Biomedical Engineering Reference
In-Depth Information
replace volume by administering fluid either by intraosseous
administration or performing a surgical cut down to access
peripheral vessels. In less critical cases, subcutaneous or
intraperitoneal fluids may provide sufficient volume resus-
citation in the short term in order to gain subsequent venous
access. The most common site for intravenous fluid therapy
administration in most species of nonhuman primates is the
saphenous vein (
Figures 15.1, 15.2
).
The pace at which animals are rehydrated depends on
the etiology of their dehydration. Animals that are exhib-
iting signs of shock require rapid administration of a large
volume of fluid. This large volume should be divided into
aliquots in order to assess response to therapy, and these
animals should be monitored for urine output to assess
kidney function and for signs of overhydration, which
include pulmonary edema, ascites, and dyspnea. Body
weights should be taken frequently to assist in the assess-
ment of hydration status during treatment. Oral rehydration
is preferred in animals that are able to drink and absorb
fluids by this route. The risk of overhydration is greatly
minimized when rehydrating by the oral route. Even in
cases where intravenous administration is required, oral
rehydration should be used supplementally, when the
patient's condition allows. Oral rehydration solutions used
in companion animal medicine as well as sports drinks can
be utilized.
So as to avoid laminar necrosis of the brain, squirrel
monkeys and other nonhuman primate species that have
experienced inadvertent water deprivation need to be
rehydrated slowly (A. Carville, personal communication,
2010). This might include a combination of intravenous,
subcutaneous, and oral fluid therapy as discussed above.
Electrolytes should be expected to return to within normal
ranges over the course of days to weeks rather than
immediately after treatment (
Abee, 1985
). Appetite and
water consumption should be continually monitored in
these cases after the acute stage of the disease has passed,
as animals that are not consuming adequate food and water
will need additional fluid supplementation. Bottles con-
taining sports drinks designed to replenish fluid, carbohy-
drates, and electrolytes may be hung from the animal's cage
to allow ad libitum consumption.
In order to minimize the risk of water deprivation
secondary to water system failure, it is critically important
to have husbandry procedures in place to regularly monitor
access to water. Monitoring practices should include a way
to determine that there is a functioning water supply point
that each animal has access to. For animals housed indoors
in individual caging with their own on-demand water
valves, an instrument should be used to ensure that water
flows from the automatic watering systems when the valves
are depressed. This procedure can be performed daily if
necessary and with the animal in the cage. The animal will
need to be acclimated to the procedure as some nonhuman
primates may initially try to wrestle with the device as it is
advanced to the water valve at the rear of the cage. Proto-
cols for monitoring water availability should include
checklists to be used after cage changing or maintenance.
Checking water supply at points prior to the final valve may
be useful to localize a disruption, but the most critical
location to evaluate from the standpoint of animal health is
the terminal point in the supply pipeline, which is the valve
in the animal's cage. Animals that are transferred from an
outdoor breeding colony to indoor housing for the first time
may be unfamiliar with the location and function of the
automatic watering system within the cage. For these
animals, it would be prudent to house them in cages that
face animals that are experienced in using an indoor auto-
matic watering system so that they can learn through
observation. In addition, keeping the water valves open
with a short piece of wood dowel will demonstrate to the
animal the location of the water source. These consider-
ations should also be made for animals imported into
research facilities, as they may also be unfamiliar with
automatic watering systems.
Tetanus
Tetanus is most often seen in nonhuman primates that
are housed outdoors, as a sequel
l
to either wound
contamination or dystocia.
Diagnosis is made via clinical signs, which are neuro-
logical in nature and consist of torpor, inability to pre-
hend food, hypersensitivity to stimuli, thirst, altered
gait, difficulty swallowing, flexion of the carpi, trismus,
and opisthotonus.
l
Treatment is aimed at neutralizing the toxin via tetanus
immunoglobulin or tetanus antitoxin, destroying the
bacteria via antibiotics, and providing treatment for
seizure activity and nutritional support.
l
Etiology/Risk Factors/Transmission/Species
Tetanus is caused by Clostridium tetani, a gram positive,
rod-shaped bacterium. C. tetani is a nonencapsulated,
obligate anaerobe that produces terminal end spores.
Spores are ubiquitous in the environment and can be found
as normal flora in the intestines of many animals including
livestock, companion animals, wildlife, and humans.
Spores can persist for years in contaminated soil and on
fomites. Spores are usually introduced through contami-
nation of existing wounds or penetrating injuries where
vegetative growth occurs under anaerobic conditions.
Germination is enhanced by the presence of a foreign body,
tissue necrosis, or concomitant microbial infection with
other organisms. The incubation period in nonhuman
primates has been described to be between 4 days and 3
weeks (
Rawlins and Kessler, 1982
).
