26 February 1993
wash room. Heavy soil is rinsed from the cages in a prewash
CONSTRUCTION NOTE: It is imperative that the equipment
area before placing them in the cage washer.
selected and installed by the user conforms to the voltage and
Occasionally special flushing racks are used for rodents and
phase supplied during construction. Thus, the A/E should note
rabbits. When flush racks are used, special plumbing will be
on the construction documents the voltage and phase at each
required. If flushing rack systems are planned, provisions for
special outlet to insure compatibility with the equipment to be
preventing excess humidity in the animal rooms are essential.
used by the VMU.
An autoclave is necessary for all VMUs; however the
Sanitation Equipment
chamber size needed will depend to some extent on
characteristics of the research program. If survival surgery is
Frequent and thorough cleaning of cages and room surfaces
contemplated, an autoclave is required to sterilize surgical
is essential to prevent noxious odors and avoid dissemination of
instruments. Use of the steam autoclave in the operating suite
microbial agents.
should be confined to instruments and other surgical items. In
Animal room walls and ceilings are typically scrubbed
addition to an autoclave in the surgical suite, a separate
manually with detergent/disinfectant compounds or sprayed with
autoclave with a chamber size adequate to accommodate large
water using either line pressure or high pressure sprayers. If
rodent cages is usually needed. The additional autoclave is
vacuum cleaners are used, they must be equipped with HEPA
essential when immunodeficient animals are present, or when
filters to avoid spreading infectious material throughout the
design includes a barrier suite. In these instances, feed, bedding,
facility. Floors may be damp mopped or cleaned by means of an
water, and cages, will ordinarily be autoclaved. An autoclave is
electric floor scrubber or high pressure sprayer. Hose bibbs are
also essential when infectious agents are used in animal studies.
needed if running water is to be used in cleaning room surfaces
Steam autoclaves are suitable for most applications.
or fixed equipment.
Mechanical Cage Washers
Fixed equipment such as pens and large cages are routinely
cleaned in place using sanitizing chemicals. The animals must
A mechanical cage washer is virtually the "heart" of a VMU
be removed from the primary enclosure (cage) before cleaning.
and the washer type(s) and location require careful consideration.
Large cages may be cleaned in place on a daily basis, then
Mechanical cage washers are of three styles: cabinet type, cage
transported to a mechanical cage washer periodically for more
and rack type, and tunnel type. Cabinet style washers are
thorough sanitizing. A dry system may be employed for some
essentially oversized glassware washers and are not
species such as domestic farm animals. With a dry system, the
recommended in VA animal facilities unless substituted for a
pen floor is covered with absorbent bedding materials.
bottle washer.
Periodically, animals and all bedding are removed and pen
A cage and rack style washer features a chamber of
surfaces are thoroughly sanitized. Use of a dry system imposes
sufficient size to accommodate one or more cage racks or large
additional spatial requirements for bedding storage and disposal.
cages. Cage rack washers should be mounted in a pit to prevent
the need for ramps with the danger of attendant falls, back
Portable cages are transported to a mechanical cage washer
injuries and scalding water. Tunnel style washers transport items
for cleaning as needed. Soiled cages are taken to the cage wash
on a continuously moving conveyer through a pre-rinse,
room after transferring animals to a clean cage. The soiled
detergent wash, rinse, final freshwater rinse, and drying. These
bedding is dumped into a soiled bedding receptacle in the cage
VA Design Guide -- Veterinary Medical Unit
Page 2-7
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