Specific answers for common Animal Hospital roadblocks.
Community rankings (not official) put Surgeon at S-Tier as the best free-to-play class, with Secretary, Doctor, Head Nurse, and Secret Agent in A-Tier. Surgeon heals for Sanity plus a speed boost; Secret Agent (Robux) adds a Gun and Scanner for interior threats; Head Nurse (Robux) adds inventory slots.
Ghosts appear after a patient dies and drain Sanity while invisible. Reveal one with the Fire Extinguisher, then defeat it with the Taser (restores a little Sanity) or the Gun. A revealed Ghost usually goes down in one hit.
Animal Hospital is a Roblox experience, so most load or crash problems come from the Roblox client or your device. Restart the client and device, check for a pending Roblox update, clear the Roblox cache, and confirm your device meets Roblox requirements. Large updates like the Aug 22 Even More Lore update can cause temporary load issues that clear after a restart.
Find the Animal Hospital wheelchair, use it to move a patient faster, and check the known reasons it may not be available or work.