything that will make a three-beat sound, that’s the safe signal. You do that, and I will stop whatever I am doing, make sure you can breathe, and then talk with you to find what the problem is and get it resolved. Does that make sense?”
88 opened her mouth to respond, closed it again, and then nodded, still looking perplexed. 90 nodded as well, but her expression suggested that she was mulling this idea over. “So—safe signals are a way you take care of us. We tell you if there’s an emergency, so you can fix it and keep us from getting hurt.”
“Exactly,” Sierra agreed. “And it’s not just physical hurt that safe signals prevent. If you are scared beyond reason, use a safe signal and I’ll stop and help you calm down, rather than traumatizing you. As your master, I’d have a lot of power over you both—safe signals are there to make sure that I don’t go too far. That keeps you healthy, and keeps our relationship enjoyable for everyone involved.” He contemplated for a moment. 88 looked like she understood at least a little bit better, and 90 smiled at him, liking the idea of having such a considerate and caring master. Sierra got his thoughts into order, or at least enough of them to ask a question. “So, if I’m your master, what does that make you to me? Pets? Slaves? Horses? What do you prefer?”
“Any of those work,” 88 said. “We’re all yours—Master.”
“Master,” 90 agreed, beaming with happiness.
“Okay. I’ll take you in as my pets,” Sierra said, to a double squeal of delight. Both horses started to stand up from their excitement, but he waved them back down and they settled again, then moved over to them. “That means that you need new names. 88, I’m going to call you—Lorianne, Lori for short. 90, you’re now—Azimuth, Azzy for short.” He smiled at each one and rested his hand on their brow as he named them, eliciting a gasp and another happy squeal from each of the horses—his horses now. They nuzzled affectionately against his hands and body, and he petted their manes and scratched their ears, then took them by the rope and gave it a short pull up. Both horses worked themselves up to their hooves with as much grace and speed as they could muster; Lorianne worked herself to one knee and stood quickly enough, but her legs had gone a bit numb from how she had sat on them for so long. Azimuth fumbled a little more to get her legs under her, since she couldn’t use her arms to counterbalance herself, but then she stood easily once she had legs in place. Sierra led them over to the car, quickly looping the end of their rope around the spokes of one wheel to keep them tethered. They could stand, but not move away from the car. “Good girls. Stay,” he said, and then went to gather up the picnic blanket and the two metal bits. His gaze fell on the luggage case that Azimuth had used as a chair up until his arrival. “Is that box yours?” He asked the two horses.
Both horses stomped their right hooves once, Azimuth adding a verbal “Yes, Master” to her trained response. Sierra nodded, and, slinging the bundled blanket over one shoulder, moved to examine the case. It wasn’t anything too fancy, just a sturdy box with handles and a few faded stickers on its surface. Like the horses, it had a fair bit of dirt and other debris on it. It also had the tip of a riding crop sticking out from between the locking lid and the main box. That caught his attention, and he set down the picnic blanket to have a look at the case’s contents. The latch opened easily enough, and the case opened to reveal two matched sets of restraints and items for use on the horses—two leather armbinders, a full set of arm and leg cuffs for each horse, two ball gags, two ring gags, a few spare bits, two sets each of fetters, reins, and blinders. The only thing that didn’t seem to be doubled was the crop, which was also the only item that didn’t fit all the way in the case.
Sierra whistled softly—a collection of gear like this would cost a lot at a fetish shop, or earn some odd looks and questions if he had it custom fabricated somewhere. Finding it with the horses was a prize well worth keeping. He closed up the case, set the blanket bundle and crop on top, and hoisted the case into his arms. It was heavy, probably at least 30 pounds. Nothing unmanageable, but it did strike him as interesting that the horses had elected to carry this box of items that weren’t useful for survival, rather than something with water and other useful supplies. How had they managed to gather up so much of their bondage gear while escaping, for that matter? He pushed that thought aside and made his way back over to the car and waiting horses. Returning, he placed the items in the car’s trunk, and then walked behind his horses, tracing his hands along their backs and bound arms. He found himself struck by a sudden impulse, and although he easily could have resisted it, he elected not to. “Bend forwards, present those lovely rear ends to your master!”
“Yes Master!” Lorianne and Azimuth said together, almost knocking Sierra over as they bent over at the waist and shifted their hips back to stay balanced. Azimuth squeaked, glancing over her shoulder to make sure he was alright, and then resumed shaking her tail end in a very sensual display once she was sure that Sierra wasn’t angry at her for the unintended hip check.
“Mmmm, good girls—and next time, I’ll remember to stay out of your way when I give an order like that,” Sierra chuckled once he had caught his breath, or at least most of it. Presented with a pair of sculpted feminine hinds, topped off with that sheen of tight latex and the smell of eager horse, oxygen seemed to be in short supply. “Can I touch, or just look?” He asked, hands hovering a few inches away from the tantalizing display.
“Touch, yes, Master!” Lorianne cried out, while Azimuth took the more direct approach of backing herself up right into Sierra’s waiting hand and moaning in ecstasy as contact was made, and then reciprocated.
Sierra traced his hands over the well-muscled curves, tweaked both swishing tails, and generally had both horses gasping and squeaking in pleasure. “Alright, that’s enough for now,” he said, giving them both an affectionate pat. “And certainly, there will be more later. Now, should I give my good horses some gear from the box, or are you restrained well enough with the paracord and your outfits?”
“Bind us how you like, Master!” Lorianne said, a sentiment echoed by Azimuth as well, who was still shaking her hips and tail in hopes of getting some more attention there.
“Settle down, naughty girl,” Sierra chuckled, giving Azimuth a teasing slap on the backside. She jumped and squeaked, then giggled a little, settling down with one final swish of her tail and gentle rock of her ample hips. Sierra retrieved the sets of cuffs from the case, debated for a moment on some of the other items in there and then decided that he would keep them on hand but not put them into use just yet. He put the leg, elbow, and wrist cuffs on both horses, taking off the paracord bindings when he got to them. That left both horses far less restrained, but ready to be tied up more extensively. “Alright, let’s load you two up for a trip—unless there’s something else you need here?” He asked, untying the loose tether from the car’s wheel.
“Um, Master—will we fit in your car?” Lorianne asked, looking the vehicle over uncertainly—the roof only came up to her waist. Azimuth looked similarly dubious.
“I think so,” he said, opening the rear passenger door. Like the front door, this one slid out and then towards the end of the car, revealing an uncluttered interior. The car had five seats in it currently, and room for six; all of the seats could be adjusted in height and repositioned most anywhere in the cabin, or fold away to take up almost no space. Sierra folded two of them, positioned the third front and center in the cabin, and the remaining two he collapsed down to their minimum height and moved almost all the way to the back of the space. He nodded in satisfaction when that was done. “Take your seat, Lori, let’s see if you have enough headroom,” he said. She obliged him, sitting down into the left passenger chair which was practically flat on the floor. Her tail tucked between the backrest and seat, and her ears brushed the ceiling, but she fit. Sierra showed her how to buckle in, as well as how to unbuckle the seatbelt when needed. He then helped her to recline and adjust the seat so that she would have more headroom. “Comfortable enough?”
Lorianne’s right leg jerked once, purely by reflex. She blushed a little as her hoof clomped against the carpeted flooring. “Yes master—are you going to bind my arms?” She asked, trying to adjust herself in the confines of the car so that her arms could be cuffed behind the back of the seat.
He shook his head. “I’d rather you be able to unbuckle your own seatbelt and get out if you need to. Car crashes are rare, but there are still some incidents that no driver, computer or otherwise, can avoid safely.” Having explained that, he unhooked the lead rope from Lorianne’s halter, patted her shoulder affectionately, and then led Azimuth around to the other side and got her situated as well. With the horses seated and comfortable, Sierra swung himself into the singular front seat, and tapped a button to close all the doors. In the enclosed space, the smell of leather, latex, and horse went from noticeable to almost overwhelming, and Sierra turned on a series of airflow vents which ran whisper-quiet. He folded out a small joystick onto the armrest of his chair, and used that to start the car and steer it back onto the road.
This planned camping trip promised to be much more interesting than Sierra had expected.