Biomedical Engineering Reference
In-Depth Information
The paint surface does not withstand exposure to caustic
chemicals, heat, or pressure washing, thus exposing the
underlying steel to rust and corrosion. The corroded metal
is difficult to sanitize and may break, easily exposing sharp
edges that could injure animals.
Galvanized metal is a less expensive material for cage
construction but has a shorter life expectancy than
aluminum or stainless steel. The zinc coating oxidizes
when exposed to frequent washing at the minimum sani-
tization temperature of 180
F and the underlying metal
rusts and disintegrates at these temperatures. If exposed to
acid cleaning agents, the zinc coating will deteriorate even
more rapidly and expose the underlying metal. Steel that
has been protected utilizing the hot dipped galvanizing
process will last longer than steel that has been subjected to
electroplating application of the zinc material. However,
the hot dipped galvanizing process may leave sharp points
that must be blunted by grinding or sanding and the
blunting process may expose the underlying metal to
oxidation. The zinc component in galvanized cages may
prove toxic to some nonhuman primates (
Obeck, 1978;
Stevens et al., 1978; Frost et al., 2004
). This exposure to
zinc has been reported to be a cause of severe anemia in
nursing infants. The clinical syndrome associated with zinc
toxicity in infants has been called the “blonde baby”
syndrome because the hair of affected infants was usually
blonde. Nursing mothers and teething infants lick the
zinc-coated cage surfaces and consume small amounts of
zinc. The zinc is excreted in the mother's milk, causing zinc
toxicity in nursing infants. Therefore, nursing mothers
should not be housed in primary enclosures that have all the
surfaces coated with zinc. However, zinc toxicity has not
been reported in animals housed in enclosures with some
zinc-coated surfaces, such as corrals enclosed with zinc-
coated panels or field cages enclosed with zinc-coated
chain link wire material.
Aluminum is comparatively lightweight and is easily
fabricated into cages. It lacks the strength of galvanized
metal or stainless steel and is more easily damaged.
Routine moving, sanitization procedures, and animals
chewing on the cage may damage aluminum cages.
Aluminum requires more material to be used in cage
construction because it lacks the structural strength of
stainless steel. This extra material restricts light from
entering the cage and limits visualization of animals by
personnel. Aluminum oxidizes when exposed to routine
sanitization procedures. This does not affect the utility of
equipment constructed of aluminum, but it may become
stained and unsightly. Cages constructed of aluminum
may have an expected life of 5
Stainless steel is the most durable material for
nonhuman primate caging. This material has an indefinite
life expectancy. In order to provide adequate strength and
resistance to rust and corrosion, primary enclosures should
be manufactured entirely of type 304 stainless steel. All
welds should be smooth and electronically polished.
In some situations where sufficient quantities of the
type 304 stainless steel material may not be available in the
correct format (e.g. sheets, bars, etc.), use of a combination
of materials may be a reasonable alternative for housing
certain species. For example, it may be feasible to build
some of the cage using hot dipped galvanized sheet metal
and build other parts of the cage that are more subject to
corrosion (such as the cage floor) in prefabricated type 304
stainless steel mesh.
The long-life and initial expense of stainless steel
caging makes it especially important to select cages of
appropriate design as they are likely to be in use for many
years.
Design Criteria
Species Considerations
Most cage design considerations listed in this review are for
the more commonly used macaque species. Cage design
should accommodate needs of different species (
Rennie
and Buchanan-Smith, 2006
). Long-legged species, such as
baboons (Papio sp.) and patas monkeys (Erythrocebus
patas), or long-tailed species, such as cynomolgus
macaques (Macaca fascicularis), may need more height
than some macaque species. New World species with long
or prehensile tails may also require cages with more height.
Cage height for brachiating species should allow for
brachiating movement and allow animals to swing fully
extended from the ceiling without their feet touching the
floor (
National Research Council (Institute for Laboratory
Animal Research), 2011
). Linear perches and climbing
apparatuses should be provided in New World primate
cages (
Williams et al., 1988; Pines et al., 2005
). Old World
species such as macaques and baboons also use perches and
benefit from their inclusion in primary caging (
Reinhardt,
1990; Bayne et al., 1992; Shimoji et al., 1993
). These cage
accessories increase the functional space in the cage.
Marmosets, tamarins, and owl monkeys should be provided
with nesting boxes. Large baboons or chimpanzees may
have to be housed in much larger and stronger enclosures
that are specifically designed for these species.
Cage design and construction may vary for different
species. Cages designed for housing macaques may be
constructed of 8-gauge stainless steel wire welded on
a 1 inch
10 years depending on
the alkalinity of detergent and disinfectants used to
sanitize the equipment. Aluminum equipment will last
longer if sanitized with chemical agents at pH 11 or
greater.
e
3 inch grid pattern for the front and top.
Traditionally, the narrower dimension has been vertically
oriented, but recently some caging manufacturers have
