Biomedical Engineering Reference
In-Depth Information
FG7142, an inverse agonist at the benzodiazepine binding
site of the GABA-A receptor, showed a similar bimodal
pattern of response. Half of the monkeys displayed higher
levels of SIB (indicating elevated anxiety as a trigger) and
half showed no response (indicating other underlying
factors).
Although only a few studies have assessed the efficacy
of pharmacological intervention on reducing abnormal
behavior, it is evident that there are many potential systems
through which abnormal behaviors may develop and be
maintained. Furthermore, very little is known about the
long-term effects of such treatments. Clearly more research
is needed to evaluate long-term efficacy of pharmaco-
therapy and to determine whether efficacy can be increased
in combination with other methods (e.g. environmental
enrichment, social housing). Given different etiologies,
different research needs, and individual variation in
response to chemical compounds, treatment regimens will
most likely require tailoring to specific animals.
information on possible levels of distress (
Hennessy et al.,
1982
). A recently developed technique of measuring
cortisol in hair provides a chronic estimate of stress expo-
sure over weeks or months (
Davenport et al., 2006
). Unlike
plasma samples, the impact of the stress of sample
collection and circadian variation are negligible. Addi-
tionally, various immune functions are suppressed during
times of stress. Lymphocytes taken from juvenile monkeys
exposed to repeated mother
infant separation had lower
than normal concanavalin A- and pokeweed mitogen-
stimulated proliferation (
Coe et al., 1989
). A reduction in
CD4(
e
) ratios was observed in individually
housed as compared to socially housed rhesus monkeys
(
Schapiro et al., 2000
).
þ
)/CD8(
þ
Ruling Out Alternatives
As with any other disease condition, behavioral pathology
must be considered only one differential diagnosis on a list
of rule-outs for abnormal behavior or for the occurrence of
physiological measures outside the normal range. For
example, urine drinking in macaques is frequently
considered an aberrant behavior occurring in individually
housed monkeys with ad libitum access to water.
However, glucosuria resulting from diabetes should be
considered as well, and a urine dip-stick test can readily be
performed to eliminate this endocrinological disorder
from the differential diagnosis list (
Levanduski et al.,
1992
). Severe hair loss can be due to a physical disorder
(e.g. hypothyroidism, Sertoli cell tumor, hyper-
adrenocorticism) or a behavioral disorder (hair pulling by
the animal). Similarly, self-mutilation of the extremities
might be related to peripheral neuropathy or a manifesta-
tion of a behavioral disorder.
Knowledge of an animal's rearing history, clinical
history, and in particular the previous studies in which the
animal has been used may assist in the differential diag-
nosis of an apparent behavioral problem. For example,
a nonhuman primate used in certain pharmacological
investigations, such as cocaine studies, can manifest
tremors and “floating limbs.” If the experimental history of
the animal was not examined, these behaviors might be
attributed to fear and withdrawal, rather than to the effects
of the drug, and an inaccurate diagnosis could be made. In
such a case, the behavioral therapy typically used for
fearful and withdrawn animals would be inappropriate.
A PRACTICAL GUIDE TO MANAGING
ABNORMAL BEHAVIOR IN THE
LABORATORY
Identifying and Assessing Abnormal
Behavior
Monitoring an animal's behavioral repertoire (the range of
normal behaviors exhibited by a species) for the occur-
rence of potentially maladaptive patterns is a common
approach to assessing the presence of behavioral
pathology (
Novak and Suomi, 1988
). As described earlier,
abnormal behaviors may include whole-body stereotypies
(pacing, rocking, somersaulting), self-directed stereoty-
pies (digit sucking, clasping, eye saluting), and more
serious behavioral anomalies such as SIB. However, it is
important to recognize that not all pathology is reflected in
odd or bizarre behavior. Monkeys can also exhibit
emotional reactions which, if extreme enough, might
constitute a pathological state. Monkeys that cower in the
back of their cage, hyperventilate, and fear grimace
excessively are exhibiting distress (see
Morton and
Griffiths, 1985
). Conversely, pathology may be present if
monkeys show frequent and repetitive bouts of attack
behavior (lunging against the cage, vocalizing, and
threatening) to different social stimuli with no evidence of
habituation.
Although behavioral indices are clearly important in
ascertaining an animal's psychological well-being, a more
complete assessment can be obtained by including addi-
tional indices of its physiological and immunological
status. For example, studying the stress-response system by
measuring plasma or salivary cortisol levels can provide
Determining the Severity of the Problem
One question facing those who encounter abnormal
behavior is “how serious is the problem?” Abnormal
behavior clearly varies in severity, and what is needed is
some type of “yardstick” by which monkeys can be evalu-
ated objectively. Our proposed severity scale is provided in
Table 7.2
. In this table, behaviors such as pacing for which
