if a stray dog has you in a viceroy grip of lockjaw. A gentle yet firm "Thumb In The Bum" will distract any animal, giving enough time to escape.
Or for the Americans, a round or two discharged from your eagle dicked, patriotic AR15 should do the trick just as well.
Muh double-barrel 10 gauge with 3.5in shells has never failed within 10yds.