(Cassie on the left. The girl with glasses. Maddie is the girl on the right in the jean jacket and has adult braces.)

 “Ok... this should do it...” Cassie said to herself, looking over at the mixture she had concocted with some of the old unicorn horn she had been sent a few days ago. It was a powder-like substance, similar to those instant food mixtures; all that needed to be added to it was water. “The only thing is I’ve got no one to try this out on....” She thought. She could try it on herself, but then she might lose the form she had, as well as all her magical skills. “Maybe I could call one of my friends... I’m sure they won’t mind being a test subject for me...”

She went over to the phone, dialing in a number as she glanced back at the antique wooden chest. It was delivered to her house a few days ago, containing the unicorn horn that had been the cause of her transformation into a beautiful anthropomorphic unicorn. And now that she had been turned from human to animal, she wanted to spread the changes around. The mixture she was working on now was her first attempt at something transformative, so she hoped that it would work.

“Hey, Maddie, it’s me. Yeah, I’m sorry it’s been a little while since we last met, but I’ve been kept really busy. I’ve got some free time now though, so I was wondering if you’d like to go out somewhere. Why don’t you come by my house first? We’ll have a drink, and then we’ll hit the town. Ok, I’ll see you soon then, bye!” She hung up with a big grin. “Alright, the bait has been set...”

~~~

Half an hour later, Maddie arrived at her house, knocking on the front door. “Cassie, I’m here!”

The door opened as Cassie stepped into view in front of her, Maddie looking at her in awe. “Woah... is that a costume?”

“Nope, what you see is 100% real. If you come in, I’ll explain everything to you.”

“Well... OK. It has been a while after all.” She stepped into the house, Cassie closing the door behind her. “So what caused this to happen to you?”

“I got sent some stuff in that chest, and there was a unicorn horn in there. I accidentally jabbed myself with it, causing me to turn into what you see now.”

“That’s interesting... must have been some magic left in that horn.”

“I’m hoping there still is. I’m trying to use it to create potions that could trigger transformations.”

“I wish you luck with those. You wouldn’t happen to have a drink to spare, would you?”

“I do, just bear with me one second!” She turned away from Maddie, a grin on her face as she went to the kitchen with some of the powder, putting it in a glass as she poured some water into it, stirring it all up. “There we go, flawless...” She smirked as she picked it up, going back over to Maddie.

“Here’s your drink. I hope milk’s ok!” She passed her the glass.

“That’ll do just fine, thank you.” She drank some of it up, moving to sit down on the sofa. “Mmm, nice and fresh!”

“I would hope so. I brought that this morning!” Cassie tried her best not to laugh as Maddie drank down the rest of the ‘milk’.

“Where did you get this stuff from?”

“From the supermarket, I think. I think it was their own brand.”

“It’s really tasty.” She finished the glass, putting it down on the table. “You wouldn’t happen to have any moooooore, would -” she stopped when she heard the noise that she had made. “What was that about?”

“Hehe, seems that stuff is quick acting... I’m sorry for lying, but that wasn’t normal milk. It’s a mix I made myself, and it’s taking effect.”

“Effect... what are y... yooooooooou!” She groaned, her clothes suddenly feeling constricting, getting tighter against her. Cassie looked on with a big grin as she saw the buttons on Maddie’s shirt ping off one by one, her bra snapping apart as her breasts suddenly surged in size. She gasped as they felt heavier, filling up with milk. Her nipples expanded, growing cylinder like as they protruded off her breasts, just like they were udders.

“That’s a good sign.” Cassie giggled. “An enlarged set of mammaries and proper teats... I should have been recording this.”

“Oooooohhh....” She moaned, stomach gurgling as it grew a little larger, white fur starting to spread slowly over her body. Splotches of black fur grew in random places as she tore off the remnants of her shirt, her stomach pushing outwards as she gained some bulk.

“That must feel quite good... and it’s just going to get better!” She commented as Maddie’s crotch bulged outwards, starting to swell and discolor, inflating as if someone was pumping air into it. As it grew larger, four large teats grew along the front, all of them standing erect as fresh milk trickled through each one. It was hanging down between her legs, her thighs bulking as her shorts tore open.

“Muh... muhhoooooo!” She fell forward, groaning as she rolled onto her back, looking at her new udder and her swollen breasts. “Ahhhh.... soo heavy.... need to be muh... muhh.... milked!” Her spine stretched outwards, a slender tail emerging from her growing rump, tipped with a tuft of black fur. She felt the muscles in her ass tone up as it became slightly more square. She groaned more as her shoes got tighter, her feet stretching as her toes fused together. They burst out of her shoes as the nails grew around her feet, turning them into a pair of cloven hooves.

“Well then, I suppose we better get you milked!” Cassie summon up some buckets, as well as a milking machine, attaching them to each of her teats as it began pulling on each one, milk flowing freely.

“Oooooohhh! That’s goooood!” She moaned, her hands twitching as her fingers grew a little thicker, nails wrapping around the base of each finger as they were tipped with mini-hooves.

“I can imagine it is... maybe there’s a way I can help you further though...” She moved to get behind the changing girl, lifting her up slightly as she lined her horn up with her furry lips. “I’ll try not to go too hard!” She began to thrust her horn in gently.

“...ah.... ahhhhhh!” She gasped, bucking against Cassie’s horn as the changes reached Maddie’s head. Her tongue hung from the side of her mouth as her jaws stretched outwards, her nose sinking into her upper jaw as the nostrils flared wide, her jaws growing broader as they formed into a bovine muzzle. Her teeth grew broader and flatter as her hair grew longer, her ears growing as they sat atop her head, a small pair of horns emerging from her head. Her eyes moved to the sides of her head, ending her transformation.

“Huhhr.... oooh... I bet you’re loving this.... getting milked and horn-drilled at the same time... must feel like heaven...” Cassie panted, feeling Maddie’s juices drip down her horn and onto her muzzle.

“Y... yesss! Soooooo much!” She groaned, her body tensing up as she grew closer to orgasm, the walls of her womb constricting against her horn as she threw her head back, a low ‘MOOOOOOOO!!!’ emerging from her muzzle as she came hard, soaking her horn and her head in her juices.

“Muruh....” Cassie snorted, licking up the sweet nectar that dripped from her friend’s cunny as she pulled away from her, the milking machine stopping as she was left to calm down.

“Ooooh.... damn.... that was something else!” Maddie chuckled, groaning as she sat up, pulling the hoses carefully away from her teats. She looked around her, the six buckets set up around her all full up. “Looks like you’re not going to need to buy any more milk for a while, anyway.”

“Well before I was to use it, I’d have to do some tests on it. I don’t want to drink it and go bovine like you; otherwise, I’d lose all my magic.” She told Maddie.

“True... how about you call a few more people over, or try selling it off?”

“Actually, that’s a great idea!” Cassie grinned. “I could set up a stall outside and give out free samples, and watch if anyone turns!”

“Well, you’ve got all this milk after all, so it’d be a shame to let it go to waste. Plus if you need any more, I’m pretty much a walking milk tank now.” She winked.

“That is true. Well, then...” She picked up a couple of the buckets, summoning up some bottles. “Let’s do this!”