Blood concentrations of serotonin, cortisol and dehydroepiandrosterone in aggressive dogs

Dog Neuter, Yes or No? A Summary of the Motivations, Benefits, and Harms, with Special Emphasis on the Behavioral Aspect

The decision to neuter pet dogs remains a significant and ongoing debate from ethical, animal health, and animal welfare perspectives. Millions of dogs worldwide are considered integral family members, and their behavior, as well as the bond they form with their owners, play a key role in the decision to keep them as pets. When behavioral problems arise, neutering is often viewed as a potential solution. However, by removing the source of sexual hormones, neutering creates the potential for both beneficial and harmful effects on a dog's health and behavior. It is crucial for society to rely on professionals to provide informed advice about whether and when the procedure should be performed on a pet, taking into account the unique risks and benefits of each individual case. Instead, the conclusions drawn from existing research-both in terms of behavior and health aspects-remain inconclusive and sometimes conflicting. Studies have reported higher risks for developing reproductive, urinary, metabolic, and musculoskeletal disorders in neutered dogs. Additionally, some studies suggest increases in stress, fear, anxiety, and even certain types of aggression following neutering. The limitations of current research, the subjectivity of pet owners' evaluations of their dogs' behaviors, the influence of various demographic factors, and the complex relationships between sex hormones and other hormones or neurotransmitters all contribute to the challenges in this field of study. Despite these complexities, they also offer promising avenues for future research. This review aims to provide a comprehensive overview of the various effects of neutering on dogs, with a particular focus on behavioral outcomes.

Behavioral, Physiological, and Pathological Approaches of Cortisol in Dogs

Cortisol, an essential glucocorticoid hormone, is crucial in regulating the stress response and maintaining physiological and behavioral homeostasis in mammals, including dogs. This review explores cortisol's physiological and behavioral role in canines, focusing on its effects on stress, immune function, and metabolism. Various methods of measuring cortisol levels in dogs, invasive (blood, saliva, urine) and non-invasive (hair, fecal assays), are discussed regarding their accuracy and practical applications. The review also highlights the influence of different environmental factors, such as shelter conditions, human interaction, and music, on cortisol levels in dogs. Furthermore, the clinical and behavioral implications of abnormal cortisol levels are examined, with particular attention to conditions like Cushing's disease and stress-related behavioral issues. The findings emphasize the importance of cortisol monitoring in veterinary practice and animal welfare, proposing future research directions to improve canine health and stress management.

Personality Unleashed: Surveying Correlation of Neuter Status and Social Behaviour in Mixed-Breed Male Dogs across Weight Classes

This study investigates the behavioural differences between neutered and intact dogs. A total of 230 questionnaires of neutered (n = 115) and intact (n = 115) mixed-breed male dogs were collected. Small, medium, large, and giant dogs were analysed to investigate a possible influence of body size. The results showed neuters were significantly more stressed than intacts (multinomial logistic regression, p = 0.001). In terms of stress by influences (such as separation anxiety and anxiety at car rides), neutered small, medium, and large dogs were more stressed than giant dogs (multinomial logistic regression, p = 0.05). Neuters were also found to be more aggressive in general (multinomial logistic regression, p = 0.04) and more aggressive on the walk (multinomial logistic regression, p = 0.02). In addition, personality questionnaires revealed significant differences in all characteristics. Neuters were less emotionally calm (multiple ordinal regression, p = 0.03), less trainable and less sociable (each multiple ordinal regression, p < 0.001). They also scored lower on extraversion (multiple ordinal regression, p = 0.04). These findings highlight the importance of further research into the behavioural effects of neutering dogs, as well as the need for evidence-based guidelines for neutering practices.

Effects of weaning and inactivated Lactobacillus helveticus supplementation on dairy calf behavioral and physiological indicators of affective state

The objectives of this study were to determine if weaning would induce behavioral and physiological indicators of a negative affective state, and if supplementation of inactivated Lactobacillus helveticus (ILH) to dairy calves would reduce those indicators of negative affect during weaning. Male Holstein calves (n = 23) were enrolled in the study on d 1 of life. The calves were housed in individual pens in 1 of 4 rooms for the 42 d study. Calves began a stepdown weaning from 9 L/d of milk replacer (MR), at 150 g of MR powder/L, on d 35 and received 6 L/d on d 35 - 36, 3 L/d on d 37 - 38, and 0.4 L/d on d 39 - 42. The MR was divided between 3 meals/d until the last 0.4 L/d phase which was divided between 2 meals/d. Calves had ad libitum water access throughout the study and calf starter from d 28 onwards. Within room, calves were assigned to 1 of 2 treatments: 1) control (CON; n = 11) and 2) 5 g of ILH/d split over and mixed into the 0800 h and 2000 h milk feedings from d 3-42 (ILH; n = 12). Lying behavior was recorded using HOBO data loggers from d 21-41. On d 33, 37 and 41, infrared eye images were taken to determine maximum eye temperature (MET), saliva samples were collected to determine cortisol concentration, and play assessments were conducted to quantify play behavior. On d 34, 38, and 42, blood samples were collected to determine blood serotonin concentration, whereas on d 38 and 39, calves were tested with a cognitive task. A subset of calves (n = 5/treatment) were euthanized to collect gut and brain tissue samples for serotonin concentration on d 43. Weaning resulted in fewer (d 37-41, tendency: d 36), but longer (d 38-41, tendency: d 37), lying bouts and reduced play (d 41), although no changes in lying time, MET, saliva cortisol, nor blood serotonin were detected with initiation of weaning. Supplementation of ILH was associated with lower lying time throughout the study, and reduced play duration and higher salivary cortisol and MET during weaning. No differences in lying bouts, play count, blood and tissue (colon, ileum, prefrontal cortex and brain stem) serotonin concentration, and time to complete the cognitive task were detected between the treatments. Overall, weaning induced behavioral changes indicative of negative affective state, and some behavioral differences were observed with ILH supplementation both before and during weaning, with some physiological changes observed during weaning.

New Advances in Attention-Deficit/Hyperactivity Disorder-like Dogs

Similar to humans, dogs could suffer an Attention-Deficit/Hyperactivity Disorder-like syndrome (ADHD-like). In fact, several studies highlight the use of dogs as a model for studying ADHD. This condition entails behavioral problems expressed through impulsivity, attention issues, hyperactivity, and/or aggression, compromising the quality of life for both the caregiver and the dog. The pathophysiology of ADHD-like is complex and is associated with dysregulation of various neurotransmitters such as serotonin and dopamine. The expression of ADHD-like behavior in dogs would appear to depend on a classical gene-environment interaction as is the case with many neurological disorders in humans. In addition to the described symptomatology, ADHD-like dogs can exhibit strong comorbidities with compulsive behaviors, aggressiveness, inappropriate elimination and fearfulness, in addition to epilepsy, foreign body ingestion, and pruritus. In spite of the fact that there is no veterinary consensus about the diagnosis of ADHD-like, some validated questionnaires could be helpful, but these cannot be used as a unique diagnostic tool. The use of drugs, such as fluoxetine, in addition to an adequate environmental enrichment, relaxation protocols, and behavior modification can achieve an adequate quality of life for both the dog and caregivers.

The Relationship between Canine Behavioral Disorders and Gut Microbiome and Future Therapeutic Perspectives

Canine behavioral disorders have become one of the most common concerns and challenging issues among dog owners. Thus, there is a great demand for knowledge about various factors affecting dogs' emotions and well-being. Among them, the gut-brain axis seems to be particularly interesting, especially since in many instances the standard treatment or behavioral therapies insufficiently improve animal behavior. Therefore, to face this challenge, the search for novel therapeutic methods is highly required. Existing data show that mammals' gut microbiome, immune system, and nervous system are in continuous communication and influence animal physiology and behavior. This review aimed to summarize and discuss the most important scientific evidence on the relationship between mental disorders and gut microbiota in dogs, simultaneously presenting comparable outcomes in humans and rodent models. A comprehensive overview of crucial mechanisms of the gut-brain axis is included. This refers especially to the neurotransmitters crucial for animal behavior, which are regulated by the gut microbiome, and to the main microbial metabolites-short-chain fatty acids (SCFAs). This review presents summarized data on gut dysbiosis in relation to the inflammation process within the organism, as well as the activation of the hypothalamic-pituitary-adrenal (HPA) axis. All of the above mechanisms are presented in this review in strict correlation with brain and/or behavioral changes in the animal. Additionally, according to human and laboratory animal studies, the gut microbiome appears to be altered in individuals with mental disorders; thus, various strategies to manipulate the gut microbiota are implemented. This refers also to the fecal microbiome transplantation (FMT) method, based on transferring the fecal matter from a donor into the gastrointestinal tract of a recipient in order to modulate the gut microbiota. In this review, the possible effects of the FMT procedure on animal behavioral disorders are discussed.

Behavioural and physiological responses to stressors in sheep with temperament classified by genotype or phenotype

The single nucleotide polymorphism (SNP) rs107856856, located in the tryptophan hydroxylase-2 gene, is associated with the behavioural phenotype for sheep temperament measured at weaning. Here, we tested the association between that SNP and physiological and behavioural responses to stressors in adult sheep. Two groups of adult sheep, one with genotype A/A (calm genotype) and the other with G/G (nervous genotype) in rs107856856, were selected from 160 sheep and were exposed, twice, to an open-field arena and an isolation box test (IBT). During each repeat, the behaviour and physiological responses (cortisol, prolactin, dehydroepiandrosterone [DHEA], brain derived neurotrophic factor [BDNF], characteristics of the response of body temperature, and oxidative stress) were measured. The behavioural and physiological responses of the sheep were compared between genotypes and also between groups classified on their phenotype as assessed by their initial isolation box score ("low responders" and "high responders"). The SNP rs107856856 had some effects on the behavioural phenotype (IBT score) but no effects on the physiological response to stress (cortisol, prolactin, DHEA, BDNF, oxidative stress or changes in body temperature) in the adult sheep, probably because the sheep were exposed, and therefore had adapted, to human contact during their life.

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.

A Multidimensional Evaluation of the Factors in the Animal Welfare Assessment Grid (AWAG) That Are Associated with, and Predictive of, Behaviour Disorders in Dogs

Behavioural disorders in dogs are common and have severe welfare consequences for dogs. This study aimed to assess the factors that are significant and predictive of behaviour problems in dogs using the animal welfare assessment grid (AWAG) to further understand what factors influence their welfare. 177 AWAG assessments were undertaken across 129 dogs that clinicians deemed to have a behavioural disorder. Wilcoxon rank-sum tests were used to assess the difference in scores between dogs with behaviour disorders and a cohort of healthy dogs (n = 117). This analysis showed that all physical factors besides body condition, all procedural factors besides procedure pain, and all psychological, and environmental factors were significantly different between healthy dogs and dogs with behaviour disorders. Spearman rank correlation coefficient (RS) revealed several significant strong positive correlations including the procedural impact on the dog's daily routine with aggression towards unfamiliar people and procedure pain, as well as other correlations between the dog's behaviour during assessment with the frequency at which they encounter fears and anxieties, clinical assessment and procedure pain, and reaction to stressors and social interactions. These findings highlight the interdependent nature of the various influences of welfare. Logistic regression analysis identified that aggression towards the caregiver, fears and anxieties frequency, and choice, control, and predictability were all significant predictors of behaviour disorders. The findings have important implications for veterinary, behaviour, and animal welfare professionals as any changes across these factors may indicate poor welfare linked to emotional disorders in dogs.

Fewer culturable Lactobacillaceae species identified in faecal samples of pigs performing manipulative behaviour

Manipulative behaviour that consists of touching or close contact with ears or tails of pen mates is common in pigs and can become damaging. Manipulative behaviour was analysed from video recordings of 45-day-old pigs, and 15 manipulator-control pairs (n = 30) were formed. Controls neither received nor performed manipulative behaviour. Rectal faecal samples of manipulators and controls were compared. 16S PCR was used to identify Lactobacillaceae species and 16S amplicon sequencing to determine faecal microbiota composition. Seven culturable Lactobacillaceae species were identified in control pigs and four in manipulator pigs. Manipulators (p = 0.02) and females (p = 0.005) expressed higher Lactobacillus amylovorus, and a significant interaction was seen (sex * status: p = 0.005) with this sex difference being more marked in controls. Females (p = 0.08) and manipulator pigs (p = 0.07) tended to express higher total Lactobacillaceae. A tendency for an interaction was seen in Limosilactobacillus reuteri (sex * status: p = 0.09). Results suggest a link between observed low diversity in Lactobacillaceae and the development of manipulative behaviour.

Serotonin and Dopamine Blood Levels in ADHD-Like Dogs

As with humans, dogs can suffer from attention deficit hyperactivity disorder-like (ADHD-like) behaviors naturally and exhibit high levels of hyperactivity/impulsivity and attention deficit problems, making the domestic dog a potential animal model for ADHD. ADHD has a very complex pathophysiology in which many neurotransmitters are involved, such as serotonin and dopamine. The aim of the study was to evaluate serum serotonin and dopamine levels in dogs with ADHD-like symptomatology. Fifty-eight dogs were studied, of which, thirty-six were classified as ADHD-like after physical and behavioral assessments. Additionally, the dogs’ owners performed a series of scientifically validated questionnaires which included C-BARQ, the Dog Impulsivity Assessment Scale, and the Dog-ADHD rating scale. Serum from every animal was collected after the behavioral assessments and analyzed with commercial ELISA tests for serotonin and dopamine determination. Kruskal–Wallis tests and Lasso regressions were applied to assess the relationships between both neurotransmitters and the ADHD-like behaviors (as assessed by clinical evaluation and through the different questionnaires). The dogs clinically classified as ADHD-like showed lower serotonin and dopamine concentrations. Further, serotonin and dopamine levels were also linked to aggression, hyperactivity, and impulsivity. Decreased serotonin concentrations were also related to fear, attachment, and touch sensitivity. Finally, it must be noted that our data suggested a strong relationship between serotonin and dopamine and ADHD-like behaviors.

Hair cortisol levels in cats with and without behavioural problems

OBJECTIVES

The aim of the study was to analyse hair cortisol levels in cats whose owners had reported behavioural problems and undesirable behaviour. In addition, feline hair cortisol levels were compared between sexes, for indoor and outdoor cats and also for cats living in single or multi-cat households.

METHODS

In total, 55 cats participated in the study, including 31 females and 24 males from various households. The cats belonged to 25 different owners who answered a questionnaire survey. The biological material used for the research were 2-3 cm fragments of hair removed at the level of the skin with scissors by the owners from the cats' lumbosacral area. The cortisol concentration in the samples was determined with the DRG Salivary Cortisol HS ELISA. Statistical analysis of the results was performed with Statistica 13.3.

RESULTS

A tendency toward lower cortisol levels was found in outdoor cats vs indoor cats (U = 251.5, P = 0.066). It was also found that the cats exhibiting behavioural problems (eg, house soiling [eliminating outside the litter box]) or aggressive behaviour towards household members had statistically significantly higher hair cortisol levels (U = 162.0 [P = 0.027] and U = 9.0 [P = 0.040], respectively).

CONCLUSIONS AND RELEVANCE

High levels of stress in cats can affect their interactions with other cats and with humans. The incidence of undesirable behaviour was observed more frequently in indoor cats. Significantly higher cortisol levels were found in cats that eliminated outside the litter box or that showed aggression towards their owners.

The Variation of Serotonin Values in Dogs in Different Environmental Conditions

Simple Summary

The multiple implications of serotonin in behavior manifestations have shaped the goal of the present study, which was to evaluate the variation of serum serotonin levels in different experimental groups of dogs to establish whether serum serotonin levels could serve as indicators of aggressive behavior, especially when adoption is considered. The experimental groups were divided into three variants: Variant 1—two groups of medium (n = 6) and small (n = 4) breed shelter dogs; Variant 2—dogs with owners (n = 15) and dogs without owners but in foster care (n = 10), after administration of pre-spaying/neutering anesthesia; and Variant 3—dogs in different behavioral states (n = 8), classified as follows: M1—happy, M2—aggressive, M3—calmed status, post-exposure to a stressful situation, compared to the reference time referred to as M0. Significant results were found between M1 and M2 (p ≤ 0.05, decrease of serotonin by 89.61 ng/mL), as well as between M2 and M3 (p ≤ 0.008, increase by 112.78 ng/mL). Following anesthesia, the average mean serotonin values were significantly lower (p ≤ 0.003), by 63.85 ng/mL, in stray dogs compared to dogs with owners, leading to a presumptive conclusion that serotonin levels could serve as indicators for potentially aggressive behaviors.

Abstract

Serotonin is considered to be the neurotransmitter that controls several types of behavior: aggressiveness, impulsivity, food selection, stimulation, sexual behavior, reaction to pain, and emotional manifestations. The aim of this study was to determine the serotonin values in 43 dogs, divided into three different experimental variants: (1) between two groups of medium (n = 6) and small (n = 4) breed shelter dogs; (2) in dogs with (n = 15) and without (n = 10) owners after administration of pre-spaying/neutering anesthesia; (3) in different behavioral states (n = 8) classified as follows: M1—happy, M2—aggressive, M3—calmed status, post-exposure to a stressful situation, compared to the reference time referred to as M0. There were no significant differences (p ≥ 0.05) regarding the serotonin values between the two groups of medium and small breed shelter dogs. Following anesthesia, the average mean serotonin values were significantly lower (p ≤ 0.003), by 63.85 ng/mL, in stray dogs compared to dogs with owners. No significant differences (p ≥ 0.05) were found when comparing the reference time M0 to M1, M2, and M3. The differences decreased significantly (p ≤ 0.05), by 89.61 ng/mL, between M1 and M2 and increased significantly (p ≤ 0.008), by 112.78 ng/mL, between M2 and M3.

Urinary Neurotransmitter Patterns Are Altered in Canine Epilepsy

Epilepsy is the most common chronic neurological disease in humans and dogs. Epilepsy is thought to be caused by an imbalance of excitatory and inhibitory neurotransmission. Intact neurotransmitters are transported from the central nervous system to the periphery, from where they are subsequently excreted through the urine. In human medicine, non-invasive urinary neurotransmitter analysis is used to manage psychological diseases, but not as yet for epilepsy. The current study aimed to investigate if urinary neurotransmitter profiles differ between dogs with epilepsy and healthy controls. A total of 223 urine samples were analysed from 63 dogs diagnosed with idiopathic epilepsy and 127 control dogs without epilepsy. The quantification of nine urinary neurotransmitters was performed utilising mass spectrometry technology. A significant difference between urinary neurotransmitter levels (glycine, serotonin, norepinephrine/epinephrine ratio, ɤ-aminobutyric acid/glutamate ratio) of dogs diagnosed with idiopathic epilepsy and the control group was found, when sex and neutering status were accounted for. Furthermore, an influence of antiseizure drug treatment upon the urinary neurotransmitter profile of serotonin and ɤ-aminobutyric acid concentration was revealed. This study demonstrated that the imbalances in the neurotransmitter system that causes epileptic seizures also leads to altered neurotransmitter elimination in the urine of affected dogs. Urinary neurotransmitters have the potential to serve as valuable biomarkers for diagnostics and treatment monitoring in canine epilepsy. However, more research on this topic needs to be undertaken to understand better the association between neurotransmitter deviations in the brain and urine neurotransmitter concentrations in dogs with idiopathic epilepsy.

Protecting Animal Welfare in Animal-Assisted Intervention: Our Ethical Obligation

When incorporating therapy animals into clinical practice, there are essential ethical considerations that must be considered to protect the welfare of both the people and the animals who are involved in the intervention. The field of animal-assisted interventions (AAIs) and more specifically animal-assisted therapy (AAT) is just beginning to appreciate the critical role that animal welfare has in enhancing the quality of the entire process of working with a therapy animal. In this article, the authors will present ethical models that are incumbent for practitioners to consider prior to partnering with a therapy animal. Examples of how a speech-language pathologist (SLP) might work with a therapy animal will be integrated throughout the article to demonstrate applied awareness of how good welfare not only protects the animal but also the clients who engage in the intervention. Key aspects to consider at all stages of AAT will be described, including considerations of welfare as they relate to selecting and working with a therapy animal, preparing clients for AAT, and developing specific competencies as an AAT practitioner. Theoretical support for these recommendations will also be outlined, preparing AAT providers to not only incorporate the highest standards in AAT but to also serve as an advocate in championing these standards as the field develops.

Review on Selected Aggression Causes and the Role of Neurocognitive Science in the Diagnosis

Simple Summary

Aggression in dogs is often a reason for abandonment and/or euthanasia. Recently, knowledge about aggression has been subjected to more detailed analysis. In recent years, it has been studied in terms of factors affecting it, such as diet (especially nutritional supplements) and physiology (endocrine system). In addition, recently, new methods of brain research, such as neurocognitive research, have appeared, which enable a significant increase in knowledge about dog behavior, including aggression.

Abstract

Aggression as a behavior is not always desirable, often ends in abandonment and/or euthanasia. However, it is possible to prevent the occurrence of unwanted aggression in domestic dogs. Aggression is not a fully understood phenomenon. In recent years, many studies have focused on the influence of diet and physiology (including the endocrine system) on the emergence of behavioral disorders. In particular, the emphasis was put on nutritional additives such as fatty acids, amino acids, and probiotics. In addition, the possibility of using neurocognition in the observation of abnormal behavior in dogs has also been discussed, which may allow for a more detailed determination of the basis of aggressive behavior in dogs. In this review, the concepts related to aggression and its potential causes have been gathered. In addition, the possible influence of diet and hormones on aggression in dogs has been discussed, as well as the application of neurocognition in the possibility of its diagnosis.

Neuroendocrine and Cardiovascular Activation During Aggressive Reactivity in Dogs

Our aim was to investigate cardiovascular activation by measuring changes in facial and body surface temperature using infrared thermography, and neuroendocrine activation using salivary cortisol (CORT) and serotonin concentration (SER) in dogs exhibiting aggressive reactivity in real time. Based on two factors, owner-reported past aggressive behaviors, and detailed behavioral observations collected during a Socially Acceptable Behavior test consisting of 16 subtests and, each individual was categorized as aggressive or non-aggressive. CORT and SER showed no difference in neuroendocrine activity between dogs, but aggressive dogs with higher levels of aggression were found to have lower SER. Aggressive dogs also had an increase in facial temperature from pre-test values. The discovery of a correlation between tail wagging and left tail wagging with aggression level and aggression-related behaviors in aggressive dogs is further evidence of the right hemisphere specialization for aggression previously reported in the literature. This study provides the first evidence that both cardiovascular and neuroendocrine systems are activated during an active act of aggression in dogs.

Effect of exogenous melatonin on endocrinological profiles, biochemical and antioxidant and oxidative stress profiles in post-partum anestrus Andaman local buffaloes (Bubalus bubalis) in tropical island ecosystem

Andaman local buffalo (ALB) is distributed in Andaman and Nicobar Islands. ALB is non-descriptive and represents admixture of different Indian breeds of buffaloes. ALB is suffering infertility due to anestrus in dry (summer) season. Therefore, this study was conducted to assess the effect of slow release subcutaneous exogenous melatonin (MT) implant on hematological profiles, endocrinological profiles (cortisol and prolactin), biochemical profile (total protein, albumin, globulin, glucose and total cholesterol), antioxidant profiles [total antioxidant capacity (TAC), catalase (CAT), glutathione (GSH) and superoxide dismutase (SOD)] and oxidative stress profile (malondialdehyde; MDA) in anestrus buffalo cows during summer to improve its reproductive efficiency. Experimental buffaloes (5–7 years of age) were selected and divided into two groups, Gr I: Control (n=6) and Gr II: Treatment (n=6; melatonin implant @ 18 mg/50 kg b.wt). Statistical analysis revealed that these experimental profiles differed significantly between treatment and control groups. Blood profiles revealed that anestrus buffalo suffered severe macrocytic hypochromic anemia with increased leukocytosis and MT has improved the health status of reproductive system and whole body systems. Concentration of cortisol and prolactin were lower in MT treated than in control group. Similarly, antioxidant profiles were higher and oxidative stress profile was lower in MT treated group than in control group. Biochemical profiles were increased in MT treated than in untreated buffalos. Study concludes that melatonin had significant beneficial effects in improvement of the antioxidant profiles, minimization of oxidative stress with cascading beneficial effects on hormone, biochemical and hematological profiles, which will improve the cyclicity and fertility rate in anestrus buffalo during summers in humid tropical island ecosystem.

Short-term effect of ovariohysterectomy on urine serotonin, cortisol, testosterone and progesterone in bitches

Objective

This study aimed to investigate the short-term effect of ovariohysterectomy on urine levels of serotonin and its relation to levels of cortisol, testosterone and progesterone in female dogs. Seven bitches were studied before surgical ovariohysterectomy and then once a week during 4 weeks. Spontaneously voided urine samples were collected and concentration ratios of hormone/creatinine in urine were analysed.

Results

The bitches had significantly lower levels of cortisol, testosterone, and progesterone 1 week after ovariohysterectomy compared with before and the levels stayed low throughout the study (P ≤ 0.05). Interestingly, serotonin levels tended to increase 4 weeks after surgery (P = 0.08). A positive correlation between cortisol and progesterone was found before and after surgery. After surgery, serotonin was positively correlated with cortisol and progesterone (P ≤ 0.05).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05680-y.

[Hypothyroidism in dogs: an overview]

Hypothyroidism is one of the most common endocrinopathies in dogs. In rare cases, it may be associated with further endocrinopathies. The most common combination is the con-currence of hypothyroidism and hypoadrenocorticism. The diagnosis of hypothyroidism is based on the measurement of thyroid hormones (T4/fT4) and thyroid stimulating hormone (TSH). As thyroid hormone concentrations in the blood are influenced by various factors (e. g. systemic diseases or drugs), test results must be interpreted in conjunction with complaints demonstrated by the patient. In cases when diagnosis is not definite, stimulating tests or diagnostic imaging techniques (ultrasound, scintigraphy) are advisable. Dogs with hypothyroidism should be diagnosed and treated with thyroid hormones. When addiditional clinical signs are not consistent with hypothyroidism, co-existing additional endocrinopathies need to be considered. Furthermore, when treatment fails to result in the expected clinical response, the diagnosis of hypothyroidism must be subject to critical re-evaluation. This article provides an overview of the current diagnostic and treatment methods in canine hypothyroidism.

Detection of owner-perceived emotional eating in companion dogs: A regression modelling approach

BACKGROUND

Emotional eating has been largely demonstrated in humans and laboratory rodents, but a recent survey conducted by the authors revealed that dog owners have also detected this phenomenon in their pets. However, due to the lack of diagnostic tools, veterinarians and researchers might encounter serious difficulties in detecting emotional eating in clinical settings. The present study aimed to explore different variables associated with owner perceived-emotional eating in companion dogs with the ultimate goal of designing a tool that could facilitate its detection.

METHODS

The mentioned survey included information on feeding habits, eating behaviour, temperament and emotional state of the dogs, as well as a specific question for assessing the owners' perception on emotional eating. From these data (n = 1137), a stochastic model based on binary logistic regression was used to design a regression model.

RESULTS AND CONCLUSION

The final model (r² = 0.179, p < 0.001) included a constant and nine variables and, of these, five did act as risk factors whereas the rest were considered as protective factors, in line with a congruent clinical perception. These variables could make up an easy-to-respond nine-item checklist to be answered by dog owners that could help veterinarians identify those companion dogs susceptible to emotional eating.

Effect of alpine grazing on plasma and hair cortisol, serotonin, and DHEA in dairy cows and its welfare impact

Through the analysis of blood and hair samples, this study evaluated the effects of grazing in alpine areas on welfare indices and indicators of stress in dairy cows. Twenty-one Holstein dairy cows (body weight: 637 ± 21.5 kg; days in milk: 133 ± 17.7, and second parity) were randomly assigned to 3 groups: control (nongrazing), 12 h of alpine grazing (12 hG), and 24 h of alpine grazing (24 hG). Blood samples for plasma collection were taken for 3 consecutive days at the end of the experiment. Hair samples were collected at the beginning and end of the experiment. Hormone measurements included cortisol, serotonin, and dehydroepiandrosterone (DHEA) in both plasma and hair samples. Plasma cortisol and DHEA levels did not differ among the 3 groups, whereas the plasma serotonin level was higher in the 24 hG group than that in the other groups. The plasma cortisol to DHEA ratio was lower in the 24 hG group than that in the control and 12 hG group. The hair samples taken at the end of the experiment showed that the cortisol level was significantly higher in the control group than that in both of the grazing groups and also higher in the 12 hG than that in the 24 hG group. Hair DHEA and serotonin levels were highest in the 24 hG group. The hair cortisol to DHEA ratio was significantly higher in the control group than that in the 12 hG and 24 hG groups and in the 12 hG group than that in the 24 hG group. Our study showed that grazing dairy cows in alpine areas for 24 h improved their welfare, as indicated by increased serotonin levels in hair and plasma, increased hair DHEA level, and decreased stress indicators, including the hair cortisol level and cortisol to DHEA ratio. Farm facilities should allocate optimal grazing time for optimal welfare of dairy cows.

Effect of Stroking on Serotonin, Noradrenaline, and Cortisol Levels in the Blood of Right- and Left-Pawed Dogs

Simple Summary

The endocrine balance, reflected in the level of neuromodulators, is necessary for maintenance of homeostasis and facilitates adaptation to stressful conditions. An important role in processing the information reaching the brain is played by the asymmetric specialization of cerebral hemispheres referred to as laterality. The domestic dog shows preference of the forelimb determined by the predominance of the activity of the right or left brain hemisphere. Investigations of various animal species indicate that the left-brain hemisphere is involved in the control of unchanging stimuli or repetitive actions, while the right hemisphere is specialized in the quality of emotional reactions such as aggression or fear. A skillful observation of combined behavioral and physiological symptoms of stress in dogs provides better insight in the dog’s perception of veterinary care, and any means of reduction of the stress level is highly recommended, as it improves animal’s welfare. The results of the present study indicate that dogs’ laterality and sex affect the stress response and stroking can relieve stress. The level of the analyzed neuroregulators indicating intensification of stress or adaptation to stress conditions was higher in the males and in the right-pawed dogs. Our results confirm our assumptions that right-pawed dogs are better adapted to stressful conditions.

Abstract

It has been assumed that stroking relieves stress responses in dogs, and dogs with the activation of the left-brain hemisphere (right-pawed) may show better adaptation to stress conditions. The aim of the study was to determine whether the stroking stimulus induced changes in the level of selected neuroregulators in dogs’ blood and whether these changes depended on the sex and the predominance of the activity of one of the brain hemispheres. The study involved 40 dogs of various breeds and both sexes. The experimental animals were subjected to a behavioral tests (Kong test), and the levels of noradrenaline, serotonin, and cortisol were determined in their blood plasma. The results of the behavioral test revealed that most dogs exhibited increased activity of the left hemisphere. Furthermore, irrespective of the sex and paw preference, stroking the animal was found to alleviate the stress response, which was reflected in reduced cortisol levels and increased serotonin levels. It was found that the plasma noradrenaline, cortisol, and serotonin levels were lower in the female dogs than in the males. Additionally, the plasma noradrenaline and serotonin levels were higher in the right-pawed dogs than in the left-pawed dogs. The present results confirm the assumption that right-pawed dogs adapt to stressful conditions more readily.

Serotonin and Tryptophan Serum Concentrations in Shelter Dogs Showing Different Behavioural Responses to a Potentially Stressful Procedure

In mammals, serotonin (5-HT) levels depend on the availability of tryptophan (TRP). Low 5-HT concentrations have been linked to behavioural disorders in dogs. This study aimed at investigating possible differences in dogs’ serum TRP and 5-HT concentrations according to their behavioural response to a potentially stressful procedure. Thirty-nine physically healthy shelter dogs, 15 females and 24 males, mean age = 5.6 years, were categorized by a certified veterinary behaviourist according to their behavioural response to medical examination and blood collection, in: relaxation, stress signals, tension without growling, tension with growling, escape attempts, and aggression attempts. Extraction and quantification of 5-HT and TRP were performed using a HLPC method. Data were statistically analysed, applying Chi-square and Spearman tests. Results showed no significant difference in TRP (χ² = 2.084, p = 0.555) nor 5-HT (χ² = 0.972, p = 0.808) serum concentrations among different categories of dogs; however, some categories were underrepresented (relaxation = 20.5%, stress signals = 30.8%, tension without growling = 43.6%, tension with growling = 5.1%, escape attempts = 0%, aggression attempts = 0%). No correlation between serum TRP and 5-HT concentrations was found (ρ = 0.086, p = 0.602). Serum 5-HT levels do not seem to be associated with dogs’ behavioural response to a stressful situation nor with serum TRP concentrations. The relationship between serum TRP and 5-HT concentrations and behaviour needs further research.

Slow release exogenous melatonin modulates scrotal circumference and testicular parameters, libido, endocrinological profiles and antioxidant and oxidative stress profiles in mithun

Mithun (Bos frontalis) is a unique domestic free-range bovine species available in North Eastern hilly (NEH) regions of India and is reared for its protein rich meat. Although, mithun suffers from severe non-cyclical population fluctuations, it is not yet declared as endangered. Therefore, present study was conducted to assess the effect of slow release subcutaneous exogenous melatonin (MT) implant on sexual behaviour, scrotal circumference (SC) and testicular parameters, endocrinological profiles and antioxidant and oxidative stress profiles in mithun during different seasons (winter, spring, summer and autumn) to improve its reproductive efficiency. Experimental mithun bulls (5-6 years of age) were selected and divided randomly into two groups, Gr I: Control (n = 6) and Gr II: Treatment (n = 6; melatonin implant @ 18mg/50 kg B. Wt). Scrotal circumference and testicular parameters [total testicular volume and weight], endocrinological profiles [follicle stimulating hormone (FSH), luteinizing hormone/interstitial cell stimulating hormone (LH/ICSH), testosterone, thyroxine (T4), cortisol, prolactin and melatonin (MT)], sex behaviour profiles [libido score, mating ability score and sexual behaviour score], antioxidant profiles [total antioxidant capacity (TAC), catalase (CAT), glutathione (GSH), glutathione reductase (GSHRx) and superoxide dismutase (SOD)] and oxidative stress profile [malondialdehyde (MDA)] were estimated. Statistical analysis revealed that these experimental profiles differed between treatment and control groups within the seasons and among the seasons within the experimental groups. FSH, LH, testosterone, T4 and MT were higher and cortisol and prolactin were lower in spring and winter than in summer season. Concentration of FSH, LH, testosterone and MT were higher and concentration of T4, cortisol and prolactin were lower in MT treated than in untreated control group. Similarly, sexual behavioural scores, SC, testicular parameters and antioxidant profiles were higher and oxidative stress profile was lower in MT treated than in untreated control group and in winter and spring than in summer season. The study concluded that exogenous slow-release melatonin implantation and spring and winter seasons had significant beneficial effects in improvement of the antioxidant profiles, minimization of oxidative stress with cascading beneficial effects on endocrinological profiles, SC, testicular parameters and libido, which will improve the semen production, higher sperm cryo-survivability and fertility rate in mithun species.

Beyond Glucocorticoids: Integrating Dehydroepiandrosterone (DHEA) into Animal Welfare Research

Animal welfare researchers are committed to identifying novel measures for enhancing the quality of life of individual animals. Recently, welfare scientists have emphasized the need for tracking multiple indicators of an animal's behavioral, emotional and mental health. Researchers are currently focused on integrating non-invasive physiological biomarkers to gain insight into an individual's welfare status. Most commonly, the animal welfare community has analyzed glucocorticoid hormones and their metabolites as a measure of stress. While glucocorticoids provide valuable information about hypothalamic-pituitary-adrenal (HPA) axis activity, there are limitations to utilizing these hormones as the sole measure of long-term stress and welfare. Other biomarkers, such as dehydroepiandrosterone and its sulfate ester-collectively referred to as DHEA(S)-help provide a more complete picture of HPA activity. DHEA(S) counteracts the effects glucocorticoids by having anti-aging, immune-enhancing and neuroprotective properties. Recent studies have examined the ratio of glucocorticoids to DHEA(S) as a way to better understand how the HPA axis is functioning. There is evidence that this ratio serves as an indicator of immune function, mental health, cognitive performance and overall welfare. We review studies that employed the glucocorticoid:DHEA(S) ratio, outline methodological considerations and discuss how researchers can integrate glucocorticoids, DHEA(S) and the glucocorticoid:DHEA(S) ratio into welfare assessments.

Gut microbiome structure and adrenocortical activity in dogs with aggressive and phobic behavioral disorders

Accompanying human beings since the Paleolithic period, dogs has been recently regarded as a reliable model for the study of the gut microbiome connections with health and disease. In order to provide some glimpses on the connections between the gut microbiome layout and host behavior, we profiled the phylogenetic composition and structure of the canine gut microbiome of dogs with aggressive (n = 11), phobic (n = 13) and normal behavior (n = 18). Hormones' determination was made through Radio Immuno-Assay (RIA), and next generation sequencing of the V3-V4 gene region of the bacterial 16S rRNA was employed to determine gut microbiome composition. Our results did not evidence any significant differences of hormonal levels between the three groups. According to our findings, aggressive behavioral disorder was found to be characterized by a peculiar gut microbiome structure, with high biodiversity and enrichment in generally subdominant bacterial genera (i.e. Catenibacterium and Megamonas). On the other hand, phobic dogs were enriched in Lactobacillus, a bacterial genus with known probiotic and psychobiotic properties. Although further studies are needed to validate our findings, our work supports the intriguing opportunity that different behavioral phenotypes in dogs may be associated with peculiar gut microbiome layouts, suggesting possible connections between the gut microbiome and the central nervous system and indicating the possible adoption of probiotic interventions aimed at restoring a balanced host-symbiont interplay for mitigating behavioral disorders.

Endocrine Regulations in Human-Dog Coexistence through Domestication

Endocrine system regulation is important for the maintenance of homeostasis; it controls hormonal functions in complex physiology and behavior and adaptations to social environments. Evidence indicates that for more than 35 000 years, dogs (Canis familiaris) have been domesticated through living with humans. For example, they have acquired human-like social skills, such as eye gazing and pointing gestures. These unique behaviors are, at least partially, regulated by hormones and are thought to have been genetically altered throughout domestication. Glucocorticoids affect social tolerance, while oxytocin facilitates social coordination and familiarity between individuals. We review historical and recent literature to facilitate an understanding of the roles of glucocorticoid and oxytocin functions in the human-canine coexistence dynamic established during domestication.

Physiological stress reactivity and recovery related to behavioral traits in dogs (Canis familiaris)

This study investigated whether stress responsiveness (in one context) can be used to predict dog behavior in daily life. On two occasions (N_T1 = 32 puppies; N_T2 = 16 young adults), dogs’ physiological stress response after a behavioral test at home was measured in terms of reactivity (10 min post-test) and recovery (40 min post-test) for three salivary markers: cortisol, chromogranin A (CgA) and secretory immunoglobulin A (sIgA). For each marker, it was determined whether dogs with a strong physiological response displayed different behavior in daily life compared to dogs with a weaker physiological response. The results revealed three main findings: first, for CgA and cortisol, different patterns were identified according to sample time. High reactivity related to desirable traits, whereas slow recovery after the behavioral test related to undesirable traits. The findings suggest that increased levels of CgA and cortisol 10 minutes after the behavioral test reflected an adaptive stress response, whereas elevated levels 40 minutes after the test reflected unsuccessful coping. Second, patterns for sIgA differed from CgA and cortisol: significant associations were only found with behavioral traits at T2, mostly considered desirable and related to Trainability. Possibly, the delayed reaction pattern of sIgA caused this difference between markers, as sIgA reflects the (secondary) immune response to stress, due to immunosuppressive effects of cortisol. Third, predictive capacity of puppies’ physiological stress response (T1) was inconclusive, and contrary relations were found with behavioral traits at T2, suggesting that developmental factors play an important role. This study provides new insights about the relation between stress physiology and behavioral traits, and methodological advice is given to study these patterns further. In conclusion, physiological markers could provide additional insights in dogs’ tendencies to display certain behaviors, especially at the young adult stage. Further studies are needed to confirm these patterns.

Dog appeasing pheromone prevents the androgen surge and may reduce contact dominance and active submission after stressful interventions in African wild dogs (Lycaon pictus)

The endangered African wild dog (AWD; Lycaon pictus) is a highly social canid living in packs with a separate male and female hierarchy. Immobilisation, handling and translocations are acute stressors for AWDs, however such interventions are often needed for species management. In addition, new pack formation or temporary pack separation can lead to an increase in intra-pack aggression. The goal of this double-blinded placebo-controlled study conducted in captive zoo populations was to evaluate whether dog appeasing pheromone (DAP) reduces behavioural stress and faecal glucocorticoid metabolite levels (fGCM) normally associated with pack separation, immobilisation and reintroduction (SIR), and to assess whether this reduces aggressive behaviours and faecal androgen metabolite levels (fAM). Four packs (n = 11 males) were treated with DAP and 4 packs (n = 12 males) were treated with a placebo solution, applied at the end of anaesthesia. Behavioural interactions as well as fGCM and fAM were determined from 3 days before until 4-6 days after SIR. No effect of DAP on fGCM was observed, however, fAM increased after SIR in placebo but not DAP treated animals. Moreover, on the day of reintroduction, DAP treated packs tended to have lower rates of contact-dominance and active-submission behaviour, but higher rates of non-contact dominance behaviour. As these effects could decrease the risk of agonistic interactions, DAP may be a useful tool to help manage new pack formations and temporary pack separation.

The gut microbiome correlates with conspecific aggression in a small population of rescued dogs (Canis familiaris)

Aggression is a serious behavioral disorder in domestic dogs that endangers both dogs and humans. The underlying causes of canine aggression are poorly resolved and require illumination to ensure effective therapy. Recent research links the compositional diversity of the gut microbiome to behavioral and psychological regulation in other mammals, such as mice and humans. Given these observations, we hypothesized that the composition of the canine gut microbiome could associate with aggression. We analyzed fecal microbiome samples collected from a small population of pit bull type dogs seized from a dogfighting organization. This population included 21 dogs that displayed conspecific aggressive behaviors and 10 that did not. Beta-diversity analyses support an association between gut microbiome structure and dog aggression. Additionally, we used a phylogenetic approach to resolve specific clades of gut bacteria that stratify aggressive and non-aggressive dogs, including clades within Lactobacillus, Dorea, Blautia, Turicibacter, and Bacteroides. Several of these taxa have been implicated in modulating mammalian behavior as well as gastrointestinal disease states. Although sample size limits this study, our findings indicate that gut microorganisms are linked to dog aggression and point to an aggression-associated physiological state that interacts with the gut microbiome. These results also indicate that the gut microbiome may be useful for diagnosing aggressive behaviors prior to their manifestation and potentially discerning cryptic etiologies of aggression.

Non-invasive genotyping with a massively parallel sequencing panel for the detection of SNPs in HPA-axis genes

We designed a genotyping panel for the investigation of the genetic underpinnings of inter-individual differences in aggression and the physiological stress response. The panel builds on single nucleotide polymorphisms (SNPs) in genes involved in the three subsystems of the hypothalamic-pituitary-adrenal (HPA)-axis: the catecholamine, serotonin and corticoid metabolism. To promote the pipeline for use with wild animal populations, we used non-invasively collected faecal samples from a wild population of Assamese macaques (Macaca assamensis). We targeted loci of 46 previously reported SNPs in 21 candidate genes coding for elements of the HPA-axis and amplified and sequenced them using next-generation Illumina sequencing technology. We compared multiple bioinformatics pipelines for variant calling and variant effect prediction. Based on this strategy and the application of different quality thresholds, we identified up to 159 SNPs with different types of predicted functional effects among our natural study population. This study provides a massively parallel sequencing panel that will facilitate integrating large-scale SNP data into behavioural and physiological studies. Such a multi-faceted approach will promote understanding of flexibility and constraints of animal behaviour and hormone physiology.

Plasma Tryptophan/Large Neutral Amino Acids Ratio in Domestic Dogs Is Affected by a Single Meal with High Carbohydrates Level

Aim of this study was to evaluate the plasma ratio between l-tryptophan (TRP) and five large neutral amino acids (isoleucine + leucine + phenylalanine + tyrosine + valine) (5LNAAs) after a single meal with high carbohydrates level. Five female Labrador Retrievers were involved. Each dog was fed three different meals: M1 (a mix of puffed rice, minced meat and olive oil), M2 (puffed rice and olive oil) and M3 (commercial dry food usually consumed) once in the morning per day for 30 days. Blood was collected right before the first meal (t0) and after 2, 4, 6, 8, 10 and 24 h. Plasma amino acids’ concentrations were measured using an HPLC (High-performance liquid chromatography) method with fluorimetric detection. Plasmatic TRP concentrations showed no significant difference between M1, M2 and M3 samples at any sampling time. M2 led to a decrease in 5LNAAs levels and consequently led to a significant higher TRP/5LNAAs ratios in the 6 h period after the provision of carbohydrates, compared to both M1 and M3. In addition, the mean TRP/5LNAAs ratio was significantly higher in M2 than in M3 at t8 and t10. These results indicate that meal composition affects TRP/5LNAAs ratio and possibly, TRP bioavailability.

Endogenous Oxytocin, Vasopressin, and Aggression in Domestic Dogs

Aggressive behavior in dogs poses public health and animal welfare concerns, however the biological mechanisms regulating dog aggression are not well understood. We investigated the relationships between endogenous plasma oxytocin (OT) and vasopressin (AVP)-neuropeptides that have been linked to affiliative and aggressive behavior in other mammalian species-and aggression in domestic dogs. We first validated enzyme-linked immunosorbent assays (ELISAs) for the measurement of free (unbound) and total (free + bound) OT and AVP in dog plasma. In Experiment 1 we evaluated behavioral and neuroendocrine differences between a population of pet dogs with a history of chronic aggression toward conspecifics and a matched control group. Dogs with a history of aggression exhibited more aggressive behavior during simulated encounters with conspecifics, and had lower free, but higher total plasma AVP than matched controls, but there were no group differences for OT. In Experiment 2 we compared OT and AVP concentrations between pet dogs and a population of assistance dogs that have been bred for affiliative and non-aggressive temperaments, and investigated neuroendocrine predictors of individual differences in social behavior within the assistance dog population. Compared to pet dogs, assistance dogs had higher free and total OT, but there were no differences in either measure for AVP. Within the assistance dog population, dogs who behaved more aggressively toward a threatening stranger had higher total AVP than dogs who did not. Collectively these data suggest that endogenous OT and AVP may play critical roles in shaping dog social behavior, including aspects of both affiliation and aggression.

Sexually dimorphic aggression indicates male gray wolves specialize in pack defense against conspecific groups

Aggression directed at conspecific groups is common among gregarious, territorial species, and for some species such as gray wolves (Canis lupus) intraspecific strife is the leading cause of natural mortality. Each individual in a group likely has different measures of the costs and benefits associated with a group task, such as an aggressive attack on another group, which can alter motivation and behavior. We observed 292 inter-pack aggressive interactions in Yellowstone National Park between 1 April 1995 and 1 April 2011 (>5300days of observation) in order to determine the role of both sexes, and the influence of pack, age, and other traits on aggression. We recorded the behaviors and characteristics of all individuals present during the interactions (n=534 individuals) and which individuals participated in each step (i.e. chase, attack, kill, flight) of the interaction. Overall, all wolves were more likely to chase rivals if they outnumbered their opponent, suggesting packs accurately assess their opponent's size during encounters and individuals adjust their behavior based on relative pack size. Males were more likely than females to chase rival packs and gray-colored wolves were more aggressive than black-colored wolves. Male wolves and gray-colored wolves also recorded higher cortisol levels than females and black-colored wolves, indicating hormonal support for more intense aggressive behavior. Further, we found a positive correlation between male age and probability of chasing, while age-specific participation for females remained constant. Chasing behavior was influenced by the sex of lone intruders, with males more likely to chase male intruders. This difference in behavior suggests male and female wolves may have different strategies and motivations during inter-pack aggressive interactions related to gray wolf mating systems. A division of labor between pack members concerning resource and territory defense suggests selection for specific traits related to aggression is an adaptive response to intense competition between groups of conspecifics.

Hair cortisol varies with season and lifestyle and relates to human interactions in German shepherd dogs

It is challenging to measure long-term endocrine stress responses in animals. We investigated whether cortisol extracted from dog hair reflected the levels of activity and stress long-term, during weeks and months. Hair samples from in total 59 German shepherds were analysed. Samples for measuring cortisol concentrations were collected at three occasions and we complemented the data with individual scores from the Canine Behavioural Assessment and Research Questionnaire (C-BARQ). Generalised linear mixed model (GLMM) results showed that hair cortisol varied with season and lifestyle: competition dogs had higher levels than companion, and professional working dogs, and levels were higher in January than in May and September. In addition, a positive correlation was found between the cortisol levels and the C-BARQ score for stranger-directed aggression (r = 0.31, P = 0.036). Interestingly, the factor “playing often with the dog” (r = −0.34, P = 0.019) and “reward with a treat/toy when the dog behaves correctly” (r = −0.37, P = 0.010) correlated negatively with cortisol levels, suggesting that positive human interactions reduce stress. In conclusion, hair cortisol is a promising method for revealing the activity of the HPA-axis over a longer period of time, and human interactions influence the cortisol level in dogs.

High fat, low carbohydrate diet limit fear and aggression in Göttingen minipigs

High fat, low carbohydrate diets have become popular, as short-term studies show that such diets are effective for reducing body weight, and lowering the risk of diabetes and cardiovascular disease. There is growing evidence from both humans and other animals that diet affects behaviour and intake of fat has been linked, positively and negatively, with traits such as exploration, social interaction, anxiety and fear. Animal models with high translational value can help provide relevant and important information in elucidating potential effects of high fat, low carbohydrate diets on human behaviour. Twenty four young, male Göttingen minipigs were fed either a high fat/cholesterol, low carbohydrate diet or a low fat, high carbohydrate/sucrose diet in contrast to a standard low fat, high carbohydrate minipig diet. Spontaneous behaviour was observed through video recordings of home pens and test-related behaviours were recorded during tests involving animal-human contact and reaction towards a novel object. We showed that the minipigs fed a high fat/cholesterol, low carbohydrate diet were less aggressive, showed more non-agonistic social contact and had fewer and less severe skin lesions and were less fearful of a novel object than minipigs fed low fat, high carbohydrate diets. These results found in a porcine model could have important implications for general health and wellbeing of humans and show the potential for using dietary manipulations to reduce aggression in human society.