Paw shaped keyhole in hospital

lone-survivor

In the hospital I noticed a paw-shaped keyhole; You only seems to take notice of it after "new game plus" e.g. beating the game. Is there some way to open the door? Since it's optional and apparently NG+ only I assume it's required for a certain ending?

Best Answer

You have to finish the cat adoption side quest, then feed your cat all five tins, and finally offer it the cat plush. You'll get the ability to create

Chilled Can of Soda or Chilled Mexican Cola

Source