Dungey no match for Lab. Twice my labs have eaten every last bone from an 8 piece bag of fried chicken and never flinched. Other breeds or a rotten or raw crab I may worry but a full growen lab with a cooked crab I would just keep an eye on for the next few days.
Not saying I know. Just what I would do.

Let us know how it goes

God I love Labs...Art
_________________________
When Ma Nature decides to make ya her bitch, aint nothin your gonna do about it