Most carnivores, including the ferret, make a point of eating bone, especially parts of the skull and pelvis, the ribs, and the ends of the long bones--exactly where red bone marrow is found. Red bone marrow is rich in minerals, easily absorbed irons, proteins, fats, and fat-soluble vitamins, and is nearly a perfect food for carnivores. I have seen uncounted thousands of carnivore-chewed bones, and they all have identical characteristics, regardless if my ferret chewed them yesterday, a dire wolf chewed them some 15,000 years ago, or early mammals chewed them millions of years ago. The species may change, but the biomechanics of bone and bone eating are exactly the same. In terms of bone-eating biomechanics, bone can be grouped into three basic categories--that which is easy to eat, that which is hard to eat, and that which cannot be eaten. Easy-to-eat bones are those that can be effortlessly cut into pieces or crushed for swallowing, allowing stomach acids to do their magic work. Hard-to-eat bones are those that a ferret may be able to consume, but eating them requires considerable expenditure of time and effort. Those bones (or parts of bones) too hard to eat might be cached, they might even be gnawed, but they are not consumed unless small enough to swallow whole. Not surprisingly, the bones that are easy to eat are composed mostly of trabecular bone, usually covered with a thin layer of compacta. More importantly, mimicking honeycombs filled with sweet honey, the trabecular spaces are filled with high-protein, high-fat, high-micronutrient marrow. When a carnivore chews this type of bone, the bone doesn't break into small fragments having sharp edges and pointy ends. It breaks into small, irregularly shaped masses of marrow-filled spongy bone. These bone fragments are no more dangerous for a ferret to eat than dry, extruded food, and nutritionally, far better. Most do not survive the digestive process -- at least in recognizable form. Hard-to-eat bone is generally composed of layers of compacta, and can be quite hard. I have compact bone fragments that once supported the weight of dinosaurs, some 65 million years ago. I have chunks of 20,000 year-old mastodon compact bone that look as if the animal died just a few years ago. Compact bone is a bioceramic, a sort of "bone china." Consequently, it shatters like glass, and can be broken into fragments having sharp edges and points (the bone knives I mentioned earlier where made from compact bone). Compacta makes up the shafts of long bones, and is ultimately the reason why some people are afraid of ferrets eating bone. What few people understand is that these bones are HARD to eat -- few carnivores actually try, less those with special adaptations like hyenas, or those that are starving or living in marginal environments. Most carnivores will gnaw bits of the diaphysis away until the task becomes too difficult, and then they will abandon the bone for something better. There are some skeletal parts so hard that carnivores rarely attempt to eat them. If small, they may be swallowed whole, but little attempt is made to break or gnaw them. This bone includes the hardest portions of the long bone shafts, the teeth, and portions of the skull, especially the petrous portion of the temporal bone (the petrosal -- arguably the hardest part of the body). Not many carnivores are willing to attempt to eat this type of bone, not even hyenas, but it doesn't matter much because they contain few nutrients. Regardless of species, most carnivores eat off the ends of the long bones and leave the hard, potentially dangerous shafts behind; the exception are some hyenas species, whose massive teeth and jaws can eat nearly any bone from any animal. Polecats, feral ferrets, and pet ferrets only rarely eat the entire bone shaft, but will make exceptions if starving, living in a marginal environment, are "bone starved" (has a unsatisfied desire to chew), or the bone itself is soft (immature chickens, boiled bone, etc.). What this means is ferrets, like most carnivores, chew off the soft trabecular bone preferentially over the harder compact bone. Soft or hard, what is the ACTUAL impact of bone gnawing on the teeth? Bob C [Posted in FML issue 4158]