security

Intern
The sweet, hardworking, and slightly odd/oblivious newbie. Many see him as the hardest worker, even though he's the least experienced. It's quite common to have the headcanon that he's an anomaly (or at least not normal) but doesn't realize it, or that he's selectively mute/very kind and easily fooled. He's usually the "baby" of the hospital.
Nurse
Caring, empathetic, and a bit maternal. She's often seen as a chubby little dog who loves herself and wants others to be healthy. She's quite popular with Intern (secret crush).
Secretary
The most tired and burned out of them all. Always exhausted, he drinks a lot of coffee to avoid becoming Hollow Eyes, and he's the hardest worker at reception. Best friend of the Paramedic.
Energetic, hyperactive, and talkative. The one who never sits still and drinks way too much Speed ​​Cola. The Secretary's best friend (he keeps him company while the other works).
Psychologist
The oddball/the "Kinger" of the group. He likes to tell weird jokes, study anomalies instead of just dismissing them, and is the biggest or most intellectual.
Doctor / Surgeon
Competent, a little serious, or arrogant. The surgeon, in particular, comes across as the confident professional who has seen it all.
Security
The serious, protective, and somewhat grumpy one. The one who scolds others and takes safety very seriously.
Head Nurse
The strict but caring boss. A more mature and authoritarian version of the Nurse. Mysterious, quiet, and cool. The one who knows more than he lets on (sometimes he headcans that he's the only one who knows Intern is weird/anomalous).
Quick summary of the fandom vibe:
Intern = the weird and adorable baby
Nurse = the mom of the group
Secretary + Paramedic = the tired + energetic duo
Secret Agent = the mysterious
Surgeon / Head Nurse = the competent ones

Intern
Simple beige/cream rabbit, basic white apprentice clothing. It is the only class where the fur color changes depending on the player to distinguish them.
Nurse
Dog or rabbit wearing a light blue nurse's uniform, white cap with red cross and stripes on its face.
Secretary
Office animal (usually a rabbit or similar) wearing a shirt, tie, and looking like a receptionist.
Paramedic
More sporty/mobile look, paramedic clothing with emergency details.
Psychologist
Animal with glasses, more formal or "intellectual" clothing (sometimes with unusual hair or accessories). Has a darker "Psycho" skin. Doctor
Deer or animal wearing a white coat, mask, and front mirror (similar to Dr. Harlow but different).
Security
Animal (often cat or dog) in a security uniform, cap, and police appearance. It has a "Hospital Cop" skin.
Surgeon
Similar to Doctor but with a surgeon's coat, gloves and a more "operating room" look.
Head Nurse
Premium version of Nurse: head nurse uniform, sometimes with extra details (fox in some skins).
Secret Agent
Animal in a black/formal suit, secret agent look (has skins Noir, Blueberry, etc.).

Intern → For beginners only (learn the game).
Nurse → Very useful at the beginning: you carry more medicines and items.
Secretary → Ideal if you stay in reception.
Paramedic → Mobility (run faster).
Psychologist → Specialist in Sanity (risky but strong).
Doctor → Good at curing patients and maintaining sanity.
Security → Defensive approach (taser against anomalies).
Surgeon → The best free-to-play class according to most. Heals and recovers Sanity + speed.
Head Nurse → Premium version of Nurse (large inventory + medicines at the start).
Secret Agent → The strongest in combat (gun + utility).

Anomalous patients (at reception): They are detected by their appearance (hollow eyes, three eyes, sharp teeth, tremors, strange smile…), by their developed photo, or by security cameras. If you let them in, they can transform into Skinwalkers (formerly called that; it was renamed) and attack.
Hospital monsters: Bed Monster, Mass of Eyes, Stalker, Ghost, Headbanger, etc. Each one has its own way of neutralizing or avoiding it.
In short: you work in a seemingly normal hospital, but it's actually an Animal Corp experiment facility investigating an infection that transforms animals into anomalies/monsters. Recurring characters gradually reveal just how rotten everything is.

Key characters and their stories
Dr. Harlow: The head of the hospital. He's beholden to Animal Corp. The corporation "saved" his life (or what was left of it), and now he works for them. He carries a secret briefcase and meets with hazmat agents. He says the research will "improve the lives of all animals," but he doesn't explain how.
Barney (the rabbit with a mustache and cap): He seems like a friendly patient who only asks for coffee. Gradually, he asks for stranger things (that you keep his red briefcase, take his picture, a scalpel...). In the end, it's revealed that he's a serial killer. Officer Duckman arrives looking for a suspect, and the photo is of Barney. You can either betray him or protect him; depending on your choice, the ending of his arc changes. Ratthew (the black rat): He's the character with the most lore. At first, he hides his identity and warns you not to trust anyone. Later, he reveals that people mistakenly believe he's an anomaly. His twin sister, Rattina, worked for Animal Corp and disappeared. In the end, he gives you a key and a note and leaves because "the government" is after him. The key opens a safe in Room 5 related to his story.
Ron from Accounting: He gradually confesses the truth to you. On one of your visits, he says, "The patients aren't sick. They're infected." He also mentions that old files were moved under the guise of routine cleaning. Liz the photographer: She gives you her camera and asks you to take photos of a specific patient over several visits. Each photo shows a more advanced stage of the infection. The last one can transform the patient into a Mimic/Shapeshifter that attacks. Liz was fired for reporting "fake news" about the anomalies when she was actually getting too close to the truth.

Animal Hospital (Anomaly) is a cooperative horror game on Roblox where you work the night shift at a veterinary hospital. Your main job is to register animal patients, treat them, and, most importantly, detect anomalies (monsters disguised as normal animals) before they enter.
The main background
The story is told primarily through recurring characters at the reception window and hidden documents, not with lengthy cutscenes.
Animal Corporation (or Animal Corp) is the mysterious company that funded and controls the hospital. It appears to be a normal clinic, but in reality, it conducts bioengineering experiments in the basements and on the patients. The "patients" aren't actually sick: they're infected. Standard treatments (maple syrup, eye drops, etc.) only suppress the anomaly, not cure it. Coffee (and caffeinated things like chocolate or peppermint tea) seems to soothe or control some anomalies.
The hospital was built on top of the source of the anomaly instead of relocating it. There's a secret archive room (behind a panel in the supply room) with records from the former director that explain some of this.