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Several studies have assessed different components of lateralization. To date, the relationships between the 3 measures of laterality, structural, motor, and sensory, have not widely been assessed. Specifically, the relationships between structural (hair whorl characteristics) and motor or sensory lateralization have largely been overlooked. This study investigated the associations between these measures of lateralization in dogs (n = 114), using hair whorl characteristics (structural), the Kong and First-stepping Tests (motor), and the Sensory Jump Test (sensory). Several associations emerged, revealing the first evidence of a relationship between structural asymmetry (both the presence and direction of a hair whorl in various regions of the body) and sensory lateralization. Specifically, the presence of a whorl on the dog's left side of the head (cephalic) and thorax was associated with a right visual bias. In addition, right visual bias was probable if the ventral mandibular whorl was present in a counter-clockwise direction ( P = 0.008). Our data also demonstrated an association between structural and motor laterality (paw preference). Most notably, dogs with clockwise chest whorls were significantly more right-preferent in the First-stepping Test than those with counter-clockwise whorls ( P = 0.010). In addition, an association between measures of motor and sensory lateralization also emerged, representing some of the first evidence of such a relationship in nonhuman animals.

A range of mobility aids are available to assist people living with vision impairment, and of these, guide dog ownership offers them several unique benefits. However, training a dog to be a successful guide dog comes at a high cost (approximately AU$30,000). Therefore, the aim of this study was to determine whether temperament testing and kennel behavior measures could be used by Guide Dog Organizations for the early identification of dogs suitable for guiding work and thus to reduce production costs. Temperament tests (Passive and Noise, Sudden Appearance, and Dog Distraction Tests) and kennel behavior assessments (Activity Level, Salivary Immunoglobulin A Concentration, and Kennel Surveillance) were assessed in potential guide dogs (n = 25-113) at the Guide Dogs NSW/ACT Training Centre, Glossodia, New South Wales, Australia. Several significant predictors of guide dog success were identified. The presence of panting (P = 0.029) and licking (P = 0.005) when contrasted with baseline observations in the Dog Distraction Test, significantly reduced the probability of guide dog success. Success was also reduced with the latency for a dog to sit in the third Noise Test (P = 0.028), and when the time spent resting was reduced during the evening period (P = 0.018) in the Kennel Surveillance assessment. This study reports that 4 specific behavioral responses, which may reflect anxiety and restlessness, predict low suitability of dogs for guiding work. Through the identification of early predictors of guide dog success, resources can be more appropriately focused on dogs with a higher probability of success, whereas unsuitable dogs can be rehomed.

Over the past 2 decades, numerous studies have been undertaken to assess motor laterality in the domestic dog. In anticipation of growth in this area of enquiry, we decided to review the literature on canine motor biases to identify any shortcomings, reflect on the lessons to be learned from and offer ways forward for future research into canine laterality. The aim of this review is to (i) summarize motor laterality findings in the dog, (ii) highlight areas lacking in standardization, and (iii) propose necessary criteria for future tests and global reporting protocols. Our review of the literature highlighted the lack of standardization between studies in task selection, sample size, number of behavior scores recorded, and the methods by which motor laterality were classified and reported. This review illustrates the benefits of standardizing methods of motor laterality assessment so that comparisons can be made between the populations sampled. By adopting such an approach, researchers should mutually benefit as motor laterality data could then be compared and subjected to meta-analysis.

Motor laterality in potential guide dogs (n = 113) was determined using two methods: the Kong™ Test (the current benchmark test) and our innovation, a First-stepping Test. Kong™ studies record paw use during foraging from a rubber cylinder. However, motivation to feed varies markedly among dogs and breeds, and the test comprises 50 observations which for a single dog can take up to 4 hours to collect. The First-stepping Test bypasses hunger, and simply records the first foot advanced after standing with both forelegs level. In contrast to the Kong™ Test, it allows 50 observations to be gathered in 20 minutes. The findings of the current study indicate that lateralized behavior in the domestic dog is strongly task-dependent. The First-stepping Test revealed more significant paw preferences (PPs) than the Kong™ Test (76.1% vs. 52.2%). A significant right population bias ( P = 0.036) was revealed using this novel test, whereas there was no bias in the direction of laterality observed using the Kong™ Test ( P = 0.30). Instead, there was a significant population bias for the category of ambidextrous PP using the Kong™ ( P = 0.005). Strength of laterality (regardless of direction) was significantly high in the First-stepping Test ( P 0.001), but only weak PPs were observed for the Kong™ Test ( P = 0.65). Measures of laterality from the First-stepping Test were not influenced by dog factors, whereas age, breed, and sex of the dog were significantly associated with several laterality measures during the Kong™ Test. The occurrence of using both paws simultaneously to either hold the Kong™, or to step-off by means of jumping, was associated with a decrease in lateral strength for both tests. The First-stepping Test was repeatable, and the intraobserver (κ = 0.988) and interobserver (κ = 0.975) reliabilities were high. It offers a simple, quick and, when compared with the Kong™ Test, a more discriminative method of determining PP that is less influenced by dog factors.

Sensory lateralization in dogs (n = 74) was investigated in this study using our innovation, the Sensory Jump Test. This required the modification of head halters to create three different ocular treatments (binocular, right, and left monocular vision) for eye preference assessment in a jumping task. Ten jumps were recorded as a jump set for each treatment. Measurements recorded included ( i ) launch and landing paws, ( ii ) type of jump, ( iii ) approach distance, ( iv ) clearance height of the forepaw, hindpaw, and the lowest part of the body to clear the jump, and ( v ) whether the jump was successful. Factors significantly associated with these jump outcomes included ocular treatment, jump set number, and replication number. Most notably, in the first jump set, findings indicated a left hemispheric dominance for the initial navigation of the Sensory Jump Test, as left monocular vision (LMV) compromised of jumping more than right monocular (RMV) and binocular vision, with a significantly reduced approach distance and forepaw clearance observed in dogs with LMV. However, by the third jump set, dogs undergoing LMV launched from a greater approach distance and with a higher clearance height, corresponding to an increase in success rate of the jump, in comparison with RMV and binocular vision dogs. A marginally non-significant RMV bias was observed for eye preference based on the laterality indices for approach distance ( P = 0.060) and lowest body part clearance height ( P = 0.067). A comparison between eye preference and launching or landing paws showed no association between these measures of sensory and motor laterality. To our knowledge, this is the first study to report on sensory lateralization in the dog, and furthermore, to compare both motor and sensory laterality in dogs.

Hair whorl characteristics were assessed in the domestic dog (Canis familiaris) in the regions of cephalic, cervical (dorsal, ventral, and lateral), thoracic and brachial axillary regions, the chest, shoulders, elbows, ventral abdominal region, and on the caudal thighs (ischiatic). They were classified as simple or tufted, and their position was recorded as the distance between their centers and bony landmarks within each region. The distribution of whorls was explored in a cohort of domestic dogs (N = 120) comprising a variety of breeds and cross-breeds, sourced from shelters (N = 60) and the general public (N = 60). Whorls observed in the majority of dogs in this cohort typically occurred on the chest, brachial axillary region, elbows, and ischiatic region. Atypical whorls were present in fewer than 20% of the population, and included those on the head (cephalic), cervical regions (dorsal, ventral, and lateral), shoulders, thoracic axillary region, and on the ventral abdominal region. The majority of whorls on dogs were classified as simple. In contrast, those located on the elbows and the majority of chest whorls were tufted. The presence and position of whorls were often associated with several variables including coat length and thickness, and the sex and source of the dog. The palpation and hair-cluster method of whorl assessment described in this article is best suited to dogs with short-to-medium coat lengths. The current methodology developed to assess hair whorl characteristics provides a framework for future investigations into any associations between hair whorl characteristics and other canine traits such as temperament.

The aim of this study was to determine whether objective measures of laterality could be used to identify dogs with a high probability of successfully completing a Guide Dog Training Programme. Three categories of laterality (motor, sensory, and structural), were assessed in 114 dogs entering guide dog training. Significant predictors of success were identified: the direction of laterality (P=0.028), paw preference category in the 'Kong' test (P=0.043), hindpaw clearance height (P=0.002), laterality indices for a number of measures in the Sensory Jump test, and chest hair whorl direction (P=0.050). This is the first study to report a structural marker of canine behaviour. All three categories of laterality may be used to predict the suitability of dogs for guiding work, and by identifying predictors of success, resources can be more efficiently utilised on dogs with greater potential.

In horses and cattle, hair whorls have been shown to act as a structural marker of reactivity and behavioral lateralization. Few studies on canine whorls have been reported and none have assessed whorl position or direction of flow. This study describes the distribution and characteristics of whorl in each of 10 regions in which whorls are typically located in dogs. Hair whorls were assessed in dogs (n = 120) and were recorded as clockwise or counterclockwise in the cephalic, cervical (dorsal, lateral, ventral), thoracic and brachial axillary, chest, shoulders, elbows, abdominal, and ischiatic regions. Bilateral whorls, including brachial axillary, elbow, abdominal and ischiatic whorls, rotated in opposing directions, allowing the dog's overall hair coat to be symmetrical. Cephalic, brachial axillary, and ischiatic whorls were consistent in their direction; cephalic and ischiatic whorls were clockwise on the right side of the body, and counterclockwise on the left, whereas right brachial axillary whorls were counterclockwise and left were clockwise. The central chest whorl was predominantly counterclockwise (91.21%). Direction of whorls was associated with several factors, including coat length, coat thickness, sex and source of the dog.