Fang paced the fenceline as she watched her master's truck pulling up with a livestock trailer attached. The livestock guardian dog was always excited to meet new members to the goat and sheep herd she protected, but the scent from the trailer didn't smell like either of those. She barked and whined as she watched him walk to the back. He yelled something, most likely "shut up already", but Fang continued to bark and pace as she watched him go to the back of the trailer with a harness. After a few moments, he stepped out with a huge hooved creature falling in line behind him - a stallion! It was a gorgeous black stallion with a small white star between his eyes. Fang paused. The dog had seen them before, mostly riding past on the dirt road near the barn, but had never seen one up close.

Not long after he was lead into the barn, Fang's master into the pasture and whistled for her to come. She followed him into the barn, where the stallion was hitched and eating some grain. He looked up at Fang and held his gaze for an oddly long time. Her master used some words she recognized. "Gentle", "guard", and "nice". she understood, the horse was just another friend in the herd to protect. Still, Fang found herself shaking slightly around him. He was so imposing looking, even though he was calmly eating grain. Her master rubbed her ears and lead the stallion to a stall. She tried to focus on her job, but kept glancing back towards the barn, distracted. One of her lambs snapped her out of it by hopping up on her back. She playfully mouthed and pawed at the little lamb, then went back to work.

That night, as the sheep and goats returned to the barn, Fang joined them. The stallion eyed her from behind his stable door, which was high enough for him to not get out, but open on the bottom so Fang could come in and out if she wished. As the stallion watched her, Fang paused. The dark stallion shuddered before pawing at the ground with a snort. She began to walk up to his gate, and then stopped. With his eyes focused on her, the stallion began getting [i]excited[/i], as if he were thinking about her the same way while stuck in his pen. The dog felt her heart start to pound and her legs start to shake as the stallion's sheath twitched. She watched it flex and twitch before the stallion's cock slowly began to unfold from the sheath. Fang began to pant and drool as the cock grew to an impossibly massive length and girth. Her body started to feel hot and she whined, gazing up at the stallion's warm gaze. With a smacking noise, his cock slapped up against his belly and he whinnied, clearly beckoning the female dog closer. She couldn't deny the heat growing between her legs, her pussy aching uncomfortably. She slid under the gate, continuing to shake anxiously.

The stallion lowered his head, the two sniffing and licking at one another's mouths. As they greeted, the stallion's excitement grew, and he neighed and shook his head, his cock flexing. She couldn't help her curiosity and stood beneath him, sniffing and licking at his impressive equipment - but felt nervous suddenly as it continued to flex. The stallion pawed the ground impatiently, clearly begging to breed her, but compared to the times she'd been bred for litters, this was...[i]way[/i] too big, right? But with the lack of mares for him, and the lack of canine studs for her, the desperation grew. She turned, presenting her dripping canine pussy to him and lifting her tail to the side like she'd offer any of the males she'd bred with before. With a snort, the stallion's cock began to slide and press to her hindquarters, his legs shaking as he struggled to properly enter her. She stayed still, panting hard in anticipation.

It took a bit of prodding, but the enthusiastic stallion soon found his mark - and slammed the entire length of his massive cock into her without hesitation. Fang's nails dug into the ground as she yelped, her insides suddenly stretched to their limit by the stud. Her eyes rolled back a bit, her body shuddered, and her tummy became distended by the outline of the huge cock. But the stallion didn't stop there, and began roughly breeding her while snorting and grunting, grinding his teeth as he experienced a cunt tighter than any mare's. Fang made a low "guh" noise as her pussy was tugging against him, dripping onto the ground below. She fell to her front legs, ass up high to allow the stallion to continue his frenzied breeding. Though she felt like her insides were being torn apart, she eagerly began humping back against his cock, unable to think anything beyond how good it felt to be bred to her limit. She shuddered deeply with a low growl as she came, her body tensing around the stallion's cock - which caused him to follow with a loud whinny. 

The stallion's cock flexed inside her, literally lifting the dog off the ground a few inches as it tugged up towards his belly. Hot cum - what felt like [i]gallons[/i] of it, flooded the bitch and made her tummy grow round as it was inflated by the stud's semen. She groaned as she felt the head of the stallion's cock suddenly flare out. The stallion's balls slowly stopped twitching, and his cock drooped, setting the pup back on solid ground. Panting, whining, and falling facefirst into a puddle of drool she'd left on the ground, she had never felt so [i]completely[/i] bred. Her stomach sloshed as she moved, but she quickly realized something - she couldn't move very far. The stallion's flare was acting the same a canine stud's knot, locking the two in place. She came again when the spent stallion's cock twitched inside her again, her hips humping desperately against him, tummy sloshing, panting and drooling like mad. Resigned to her fate, she came several more times from the stallion's slowly shrinking, twitching cock. 

Before he pulled out completely, the stud seemed to have one more thing he needed before she parted - and that was to piss. She felt a familar warmth filling her up again, her tummy growing even rounder, straining from the stallion's fluids and growing so big that it touched the ground as she stood on all fours. She tried to move, but the stallion reached down to shove her close - they would be done when [i]he[/i] decided they were done. The dog's round, wobbly body shook and audibly strained from her inflated belly, before the stallion finally slipped out her her. With a loud gush, liquid drenched the ground beneath them, splashing loudly. She couldn't move for several minutes, just stood beneath him dripping all over the ground and panting. Finally, she slowly made her way from the stall, but not before the stallion offered her a love nip on her rump. 

Fang dragged herself and her distended belly back to her usual herd, legs shaking like a newborn lamb the entire time. As soon as she was in the center of her herd, she passed out.

As she roused the next day, she stepped out into the pasture, her master immediately berating her for waking up late, not bothering a second glance at her. She ate her breakfast, stepped out into the open - and saw the stallion eyeing her nearby. He was fully erect, and had the same beckoning eyes. Fang slowly broke into a puppyish grin as she approached - who was she to deny the needs of her herd, after all?