Bar spacing decides suitability before anything else
Start with a tape measure, not the seller's description of which animal lived there before. Bar spacing that suited a large Syrian hamster can let a dwarf hamster or a young rat squeeze or, worse, push a head through and become trapped. Measure the widest gaps, including around doors and corners where bars are often spaced further apart, and compare them honestly with the size of the animal you actually own. Check vertical and horizontal bars for bowing — a bar that flexes when you press it will flex much further under a chewing, climbing pet at night.
Hands-on hunt for cracks, rust, and chew damage
Run your palms slowly over every surface your pet will touch. You are feeling for sharp wire ends where coating has worn away, rust patches that flake, cracked plastic bases with whitened stress lines, and gnawed edges on shelves, ramps, and hide houses. Plastic that has gone brittle with age can snap into sharp points under weight. Wooden accessories from an unknown animal are usually best discarded rather than cleaned, because porous wood holds urine and cannot be properly disinfected. Any cage with peeling paint or an unknown coating history should be rejected outright for a chewing species.
Doors and latches get tested like an escape artist would
Small pets learn latches. Open and close every door twenty times, tug each clip, and check whether the door can be pushed ajar from inside by pressure in the middle rather than at the catch. Spring clips that have lost tension and sliding bolts that stop short are common on used cages and are the difference between a pet in its cage and a pet behind the washing machine. Replace tired clips with new ones or add secure secondary fasteners before the cage is used, and confirm any replacement wheel has a solid running surface and turns silently without wobbling on its axle.
The deep clean a used cage always needs
You do not know what the previous occupant carried, so clean as if it matters: strip the cage completely, wash every part with pet-safe disinfectant at its stated dilution, scrub corners where residue builds, rinse until no smell of cleaner remains, and dry fully before adding bedding. Bin any included soft furnishings, wooden chews, and opened food. Let the empty, clean cage stand for a day and sniff it again — lingering chemical or urine odour trapped in cracked plastic is a reason to walk away even after cleaning. Only then set up bedding, water, and hides as you would for any new home.
A second checker before moving day
A fresh cage setup invites a second inspection by someone who did not do the first: fresh eyes find the one loose corner the cleaner stopped noticing. Make a short list — spacing, edges, latches, clean, dry — and work through it together rather than relying on memory. Recording that list in KinsLe Care Teams lets you assign the latch test, the clean, and the final check to different family members, with each completed task marked off so the cage is only occupied once every check is visibly done.