In The Battle of The Five Armies movie, we see Thorin lead a shock troop of Fili, Kili and Dwalin to Ravenhill to take out Azog. They ride on huge-horned-rock climbing-goats. Now, I have not read the books but I have come to know that the character of Azog was not there in the books, instead it was Bolg who led the Orcs in the battle for the lonely mountain.
So my question is, where did Thorin get those All Terrain Goats ? Did Dain bring them along with him? are they mentioned in the books or they are just Jacksonian innovation ?