Biomedical Engineering Reference
In-Depth Information
presentation are CBC, serum biochemistry, coagulation
parameters, and urinalysis. Because cardiac arrhythmias
may be present, ECG should also be evaluated (
Plunkett,
2000
).
outdoor setting, misters, hoses, shades, and fans should be
employed during periods of warm ambient temperature. In
addition, management practices during the hottest months
of the year might include avoiding procedures requiring the
access of animals or adjusting the daily work schedule so
that animals are anesthetized and recovered prior to the
hottest part of the day. Acclimation to a hot environment
may take 60 days to complete (
Serrano, 2007
). Therefore,
movement of animals from a temperature-controlled envi-
ronment to an outdoor environment should be avoided
during the hottest months of the year. Heating, ventilation,
and air-conditioning systems should be monitored and
serviced regularly, and room temperature and air changes
per hour should follow the appropriate animal welfare
regulations.
Treatment/Management/Prognosis
In outdoor social housing environments, observation of
unrelenting aggression that targets a few individuals should
result in immediate removal of subordinate animals espe-
cially during the warmer months of the year. If several
animals from a single matriline are targeted in established
social groups then it may be prudent to remove all animals
within the matriline to prevent serious wounding and
hyperthermia of many animals. Close observation by
trained personnel is required during any introduction of
animals to established social groups or during the estab-
lishment of new social groups.
Once the existence of hyperthermia has been estab-
lished, the animal should be rapidly cooled by wetting it
and placing it near a fan to enhance evaporative cooling.
Application of alcohol-soaked gauze to the palmar and
plantar surfaces of the hands and feet will rapidly decrease
body temperature. This measure is controversial as body
temperature can drop rapidly and uncontrollably and may
predispose the animal to disseminated intravascular coag-
ulation (DIC) (
Plunkett, 2000
), but may be indicated in very
serious cases. Animals should be provided oxygen therapy,
and then intravenous crystalloid fluids should be adminis-
tered at shock doses and secondary complications
addressed as indicated (
Plunkett, 2000
). Dexamethasone
sodium phosphate should be administered at a rate of
2
Hypothermia
At body temperatures of less than 31
C (88
F), death is
imminent without intervention.
l
Neonatal animals and new world primate species are at
increased risk of hypothermia.
l
Decreased core body temperature is diagnostic.
l
Treatment should be aimed at re-warming at a rate of no
greater than 1
e
2
C(2
e
4
F) per hour.
l
Prevention consists of frequent monitoring of anes-
thetized animals and providing appropriate shelter to
outdoor-housed animals.
l
Etiology/Risk Factors/Transmission/Species
Primary hypothermia occurs as the result of a cold external
environment, and secondary hypothermia occurs when the
body's normal heat-producing mechanisms are impaired
(
Serrano, 2007
). Iatrogenic factors such as anesthesia are
often involved in secondary hypothermia. In addition,
certain species of laboratory nonhuman primates, such as
squirrel monkeys, are uniquely susceptible to hypothermia
by virtue of their low body fat percentage and relatively
high surface area to volume ratio (
Brady, 2000
). Animals
that are housed singly in metal cages are at an increased
risk for hypothermia when HVAC systems fail during cold
months and animals housed in outdoor environments are at
risk for hypothermia during the winter months. Avascular
necrosis (frostbite) is most likely to occur in the pinnae and
distal extremities (fingers, toes, tail) (
Plunkett, 2000
).
These lesions may not be demonstrable until after the
immediate hypothermic crisis has resolved.
Hypothermia is a complicated physiological phenom-
enon, and because it can result from either cold external
temperatures or failure of the body's thermoregulatory
mechanisms, the same low body temperature can have
different ramifications depending on the etiological
process. For example, negative sequelae are observed with
4 mg/kg i.v. once if signs of shock and/or cerebral
edema develop, and diazepam may be given for seizures at
a dose of 1.0 mg/kg i.v. (
Plunkett, 2000; Hawk et al., 2005
).
Lidocaine may be administered if arrhythmias are present.
For animals in which gastrointestinal ulceration is sus-
pected, sucralfate should be administered in conjunction
with H
2
blockers (
Plunkett, 2000
). Signs of hypoglycemia
and septic shock should be addressed with glucose and
broad-spectrum antibiotics, respectively. Because animals
with heat stroke are at risk for DIC, heparin therapy should
be considered, and DIC should be treated with heparinized
plasma (
Plunkett, 2000
).
Efforts to decrease body temperature should be dis-
continued when the temperature decreases to 39.4
C
(103
F). In terms of prognosis, most fatalities from heat
stroke occur within the first 24 hours, and the occurrence of
seizures is associated with an increased risk of death
(
Plunkett, 2000; Serrano, 2007
).
Appropriate management and husbandry procedures are
the most important factor in preventing emergencies
involving temperature extremes. For example, when
animals are anesthetized for routine procedures in an
e
