It was a sunny late afternoon, many cars and vehicles drove on by the seemingly endless roads of the highway. The sound of cars passing by booming throughout the area. This all made a single stray dog, that stood alone underneath a nearby bridge, all too scared to move the slightest inch, not knowing how they've managed to get themselves in the situation that they're in. His name was 'vanilla', a pit bull terrier. Vanilla was given that name due to his coloration of fur being off white. For him, life as a stray was simply harsh for him, other dogs hogging up his scraps of food, having been bit by bigger and stronger strays in fights that he didn't want any part in. He simply just wanted to be left alone and leave it at that, but they just keep coming back for him again and again and again. He couldn't stand it anymore and decided to run off as fast as he could. This eventually led up to the situation he is currently in, trapped right next to a busy highway. He whimpered in fear, not wanting to be instantaneously crushed into a meaty pile of roadkill. He slowly looks around for a free path to escape, still hiding underneath the nearby bridge. After a bit of time passed, the number of passing cars became less frequent, now was his chance. Stepping out from his hiding spot, he quickly ran across the road, his heart pounding out of his chest with adrenaline, panting loudly with there tongue dangling out. Just as they had made it across, a car zooms on by just inches away from him. This startled vanilla so much, it caused him to fall back, causing him to roll down a large grassy hill. This went on for about a minute before he had finally stopped spinning, feeling incredibly dizzy. He stood up, or at least tried to, trying to regain their line of sight. Once he did, he came face to face with a river. feeling relieved on finally finding a water source, vanilla quickly went to the river and drank out from it, careful not to accidentally fall in. What he is unaware of is that not too far off in the river, there lies radioactive waste!. Multiple broken barrels of nuclear materials have contaminated the running waters of the river, and vanilla is drinking it. After his thirst was quenched,  he began to feel odd. He stood still, his body felt numb all over, yet so tingly. His heart slowly began pounding, beat after a beat it increased faster and faster, causing him to pant. He shivered as the tingling intensified. But then, it happened. Vanilla's eyes shot up wide open, letting out a loud growl. His body tensed up, veins becoming visible throughout every inch of his form. His eyes shut as his muscles began to swell up, slowly becoming a hulking beast. His bones reshape as he abruptly grows bigger in size. As this was happening, multiple physical changes began to kick in. He growls more and more as his fangs became much sharper and intimidating, his rear also seemed to swell up in size, giving vanilla a bit of a bubble butt, his pointy ears grew pointer, his muzzle grew more, making it appear to have a Cheshire smile, and lastly, his genitals grew in size and girth. His once golf ball-sized balls swelled up in size, now being the size of two large yoga balls. He opened his eyes and looked down in shock to see this. He blushed immensely at the sight of his now large balls, causing him to get erect. His canine member swells bigger, leaking beads of precum as it does. The knot comes out from the sheath as vanilla's member throbs up and down, now being 7'0" in length and 4'0" in girth. Now feeling horny, he instinctively began to hump the air, panting and blushing. His muscles continue to swell more and more, his pectorals jutting outwards, and his abdomen rippling in to define 6 pack abs. He looks up to the sky, panting and blushing more. He quickly shits his eyes and opens them back up to reveal bright green ones. He growls deeply, moving a paw to his cock as he began 'stroking' it. Deep growls and pants engulfed the area, along with the strong and powerful dog musk that was him. He growled more and more, his member slowly tensing up as he was coming close. Then finally, his cock jutted upwards as he finally came, letting out the biggest and loudest howl ever known to humanity. Throb after throb, his cock let out a torrent of dog seed, some of it entering the river. After an entire minute, his orgasm subsided, panting heavily and blushing a deep red. His seed covered a large portion of the area he was in. Now standing at 10 times his original size, he looked around in amazement. His thunderous footsteps could be heard out for many yards in the woods. He towered over several trees around the area and could see out from far away. Vanilla wagged his stubby little tail in glee, now with his new form, he would not have to worry about other dogs attacking him anymore!.