true enough. But dogs don't need fiber- you can not-feed your dog any fiber at all his entire life and he'll be robustly healthy, indicating he has no dietary NEED for it. You can not-feed your dog a single food item that grew on a plant his entire life and he'll be robustly healthy, because he has no dietary NEED for any plant-derived foods. Because at base the dog's body is that of a carnivore.
however blanket statements like "dogs do not need fibre, and "wild dogs only eat meat are ridiculous". I have personallly seen hyena and wild dogs in the maize fields, eating corn cobs, and eating wild watermelon, and i bet every dog owner who has horses has seen their dog eat manure. the Jackals can survive for quite a long time just on manure etc.