I have some marrow bones sent from our butcher as freebies, in our freezer - they are for our dog and I am sure he will enjoy them, but do I need to cook them before giving them to him?

no need to cook them, just defrost and let him at them

i've never cooked them anyway, i fear it would make the bones even harder than they are already. to be honest.

you also need to watch your dog with them as the actual bone is very hard & some dogs can even manage to break teeth on them.

usually i let mine have a them for a while to strip the meat & connective tissue out, lick at the marrow (and then it help him get it all out) but then they go in the bin, don;t really like the thought of him chewing on it too hard and ending up with no teeth!
they're usually around no longer than a couple of days (any longer and they really start to smell - he doesn't mind of course & neither do i, but my mother is really fussy when it comes to odours )

Never give cooked bones of any kind! Raw only, just defrost and chuck in general direction of dog, they'll take care of the rest

I've only just got back to this, sorry Thanks - I'll dig one out of the freezer in the morning, and it should be defrosted by tomorrow evening for him.