‘Bite proof’ is made up, with no dictionary definition, no outlined parameters and therefore no minimum standard. So in theory, any brand could call themselves ‘bite proof’ because there is no criteria for them to meet. There is no muzzle equivalent to the car harness’s crash test, or a leash tension meter.
Let start by breaking down ‘Bite proof’ into its most simple terms. The word proof was originally used in the sense of a test of something—such as a test of quality, worth, truth, etc. However, it is now often interpreted as meaning the same thing as evidence.