Man's Best Friend, Part 2
When you return to the sanatorium, the now-friendly wolf will guide you through the psych ward. This will make your trip a lot easier in general. If you get overwhelmed by a Wendigo, he'll come to your rescue - but only once. Better to make sure you complete the quick time events.
When you reach the gated bridge, be sure to roll the oil drum over and kick it forward. When the pair of Wendigo attack, blast the barrel to kill them both.
Man's Best Friend, Part 3
In the final moments of the Wendigo chase, you have some split-second decisions to make. If you're looking to get your wolf friend out alive, make sure to barricade the door when you have the chance. Then in the final room, you'll have the option to shoot the remaining Wendigo or blast the explosive barrels all around you. Do not shoot the barrels - you'll die in the explosion.
When you take control of Ashley in the tunnels, you'll immediately have a choice to leave Chris behind. You've stuck together up to this point, so keep it up - don't let him stay back.
Shortly after, you'll have a choice to investigate a voice or stick with the group. You can follow the voice to find a totem, but you'll see a trap door too. Whatever you do, do not open it - Ashley will be instantly killed by a Wendigo on the other side.