State In Dogs Research Articles

Pulmonary hypertension is associated with hypocoagulability in dogs: a retrospective analysis of 66 cases (2013-2021).

To describe coagulation profiles in dogs with echocardiographic evidence of pulmonary hypertension (PH), to compare them to coagulation profiles in dogs without echocardiographic evidence of PH, and to determine the relationship between coagulation profiles and echocardiographic probability of PH. 66 dogs with PH (cases) and 86 dogs without PH (controls). Retrospective evaluation of records between 2013 and 2021 of dogs that had both an echocardiogram and a coagulation panel performed within 7 days. Dogs that received antithrombotics within 7 days of evaluation and dogs diagnosed with congenital or acquired coagulopathy or other severe systemic disease that could lead to coagulopathy were excluded. Dogs with a low echocardiographic probability of PH were also excluded. The dogs were divided into a PH group and non-PH group based on echocardiographic results. Demographic, clinicopathologic, and traditional coagulation parameters and VCM Vet (Entegrion) parameters were compared between the 2 groups. Dogs with PH were significantly older (median, 11 years vs 9.5 years, P = .02) and had a significantly lower body weight (median, 7.3 kg vs 19.3 kg, P < .001) than controls. Dogs with PH also had a significantly greater percent increase in prothrombin time (PT; P = .02), partial thromboplastin time (PTT; P < .0001), and fibrinogen (P = .045); however, their antithrombin concentration was lower (P = .005) compared to controls. Eight of 65 dogs (12.3%) in the PH group and 1/86 (1.2%) dogs in the non-PH group had an elevation of PT and/or PTT greater than 50% above the reference interval (P = .005). Dogs with PH had 11.9 times (95% CI, 1.5 to 97.9; P = .02) greater odds of being hypocoagulable than dogs without PH based on PT and PTT. This study demonstrated an association between a moderate to high echocardiographic probability of PH and a hypocoagulable state in dogs as determined by traditional coagulation assays. It underscores the importance of monitoring the coagulation status in canine patients with PH, particularly before initiating antithrombotic medications.

Evaluation of indicators of acute emotional states in dogs

A complete assessment of animal welfare requires not just an understanding of negative emotional states, such as fear and anxiety, but also of positive states, such as calmness and happiness. However, few studies have identified accurate and reliable indicators of positive emotional states in dogs. This study aimed to identify parameters that may serve as indicators of short-term emotional states in dogs. Using a cross-over design, 60 dogs living at a research facility were exposed to six different 10-min scenarios expected to elicit responses varying in emotional valence and arousal. A range of behavioural and physiological parameters were collected and their relationship to anticipated emotional valence and arousal was analysed using linear and logistic mixed models. Cortisol, adrenocorticotropic hormone, heart rate variability, panting, whining, and body shake all demonstrated significant differences based on arousal levels, but only within negative valence scenarios. Scores from a qualitative behavioural assessment (QBA) were associated with both emotional valence and arousal and were considered the best indicator of positive valence. Activity, ear temperature, and sitting were associated with positive high arousal, although this may have been influenced by differing levels of movement induced during these scenarios. Meanwhile, heart rate, secretory immunoglobulin A, standing and lying all showed similar changes associated with arousal for both positive and negative valence scenarios. This study provides a critical first step towards identifying evidence-based indicators of short-term emotional states in dogs, while highlighting considerations that should be made when employing these parameters, including the influence of coder bias, food provision, exercise, and external temperature. Overall, it is recommended future dog emotion and welfare research use a combination of parameters including indicators of both emotional valence and arousal.

Characterization of Canine Peyer's Patches by Multidimensional Analysis: Insights from Immunofluorescence, Flow Cytometry, and Single-Cell RNA Sequencing.

The oral route is effective and convenient for vaccine administration to stimulate a protective immune response. GALT plays a crucial role in mucosal immune responses, with Peyer's patches (PPs) serving as the primary site of induction. A comprehensive understanding of the structures and functions of these structures is crucial for enhancing vaccination strategies and comprehending disease mechanisms; nonetheless, our current knowledge of these structures in dogs remains incomplete. We performed immunofluorescence and flow cytometry studies on canine PPs to identify cell populations and structures. We also performed single-cell RNA sequencing (scRNA-seq) to investigate the immune cell subpopulations present in PPs at steady state in dogs. We generated and validated an Ab specifically targeting canine M cells, which will be a valuable tool for elucidating Ag trafficking into the GALT of dogs. Our findings will pave the way for future studies of canine mucosal immune responses to oral vaccination and enteropathies. Moreover, they add to the growing body of knowledge in canine immunology, further expanding our understanding of the complex immune system of dogs.

Magnetocardiography using optically pumped magnetometers array to detect acute myocardial infarction and premature ventricular contractions in dogs

Objective. Optically pumped magnetometers (OPMs) are recently developed magnetocardiography (MCG) sensors that can detect cardiac diseases. This is of great clinical significance for detecting acute myocardial infarction (AMI) and premature ventricular contractions (PVC). This study investigates the use of an array of OPMs to detect heart disease in animals. Approach. An array of OPMs was used to detect the MCG of AMI and PVC in dogs. We used four dogs in this study, and models of AMI with different degrees of severity were established by ligating the middle and proximal segments of the left anterior descending coronary artery. The dogs had PVC at the time of AMI. Continuous MCG time series with corresponding electrocardiograms (ECGs) and average MCG for each dog in different states are presented. The MCG features were extracted from the MCG butterfly diagram, magnetic field map, and pseudo current density map. The MCG features were used to quantify and compare with the gold-standard ECG measures. Main results. The results show that MCG features can accurately distinguish different states of dogs. That is, an array of OPMs can effectively detect AMI and PVC in dogs. Significance. We conclude that the array of OPMs can detect heart diseases in animals. Moreover, OPMs can complement or even replace superconducting quantum interference devices for MCG measurement in animals and diagnosis of human heart diseases in the future.

Untargeted Analysis of Serum Metabolomes in Dogs with Exocrine Pancreatic Insufficiency.

Exocrine pancreatic insufficiency (EPI) is a malabsorptive syndrome resulting from insufficient secretion of pancreatic digestive enzymes. EPI is treated with pancreatic enzyme replacement therapy (PERT), but the persistence of clinical signs, especially diarrhea, is common after treatment. We used untargeted metabolomics of serum to identify metabolic disturbances associated with EPI and generate novel hypotheses related to its pathophysiology. Fasted serum samples were collected from dogs with EPI (n = 20) and healthy controls (n = 10), all receiving PERT. Serum metabolomes were generated using UPLC-MS/MS, and differences in relative metabolite abundances were compared between the groups. Of the 759 serum metabolites detected, 114 varied significantly (p < 0.05, q < 0.2) between dogs with EPI and healthy controls. Differences in amino acids (arginate, homoarginine, 2-oxoarginine, N-acetyl-cadaverine, and α-ketoglutaramate) and lipids (free fatty acids and docosahexaenoylcarnitine) were consistent with increased proteolysis and lipolysis, indicating a persistent catabolic state in dogs with EPI. Relative abundances of gut microbial metabolites (phenyllactate, 4-hydroxyphenylacetate, phenylacetyl-amino acids, catechol sulfates, and o-cresol-sulfate) were altered in dogs with EPI, consistent with disruptions in gut microbial communities. Increased kynurenine is consistent with the presence of intestinal inflammation in dogs with EPI. Whether these metabolic disturbances participate in the pathophysiology of EPI or contribute to the persistence of clinical signs after treatment is unknown, but they are targets for future investigations.

Positive human interaction improves welfare in commercial breeding dogs: Evidence from attention bias and human sociability tests

Intensive breeding practices found in large scale Commercial Breeding Establishments (CBEs) raise significant concerns about breeding dam welfare. Large-scale CBE dams spend most of their reproductive lives confined to kennels, with limited access to enriching experiences including positive human interaction. Long-term confinement can have detrimental effects on dog welfare, inducing negative affective states like anxiety and depressive-like behaviour, and leading to the development of behavioural problems such as fearfulness towards unfamiliar people. Evidence in humans and other animals shows that negative affective states increase the subject’s attention towards a threatening stimulus. We tested the impact of positive human interaction on the welfare of breeding dams from a licensed UK CBE. After receiving four weeks of either baseline levels (control, N = 16) or additional positive human interaction (enriched, N = 15), an attention bias test (ABT) was conducted to assess dogs’ affective states. Afterwards, dams’ human sociability level was evaluated using a stranger approach test. Pre- and post-intervention hair cortisol samples were collected to determine the effect of enrichment on chronic stress. In the ABT, we predicted that, compared to enriched dams, control dams would look more frequently and for longer towards the position of a negative threatening stimulus (opening and closing umbrella) and would spend less time interacting with a positive rewarding stimulus (food bowl). In the stranger approach test, we expected enriched dams would score higher, suggesting more affiliative behaviour towards unfamiliar people. Results showed that control dams looked more frequently (p = 0.005) but not for longer (p = 0.148) towards the negative stimulus in the ABT. Moreover, enriched dams spent more time sniffing (p = 0.032) and eating (p = 0.005) from the food bowl. Additionally, enriched dams scored higher on average in the stranger approach test than dams in the control group (p = 0.026). No significant difference was observed in the percentage change of hair cortisol concentration between treatment groups (p = 0.135). To our knowledge, this is the first evidence for attention bias indicating affective state in dogs. This study demonstrates that a positive human interaction used as a form of enrichment can improve welfare and sociability towards strangers in commercial breeding female dogs. However, longer-term enrichment protocols may be needed to influence hair cortisol levels. Dams in large-scale breeding facilities would benefit from additional positive human interaction, particularly near the end of their reproductive life when they are rehomed as pets.

How Do Dogs Behave When Presented with Situations of Different Emotional Valences?

Dogs are good models for studying behaviour and cognition as they have complex social capabilities. In the current study, we observed how human emotional valences (positive, neutral and negative) affected aspects of dogs' behaviour. We expected that dogs would exhibit more approaching behaviours in the positive condition and more signs of avoidance in the negative one. We analysed videos of 70 adult pet dogs of various breeds taken from an experiment in which one of two actors expressed an emotion and dogs could freely explore the environment for 30 s. Our results show that dogs exhibit differential behaviour when presented with different emotional valences. Two behaviours arose that might be linked to a reciprocal positive emotional state in dogs: tail raised between 90° and 180° and physical contact during sniffing. These behaviours are associated with an active search for information. In the positive conditions, dogs were more willing to explore the social environment and gather information from the actors.

Long-Lasting Chews Elicit Positive Emotional States in Dogs during Short Periods of Social Isolation

Dogs may experience negative emotional states when isolated from human caregivers and conspecifics. This study aimed to evaluate how dogs interact with different enrichments during a short period of social isolation, as a first step towards identifying methods for improving their emotional wellbeing. Using a cross-over design, dogs (n = 20) at the Waltham Petcare Science Institute were exposed to four different food-based enrichments while left alone in a familiar room for 20 min: long-lasting chew (Chew), kibble in a treat-dispensing toy (Toy), and kibble dispensed through a smart treat-dispensing device with (Device + Voice) and without (Device) a person talking to the dog. Time spent engaging with each enrichment item and emotional valence and arousal (7-point scale collected every 5-min) were scored from videos. The results of linear mixed models indicated Chew was the most successful enrichment, with dogs having lower arousal scores (p < 0.05 vs. Device and Toy) during the first five minutes of isolation, higher positive valence scores (p < 0.05 vs. all) during the second five minutes of isolation, and spending the most total time engaged (p < 0.01 vs. all). Based on these findings, long-lasting chews should be further explored to assess their impact on dog emotional wellbeing.

Investigating attentional scope as a novel indicator of emotional state in animals

In humans, contrasting emotional states can lead to a broadening or narrowing of attentional scope. Whether this is also the case in animals has yet to be investigated. If confirmed, measurement of attentional scope has potential as a novel cognitive method of welfare assessment. In this study, we therefore aimed to investigate a test of attentional scope as a measure of emotional state in animals. We did this by inducing four putatively different emotional states in dogs (N = 10), varying in valence (positive, negative) and arousal (high, low), in two different reward contexts (food rewards in Experiment 1, social rewards in Experiment 2) and then assessing dogs’ behavioural responses in a test of attentional scope. We also recorded heart rate variability (HRV) parameters as additional confirmatory affective indicators. In Experiment 1, the dogs showed a narrowing of attentional scope after the induction of both positively valenced emotional states. That dogs were in a positive state was supported by the reduced Standard Deviation of normal-to-normal R-R intervals (SDNN) and the reduced Low Frequency (LF) and Very Low Frequency (VLF) HRV. In Experiment 2, when responses to social rewards were examined, we did not detect any statistically significant differences in attentional scope between the emotional states, but dogs had a slightly narrow attentional scope in the negatively valenced emotional states. The LF tended to be reduced in the high arousal positive treatment. In conclusion, our study provides the first indication that emotional states can also alter attentional scope in animals. The results justify further investigation of this approach for use in animal welfare assessment, although additional studies are needed to refine predictions.

The effect of repeated testing on judgement bias in domestic dogs (Canis familiaris)

Judgement bias paradigms are increasingly being used as a measure of affective state in dogs. Approach to an ambiguous stimulus is commonly used as a measure of affect, however, this may also be influenced by learning. This study directly measured the impact of learning on a commonly used judgement bias paradigm in the absence of an affective state manipulation. Dogs (N = 15) were tested on a judgement bias task across five sessions. The dogs’ latency to approach a bowl placed in one of three ambiguous locations between non-baited (negative) and baited (positive) locations was measured. Results show that session number had a significant effect on the dogs’ latencies to reach the ambiguous bowl locations, with post-hoc tests revealing that dogs were significantly slower to approach the locations as the number of sessions increased. Session number also had a significant effect on the number of times the dogs did not approach the bowl within 30 s of being released, with the number of no approaches generally increasing across sessions. When dog identity was included as a fixed effect, a significant effect on latency to approach was found, suggesting that some dogs were consistently faster than others across sessions. To assess whether the paradigm produced repeatable results, Intraclass Correlation Coefficients were used. A low degree of reliability was found between latencies to approach each bowl position across sessions. This study demonstrates that dogs learned that the ambiguous locations were not rewarded with repeated exposures, and that this impacted their responses. We conclude that this judgement bias paradigm may require further consideration if applied across multiple exposures and that repeated results should be interpreted with caution as they are likely impacted by learning.

Serum procalcitonin and C-reactive protein concentrations in dogs with degenerative mitral valve disease and infective endocarditis

This study aimed to investigate the clinical significance of serum C-reactive protein (CRP) and procalcitonin (PCT) concentrations in dogs with degenerative mitral valve disease (DMVD) and infective endocarditis. It also aimed to evaluate whether there is a relationship between the degree of disease and serum PCT and CRP concentrations. A total of 100 dogs with MVD were prospectively recruited into the study. According to clinical/laboratory signs and echocardiography, the dogs were divided into infective and degenerative groups. The degenerative group was also classified into four stages based on the American College of Veterinary Internal Medicine (ACVIM) guidelines (Stages A-D). Serum PCT and CRP concentrations were determined with dog-specific commercial test kits. The serum CRP (P&lt;0.05) and PCT (P&lt;0.001) concentrations in the infective group were significantly higher than the degenerative group. In the degenerative group, the serum CRP concentration of stage D dogs was significantly higher than the other stages (P&lt;0.001), and the degree of disease correlated significantly positively with serum CRP concentration (r=0.531 P=0.000). In conclusion, serum CRP and PCT concentrations may aid traditional diagnostic techniques to differentiate infective and degenerative mitral valve disease. This study also demonstrated that serum CRP concentrations were elevated in Stage D dogs, and that there is a positive correlation between the degree of disease and serum CRP concentration. This can be useful in determining the severity of the inflammatory state in dogs with DMVD.

Correlation Between D-Dimer Concentrations and Thromboelastography in Dogs With Critical Illness: A Retrospective, Cross-Sectional Study.

A hospital-based, retrospective, cross-sectional study was performed to assess the correlation of kaolin-activated thromboelastography (TEG) with D-dimer concentrations in 59 dogs with critical illness. Dogs were included if they had one or more serious disease detected upon performing TEG and D-dimer concentration determination based on the same blood sample. According to the coagulation index (CI), the 59 dogs were divided into two groups: a hypercoagulable state, with CI > 4 (44 dogs) and a normocoagulable state, with CI < 4 (15 dogs). Moreover, the 44 dogs with CI > 4 were divided into three sub-groups according to the disease etiology, i.e., inflammatory/tumor (I/T: 25 dogs), hemodynamic compromise (H: 11 dogs), and both conditions (I/TH: 8 dogs). The median values (interquartile ranges) of the CI and D-dimer concentration were 5.46 (4.55–6.33) and 410.25 (74.63–2206.12) in the 44 dogs with CI > 4 and 3.29 (2.92–3.75) and 1164.7 (50–2250.05) in the 15 dogs with CI < 4, respectively. The D-dimer concentration was significantly increased over the reference value in the 44 dogs with a CI > 4, particularly in dogs in the I/T group. It was also significantly increased in the 15 dogs with a CI < 4. D-dimer concentrations did not correlate with any of the TEG parameters in any of the dogs. Given this lack of correlation, the D-dimer concentration may be limited as an indicator of a possible hypercoagulable state in dogs with critical illness.

A promising novel judgement bias test to evaluate affective states in dogs (Canis familiaris).

The judgement bias test represents one of the most applied tools to evaluate animals' optimistic/pessimistic attitude and to infer their emotional and welfare state accordingly. The judgement bias test (JBT) has been used several times with dogs (Canis familiaris), in most cases using a spatial test that evaluates the dog's attitude towards a bowl placed in ambiguous positions (located between two unambiguous trained positions associated with opposite outcomes). Results are contrasting and methodological and statistical caveats emerged: dogs struggled to learn the association between unambiguous positions and their outcomes, they hardly discriminated between adjacent locations and they might be influenced by researchers. Therefore, we propose a novel paradigm, aimed at easing the learning process and at achieving more reliable measures. Improvements of the novel paradigm are the increased difference between payoffs of trained locations, the reduction of the number of trials and of their length and the removal of the potential influence of researchers. Results showed that 98% of dogs reached the learning criterion and that their learning appeared more stable: dogs behaved differently between the two trained stimuli and the variability of responses towards these stimuli was lower than the one towards ambiguous stimuli. Behavioural analyses confirmed that dogs fully learned outcomes associated with trained stimuli and that they were hesitant towards ambiguous stimuli. Furthermore, dogs managed to successfully discriminate between each pair of adjacent locations. These results suggest that this protocol is a promising tool to assess judgement biases in dogs and to evaluate their affective state.

Impact of gastrointestinal differences in veterinary species on the oral drug solubility, in vivo dissolution, and formulation of veterinary therapeutics

Many gaps exist in our understanding of species differences in gastrointestinal (GI) fluid composition and the associated impact of food intake and dietary composition on in vivo drug solubilization. This information gap can lead to uncertainties with regard to how best to formulate pharmaceuticals for veterinary use or the in vitro test conditions that will be most predictive of species-specific in vivo oral product performance. To address these challenges, this overview explores species-specific factors that can influence oral drug solubility and the formulation approaches that can be employed to overcome solubility-associated bioavailability difficulties. These discussions are framed around some of the basic principles associated with drug solubilization, reported species differences in GI fluid composition, types of oral dosage forms typically given for the various animal species, and the effect of prandial state in dogs and cats. This basic information is integrated into a question-and-answer section that addresses some of the formulation issues that can arise in the development of veterinary medicinals.

Dogs are more pessimistic if their owners use two or more aversive training methods

Domestic dogs are trained using a range of different methods, broadly categorised as reward based (positive reinforcement/negative punishment) and aversive based (positive punishment/negative reinforcement). Previous research has suggested associations between use of positive punishment-based techniques and undesired behaviours, but there is little research investigating the relative welfare consequences of these different approaches. This study used a judgement bias task to compare the underlying mood state of dogs whose owners reported using two or more positive punishment/negative reinforcement based techniques, with those trained using only positive reinforcement/negative punishment in a matched pair study design. Dogs were trained to discriminate between rewarded and unrewarded locations equidistant from a start box, and mean latencies recorded. Their subsequent latency to intermediate ‘ambiguous’ locations was recorded as an indication of whether these were perceived as likely to contain food or not. Dogs trained using aversive methods were slower to all ambiguous locations. This difference was significant for latency to the middle (Wilcoxon Z = − 2.380, P = 0.017), and near positive (Wilcoxon Z = − 2.447, P = 0.014) locations, suggesting that dogs trained using coercive methods may have a more negative mood state, and hence that there are welfare implications of training dogs using such methods.

PSVI-20 The Effect of Resistant Starch Type II on Satiety Hormones of Fasting Dogs

Abstract Resistant starches comprise the starch fraction that escapes small intestine (SI) digestion and reaches the colon, where it is fermented by saccharolytic bacteria that produce beneficial postbiotics. Moreover, slowly digestible starches lower glycemic index and may promote satiety. The objectives of this study were to assess whether diets having increased RS perturbed fasting levels of satiety hormones in dogs. Diets with three levels of resistant starch (RS type II) were produced via extrusion at three levels of mechanical energy. Nine male and 15 female adult Beagle dogs were fed the low, medium and high RS foods in a 3x3 Latin square design (n = 24). The study was approved by IACUC at Hill’s Pet Nutrition (# 883.0.0.0). Fasting blood was collected in the morning on days 27 and 28 of each period, and serum was separated and frozen at -70°C until analysis. Satiety hormones were measured by ELISA. Data was first converted to natural log to approximate normal distribution and then analyzed as a mixed model by the GLIMMIX procedure from SAS (v 9.4) with diet as fixed effect and dog and period as random effects. Ghrelin, gastric inhibitory polypeptide (GIP), glucagon-like peptide 1 (GLP-1), glucagon, leptin, pancreatic polypeptide (PP) and peptide YY (PYY) were not different across treatments likely due to the fasting state of dogs. Surprisingly, only insulin increased with higher RS consumption. It is possible that more propionate (not measured) was produced in the colon of dogs fed the high RS diet, which went through gluconeogenesis in the liver and resulted in a change in the time of glucose entering the blood stream. This could explain the insulin increase during fasting, but needs to be verified by measurement of fecal SCFA. Future research should explore the effect of type II RS on satiety hormones at multiple time points postprandial.

Comparative Analysis of C-Reactive Protein Levels in the Saliva and Serum of Dogs with Various Diseases.

Simple SummaryWhen collecting blood samples in dogs for evaluating inflammatory conditions, this method is invasive and stressful to dogs. We compared the C-reactive protein (CRP) level in both blood and saliva samples to investigate the non-invasive test method for inflammation. There was a correlation between the blood and saliva CRP levels. This non-invasive test using saliva seems to be a useful method with which to assess inflammatory conditions in dogs.We performed this study to characterize the difference between the inflammatory and non-inflammatory status in diseased dogs by measuring salivary C-reactive protein (CRP) levels. In addition, we assessed whether a correlation exists between CRP levels in saliva and those in serum. CRP levels were measured in 32 client-owned dogs, which were then divided into inflammation and non-inflammation groups based on the serum CRP level. The salivary CRP level was higher in the inflammation group than in the non-inflammation group (p < 0.05). Furthermore, there was a positive correlation between the salivary and serum CRP levels (R = 0.866, p < 0.001). These data suggest that canine salivary CRP measurements can effectively and non-invasively detect an inflammatory state in dogs.

Intravenous vitamin K1 normalises prothrombin time in 1 hour in dogs with anticoagulant rodenticide toxicosis.

Four dogs with anticoagulant rodenticide toxicosis were treated with intravenous vitamin K1 in lieu of plasma transfusion due to client cost constraints. Two dogs experienced a suspected anaphylactoid reaction, necessitating cessation of the treatment in one dog. Prothrombin time was rechecked 1 h after treatment in the remaining three dogs and all results were within the normal reference range. All four dogs were discharged from hospital within 48 h of presentation. Intravenous vitamin K1 rapidly reverses the coagulopathic state in dogs with anticoagulant rodenticide toxicosis. It is a viable alternative therapy to plasma transfusion if circumstances preclude its use; however, patients must be monitored for anaphylactoid reactions.

Can Children of Different Ages Recognize Dog Communication Signals in Different Situations?

The presented study examines the ability of 265 children aged 4–12 years to correctly assign contextual cues and inner state values to a set of audio and audio-visual recordings of dog vocalizations and behaviors in different situations. Participants were asked to mark which situation each recording captured, what inner state of the dog it showed, and what inner state a human would feel in the same situation. Recognition of the inner state of dogs was affected by the age of the child when evaluating the audio recordings (p < 0.001), and such a tendency was revealed in evaluating the audiovisual materials (p = 0.08). The inner state of dog evaluation was associated with both the situation assessment (p < 0.01) and human inner state (p < 0.001) in the case of audio recordings, but it was only correlated with situation assessment in audio-visual recordings (p < 0.01). The contextual situations were recognized by the participants only in the audio materials, with “stranger” being the best recognized situation, while “play” was the least recognized. Overall, children aged 4–5 years showed a limited ability to understand dog signals compared to children aged 6–12 years, who were successful in recognizing the dogs’ stimuli more than 80% of the time. Therefore, children younger than 6 years of age require increased supervision when interacting with dogs.

Potential Physiological Parameters to Indicate Inner States in Dogs: The Analysis of ECG, and Respiratory Signal During Different Sleep Phases.

The sleeping activity of family dogs has been studied increasingly in the past years. Recently, a validated, non-invasive polysomnographic method has been developed for dogs, enabling the parallel recording of several neurophysiological signals on non-anesthetized family dogs, including brain activity (EEG), eye movements (EOG), cardiac (ECG), and respiratory activity (PNG). In this study, we examined the ECG (N = 30) and respiratory signals (N = 19) of dogs during a 3-h sleep period in the afternoon, under laboratory conditions. We calculated four time-domain heart rate variables [mean heart rate (HR), SDNN, RMSSD, and pNN50] from the ECG and the estimated average respiratory frequency from the respiratory signal. We analyzed how these variables are affected by the different sleep-wake phases (wakefulness, drowsiness, NREM, and REM) as well as the dogs’ sex, age and weight. We have found that the sleep-wake phase had a significant effect on all measured cardiac parameters. In the wake phase, the mean HR was higher than in all other phases, while SDNN, RMSSD, and pNN50 were lower than in all other sleep phases. In drowsiness, mean HR was higher compared to NREM and REM phases, while SDNN and RMSSD was lower compared to NREM and REM phases. In REM, SDNN, and RMSSD was higher than in NREM. However, the sleep-wake phase had no effect on the estimated average respiratory frequency of dogs. The dogs’ sex, age and weight had no effect on any of the investigated variables. This study represents a detailed analysis of the cardiac and respiratory activity of dogs during sleep. Since variations in these physiological signals reflect the dynamics of autonomic functions, a more detailed understanding of their changes may help us to gain a better understanding of the internal/emotional processes of dogs in response to different conditions of external stimuli. As such, our results are important since they are directly comparable to human findings and may also serve as a potential basis for future studies on dogs.