Grabbing the bottle quickly, Chris turns the vial to its label and reads all its information.
"Horse. Anthropomorphic variant. 15 milliliters. Ingest Orally for quickest effect. Full transformation, Five minutes. Refill and ingest again for exaggerated effects. Excites subjects."
Exaggerated effects? Chris stares at the label. The information was either obvious, irrelevant to his situation, or cryptic. All except the transformation time. Even then, it was also vague. He sighs, already regretting what his actions.
Suddenly a loud thud followed by a shattering sound comes from the living room. Shoving the vial in his pocket, Chris runs back to the living room, where Katherine, his mother, was sitting at the table. Upon entering, he sees his mother forward on her knees. In front of her, what remains of the mug lays without any coffee. Chris groans to himself; She drank the entire mug, and the vial. Snapping out of his self-pity, he realizes his mother is down on her knees. He goes to help her up.
"Oh, Chris!" She says as he helps her up. "I went to put the mug in the sink, and it's like my feet turned to stone!" She rests on his shoulder. He moves to the couch, and sits her down. As she falls back on the couch, Chris looks down at her feet. He's stunned silent as he looks at them. Instead of normal feet, she had large hooves! Eyes wide, he just stares. They look like they belong to a Clydesdale. The fur from her hooves was white, and still growing upward!
"Chris, what's wrong--" Katherine began before being buffeted by a strong, heavy feeling from within. It was a mixture of heat and anxiety, but it wasn't unenjoyable. As a matter of fact, the longer it lingered the more enjoyable it felt. Soon, all she could focus on was how good the sensation feels as it radiates outward from her stomach, to her extremities. She quickly closes her eyes and inhales sharply. Chris looks up to respond to her, and instead grows quieter as he watches what's happening to her. First, her ears shoot up, growing longer while also exploding in brown fur. The fur appears to be growing equally along the entirety of her body. It's mostly brown, but there are traces of white fur. As the fur grows, so does her hair. Chris watches his mom's hair begins to snake along her backside, growing longer than she ever let it before. It mixes with the fur to become a sort of mane as the trail line continues into her bathrobe and out of Chris's sight. Chris couldn't help but smirk at how she looked like a mullet enthusiast.
Suddenly, she puckers her mouth, as if she just ate something bitter, which makes Chris focus on her mouth. As he watches, it extends outward into a muzzle, pulling her nose along with it. As it's pulled along, it begins growing flatter, while the nostrils grow larger and more round. Soon, her nostril openings rest on the end of her new horse muzzle, which continued to lengthen. With it, her head shape begins to alter dramatically. Her eyes sink in and separate slightly, still facing forward, but above the muzzle. Her now fully equine ears move along the top of her head, assuming a position natural to a horse. She exhales, causing her to whinny, revealing her huge teeth, an odd mix of horse and human. Chris supposes that it's fortunate his mom prefers the salad bar over steak. Just then, Katherine let's out a moan, bringing Chris back to attention. Her jaw and neck thickens, bringing the whole shape of a horse's head into recognition.
The fur had pretty much overtaken her entire body now, and Jeff wonders what the fur pattern looks like, but the bathrobe was in the way. Chris, with a bit of embarrassment, tries to lift the bathrobe to side to get a better view. Much to his shock, Katherine slaps away his hand. Feeling guilty, he was about to apologize when she grabs both sides of the robe and pulls it apart. She isn't gentle with this action, and the robe tears audibly as it ceases to cover her body. Chris turns red in the face at this, but now eyes her fur pattern. It's remains mostly brown, but at the edge of her snout, a patch of white rests, along with a light dusting traveling down her thick neck to hands her hands, which were also white furred. On her belly, another patch of white pooled around her belly-button before another dusting of white lead to her groin. Her shins are white furred, and her thighs are brown. Chris thinks back to how he thought her hooves looked like a Clydesdale's. He can't help but congratulate himself on a correct assumption.
Chris assumes she's done with her, and begins to relax. However, she immediately tenses up and clenches her teeth, resulting in him doing the same. Her arms begin bulking up, as muscle begins to flow into them. The same happens to her abdomen and legs. With every heartbeat, her muscles grow larger and more pronounced, fit for that of a work horse. At the same time, she grows in size to complement the changes. Her bra and panties are no match for her, as they strain against her body. Unceremoniously, they both snap, falling to the couch, joining the tattered bathrobe. Chris's red face grows violet as suddenly his mother's genitals are exposed to him. Before he can avert away, he can't help but observe them in great detail. Her breasts had grown as well, going from what Chis would have guessed to be C-cups to huge DD-cup knockers. Her nipples were now a dark, leathery pigment and very prominent. Speaking of leathery, her vagina was now very large and dark coloured. It is the opposite of petite, as big and deep. Chris laments his mother's spread position on the couch.
With the end of the bulk up, Katherine relaxes immediately, she tilts her head back, and let's her now completely equine head fall over the back of the couch. A tail pushes out from in-between her legs, behind her anus, which swishes lazily. Chris finally relaxes as well, and surveys his mother. Grimacing slightly, he looks over her. She's a six-foot tall, female anthropomorphic Clydesdale. Her eyes are closed and she's exposing herself.
Jeff takes the vial out of his pocket, and holds it in his hand, unsure of what to do next, or what will happen next.