Per The Free Dictionary--IAT, it may be the International Appalachian Trail? IAT also refers to a number of accounting-related items, with which we retired accountants thankfully no longer need be concerned.

To the OP: Whatever the IAT is, October is hunting season almost everywhere. Please wear a large blaze orange item and put another on your dog! Also, for the safety of your dog (so he doesn't decide to chase a game animal, which renders him legally liable to be shot in many jurisdictions), please keep him on leash!
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May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey