What Brian said is correct to the best of my knowledge Phil and I would have your dog checked out or at least phone the vet for advice.
We have a 21 month old black lab and have to watch her like a hawk as she's just a walking stomach. Her whole life revolves around food and play and she will eat absolutely anything.
Ate the flowers and leaves off a whole pot of tulips last year which are very poisonous, though the bulbs are worst. Luckily she sicked the whole lot up within 20 mins - stupid mutt!
She eats insects, chicken sh*t, you name it and we have one of those electronic fly zapper bats which she gets very excited and snaps them up as they fall. Our last lab used to eat onions and cherry tomatoes but would keep them in her mouth for ages and eventually spit them out, never did her any harm as she was 13 when she died.
Lovely little ***** with some disgusting habits. ( The dog, not the missus btw :lol: )
Bob