Biomedical Engineering Reference
In-Depth Information
rely heavily on scent marking. Frequent cage cleaning can
eliminate olfactory signals, the absence of which may then
disrupt social behavior and dominance hierarchies in these
species (
National Research Council, 1998
). Further,
common behaviors such as locomotor or resting behavior
may be performed differently across taxonomic groups, and
enrichment should address these adaptations. For example,
squirrel monkeys perch with their hands and feet rather
than sitting, and should be provided with round rather than
flat perching options (
Williams et al., 1988
). Even within
closely related species, such as the macaques, it is impor-
tant to understand species-specific patterns of behavior. For
example, the dominance style of rhesus macaques is
generally more aggressive and less tolerant than that of
stumptailed macaques (M. artoides)(
de Waal and Luttrell,
1989
), a difference that can influence social enrichment
practices (e.g. choice of partners).
Shepherdson, 1993
) is a widespread problem for captive
primates in research laboratories across the USA (
Laule,
1993; Mason and Latham, 2004
). Stereotypies can manifest
themselves in different ways, depending on the species or
individual (
W
¨
rbel, 2006
) and can include whole-body
locomotor behaviors, such as pacing, bouncing, somer-
saulting, and rocking, as well as self-directed behaviors,
such as hair pulling, eye poking, and digit sucking. Many
factors have been implicated in the development of
stereotypic behavior (see
Mason, 1991
, for review),
including genetics (
Schoenecker and Heller, 2000;
Schwaibold and Pillay, 2001
) and adverse experiences
early in life (
Lutz et al., 2003; Novak, 2003; Novak et al.,
2006; Latham and Mason, 2008
). Still, the most commonly
posited etiology is suboptimal housing conditions, such as
a barren environment with insufficient external stimuli
(e.g.
Meehan et al., 2004; Swaisgood and Shepherdson,
2006
) or the lack of appropriate socialization, particularly
early in life (
Bellanca and Crockett, 2002; Lutz et al., 2003;
Novak, 2003
).
Alopecia is a common problem in laboratory primates
(
Honess et al., 2005; Novak and Meyer, 2009
). Despite its
high prevalence, a “typical” etiology for this phenomenon
has yet to be identified (
Reinhardt, 2005; Steinmetz et al.,
2005, 2006
). As summarized by Novak and Meyer (
Novak
and Meyer, 2009
), NHPs can lose hair due to behavioral,
seasonal, reproductive, or other physiological factors.
Conditions such as bacterial infections, parasitic infesta-
tions, fungal infections, compromised immune function,
and nutritional deficiencies have been considered among
the potential etiologies for this condition (
Steinmetz et al.,
2005; Kramer et al., 2010
). Stress, in particular social or
environmental stress, has also been hypothesized as
a potential underlying factor in the development of alopecia
(
Reinhardt et al., 1986; Honess et al., 2005; Reinhardt,
2005
), although this is not a universal finding (
Kramer
et al., 2010
). Like stereotypy, alopecia (when confirmed to
have a behavioral cause) is often considered a maladaptive
behavior indicative of compromised well-being. However,
whether alopecia truly is evidence of reduced well-being is
not clear, as it does not exclusively occur in conditions
otherwise associated with reduced well-being. For
example, alopecia is seen in primates living in large social
groups, not just among caged animals, and it is not more
prevalent among nursery-reared primates. Thus, under-
standing the importance of alopecia represents a significant
challenge for laboratory animal management.
Problem Cases
Ideally, behavioral management practices and techniques
reduce the risk of the occurrence of abnormal behaviors.
Behavioral pathologies can vary by species. For example,
repeated regurgitation and reingestion is a more common
pathology in apes than in macaques (
Fritz et al., 1992
).
Within a species, there can be differences across age or sex.
Adult male rhesus macaques are more prone to self-
injurious behavior than are young female rhesus (
Novak,
2003
). The following paragraphs detail some of the more
common behavioral issues observed in NHPs housed in
biomedical facilities (also see Chapter 7).
The behavioral problem of greatest concern is self-
injurious behavior (SIB). SIB includes behaviors such as
self-biting, head banging, and damaging hair plucking
(
Novak, 2003
). SIB can result in tissue or muscle injury as
well as infection. As with most other behavioral patholo-
gies, the etiology of SIB is thought to involve an interaction
of environmental and genetic/biological factors. Lack of
proper socialization early in life (e.g. rearing in a nursery or
early placement into single caging) has been found to be the
biggest risk factor for the development of SIB in macaques
(
Bellanca and Crockett, 2002; Novak, 2003; Rommeck
et al., 2009a,b
; also see Chapter 7). Common husbandry
practices, such as relocating animals to new rooms, can
exacerbate bouts of SIB in animals with a history of the
behavior (
Davenport et al., 2008
). There have been several
genetic and/or biological factors implicated in the devel-
opment of SIB, including dysregulation of the hypotha-
lamic-pituitary-adrenal axis among subsets of individuals
(
Novak, 2003; Tiefenbacher et al., 2004
) and alterations in
serotonergic function (
Henderson et al., 2008; Chen et al.,
2010
).
Stereotypic behavior (repetitive, habitual behavior
patterns with no obvious
Threshold for Concern
One issue that becomes apparent in dealing with problem
cases in captive colonies of NHPs is the point at which to
intervene. In some situations, such as when NHPs are
seriously injured, the decision is straightforward. However,
function;
Mason, 1991;
