C4C. 4″ is pretty small for a 80 lb. dog. Also, myself and others are not crazy about beef marrow bones because of the marrow. The marrow is a very high fat with no nutritional benefit. Of course, I guess it depends on the % of fat in the food you are already feeding. C4C if it were I, I would switch to a bone without marrow and a much, much large size. You know how small my girls are and I would never feed them a bone that small. If your dogs haven’t broken or cracked any teeth then they have strong teeth and that’s good, my concern is over the 4″ size of the bone and that it contains marrow.
