It was a clear and cloudless sunny day at an anthro beach where the surf calmly ebbed and flowed along the over two-mile-long shoreline. The sands had a sea of umbrellas with towels and blankets underneath and a couple of volleyball courts with five lifeguard posts evenly spaced miles apart and overlooking the entire area. Behind that were a bathroom/shower building and some food vendors and vending machines. 

A trio of border collie brothers settled on a spot that was in between the waters and the shoreline's edge. Cam, the eldest brother who has some blotches of purple and brown along with black and white fur, wore purple swim trunks and pitched up an umbrella. Jesse, the middle athletic teen brother with mostly white fur with spots of black on his right ear and left eye, wore white swim shorts, sat on the large white beach blanket with red stripes, reading a magazine while listing to music. Tyrone, or Roni as he preferred, the youngest slightly tubby brother who had black fur mainly but had white on his forelimbs, torso, left ear tip and tail tip, wore light blue swim trunks, and had a yellow inner tube around his waist. 

Roni was about to head into the water before the older brother stopped him.

"Whoa there, squirt. You better take a shower first and wash up. Don't want to get your fur too tangled with salt water."

"Aww...do I have to?" Roni pouted. 
His oldest brother gave him a stern look that caused a floppy ear and tail to twitch. 
"Oh alright..." he said begrudgingly as he took off the inner tube and began to trek towards the restroom.
He went inside male restroom and was greeted with brown sandy tiles, white painted walls, and low hanging ceiling lights. Along the right wall there were a couple of urinals and toilets and four shower stalls with milky white shower curtains. Opposite wall had the three steel sinks with mirrors above them and a hand dryer at the end. It seemed like he was the only one there.

He headed over to the second stall, opened the curtain and stepped inside, closing it behind him. However, he found something peculiar in the stall.
Laying in the middle of the shower stall floor was a pair of yellow that had a large sunflower decor on each strap. Now how did these get here, he wondered. Curiously, he decided to slip them on, one foot at a time. Despite being woman sizes, they were a few inches larger than his white furred feet, flexing his toes a bit. But it wasn't long until he felt a tingling sensation course throughout his body.
As the sensations grew, he let out a yelp and winced as he felt his feet begin to cramp up. Looking down his eyes went wide in shock as his feet grew a few inches, filling up the flip flops nicely with dainty toes.
His legs began to follow suit as they stretched and lengthened into long womanly slender legs, giving him about an additional foot in height. He gained toned calves and thicker thighs that ripped the leggings of his trunks. 
He grunted as his waist slimmed, his hips widened, and his butt bloated, destroying his trunks process, and leaving him basically nude as the scraps fell to the floor. His tail lengthened about a foot while becoming much fluffier. He let out a moan as his furred testicles and penis eventually shrunk until they receded into his body and replace with a drooling pussy instead.
He moaned again with now a slightly deeper yet higher pitched voice as he felt pressure in his chest. His chest grew and widened a bit before two black perky nipples stood erect from white fur. Soon, two large orbs inflated and swelled into large EE cup breasts.

Like his legs, his arms became longer and slender with hands that have thin longer fingers. He groaned as his head began to change, aging while becoming twice its size. His muzzle became longer and narrower with a feminine shape. Long flowing wavy black hair then grew from his scalp until it reached at the base of his tail.
The male pup was now a fully grown female.
“What happened to me?!” she grasped her throat, noticing how deeper and feminine it sounded as she stood there trembling in shock.
Dainty hands explored every curve and contour of her new body, moaning as she groped her tits and inserted a couple of fingers into her new orifice. Her body shuddered and knees wobbled as precum leaked out. 
But how did this happen, she questioned. Then, it dawned on her. The flip flops! Looking down, she saw the offending footwear that caused all this. She kicked them off her feet, hoping that it at least does something; however, nothing seemed to happen after a few minutes. 
“Jesse, Cam…I need their help.” She uttered, stepping out of the shower stall, and not caring for her nudity as there wasn’t anything to cover herself. 
“Is this…me?” she paused as she caught her reflection in one of the mirrors, leaning on the sink and touching her feminine face, slightly admiring it for a moment. She had to admit she looked good.
But another observation she caught in the reflection was what behind her. What happened to the urinals in the bathroom? Why are there now all toilet stalls? 
Her thoughts were interrupted by some chattering as she looked to her left. In came two female anthro canines, one reddish coated Afghan and one white poodle. They didn’t give Roni a glance as they passed her and went into neighboring shower stalls, chatting still. Yet what surprised her was that they were buck naked!
More confusing questions swirled around her head that frightened her. How did she get into the girls’ bathroom? Why were those women naked? What more did those flip flops do to her? Things were becoming more bizarre way too fast than she can comprehend. But she shook her head of such thoughts for now as she needed to find her brothers for help.
She exited the bathroom to be greeted by glistening bright sunlight that blinded her for a few seconds. As her vision returned, the beach scene looked normal briefly but, that was further from the truth. Her eyes widened as all the beachgoers were all birthday suits, genitalia and tits hung out in the open for all to see. Many were doing the usual beach activities whilst naked, but others were having public sex on towels or sand without care. Also, to note that not a kid or minor in sight, all were clearly full-grown adults. 
She blushed at the scene, feeling a bit warm and wet as she stared at the males’ unsheathed privates with her tail slightly wagging. But she shook her head, trying to focus on finding her brothers. However, before she even began to search, she was interrupted by an approaching figure calling out to her.
“Hey, honey.” Said a naked six-foot black and tan German Shepherd with a runner’s muscular build. His coat had black fur on top of his head, leading all the way down to the base of his tail while tan fur covered from his muzzle down to his feet. His sheath held guava sized gonads that Roni couldn’t help but stare at. “So, ready to get lunch?”
“Wha-? Who are…Ungh!?” she said, holding her head as a headache came over. “E-Eric?”
A memory spike caused her to remember or unlock new memories, pertaining to how she is married to this German Shepherd. In turn it just added more worry and confusion to her.  
“Are you alright, Tyra?” he asked, revealing new tidbit of information.
“I-I’m fine…Just a bit dizzy that’s all.” She said. “Um…h-have you seen my brothers anywhere?”
“Huh? Why? You know they’re living in different states, right? You sure you feel alight?” he stated.
“Y-Yeah…*Sigh…I am.” She replied, feeling more hopeless as no help to found and is stuck in her current situation.
“Come on, let’s get some food. That’ll make you feel better.” He said, reassuringly.
Roni just nodded in obligation as they went over to some food vendors that stood near a sidewalk that became a barrier between the sand and the parking lot. They hit a fish taco stand for lunch. While enjoying their meal on nearby a picnic table, more memories popped up in her head, remembering their wedding day and night and how they first met. Her mind was steadily matching her body, making it feel more natural yet didn’t help to calm her nerves.
After their meal, they headed back to their spot on the beach, marked by a large blue umbrella, a large pink beach blanket with a conch shell print, a beach canvas bag with a clam print filled with some cosmetics, feminine mags, sunscreen, her phone, and sunglasses. They sat and lied down the blanket, resting, and letting the food settle. 
Nearly an hour later, Eric awoken first and turned over to his wife, embracing her from behind. Roni flinched fully awake in response, feeling his unsheathed dick pressed up against her rear. As he held her, he groped her tit, eliciting a moan and a shudder in response. 
“Eric, wha…?”
“Hey, honey, how about we get ‘wet and wild’ here before we hit the water again?” he asked, nuzzling her nape.
More memories unlocked within her as she remembered times of sex with him, trying to bore pups and having that long eleven-inch shaft plowed deep inside her was one of the most exhilarating things she ever experienced. Her body became heated, and snatch started to wet. Both mind and body overcame by feminine urges even more so. 
She turned around and nuzzled Eric’s neck, licking it affectionately as her tail wagged.
“It’s like you’ve read my mind, dear.” She replied.
Once Eric got on top of her, they pressed their muzzles together in one long passionate kiss. Eric groped a tit, making a muffled moan come out of her. As their tongue entangled kiss ensued, his cock tip teased her crotch entrance, rubbing up against her pussy folds.
“Ready, my love?” he asked, after breaking the kiss for a moment.
“Yes, put it in me, dear. My body wants it so bad!” She said.
With one thrust, he plowed into her, making her body shudder and squirm as she let out drawn out moan. He pumped steadily in and out of her with his throbbing shaft grinding against her inner walls. With every thrust, moans and pants escape her muzzle. Not caring about some of the onlooking beachgoers that were enjoying the erotic show.
“AAaah…ooh~! Sweet Anubis! F-haah…Faster, Eric! I-oooo~h- I want puppies soooo~ooooh bad! ~Aaah!” Roni said while wrapping her legs around him.
Eric sped up his thrusts, causing her moan louder and her body shook with utmost pleasure, gripping the blanket tightly as her tongue lolled in between pants. Pressured welled up within them as their genitals throbbed greatly as climax quickly approached.
“Aaah….ooo~h! Oh, Eric, haah…I’m…oooh! CUM—MING!” she yelled as her snatch let out a tidal wave of juices that soaked his shaft entirely.
“Ungh…oooh…Yea-h! Me…-TOO!” the German shepherd cried out as his dick let out a torrent of seed that overfilled her womb, making a small puddle on the blanket. He exited her with a wet plop as more seed and nectar added to the puddle. 
The two embraced again in the afterglow of sex with muzzles pressed into a long kiss.
“That was great, Eric.” Tyra said as she placed a hand on her abdomen. “I think that might’ve did it.”
“Really?” he said while placing a hand on her stomach as well. “Well, if you don’t test positive, we can try again tonight back home.”
“*Giggles…why wait when we can do it now?” she said, giving him an affectionate lick as he gave her a somewhat puzzled look. “Race ya!” she said before getting up running towards the water.
“Hey wait up!” Eric said playfully as he followed her for some submerged ‘fun’.

The End