The key in Animal Hospital comes straight from Ratthew, the small anthropomorphic mouse who visits your reception window across multiple night shifts. He is a friendly recurring character rather than an anomaly, and he only hands the key over after his story reaches a specific point. Once you have it, the key opens a hidden safe tucked behind a cat poster in room 5.
Quick answer: Keep talking to Ratthew through his repeat visits until the conversation where he says he has to disappear and mentions his twin sister Rattina. He gives you the key as he leaves. Take it to room 5, interact with one of the cat posters on the wall, and the safe behind it unlocks.
How to get the key from Ratthew
Ratthew first shows up around Shift 2-3. The key is not a one-time reward you can grab on a single visit. It only appears at the end of a chain of conversations that build up over several of his appearances, so you need to keep treating him as a normal visitor and let his dialogue progress.
Note: Because the key is gated behind Ratthew’s full dialogue arc, missing his earlier visits or shutting him out can keep this final conversation from arriving. Treat him like any ordinary patient each time he comes by.
How to use the key in room 5
The key fits a safe hidden behind the wall decoration in room 5. The interaction point is one of the cat posters, not an obvious lock, which is why it is easy to walk past.
What is inside the safe
Opening the safe ties directly back into Ratthew’s search for his missing sister. Three things are waiting inside.
| Item | Detail |
|---|---|
| Photo | A photo of Rattina, Ratthew’s twin sister |
| Suitcase | Marked with the words “Top secret” |
| Message | “The experiment was a success, the ‘Shadow’ now sees everything..” |
The contents connect to Ratthew’s earlier hints that he was caught up in government affairs and once chewed through experiment reports in Ron from Accounting’s office. The safe confirms Rattina worked for the Animal Corporation before she vanished, and the “Shadow” note explains why the government wants Ratthew kept quiet.
If Ratthew has not handed you the key yet, the answer is almost always that his dialogue has not advanced far enough. Keep letting him reach the window across shifts, avoid rejecting him, and the Rattina conversation that gives you the key will eventually play out, opening the room 5 safe and the rest of his story along with it.
