Abstract: A cage or an item of cage furniture for use by a caged rodent comprises a coloured material which is transparent or translucent to a human observer, but is perceived as being substantially darkened or opaque by the caged rodent. The cage or item of cage furniture typically comprises, and is desirably substantially or entirely formed from, a red-coloured or red-tinted material, e.g. a synthetic plastics material. The coloured material preferably transmits less than 20% of visible light with a wavelength of less than 540 nm. The plastics material is preferably resistant to repeated autoclaving and conveniently comprises at least one of polyester, polysulfone, polytheramide and polycarbonate. Also a method of making such a cage or item of cage furniture.