The arcanine clenched tightly as he waddled desperately inside his friend's house, he had forgotten to use the rest before coming over and now could barely hold it even as he arrived. Of course he knocked on the bathroom door despite his desperate squirming and holding of his stomach "H-hey I need to use the restroom". Their was silence for a moment before another boy in the restroom announced he would be a minute, but that would be too long for Reth. The arcanine whimpered and yelped as all of a sudden he couldn't hold it anymore, his butt relaxing a little too much as he started to poop into his pants and start pissing in the front of his underwear. "N-noooo" he yelped as he tried his best to clench, stop some measure of it, but his potty training was failing him as he quite liberally filled his briefs with mess. Fortunately Reth was lucky, as he filled his pants up he began to regress in age, very quickly quickly becoming the proper age to be filling his pants like a little baby. "P-please hurry!" he cried as he tried his best to keep his pants and underwear and sliding down, keeping some measure of his dignity even as he became too young to walk or even stand on his own. The small baby arcanine yelped as he fell back onto his butt, coating his rump in the ruined pants that once donned his adult form. Finally after a seeming eternity for the small pup, his friend Brandon opened the door and came upon the toddler in his dirty pants. "Oh what happened here?" he asked looking down at the smol pup.
The tiny little arcanine was lifted up out of his former big boy clothes, his ruined underwear sliding right off exposing his tiny little baby dinky and empty balls between his legs, innocently bouncing as the fox smirked at the runt as he held him in paws "Such a baby, guess we should get you padded." Brandon babysat often on the weekends so he was easily able to scrounge up diapers for his little buddy, couldn't let him run around naked of course, he wasn't house trained afterall. "Stay still little guy~" he smiled, Reth whined as he was sat back on the changing table and his legs lifted up by the fox's strong hands. Only instead the feeling up a cold wet wipe, the fox was cleaning his young charge's messy rear and soaked peepee with his tongue and mouth, his tender kisses and licks cleaning the dirty little boy of all his accident until finally he was nice and clean.
 Reth couldn't help but squirm and hide his face as the embarassment was too much for him, but his body betrayed him as his dimunitive little puppyhood stood up at attention, begging to be touched until he climaxed. "Awww you like your rear getting cleaned like that lil guy?" Brandon laughed and teased the lil member, sliding his babyish foreskin up and down even as the little tyke's balls yearned for release. "Well...that's something only big kids get to do, and yer obviously not a big kid" he patted the pups tummy before applying baby oil and powder to the sensitive little peepee in front of him, getting it so close to release, but stopping just short of a full climax. 
Reth whined and attempted to move his baby paws downstairs, desperately wanting to rub his dinky, to feel one more climax, but Brandon slapped his paws away "No touching~ You need to be diapered right now" . True to his word Brandon diapered the little runty arcanine, leaving his dinky straining against his padding, except even that passed as the little boy started to soak his diapers, his hot piddle cascading over his baby package, nice and snug in his diaper~