I’ve been consulted about puppies and dogs being afraid to go up and down the stairs.
I suggest they sit on the stairs with their dogs, and feed them their meals there, or put yummy treats like hot dogs or turkey around the stairs and slowly entice them with treats. Also to sit on their own butts and go up and down slowly while talking to their dog.
The most helpful tip is to use a snug harness so that the dog feels secure. The other day, my own aging cattle dog, Winnie (12 years old) stumbled a few times as she tried coming down our indoor staircase and became afraid. I quickly got the Freedom No Pull Harness that I use for walking the dogs and put it on her. I could then firmly hold her up as she made her way down, and she felt much safer and secure because she had physical support. Poor old Winnie.