I'm in Florida and give raw frozen marrow bones to my 7 year old GSD at least once a week.
No problems here.
FYI- My Publix only has them in the regular meat case. The store gets them in these big boxes and they make up the packages at the store level. If you are nice to the butcher, he can sort and make up special packages with bigger bones and those having a little more meat on the bones. I just found this out a couple of weeks ago. Traveler thinks the best part of the bone isn't the marrow, it's the fight to get the bits off the outside of the bone. Silly boy.
Lynn & Traveler