Fit and structure
The carrier should be appropriate for the species, size and intended form of transport. Check manufacturer weight limits and dimensions rather than relying on a photo of a similarly sized animal.
Access matters
Top-opening, front-opening and removable-top designs can make handling different animals easier. Secure latches matter more than decorative features.
Cleaning
Accidents happen. A carrier with smooth, washable surfaces and removable bedding can be easier to return to service than one with inaccessible seams.
Vehicle and airline use
Car travel restraint and airline requirements are context-specific. Follow current transport rules and manufacturer instructions rather than treating a generic carrier label as universal approval.