I think you underestimate the gulls stomach acid !i doubt it will survive , no way even a gulls stomach can digest a doggies skin ....gonna be some seriously blocked guts......................and if by miracle it does come out i hope to god i'm not anywhere near at the time !!!
After a humdinger of a winter storm a few years ago, there was a big wash-up of stuff on Borth Beach so I went to gather clams etc for bait/supper. In among the weed and debris, I found several dead whiting, all of which had made the same mistake. The storm had killed a number of corkwing wrasse along the reef and the whiting had found them and attempted to swallow then whole, head first. Each one had a corkwing sticking out of its mouth. It would be like me trying to swallow a one-pound bass whole!Nature can be strange. I once caught a Pollack that had already swallowed a rockling so large that 3 inches of the Rocklings tail was sticking out it's gut and back into it's throat ......... and it STILL took my Sidewinder Sandeel!!