Pup Lightning wore his pup hood just like any other day. Today, though, something was different. From the moment he put it on, his growth ran rampant. He scrambled to remove his hood, but his arms were pulled to his sides as it became too late. The poor pup grew and grew and grew, his pecs and traps rising around him as all semblances of mobility disappeared. Other changes occurred even, such as tusks that began to grow from his jaw. They pierced the hood, anchoring it even further in place as Lightning ascended. As the apartment was outgrown and the streets themselves began to be taken over by muscle, all Lightning could do was grow, bark, and grow some more as the helpless pup sank deeper into both his muscles and pleasure, incapable of stopping the growth for as long as the hood remained anchored onto him..

Art by Planetself
https://www.furaffinity.net/user/planetself