What makes a chew last is the part of it a dog cannot digest, and that is the figure almost nobody prints on the bag. Everything else on a chew label is about what goes in; the number that decides how long the animal is occupied is about what does not. It is worth knowing which of those you are actually buying before you decide a chew is good value.

This is ostrich wing bone and nothing else — NAW describe it as containing nothing but 100% ostrich, gluten free and grain free — and they publish the analysis, which is where it gets interesting. Protein is 30%, fat is 1%, and ash is 64%. Ash on a feed analysis is the mineral fraction, so almost two thirds of what is in the bag is bone rather than meat. It comes as a 1KG bag and NAW put the minimum age at 4 months, with fresh drinking water always available.

• 1KG bag of 100% ostrich wing bone
• Protein 30%, fat 1%
• Ash 64%
• Gluten and grain free, with nothing added
• NAW put the minimum age at 4 months
• A complementary treat rather than a meal

On the 64%. NAW describe these as high in protein and 30% is a genuine figure, but the ash number is the one that tells you what the chew mostly is, and it says bone. That is exactly why it lasts, and it is also why you should not count it as feeding the dog in any meaningful way. The 1% fat is the genuinely unusual figure here, and the real argument for it against something fattier. NAW publish no calorie figure, no piece count and no guidance on which size of dog a wing bone suits — so supervise it, and take it off the dog once it has been worked down small enough to go down whole.

Who it's for: determined chewers who get through everything else in an evening, dogs that have to stay off fat, and owners who have already tried chicken, beef and lamb and need a protein the dog has never met.