Feb 13 2015, 5:57pm
Medical care would have been crude, at best, among the Orcs. And a maimed Orc would be likely to be killed as weak, so I can see why Thorin would have thought that Azog had died. Besides all that, I think that Thorin wanted Azog to be dead so badly that he was in denial that the Pale Orc could have survived.
As for why Azog waits 40 years before he seeks revenge, it might be because he couldn't reach Thorin in the Blue Mountains of Eriador. He and his Hunters might have been able to pass through the Lone-lands in relative safety, but the farther west he went the more likely it was that he would encounter Dunedain Rangers or a company of high-elves like the brothers Elladan and Elrohir.
"At the end of the journey, all men think that their youth was Arcadia..." - Phantom F. Harlock
(This post was edited by Otaku-sempai on Feb 13 2015, 5:59pm)