Paige thought for a moment. This was her best friend's mom, wanting to get fucked by Paige's horse cock.
"No, we can't!" yelled Paige. "Your daughter is just down stairs."
"I don't care!" responded Imee. "I've... I've never felt so horny. Please, you have to fuck me!"
At that moment, Imee quickly removed her pants and panties. Bending over, she placed her hands on the desk, presenting her backside to Paige. Paige couldn't resist a moment longer. She mounted Kelsey's mom and plunged her giant cock into Imee's dripping pussy. Paige neighed as she her hair got longer, forming a mane running down the back of her neck. Her hooves dug into the floor as she thrust her cock into the moaning woman. Imee's vaginal muscles expanded for Paige's cock, her ass shaking up and down. She howled in orgasm as she reached her climax. She almost didn't hear Kelsey's hooves clomping on the stairs.
"Mom!" yelled Kelsey as she burst through the door. "What the hell are you doing with Paige?"
Imee panted as she looked up at her daughter.
"Kelsey, sweetie, I'm sorry you have to see this," she said. "We will talk in just a second. I have to--- OH!"
She screamed in orgasmic bliss as Paige continued to hump away, blowing her load into Imee's horse-like pussy.
"Oh my God mom, what did you just do?" cried Kelsey as Paige slid her cock out of Imee's folds.
"I-I'm sorry baby..." sighed a disgusted Imee. "I just couldn't help myself. I don't know what came over me."
Paige neighed with accomplishment. Her changes had progressed further. Her face jutted out somewhat, while a luscious, blonde mane ran down her neck. On each hand, her ring, index, and middle fingers had fused into a dark mass, while her pinkies and thumbs had shrunk into uselessness, their nails darkening. Short fur had begun to cover Paige as her palomino patter became more obvious.
"Paige what the fuck?" Kelsey had no idea how to react. "How are we supposed to change back now? You're almost completely a horse!"
Paige opened her mouth, revealing horse-like teeth behind leathery gums. "I don't want to change back. I want to get you pregnant. I want to get your mom pregnant with my foals."
"Mom, why are you doing this? You didn't take the pills, did you?"
"No, I didn't touch them! Paige just... smelled so good, and I couldn't think properly. We need to get out of here."
Imee got dressed, but found her clothes felt somewhat tighter. The mother and daughter left the room, but stopped as Paige followed awkwardly on all fours.
"What about meeeee?" she whinnied, clearly not fit to be around them or in public.
"Paige," said Kelsey. "We can't be in the same room with you. I don't want you to get me pregnant and I don't want a new half-sibling! We've got to take you out to the fields."
Imee checked outside to make sure the coast was clear, then led Kelsey and Paige to her car. Kelsey sat in the passenger seat while Paige was lain down in the backseat. Imee had driven only about two miles before reaching a pasture full of horses. Under Imee's tennis shoes, her toe nails start to darken. Her pussy gets wet again, permeating the air in the car. Kelsey noticed, and felt aroused by her mother. What was she thinking? She can't be attracted to her mother. The air was filled with Imee's scent, and Paige, who could barely talk, neighed excitedly in the back. Kelsey's pussy became wet as she thought of lesbian, incestuous things she wanted to do with her mother. She reached down to her equine pussy and began masturbating while gazing lustfully at her mom. Imee slammed on her breaks and parked the car on the shoulder of the road.
"Who's next?" asked Paiged seductively.