Behavioral analysis in laboratory rats: Challenges and usefulness of 50-kHz ultrasonic vocalizations.

Many rodent species emit and detect vocalizations in the ultrasonic range. Rats use three classes of ultrasonic vocalizations depending on developmental stage, experience and the behavioral situation. Calls from one class emitted by juvenile and adult rats, the so-called 50-kHz calls, are typical for appetitive and social situations. This review provides a brief historical account on the introduction of 50-kHz calls in behavioral research followed by a survey of their scientific applications focusing on the last five years, where 50-kHz publications reached a climax. Then, specific methodological challenges will be addressed, like how to measure and report 50-kHz USV, the problem of assignment of acoustic signals to a specific sender in a social situation, and individual variability in call propensity. Finally, the intricacy of interpreting 50-kHz results will be discussed focusing on the most prevalent ones, namely as communicative signals and/or readouts of the sender's emotional status.

Perceptions of laboratory animal facility managers regarding institutional transparency.

Institutions that conduct animal research are often obliged to release some information under various legal or regulatory frameworks. However, within an institution, perspectives on sharing information with the broader public are not well documented. Inside animal facilities, managers exist at the interface between the people who conduct animal research and those charged with providing care for those animals. Their perception of transparency may influence their interpretation of the institutional culture of transparency and may also influence others who use these facilities. The objective of our study was to describe perceptions of transparency among animal research facility managers (all working within the same ethical oversight program), and how these perceptions influenced their experiences. Semi-structured, open-ended interviews were used to describe perceptions and experiences of 12 facility managers relating to animal research transparency. Four themes emerged from the participant interviews: 1) communication strategies, 2) impact on participant, 3) expectations of transparency, and 4) institutional policies. Similarities and differences regarding perceptions of transparency existed among participants, with notable differences between participants working at university versus hospital campuses. These results illustrate differences in perceptions of transparency within one institutional animal care and use program. We conclude that institutions, regulators and the public should not assume a uniform interpretation of a culture of transparency among managers, and that sustained communication efforts are required to support managers and to allow them to develop shared perspectives.

The acoustic startle reflex as a tool for assessment of odor environment effects on affective states in laboratory mice.

Apart from self and conspecific odors, odors from other species also influence the affective states in laboratory mice (Mus musculus musculus) in their home cages and during experimental procedures, possibly inducing confusion and inconsistency in experimental data. Thus, it is important to detect the types of animal odors associated with housing, husbandry, and laboratory practice that can arouse different types of affective changes in mice. Here, we aimed to test the effectiveness of the acoustic startle reflex (ASR) in detecting changes in the affective states of laboratory mice due to animal-derived-odor as it has a non-zero baseline, and can be enhanced or attenuated by positive or negative affective shifts, respectively. We used ASR to examine the affective changes in mice that were induced by bedding odors and an alarm pheromone. The odor of bedding obtained from the mice' home cages significantly attenuated the ASR, suggesting positive affective shifts in the test mice, whereas that from bedding obtained from rat cages significantly enhanced the ASR, suggesting negative affective shifts. No significant changes in ASR were observed in mice presented with the odor of bedding obtained from cages of unfamiliar conspecifics. In contrast, there was significant ASR enhancement in mice exposed to volatile components of alarm pheromones trapped in water, suggesting negative affective shifts. Thus, our findings show that ASR may be a valuable tool in assessing the effects of odors on the affective states in laboratory mice.

The epidemiology of fighting in group-housed laboratory mice.

Injurious home-cage aggression (fighting) in mice affects both animal welfare and scientific validity. It is arguably the most common potentially preventable morbidity in mouse facilities. Existing literature on mouse aggression almost exclusively examines territorial aggression induced by introducing a stimulus mouse into the home-cage of a singly housed mouse (i.e. the resident/intruder test). However, fighting occurring in mice living together in long-term groups under standard laboratory housing conditions has barely been studied. We performed a point-prevalence epidemiological survey of fighting at a research institution with an approximate 60,000 cage census. A subset of cages was sampled over the course of a year and factors potentially influencing home-cage fighting were recorded. Fighting was almost exclusively seen in group-housed male mice. Approximately 14% of group-housed male cages were observed with fighting animals in brief behavioral observations, but only 14% of those cages with fighting had skin injuries observable from cage-side. Thus simple cage-side checks may be missing the majority of fighting mice. Housing system (the combination of cage ventilation and bedding type), genetic background, time of year, cage location on the rack, and rack orientation in the room were significant risk factors predicting fighting. Of these predictors, only bedding type is easily manipulated to mitigate fighting. Cage ventilation and rack orientation often cannot be changed in modern vivaria, as they are baked in by cookie-cutter architectural approaches to facility design. This study emphasizes the need to invest in assessing the welfare costs of new housing and husbandry systems before implementing them.

The impact of handling technique and handling frequency on laboratory mouse welfare is sex-specific.

Handling is a well-known source of stress to laboratory animals and can affect variability of results and even compromise animal welfare. The conventional tail handling in mice has been shown to induce aversion and anxiety-like behaviour. Recent findings demonstrate that the use of alternative handling techniques, e.g. tunnel handling, can mitigate negative handling-induced effects. Here, we show that technique and frequency of handling influence affective behaviour and stress hormone release of subjects in a sex-dependent manner. While frequent tail handling led to a reduction of wellbeing-associated burrowing and increased despair-like behaviour in male mice, females seemed unaffected. Instead, they displayed a stress response to a low handling frequency, which was not detectable in males. This could suggest that in terms of refinement, the impact in handling could differ between the sexes. Independently from this observation, both sexes preferred to interact with the tunnel. Mice generally explored the tunnel more often than the tail-handling hands of the experimenter and showed more positively rated approaches, e.g. touching or climbing, and at the same time, less defensive burrowing, indicating a strong preference for the tunnel.

Effects of repetitive gentle handling of male C57BL/6NCrl mice on comparative behavioural test results.

Mice are the most commonly used laboratory animals for studying diseases, behaviour, and pharmacology. Behavioural experiment battery aids in evaluating abnormal behaviour in mice. During behavioural experiments, mice frequently experience human contact. However, the effects of repeated handling on mice behaviour remains unclear. To minimise mice stress, methods of moving mice using transparent tunnels or cups have been recommended but are impractical in behavioural tests. To investigate these effects, we used a behavioural test battery to assess differences between mice accustomed to the experimenter's handling versus control mice. Repeatedly handled mice gained slightly more weight than control mice. In behavioural tests, repeatedly handled mice showed improved spatial cognition in the Y-maze test and reduced anxiety-like behaviour in the elevated plus-maze test. However, there was no change in anxiety-like behaviour in the light/dark transition test or open-field test. Grip strength, rotarod, sociability, tail suspension, Porsolt forced swim, and passive avoidance tests revealed no significant differences between repeatedly handled and control mice. Our findings demonstrated that mice repeatedly handled by the experimenter before behavioural tests showed reduced anxiety about high altitudes and improved spatial cognition, suggesting that repeated contact can affect the results of some behavioural tests.

Differences in Behavior Between Elderly and Nonelderly Captive Chimpanzees and the Effects of the Social Environment.

The population of NIH-owned or NIH-supported captive research chimpanzees is quickly becoming aged, and the 1998 NIH breeding moratorium has resulted in a skewed age distribution. As such, behavioral management programs aimed at refining the care of an aging captive chimpanzee population have become increasingly important. However, little research exists that addresses the ways in which captive chimpanzee behavior differs as a function of the interaction of age and aspects of the captive environment. We examined overall differences in behavior between elderly (35 y and older) and nonelderly (younger than 35 y) captive chimpanzees. Elderly chimpanzees exhibited significantly more rough scratching (a behavioral indicator of anxiety) and inactivity, less behavioral diversity, and less affiliation than their nonelderly counterparts. We also assessed whether elderly chimpanzee behavior and wounding rates differed as a function of housing in geriatric (group average age, 35 y or older) or nongeriatric (group average age, younger than 35 y) groups. In our program, geriatric social groups were characterized by smaller group size, more females within the group, and higher levels of individual mobility impairment compared with nongeriatric groups. Furthermore, elderly chimpanzees housed in geriatric groups displayed significantly increased rough scratching, decreased locomotion and submission than nongeriatric animals but no difference in wounding. These findings suggest that housing elderly chimpanzees in nongeriatric groups may be beneficial, given that doing so may stimulate locomotion. However, the establishment and maintenance of geriatric groups may be unavoidable as the demographics of the population of captive former research chimpanzees continues to age. Therefore, refinements to captive geriatric care strategies for chimpanzees should focus on methods of evaluating and enhancing functionally appropriate captive environments within geriatric groups.

Tail handling of lab mice could become a thing of the past.

Josh Loeb reports on research that shows that this practice of handling is on the wane, in favour of other - less aversive - methods.

Survey report on public awareness concerning the use of animals in scientific research in Japan.

We conducted a survey on 3,096 members of the public in order to find out about public awareness concerning the use of animals in scientific research in Japan and statistically analyzed the results. Regarding the necessity of experiments, research, and educational activities using animals, 55-62% respondents answered that "development of medicine and medical technology for human beings", "development of medicine and medical technology for animals", "practical training at medical schools", and "practical training at schools of veterinary medicine" were necessary, while 9-12% respondents answered that they were not necessary. These results showed that the Japanese public can dispassionately accept that animal experiments are necessary. Regarding the image of animal experiments, 50-70% respondents also supported animal experiments aimed at "advances in science and medicine", "securing of human health and safety", and "pursuit of economic interest". On the other hand, when faced with questions that featured emotional language, a majority (51-57% of people) felt that "animal experiments are painful and cruel acts" and that "experimental animals are to be pitied". This survey showed that the majority of the Japanese public can accept the necessity of animal experiments, but experts and researchers involved in animal experiments should consider seriously the large number of respondents that agreed with emotive descriptions of animal research.

Predator odor induced defensive behavior in wild and laboratory rats: A comparative study.

Laboratory rats are frequently used as animal models in research. Since the 1920s rats are bred and reared in laboratories which affects anatomy, physiology, and behavior responses. In the present study we exposed laboratory and wild rats to predator odor and comparatively analyzed their behavioral and physiological responses. In detail, Warsaw Wild Captive Pisula Stryjek (WWCPS) rats and Lister Hooded (LH) rats were exposed to the predator odor 2,3,5-trimethyl-3-thiazoline (TMT), their behavior was videotaped and blood samples were collected for subsequent serum corticosterone analysis. In both rat stocks, exposure to TMT induced avoidance behavior and increased freezing behavior. Notably, the increase in freezing was based on an increase number of freezing events in LH rats whereas WWCPS rats prolonged the mean duration of the single freezing events. Interestingly, TMT exposure lead to a serum corticosterone increase in WWCPS rats but not in LH rats. Furthermore, WWCPS rats generally expressed decreased but faster locomotor activity, as well as more grooming behavior than LH rats. Taken together, these data indicate differences in behavioral and physiological defensive responses to predator odors in the two rat stocks.

Intermittent pair-housing, pair relationship qualities, and HPA activity in adult female rhesus macaques.

Laboratory rhesus macaques are often housed in pairs and may be temporarily or permanently separated for research, health, or management reasons. While both long-term social separations and introductions can stimulate a stress response that impacts inflammation and immune function, the effects of short-term overnight separations and whether qualities of the pair relationship mediate these effects are unknown. In this study, we investigated the effects of overnight separations on the urinary cortisol concentration of 20 differentially paired adult female rhesus macaques (Macaca mulatta) at the California National Primate Research Center. These females were initially kept in either continuous (no overnight separation) or intermittent (with overnight separation) pair-housing and then switched to the alternate pair-housing condition part way through the study. Each study subject was observed for 5 weeks, during which we collected measures of affiliative, aggressive, anxious, abnormal, and activity-state behaviors in both pair-housing conditions. Additionally, up to three urine samples were collected from each subject per week and assayed for urinary free cortisol and creatinine. Lastly, the behavioral observer scored each pair on four relationship quality attributes ("Anxious," "Tense," "Well-meshed," and "Friendly") using a seven-point scale. Data were analyzed using a generalized linear model with gamma distribution and an information theoretic approach to determine the best model set. An interaction between the intermittent pairing condition and tense pair adjective rating was in the top three models of the best model set. Dominance and rates of affiliation were also important for explaining urinary cortisol variation. Our results suggest that to prevent significant changes in HPA-axis activation in rhesus macaque females, which could have unintended effects on research outcomes, pairs with "Tense" relationships and overnight separations preventing tactile contact should be avoided.

Linking stress and immunity: Immunoglobulin A as a non-invasive physiological biomarker in animal welfare studies.

As the animal welfare community strives to empirically assess how care and management practices can help maintain or even enhance welfare, the development of tools for non-invasively measuring physiological biomarkers is essential. Of the suite of physiological biomarkers, Immunoglobulin A (IgA), particularly the secretory form (Secretory IgA or SIgA), is at the forefront because of its crucial role in mucosal immunity and links to physical health, stress, and overall psychological well-being. While interpretation of changes in SIgA concentrations on short time scales is complex, long-term SIgA patterns are consistent: conditions that create chronic stress lead to suppression of SIgA. In contrast, when welfare is enhanced, SIgA is predicted to stabilize at higher concentrations. In this review, we examine how SIgA concentrations are reflective of both physiological stress and immune function. We then review the literature associating SIgA concentrations with various metrics of animal welfare and provide detailed methodological considerations for SIgA monitoring. Overall, our aim is to provide an in-depth discussion regarding the value of SIgA as physiological biomarker to studies aiming to understand the links between stress and immunity.

Can laboratory animals violate behavioural norms? Towards a preclinical model of conduct disorder.

Conduct disorder (CD), a disturbance characterised by excess rates of aggression - often associated with callousness, lack of empathy and shallow/deficient affect - is extremely prevalent (2-10%) in the juvenile population. CD symptoms are quantitative rather than qualitative in nature whereby, rather than exhibiting abnormal behaviours, CD patients indulge in normal behaviours at abnormal rates. Although genetic and environmental factors contribute to CD aetiology, their precise contribution is yet to be determined. Experimental animal models may aid discriminating genetic vs. environmental effects and designing innovative therapeutic approaches. Here we discuss a theoretical framework potentially favouring the design of experimental models of CD. We suggest that the latter shall recapitulate the "norm violation" typical of the human disorder across the core domains involved in CD: aggression, callousness, empathy and emotionality. We first review how these domains have been operationalised in preclinical models; we then suggest that these experimental paradigms shall be combined with appropriate statistical tools to identify a subset of individuals consistently characterised by abnormal values in CD-relevant phenotypes.

Sequelae of Occult Aggression Disqualifying Young, Socially Housed, Female New Zealand White Rabbits (Oryctolagus cuniculus) from Participation in Dermal Toxicology Studies.

International animal welfare organizations and federal, regional, and institutional oversight bodies encourage social housing of gregarious species, such as New Zealand white rabbits (Oryctolagus cuniculus), to promote animal wellbeing in research, teaching, testing and farming settings. At our institution, 2 groups of female New Zealand white rabbits (approximate age, 11 wk; mean weight, 2.35 kg), compatibly paired at the vendor for 5 wk, were paired in caging or group-housed in a floor pen. The rabbits appeared compatible, demonstrating primarily affiliative behaviors throughout 6 wk of daily observations. However, occult aggression that occurred between daily observations or nocturnally resulted in skin wounding. The skin injuries, first identified during prestudy clipping of fur from the back of each rabbit 6 wk after arrival, disqualified every animal from participation in skin toxicology and muscle implantation studies. Success meeting scientific research requirements while promoting animal welfare and health when socially housing New Zealand white rabbits requires examining the behavioral repertoire of their wild counterparts, European rabbits. Factors including age, sex, and housing density influence territoriality, dominance hierarchy, social ranking, and natural, agonistic, injurious, behavioral tendencies. IACUC and other relevant oversight bodies, researchers, and animal care staff should consider this case study and the species-specific natural history of New Zealand white rabbits when assessing the harm and benefit of social housing in regard to research utility and animal welfare.

Behavior of laboratory dogs before and after rehoming in private homes.

Although the rehoming of laboratory dogs has gained popularity, a scientific evaluation of the process is lacking. The behavior of 145 laboratory beagles was tested before leaving a research facility (Test 1). The new owners were then surveyed using a standardized telephone interview 1 week (n = 143) and 12 weeks (n = 126) after adoption. The behavior test was repeated with 68 dogs in their new homes 6 weeks after adoption (Test 2). The predictive power of Test 1 or Interview 1 on Test 2 or Interview 2, respectively, as well as the relevance of various factors was analyzed. We found no significant differences between Tests 1 and 2 regarding the behavior reactions. However, body language scores and heart rates changed significantly, indicating a more relaxed state of the dogs in their new homes. The interviews revealed a significant change toward desired behavior in most dogs within the 11 week period (p < 0.0001). The main behavior problems included separation problems (28%; n = 126), destroying objects (24%), and not being housebroken (39%). Owners of 9 dogs returned the animals, resulting in a rehoming success rate of 94%. Test 1 revealed a significant age effect (p = 0.0066), with younger and older dogs reaching higher scores than dogs who were approximately 2 years old. Dogs that had been born and reared in the research facility scored higher than dogs that had originally been acquired from a commercial breeder (p = 0.0257). The predictive power of Test 1 on Test 2 or Interview 1 on Interview 2 was moderate to low, respectively. Altogether, rehoming of laboratory dogs is a valuable alternative to euthanasia.

The Processing of Human Emotional Faces by Pet and Lab Dogs: Evidence for Lateralization and Experience Effects.

From all non-human animals dogs are very likely the best decoders of human behavior. In addition to a high sensitivity to human attentive status and to ostensive cues, they are able to distinguish between individual human faces and even between human facial expressions. However, so far little is known about how they process human faces and to what extent this is influenced by experience. Here we present an eye-tracking study with dogs emanating from two different living environments and varying experience with humans: pet and lab dogs. The dogs were shown pictures of familiar and unfamiliar human faces expressing four different emotions. The results, extracted from several different eye-tracking measurements, revealed pronounced differences in the face processing of pet and lab dogs, thus indicating an influence of the amount of exposure to humans. In addition, there was some evidence for the influences of both, the familiarity and the emotional expression of the face, and strong evidence for a left gaze bias. These findings, together with recent evidence for the dog's ability to discriminate human facial expressions, indicate that dogs are sensitive to some emotions expressed in human faces.

Naming the Ethological Subject.

Argument In recent decades, through the work of Jane Goodall and other ethologists, the practice of giving personal names to nonhuman animals who are the subjects of scientific research has become associated with claims about animal personhood and scientific objectivity. While critics argue that such naming practices predispose the researcher toward anthropomorphism, supporters suggest that it sensitizes the researcher to individual differences and social relations. Both critics and supporters agree that naming tends to be associated with the recognition of individual animal rights. The history of the naming of research animals since the late nineteenth century shows, however, that the practice has served a variety of purposes, most of which have raised few ethical or epistemological concerns. Names have been used to identify research animals who play dual roles as pets, workers, or patients, to enhance their market value, and to facilitate their identification in the field. The multifaceted history of naming suggests both that the use of personal names by Goodall and others is less of a radical break with previous practices than it might first appear to be and that the use of personal names to recognize the individuality, sentience, or rights of nonhuman animals faces inherent limits and contradictions.