funny, my dog turned his nose up at Pedigree Chum as well, he prefered the cheaper lassie brand guess you have small children for it to end up there.
if you can see the can, why not poke a knife through it and then pull it out?.
failing that you may have to remove the toilet to dislodge it from the u bend, just two screws at the base, and then pull out of the fitting, but do have a bucket to hand to empty the u bend
good luck