Hamsters are among the most commonly kept small pets but routinely housed in conditions that cause serious welfare harm, despite the evidence for their complex welfare needs being well-established.
Hamster welfare failures are among the most extreme in companion animal keeping: typical pet shop cages that appear generous to a human observer are inadequate for an animal that naturally covers kilometres daily. Bar-climbing — a stereotypy in which hamsters repeatedly scale cage bars in the same pattern — is direct evidence of spatial deprivation that is difficult to extinguish even when space is later improved. German regulatory standards (minimum 1m2) reflect the actual welfare evidence; UK and US standards remain woefully inadequate. The mismatch between commercial cage marketing and welfare reality is acute.