Biomedical Engineering Reference
In-Depth Information
in the stomach that can be passed more easily. Simethi-
cone does not reduce or prevent the formation of gas in the
digestive tract. Rather, it increases the rate at which it exits
the body. Simethicone is available in liquid form, which
can be administered via orogastric tube. Animals should
be given supportive care for shock as well as adequate
analgesia.
Preventive management for gastric dilatation includes
the avoidance of drastic changes in food intake, and care
should be taken in the administration of antibiotics that
affect intestinal bacterial populations.
signs of water deprivation due to malfunctions in watering
equipment can be quite variable. Animals housed outdoors
may have enough water available from rain to delay the
onset of clinical signs. Animals housed in indoor cage racks
with integrated water systems that have not been reattached
after cage rack movement may have hours or days of water
available depending on housing density because the piping
in these systems may act as a reservoir. Animals housed in
lower tier cages may have greater availability of water
because the top tier of cages will exhaust the water reser-
voir in the piping first.
Dehydration
Clinical Signs
Animals that are dehydrated have decreased skin turgor,
dry mucous membranes, and eyes that appear sunken. If
dehydration is severe enough to cause hypovolemic shock,
an increased heart rate, thready peripheral pulses, and
extended capillary refill time may be observed. Animals
that are obese may appear more hydrated than they actually
are, and animals that are underweight or aged may appear
less hydrated. For animals in which the cause of dehydra-
tion is water deprivation, often the first sign of dehydration
is decreased appetite. Depression and ataxia may ensue if
the water deficit is not corrected. In addition to anorexia,
animal care staff might notice excessive licking of water off
of cage surfaces during daily sanitation procedures as well
as firm pellets of stool or lack of stool production.
Important causes of dehydration in laboratory
nonhuman primates are protracted diarrhea, species
predilection (squirrel monkeys), and failure of auto-
matic water supply systems.
l
Clinical signs include decreased skin turgor, dry
mucous membranes, sunken eyes, signs of hypovolemic
shock, and potentially neurological signs.
l
The first sign of water deprivation is often anorexia.
l
Depending on the etiology, clinical pathology may
indicate hemoconcentration as well as ion derangements.
l
Rehydration via intravenous fluid administration is the
cornerstone of treatment, but the pace at which rehy-
dration should occur is dependent on the etiology.
l
Monitoring practices that minimize the risk of inad-
vertent water deprivation are critical.
l
Diagnostics
Animals that are dehydrated are generally hemoconcen-
trated and show elevated packed cell volume, total protein,
and urine specific gravity if renal function is normal.
Clinical pathology for animals with concurrent diarrhea
includes decreased sodium, chloride, and potassium.
Conversely, animals that have experienced inadvertent
water deprivation may show severely elevated sodium.
Severe dehydration may result in elevations of ALT.
Abnormalities of clinical laboratory diagnostics can be
quite variable depending on the primary disease state. The
diagnostic plan for a dehydrated animal should be based on
the result of history and thorough physical examination.
Etiology/Risk Factors/Transmission/Species
The most common cause of dehydration in laboratory
nonhuman primates is protracted diarrhea, but many
disease states may cause dehydration due to decreased
intake or increased loss of water. Some species of
nonhuman primates are more susceptible to dehydration.
Squirrel monkeys (S. sciureus) are at greater risk for
dehydration because of their decreased ability to concen-
trate urine (A. Carville, personal communication, 2010).
Inadvertent water deprivation resulting in severe dehy-
dration can result from malfunctions in automatic water
supply systems. Subsequent failure to adequately monitor
the function of the system can lead to delays in detection
thereby increasing the severity of dehydration. Disruption
in water supply most typically occurs after maintenance or
cage changing has been performed, where the water supply
is not reattached to individual caging before animals are
returned. Water deprivation can also occur after primary
malfunction of equipment independent of maintenance and
cage changing events, which is why water monitoring
policies should require frequent observation even when
cage changing and maintenance have not occurred.
Depending on housing condition and location, the onset of
Treatment/Management/Prognosis
Intravenous fluid administration of a balanced crystalloid
solution such as lactated Ringer's, Normosol-R, or Plasma-
Lyte 148 is the cornerstone of treatment for animals with
normal oncotic pressure that are severely dehydrated
(
DiBartola and Bateman, 2009
). Animals that are dehy-
drated as the result of protracted diarrhea may require
supplementation of fluids with KCl to address hypokalemia.
Venous access may be difficult for animals that are hypo-
volemic upon presentation. In these cases, it is advisable to
