The mysterious key in Animal Hospital doesn’t hand you a new pet or a pile of rewards. It opens a hidden safe in Room 5 that quietly pushes the game’s storyline forward, and the only way to get it is to pay attention to a recurring visitor named Ratthew during your shifts.
Quick answer: Serve Ratthew when he visits your office around Shift 8 to 10, then pick up the key he drops on his seat after he leaves. Carry it to Room 5, pull down the cat poster on the far wall to expose the safe, and use the key to open it.
How to get Ratthew’s key in Animal Hospital
The key comes from Ratthew, a black animal character who shows up at the hospital from time to time rather than appearing on a fixed schedule. Most players run into him and receive the key somewhere around Shift 8 to 10, so you generally need to push past the early shifts before he turns up.
You can do all of this as the Intern, so there’s no need to unlock a specific class first. Using one of the other classes won’t hurt, but it isn’t a requirement for getting the key.
How to use the key in Room 5
Once the key is in your inventory, head to Room 5. It sits at the far back of the hallway on your right. Inside, the safe isn’t out in the open. It’s tucked behind a cat poster on the far wall.
You’ll know it worked when the poster comes down and the safe swings open to display the items inside. If the safe won’t budge, you’re either missing the key or you haven’t pulled the poster down yet.
What’s inside the Room 5 safe
The safe holds three story items rather than gameplay rewards. Each one connects to what Ratthew tells you during his visits.
| Item | What it points to |
|---|---|
| Photo of Ratina | Ratthew’s twin sister, who worked for the Animal Corporation before vanishing without a note or warning |
| Suitcase marked “Top Secret” | Classified material someone has been hiding, hinting at corporate experiments |
| A short note | Reads: “The experiment was a success. The shadow knows everything,” introducing a figure called The Shadow |
These items line up with Ratthew’s dialogue. He says he needs to disappear because the Animal Corporation is searching for him, and he claims he knows secrets the company wants kept quiet. He also mentions chewing up the experiment reports in Ron’s office, which now reads as a deliberate attempt to destroy sensitive documents rather than random behavior.
The photo of Ratina ties the safe directly to his missing sister. He describes her as the smarter sibling, says she worked for the Animal Corporation, and explains that she disappeared with no message or explanation. The safe’s contents strongly suggest her disappearance is connected to whatever experiment the note is talking about.
Note: The key’s payoff is purely narrative. There’s no rare loot waiting behind it, so the reward is the set of clues themselves. It’s worth opening the safe slowly and reading everything if you care about how the Ratthew, Ratina, and Animal Corporation threads fit together, especially since these details look set up for future updates to expand on.
