Dogs, cats, rabbits, guinea pigs, hamsters, nonhuman primates, and marine mammals must be housed in primary enclosures that meet the space requirements described in Sections 3.6, 3.28, 3.53, 3.80, and 3.104, respectively. Primary enclosures for all other animals must allow space for each animal to express all species-typical postures, social adjustments, behaviors, and movements. For example, animals must be able to lie down with limbs extended in a normal manner without obstruction from enclosure sides or having to extend feet through feeder doors or bars. Animals that normally engage in occasional vertical postures, such as bears and many felines, must have sufficient vertical space available to accommodate these postures. For example, bears often stand upright on their rear legs and must be allowed sufficient vertical space within their housing enclosure to do so.
Many felines also stand on their rear legs, for example, when using scratching posts.
If a pen is used for this purpose, animals should be released at least once per day and allowed to remain for a reasonable length of time unless otherwise justified. These periods will be in addition to regular performance and practice time. When elephants are housed on chains while not in transport, chains must be of sufficient length and arrangement so as to permit each elephant to comfortably lie down, get up, self-groom, and move about within a reasonable range. If elephants are kept unchained in a truck or railway car, each elephant must have enough space to make these postural adjustments as well. These same requirements apply to tethered hoofstock.