Biomedical Engineering Reference
In-Depth Information
offered designs with horizontal bars, suggesting that visi-
bility into and out of the cage is thereby enhanced. Some
caging is constructed of 1 inch
Cages should be designed to allow adequate illumina-
tion levels within the cage for primate well-being and good
visualization of the inhabitant by care staff. Although light
intensities in lower cages may be less than upper level
cages, several studies found no significant difference in
behavior or urinary cortisol of macaques housed in lower
versus upper cages (
Crockett et al., 1993, 2000; Schapiro
et al., 2000; Schapiro and Bloomsmith, 2001; Bentson
et al., 2004
). Nevertheless, primate welfare advocates have
discouraged the use of two-tiered cages (
Rennie and
Buchanan-Smith, 2006; International Primatological
Society, 2007
). Given the choice, monkeys tend to spend
more time in the upper portion of the cage (
Clarence et al.,
2006; MacLean et al., 2009
). Lower cages may allow less
illumination making visual inspection by care staff more
difficult. The European Union cage height minimums
would not accommodate two-tiered cages in a standard
height room, and the 2011 Guide also recommends taller
cages for long-limbed or long-tailed primate species. When
planning future purchases, single-tiered taller cages should
be considered. Some currently marketed cages are designed
for removal of the floor of the upper cage to create
a double-height cage. Current nonhuman primate housing
guidelines emphasize social housing whenever possible
(
International Primatological Society, 2007; Jennings et al.,
2009
;
National Research Council (Institute for Laboratory
Animal Research), 2011
), so flexible caging providing
a variety of degrees of tactile contact is essential in the
modern primate laboratory.
Cage doors may be designed to slide up and down, like
a guillotine, or to slide from side to side. Swinging hinged
doors are not recommended because the animal is more
likely to escape when the animal is being transferred or
captured. Selection of cage door design is largely depen-
dent on the facility and equipment limitations. Personnel
experience and preference are also important factors to
consider when designing a cage door. Cage door locks
should be strong and “tamper-proof.” Padlocks or other
additional securing devices may be needed on the cage
doors of animals that become particularly clever and escape
frequently.
Movable false back panels (often referred to as
“squeeze backs”) are recommended as a method to easily,
gently, and safely restrain nonhuman primates against the
front of the cage. Squeeze mechanisms should be selected
for ease of use and safety for primate and personnel; one-
handed operation is available from some manufacturers.
Squeeze operation should also accommodate perches
(
Watson, 1991
). Movable back panels may not be desirable
for cages that house small primates because the animals
may become trapped between the false movable panel and
the back of the cage. Small primates are generally readily
trained and safely handled, making a squeeze unnecessary
(
McKinley et al., 2003; Donnelly, 2008
).
1 inch woven or welded
mesh. However, if this size mesh is used throughout, access
to some types of foraging enrichment devices is impeded
(
Sanders et al., 2008
). To prevent food waste and injuries,
the floor grid pattern is designed to retain food and prevent
injuries. The bottom pattern is commonly a 1 inch
1 inch
grid of 8-gauge welded stainless steel wire. This grid size
may also reduce the incidence of young or smaller primates
getting entrapped when reaching into the pan below.
General Features and Socialization Options
Earlier designs for individual nonhuman primate cages
were based on a solid sheet of stainless steel bent into a “U”
shape to form the sides and back (
Kelley and Hall, 1995
).
These solid sides were designed to prevent injuries from
animal-to-animal contact in adjacent cages. A grid of
welded wire bent into a “U” shape formed the bottom,
front, and top of the cage. The two “U”-shaped units wel-
ded together formed the cage. This older cage design was
simple but did not allow for socialization, prevented visual
contact with neighbors, and reduced illumination in the
cage. Although solid-sided cages are still offered by some
vendors, they should be avoided in light of increasing
emphasis regarding the importance of social contact to
nonhuman primates. When solid panels between cages are
required to provide a barrier between cages to reduce
potential disease transmission or prevent direct animal
contact, clear side panels can be used.
More modern cages typically include a removable or
side partition or door to allow the animal access to a larger
cage area or to house two or more animals together.
Removable-swappable panels allow for many options, but
the panels can be misplaced when not in use. Permanent
sliding panels are limited in number by virtue of limitations
in width of the divider section and overall cage rack width.
Some cages allow groups of four rack-mounted cages to be
joined together to form one large cage or to be attached to
a connected activity cage (
Weed et al., 1995
). Panels
separating cages, which can be inserted and removed to
provide a variety of socialization options and facilitate
introductions, include solid opaque, solid transparent
(visual contact with limited aerosol contact), small mesh
(aerosol but limited tactile contact), wider square mesh
(finger contact), vertical grooming-contact bars, and no
panel (full contact). For grooming-contact panels, spacing
should be as wide as possible to allow maximum tactile
contact while narrower than the head of the resident to
prevent entrapment; two grooming-contact panels will
prevent pregnancy in male
female pairs (
Crockett et al.,
1997
). See Figure 6.1 in Chapter 6, for an example of
a grooming-contact cage.
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