Domestic rats are intelligent, social animals that make excellent companions when their welfare needs are properly met. Solitary housing is a major welfare problem that is often overlooked.
Rat welfare is significantly shaped by social housing requirements that are frequently ignored in practice. Rats are fundamentally social animals: solitary rats show physiological and behavioural indicators of chronic stress, reduced immune function, and earlier mortality. The minimum is two same-sex rats, but larger groups are generally better for social enrichment. Cage space is the second critical variable — many commercially sold rat cages are too small for proper welfare. Rats need height for climbing, platforms, hammocks, nesting material, and cognitive enrichment such as foraging puzzles. Regular human interaction is also valuable for well-socialized rats. Geriatric rat welfare deserves particular attention: hind limb degeneration and mammary tumours (particularly in females) are common and require veterinary management to prevent unnecessary suffering.