The rules state that "barding is four times that of similar armor for humanoids". Period. But what about for a dog? While I agree that it would take considerable time to craft such armor, the materials needed would be considerably less than that for a medium humanoid. Yes, it might be difficult to find someone willing to do such an armor in small or medium towns, but any large city or castle would probably have an armorer who makes such for the dogs of the Lord or City. Regardless, the 4x multiplier for all barding seems to be a simplistic rule, specifically for horses. Otherwise, Barding for an elephant would be the same as for a horse. Thoughts?