Dog paw preference shows lability and sex differences

Brain and behavioral asymmetries in nonprimate species

Brain and behavioral asymmetries are widespread across the animal kingdom, suggesting that even simpler nervous systems benefit from such features. In the last 30 years, research conducted on several vertebrate (but also invertebrate) animal models has massively contributed to our understanding of the causation, development, evolution, and function of lateralization. Here, we review some of this research, highlighting the importance of studying this topic in nonprimate species for a deeper understanding of the mechanisms behind cerebral asymmetries. We report evidence of handedness and motor asymmetries as well as the results of research on perceptual and cognitive asymmetries in nonprimate animals, analyzing the contribution of such studies in the research field of cerebral asymmetries.

Measuring paw preferences in dogs, cats and rats: Design requirements and innovations in methodology

Studying behavioural lateralization in animals holds great potential for answering important questions in laterality research and clinical neuroscience. However, comparative research encounters challenges in reliability and validity, requiring new approaches and innovative designs to overcome. Although validated tests exist for some species, there is yet no standard test to compare lateralized manual behaviours between individuals, populations, and animal species. One of the main reasons is that different fine-motor abilities and postures must be considered for each species. Given that pawedness/handedness is a universal marker for behavioural lateralization across species, this article focuses on three commonly investigated species in laterality research: dogs, cats, and rats. We will present six apparatuses (two for dogs, three for cats, and one for rats) that enable an accurate assessment of paw preference. Design requirements and specifications such as zoometric fit for different body sizes and ages, reliability, robustness of the material, maintenance during and after testing, and animal welfare are extremely important when designing a new apparatus. Given that the study of behavioural lateralization yields crucial insights into animal welfare, laterality research, and clinical neuroscience, we aim to provide a solution to these challenges by presenting design requirements and innovations in methodology across species.

The Relationship Between the Motor Lateralization and the Concentration of Cortisol and Tyrosine in Dogs Exposed to Stress During Veterinary Activities

The aim of the study was to assess the relationship between the motor lateralization in dogs and the concentration of cortisol and tyrosine in their plasma during a visit to a veterinary clinic. The research group consisted of 56 dogs. Motor lateralization was tested by of an adhesive tape test. The stress intensity was assessed basing on the levels of cortisol and ft4 in the serum blood. The statistical analysis revealed that in the group of 56 dogs there were 14 left-pawed dogs, 36 right-pawed dogs, and 6 dogs did not show particular paw preference. The average cortisol levels in particular groups were as follows: 7.94 ug/dl, 3.92 ug/dl and 3.7 ug/dl, whereas the level of tyrosine in the subjects that demonstrated left-sided lateralization (mean ± SE) (1.95 ± 0.46 ng/dl) for those with right-side lateralization (1.56 ± 0.23 ng/dl) and ambilateral dogs (1.01 ± 0.22 ng/dl). The statistical calculation of Pearson's χ2 showed a significant relationship between the sex and the lateralization (χ2 = 6.238, df = 2, p = 0.0442).

Methodological comparison of cancellation versus two-way choice spatial attention tests in humans and dogs

Introduction

Behavioural problems in family dogs are amongst the leading reasons for relinquishment to shelters which adversely affects animal welfare. Recent research suggests that certain problematic behavioural patterns might be analogous to human psychiatric disorders. Veterinary diagnosis of such conditions, however, is scarce, probably due to the lack of appropriate measurement tools. The current study focuses on dog behaviour resembling the human hemispatial neglect condition, which manifests itself as a deficit in attention to and awareness of one side of the space.

Methods

Healthy human subjects (N = 21) and adult family dogs (N = 23) were tested with tools aimed to measure spatial attention. Tests administered to humans included validated paper and pencil neuropsychological tools to assess hemispatial neglect (cancellation tasks), as well as the canine version of that task (visuo-spatial search task). Dogs were tested with the same visuo-spatial search task as well as a two-way choice task.

Results

Results show that both in case of dogs and humans the visuo-spatial search task detects individual variation in subjects' side preferences. However, subjects' performance in the different tasks were not related.

Investigating the influence of neuter status on paw preference in dogs and cats

Motor lateralization is commonly observed through preferential paw use in dogs and cats. Previous studies have uncovered sex-related differences in paw preference, hypothesizing that these differences may be related to sex hormones. The current study aimed to compare neutered and entire individuals to further investigate whether paw preference is influenced by sex hormones. Dog and cat owners were required to fill in a questionnaire with demographic information such as sex and neuter status of their pets. They then carried out two simple paw preference tasks within their homes: a "reaching for food" task and a "reaching for a toy" task. This study revealed an overall preference among the 272 dogs and 137 cats tested to use their right paw in both tasks. In cats, the degree of paw preference (i.e., regardless of the direction) was significantly influenced by an interaction between neuter status and life stage. Also in dogs, both life stage and an interaction between neuter status and life stage tended to influence the degree of paw preference. Post-hoc power analysis revealed a lack of statistical power, suggesting that future studies using a larger sample size are needed to further investigate potential effects of neuter status on paw preference.

Food handling shapes the laterality of paw use in the Chinese red panda (Ailurus styani)

Limb preference, associated with behavioural laterality and hemispheric lateralization, has long received high attention from both ethologists and psychologists. Chinese red pandas in Shanghai Zoo perform natural unimanual actions in two different ways during food handling, making it an appropriate subject to investigate the effect of food handling on pawedness. In this study, we estimated the direction and the strength of pawedness in spontaneous feeding behaviours in zoo-housed Chinese red pandas. All the subjects exclusively used the preferred paw when handling fruit pieces throughout the observational period, with three of them preferred the left paw while the other two the right paw. By contrast, both paws were found to be used alternately in consuming bamboo. Our results indicate that different food manipulations have effects on pawedness in the Chinese red panda where more complex handling could probably enhance its pawedness.

Is There an Association between Paw Preference and Emotionality in Pet Dogs?

Research with humans and other animals has suggested that preferential limb use is linked to emotionality. A better understanding of this still under-explored area has the potential to establish limb preference as a marker of emotional vulnerability and risk for affective disorders. This study explored the potential relationship between paw preference and emotionality in pet dogs. We examined which paw the dogs preferentially used to hold a Kong™ and to perform two different locomotion tests. Dogs' emotionality was assessed using a validated psychometric test (the Positive and Negative Activation Scale-PANAS). Significant positive correlations were found for dogs' paw use between the different locomotion tasks, suggesting that dogs may show a more general paw preference that is stable across different types of locomotion. In comparison, the correlations between the Kong™ Test and locomotion tests were only partially significant, likely due to potential limitations of the Kong™ Test and/or test-specific biomechanical requirements. No significant correlations were identified between paw preference tests and PANAS scores. These results are in contrast to previous reports of an association between dog paw preference and emotionality; animal limb preference might be task-specific and have variable task-consistency, which raises methodological questions about the use of paw preference as a marker for emotional functioning.

Behavioural responses of threespine stickleback with lateral line asymmetries to experimental mechanosensory stimuli

Behavioural asymmetry, typically referred to as laterality, is widespread among bilaterians and is often associated with asymmetry in brain structure. However, the influence of sensory receptor asymmetry on laterality has undergone limited investigation. Here we use threespine stickleback (Gasterosteus aculeatus) to investigate the influence of lateral line asymmetry on laterality during lab simulations of three mechanosensation-dependent behaviours: predator evasion, prey localization and rheotaxis. We recorded the response of stickleback to impacts at the water surface and water flow in photic conditions and low-frequency oscillations in the dark, across four repeat trials. We then compared individuals' laterality to asymmetry in the number of neuromasts on either side of their body. Stickleback hovered with their right side against the arena wall 57% of the time (P<0.001) in illuminated surface impact trials and 56% of the time in (P=0.085) dark low-frequency stimulation trials. Light regime modulated the effect of neuromast count on laterality, as fish with more neuromasts were more likely to hover with the wall on their right during illumination (P=0.007) but were less likely to do so in darkness (P=0.025). Population level laterality diminished in later trials across multiple behaviours and individuals did not show a consistent side bias in any behaviours. Our results demonstrate a complex relationship between sensory structure asymmetry and laterality, suggesting that laterality is modulated multiple sensory modalities and temporally dynamic.

Sex differences in the behavioral responses of dogs exposed to human chemosignals of fear and happiness

This research focuses on sex differences in the behavioral patterns of dogs when they are exposed to human chemosignals (sweat) produced in happy and fear contexts. No age, breed or apparatus-directed behavior differences were found. However, when exposed to fear chemosignals, dogs’ behavior towards their owners, and their stress signals lasted longer when compared to being exposed to happiness as well as control chemosignals. In the happy odor condition, females, in contrast to males, displayed a significantly higher interest to the stranger compared to their owner. In the fear condition, dogs spent more time with their owner compared to the stranger. Behaviors directed towards the door, indicative of exit interest, had a longer duration in the fear condition than the other two conditions. Female dogs revealed a significantly longer door-directed behavior in the fear condition compared to the control condition. Overall the data shows that the effect of exposure to human emotional chemosignals is not sex dependent for behaviors related to the apparatus, the owner or the stress behaviors; however, in the happiness condition, females showed a stronger tendency to interact with the stranger.

Paw preference in wolves (Canis lupus): A preliminary study using manipulative tasks

Behavioural and brain lateralization is widespread among non-human vertebrates. Motor lateralization has been investigated in the domestic dog, revealing that "pawedness" in this species seems to be sex and task related; however, few if any studies considered this asymmetry in wolves (Canis lupus). The aim of this study was to investigate the paw preference of seven wolves housed at Parco Natura Viva - Italy, during the interaction with food-related (FD) and olfactory (OLF) environmental enrichment devices. Eleven sessions were done (22 session in total) per condition (FD and OLF), and data about enrichment manipulation were collected. Most of the wolves manipulated the enrichment devices using one paw rather than both paws. At the individual level, all subjects were lateralized in paw use, six were right pawed, one was left pawed (the alpha male) regardless of the enrichment condition. The fact that one paw rather than both was frequently involved in manipulation could indicate a practical advantage for each individual in being lateralized in paw use. Despite the small sample size, our results provide interesting insights about lateralization in wolves, deserving further investigations. More studies are needed considering factors such as temperament, social rank and task complexity on canid motor lateralization.

Functional cerebral asymmetry in dogs living under different environmental conditions

Investigating the link between stress and functional cerebral asymmetry (FCA) has been a subject of interest in recent years. The demonstration of this link in the field of veterinary medicine is particularly important as measuring FCA has the potential to be an alternative and non-invasive behavioral method to assess stress in dogs. The present study aimed to investigate whether FCA is affected by different environmental conditions in dogs. The main aim of this study was to investigate the changes in FCA in dogs living under different conditions. To this aim, strength and direction of FCA in 40 urban free-ranging dogs were measured by a Kong test. Dogs were divided into four groups considering their environmental conditions: The dogs in Group 1 (n = 8) were rehabilitated urban free ranging dogs, which were kept in enriched shelter conditions. The dogs in Group 2 (n = 9) were adopted free ranging dogs, which lived in home environment for more than 1 year. The dogs in Group 3 (n = 11) were urban free ranging dogs, which stayed in individual cages in a dog shelter for more than 6 months. The dogs in Group 4 (n = 12) were adopted urban free ranging dogs, which stayed in a dog pension for more than 30 days. Considering the length of their stay in a kennel environment, quality of living condition and emotional states, the dogs in Group 3 and 4 were classified as chronically stressed dogs. Statistically significant differences existed between groups considering strength and direction of lateralization. Most of the dogs in Group 1 (87.5 %) and Group 2 (77.8 %) showed significant paw preferences, whereas most of the dogs in the Group 3 (72.7 %) and Group 4 (75 %) were categorized as ambilateral. Considering the individual level asymmetry in dogs and environmental conditions of dogs in Group 3 and 4, one may suggest that high ambilaterality levels is related with chronic stress. Thus, reduced FCA may not be the reason for stress sensibility, rather it can be an outcome of stressful situations. These results are the first to demonstrate the possible link between chronic stress and ambilaterality in dogs.

Laterality as a Predictor of Coping Strategies in Dogs Entering a Rescue Shelter

It has been reported that during the first few days following entry to a kennel environment, shelter dogs may suffer poor welfare. Previous work suggests that motor bias (the preferred use of one limb over the other) can potentially be used as an indicator of emotional reactivity and welfare risk. In this study, we investigate whether paw preference could be used as a predictive indicator of stress coping (measured using cortisol levels and behavioural observation) in a sample of 41 dogs entering a rescue shelter. Cortisol levels and behavioural observations were collected for one week after admission. We scored the dogs’ paw preference during a food-retrieval task. Our results showed that increasing left-pawedness was associated with a higher expression of stress-related behaviours such as frequent change of state, vocalisations and lower body posture. These results are in keeping with previous findings showing that left-limb biased animals are more vulnerable to stress. Paw preference testing may be a useful tool for detecting different coping strategies in dogs entering a kennel environment and identifying target individuals at risk of reduced welfare.

Behavioral and Perceptual Differences between Sexes in Dogs: An Overview

In this paper, we review the scientific reports of sex-related differences in dogs as compared to the outcomes described for wild animals. Our aim was to explore whether the differences in male and female dogs were affected by the domestication process, in which artificial selection is the main driver. For this purpose, we used information regarding personality traits, cognitive processes, and perception, for which there is a wide theoretical framework in behavioral ecology. Aggressiveness and boldness, described as a behavioral syndrome, were reported as being higher in males than females. Females also seemed more inclined to interspecific social interactions with humans in tasks that require cooperative skills, whereas males appeared more inclined to social play, thus implying different levels of social engagement between the sexes, depending on the context. Studies on cognitive processes underlined a greater flexibility in resorting to a particular navigation strategy in males. Most lateralization studies seem to support the view that males are preferentially left-handed and females are preferentially right-handed. Reports on visual focusing coherently rank females as superior in focusing on single social and physical stimuli. Only male dogs are able to discriminate kin; however, the timing of the olfactory recording in sexes is related to the stimulus relevance. Dogs are largely in line with life-history theories, which indicate that sex differences in dogs are mainly rooted in their biological and evolutionary heritage, remaining unchanged despite artificial selection. In contrast, the higher intraspecific sociability in wild male animals was not replicated in dogs.

Paw preferences in the Asian small-clawed otter - using an inexpensive, video-based protocol to study laterality of rare species in the zoo

It is still debated whether limb-use preferences represent a common trait in vertebrates, which is based on a shared phylogenetic history. Unravelling the evolutionary origin and pattern of paw preferences in vertebrates requires the analysis of a larger number of species within an ecologically relevant setting. We therefore investigated whether observations in a zoo enable the collection of reliable data sets by quantifying paw use in two independent groups of Asian small-clawed otters (Amblonyx cinerea). Employing a continuous focal animal sampling method, each day one of the ten individuals was video recorded from outside of the enclosure during usual activity. We selected four types of unimanual behaviour (reaching for food, reaching for non-food, reaching into a hole, carrying an object) and quantified paw use for each animal. Our study provides first evidences for individual paw preferences in otters, which were in line with previously reported forelimb use pattern in carnivoran species. Preferences differed between motor acts but for "reaching into a hole" a population-level right paw bias was detected. These data support that observations in a zoological setting are useful to explore task-dependent paw preferences and may facilitate future studies investigating paw preferences under experimentally controlled conditions.

Lateralized Functions in the Dog Brain

Understanding the complementary specialisation of the canine brain has been the subject of increasing scientific study over the last 10 years, chiefly due to the impact of cerebral lateralization on dog behaviour. In particular, behavioural asymmetries, which directly reflect different activation of the two sides of the dog brain, have been reported at different functional levels, including motor and sensory. The goal of this review is not only to provide a clear scenario of the experiments carried out over the last decade but also to highlight the relationships between dogs’ lateralization, cognitive style and behavioural reactivity, which represent crucial aspect relevant for canine welfare.

Lateralization of splay posture in reticulated giraffe (Giraffa camelopardalis reticulate)

Motor laterality is quite often studied in non-human primates, but rarely has been investigated within ungulates. The aim of the study was to use the naturally occurring splay behavior in giraffe as a method to look for the presence of laterality. Four male giraffes housed at Zoo Atlanta were watched for three months, recording their first leg moved to begin the splay posture and the total number of leg movements to achieve a secure stance. All four giraffe significantly moved their left leg first to begin the stance, which suggests at least individual level laterality. However, using the number of leg movements overall, the last leg moved was only significant in one individual.

Illness as a source of variation of laterality in lions (Panthera leo)

Brain asymmetry--i.e. the specialisation of each cerebral hemisphere for sensorimotor processing mechanisms and for specific cognitive functions-is widely distributed among vertebrates. Several factors, such as embryological manipulations, sex, age, and breeds, can influence the maintenance, strength, and direction of laterality within a certain vertebrate species. Brain lateralisation is a universal phenomenon characterising not only cerebral control of cognitive or emotion-related functions but also cerebral regulation of somatic processes, and its evolution is strongly influenced by social selection pressure. Diseases are well known to be a cost of sociality but their role in influencing behaviour has received very little attention. The present study investigates the influence of illness conditions as a source of variation on laterality in a social keystone vertebrate predator model, the lion. In a preliminary stage, the clinical conditions of 24 adult lions were assessed. The same animals were scored for forelimb preference when in the quadrupedal standing position. Lions show a marked forelimb preference with a population bias towards the use of the right forelimb. Illness conditions strongly influenced the strength of laterality bias, with a significant difference between clinically healthy and sick lions. According to these results, health conditions should be recognised as an important source of variation in brain lateralisation.

The effect of tissue culture on suture holding strength and degradation in canine tendon

The purpose of this study was to assess tendon metabolism and suture pull-out strength after simple tendon suture in a tissue culture model. One hundred and twelve flexor digitorum profundus tendons from 28 dogs were cultured for 7, 14, or 21 days with or without a static tensile load. In both groups increased levels of matrix metalloproteinase (MMP) mRNA was noted. Suture pull-out strength did not decrease during tissue culture. While the presence of a static load had no effect on the pull-out strength, it did affect MMP mRNA expression. This tissue culture model could be useful in studying the effect of factors on the tendon-suture interface.

Stability of motor lateralisation in maturing dogs

Previous studies of motor laterality in dogs have produced some conflicting results, with inconsistencies in lateral biases across sexes, over time, and across tasks. The current study modified published food-retrieval and tape-removal tests before applying them to 43 dogs. It showed that results derived from 50 observations of a food-retrieval task (Kong test) were consistent with 100 observations. Further, observations during both Kong and the tape-removal tests were consistent both within and between observers. Lateralisation results from both the Kong and Tape tests were generally consistent between breeds and sexes and over time, the only exceptions being the categorical groups during the Tape test and the strength of lateralisation in the Kong test. Of greatest interest in this study was the lack of consistency between results from the two different motor lateralisation tasks conducted. Given that motor lateralisation is said to reflect differences in brain structure or function, differences in task results may indicate differing complexities of the two tasks.

Left gaze bias in humans, rhesus monkeys and domestic dogs

While viewing faces, human adults often demonstrate a natural gaze bias towards the left visual field, that is, the right side of the viewee's face is often inspected first and for longer periods. Using a preferential looking paradigm, we demonstrate that this bias is neither uniquely human nor limited to primates, and provide evidence to help elucidate its biological function within a broader social cognitive framework. We observed that 6-month-old infants showed a wider tendency for left gaze preference towards objects and faces of different species and orientation, while in adults the bias appears only towards upright human faces. Rhesus monkeys showed a left gaze bias towards upright human and monkey faces, but not towards inverted faces. Domestic dogs, however, only demonstrated a left gaze bias towards human faces, but not towards monkey or dog faces, nor to inanimate object images. Our findings suggest that face- and species-sensitive gaze asymmetry is more widespread in the animal kingdom than previously recognised, is not constrained by attentional or scanning bias, and could be shaped by experience to develop adaptive behavioural significance.