Parental behavior and newborn attachment in birds: life history traits and endocrine responses.

In birds, parental care and attachment period differ widely depending on the species (altricial or precocial), developmental strategies, and life history traits. In most bird species, parental care can be provided by both female and male individuals and includes specific stages such as nesting, laying, and hatching. During said periods, a series of neuroendocrine responses are triggered to motivate parental care and attachment. These behaviors are vital for offspring survival, development, social bonding, intergenerational learning, reproductive success, and ultimately, the overall fitness and evolution of bird populations in a variety of environments. Thus, this review aims to describe and analyze the behavioral and endocrine systems of parental care and newborn attachment in birds during each stage of the post-hatching period.

Impact of Semiochemicals Binding to Fel d 1 on Its 3D Conformation and Predicted B-Cell Epitopes Using Computational Approaches.

The major cat allergen Fel d 1 is a tetrameric glycoprotein from the secretoglobin superfamily. Fel d 1's biological role is unknown, but it has been previously shown that it participates in semiochemical binding/transportation. Fel d 1 has linear epitopes, but its conformational epitope sites remain unclear. In this study, we predicted the B-cell epitopes of Fel d 1 and explored semiochemical dynamics with epitopes using bioinformatics tools. The epitope residues were tabulated for chains 1 and 2 and the heterodimers of Fel d 1. The residual interactions of Fel d 1 with IgE were evaluated, and the prominent epitope sites were predicted. The molecular dynamics simulation (MDS) of Fel d 1 was performed with seven reported semiochemicals to evaluate the Fel d 1-ligand complex stability and decipher the semiochemical effect on Fel d 1 conformational epitopes. Fel d 1-lauric acid, Fel d 1-oleic acid, and Fel d 1-progesterone showed more stability and less fluctuation than other compounds. Fel d 1-linoleic acid and Fel d 1-pregnenolone displayed the most unstable complex with fluctuations. The effects of conformational changes on epitopes are discussed. All the ligand complexes drive substantial fluctuation towards the functionally exposed IgE-binding epitopes. Fel d 1 could be examined for its ligand-binding and conformational changes caused by mutations of B-cell epitopes.

The Role of Brown Adipose Tissue and Energy Metabolism in Mammalian Thermoregulation during the Perinatal Period.

Hypothermia is one of the most common causes of mortality in neonates, and it could be developed after birth because the uterus temperature is more elevated than the extrauterine temperature. Neonates use diverse mechanisms to thermoregulate, such as shivering and non-shivering thermogenesis. These strategies can be more efficient in some species, but not in others, i.e., altricials, which have the greatest difficulty with achieving thermoneutrality. In addition, there are anatomical and neurological differences in mammals, which may present different distributions and amounts of brown fat. This article aims to discuss the neuromodulation mechanisms of thermoregulation and the importance of brown fat in the thermogenesis of newborn mammals, emphasizing the analysis of the biochemical, physiological, and genetic factors that determine the distribution, amount, and efficiency of this energy resource in newborns of different species. It has been concluded that is vital to understand and minimize hypothermia causes in newborns, which is one of the main causes of mortality in neonates. This would be beneficial for both animals and producers.

Vitality in Newborn Farm Animals: Adverse Factors, Physiological Responses, Pharmacological Therapies, and Physical Methods to Increase Neonate Vigor.

Vitality is the vigor newborn animals exhibit during the first hours of life. It can be assessed by a numerical score, in which variables, such as heart rate, respiratory rate, mucous membranes' coloration, time the offspring took to stand up, and meconium staining, are monitored. Vitality can be affected by several factors, and therapies are used to increase it. This manuscript aims to review and analyze pharmacological and physical therapies used to increase vitality in newborn farm animals, as well as to understand the factors affecting this vitality, such as hypoxia, depletion of glycogen, birth weight, dystocia, neurodevelopment, hypothermia, and finally, the physiological mechanism to achieve thermostability. It has been concluded that assessing vitality immediately after birth is essential to determine the newborn's health and identify those that need medical intervention to minimize the deleterious effect of intrapartum asphyxia. Vitality assessment should be conducted by trained personnel and adequate equipment. Evaluating vitality could reduce long-term neonatal morbidity and mortality in domestic animals, even if it is sometimes difficult with the current organization of some farms. This review highlights the importance of increasing the number of stock people during the expected days of parturitions to reduce long-term neonatal morbidity and mortality, and thus, improve the farm's performance.

The Role of Oxytocin in Domestic Animal's Maternal Care: Parturition, Bonding, and Lactation.

Oxytocin (OXT) is one of the essential hormones in the birth process; however, estradiol, prolactin, cortisol, relaxin, connexin, and prostaglandin are also present. In addition to parturition, the functions in which OXT is also involved in mammals include the induction of maternal behavior, including imprinting and maternal care, social cognition, and affiliative behavior, which can affect allo-parental care. The present article aimed to analyze the role of OXT and the neurophysiologic regulation of this hormone during parturition, how it can promote or impair maternal behavior and bonding, and its importance in lactation in domestic animals.

Clinical Experiences and Mechanism of Action with the Use of Oxytocin Injection at Parturition in Domestic Animals: Effect on the Myometrium and Fetuses.

Oxytocin is a key hormone for parturition and maternal traits in animals. During the peripartum period, the levels of endogenous oxytocin dictate physiological events such as myometrial contractions, prostaglandin production with the subsequent increase in oxytocin receptors, and the promotion of lactation when administered immediately after birth. While this hormone has some benefits regarding these aspects, the exogenous administration of oxytocin has been shown to have detrimental effects on the fetus, such as asphyxia, meconium staining, ruptured umbilical cords, and more dystocia cases in females. This review aims to analyze the main effects of oxytocin on myometrial activity during parturition, and its potential favorable and negative administration effects reflected in the fetus health of domestic animals. In conclusion, it is convenient to know oxytocin's different effects as well as the adequate doses and the proper moment to administrate it, as it can reduce labor duration, but it can also increase dystocia.

Mother-Young Bonding: Neurobiological Aspects and Maternal Biochemical Signaling in Altricial Domesticated Mammals.

Mother-young bonding is a type of early learning where the female and their newborn recognize each other through a series of neurobiological mechanisms and neurotransmitters that establish a behavioral preference for filial individuals. This process is essential to promote their welfare by providing maternal care, particularly in altricial species, animals that require extended parental care due to their limited neurodevelopment at birth. Olfactory, auditory, tactile, and visual stimuli trigger the neural integration of multimodal sensory and conditioned affective associations in mammals. This review aims to discuss the neurobiological aspects of bonding processes in altricial mammals, with a focus on the brain structures and neurotransmitters involved and how these influence the signaling during the first days of the life of newborns.

Mother-young bond in non-human mammals: Neonatal communication pathways and neurobiological basis.

Mother-young bonding is a process by which the young establish social preferences for their mother. It fosters reproductive success and the survival of offspring by providing food, heat, and maternal care. This process promotes the establishment of the mother-young bond through the interaction of olfactory, auditory, tactile, visual, and thermal stimuli. The neural integration of multimodal sensory stimuli and attachment is coordinated into motor responses. The sensory and neurobiological mechanisms involved in filial recognition in precocial and altricial mammals are summarized and analyzed in this review.

Effect of wither application of an analogue of pig appeasing pheromone on encounters between unfamiliar mini-pigs.

BACKGROUND: The practice of mixing unfamiliar pigs on farms is common but results in fighting, welfare problems and performance issues. Pigs have different ways of resolving social conflicts, including aggressive and affiliative behaviours. Synthetic appeasing pheromones have demonstrated many positive effects in animal husbandry and are regularly used by breeders to improve animal welfare and performance. The aim of the study was to investigate the effect of a new method of applying pig appeasing-pheromone (PAP) to the withers in an experimental model of pig mixing to determine whether PAP reduced aggression and fighting, increased prosocial behaviours, and improved behavioural and physiological indicators of welfare. RESULTS: PAP reduced fighting between mini-pigs (df = 1; F = 13.47; P = 0.001; mixed logistic regression). Even if not significant, agonistic behaviours tended to be reduced when the treatment was applied (df = 1; F = 4.14; P = 0.058; mixed logistic regression). Likewise, mini-pigs seemed to be scored as not aggressive at all (df = 1; F = 3.61; P = 0.070; GLMM) and to be less aggressive toward the other pig than when placebo was applied. Concerning the latency of the first contact without aggression, a significant effect was found between the PAP and placebo groups (df = 1; χ2 = 4.74; P = 0.0295; Cox model). Moreover, even if not significant, the treated mini-pigs seemed to spent more time looking at each other (df = 1; F = 3.59; P = 0.071; GLMM) and immobile and/or ground sniffing (df = 1; F = 3.18; P = 0.088; GLMM) than those that received placebo. No significant difference was found between groups for salivary cortisol concentration (df = 1; F = 0.10; P = 0.752; GLMM), but variances between groups were heterogeneous at every time. No significant difference was found between groups regarding alpha-amylase activity (df = 1; F = 0.25; P = 0.621; GLMM), but variances between groups were heterogeneous at T0, T1 and T3. These results indicate that the variability (dispersion) within each group was lower when PAP was applied than when the placebo was applied. CONCLUSIONS: The new method of applying PAP improved welfare of mini-pigs (as models of domestic pigs) by reducing fighting, among other interesting results. PAP seems thus a promising biomimetic tool to enhance animal welfare in pig production systems.

Inflammation interferes with chemoreception in pigs by altering the neuronal layout of the vomeronasal sensory epithelium.

Chemical communication is widely used by animals to exchange information in their environment, through the emission and detection of semiochemicals to maintain social organization and hierarchical rules in groups. The vomeronasal organ (VNO) is one of the main detectors of these messages, and its inflammation has been linked to behavioral changes because it potentially prevents molecule detection and, consequently, the translation of the signal into action. Our previous study highlighted the link between the intensity of vomeronasal sensory epithelium (VNSE) inflammation, probably induced by farm contaminant exposure, and intraspecific aggression in pigs. The aim of this study was to evaluate the cellular and molecular changes that occur during vomeronasalitis in 76 vomeronasal sensorial epithelia from 38 intensive-farmed pigs. Histology was used to evaluate the condition of each VNO and classify inflammation as healthy, weak, moderate, or strong. These data were compared to the thickness of the sensorial epithelium and the number of type 1 vomeronasal receptor cells using anti-Gαi2 protein immunohistochemistry (IHC) and analysis. The presence of odorant-binding proteins (OBPs) in the areas surrounding the VNO was also analyzed by IHC and compared to inflammation intensity since its role as a molecule transporter to sensory neurons has been well-established. Of the 76 samples, 13 (17%) were healthy, 31 (41%) presented with weak inflammation, and 32 (42%) presented with moderate inflammation. No severe inflammation was observed. Epithelial thickness and the number of Gαi2+ cells were inversely correlated with inflammation intensity (Kruskal-Wallis and ANOVA tests, p < 0.0001), while OBP expression in areas around the VNO was increased in inflamed VNO (Kruskal-Wallis test, p = 0.0094), regardless of intensity. This study showed that inflammation was associated with a reduction in the thickness of the sensory epithelium and Gαi2+ cell number, suggesting that this condition can induce different degrees of neuronal loss. This finding could explain how vomeronasalitis may prevent the correct functioning of chemical communication, leading to social conflict with a potential negative impact on welfare, which is one of the most important challenges in pig farming.

Influencing Elimination Location in the Domestic Cat: A Semiochemical Approach.

In the domestic cat, elimination at an inappropriate location is considered by cat owners and non-cat owners as an undesirable behaviour. The aim of the study was to assess the effect of a semiochemical formulation, reconstituted volatile fraction of cat anal gland secretions on the elimination behaviour of domestic cats. The study was conducted in four catteries, which housed 33 cats, using 37 litter trays and followed a randomised crossover design using the litter tray as the experimental unit. The parameters studied included daily elimination (urine plus stools) weight, urine weight, stool weight, elimination type and urine/stool quantity scoring. The parameters were analysed using GLMM with SAS 9.4 software. Four out of the six parameters studied showed a treatment effect, consistently in favour of cats defecating significantly less in the litter trays sprayed with the treatment versus litter trays sprayed with the control (elimination weight p = 0.0199; elimination type p = 0.0251; stool weight p = 0.0005 and stool quantity p = 0.003). These results demonstrate that an intraspecific semiochemical message originating from cat anal glands influences cats' defecation location.

A Feline Semiochemical Composition Influences the Cat's Toileting Location Choice.

Unwanted toileting is amongst the most undesirable behaviors in domestic cats and can lead to conflicts between cats and the communities they are living in. This study aimed to confirm the effect of a semiochemical composition, reconstituted volatile fraction derived from cat anal glands, on the elimination behavior of domestic cats. A total of 31 cats were tested individually, for 23 h, in a blinded randomized choice test, with two litter trays, one sprayed with the treatment and the other with the control. Parameters included elimination weight, urine only weight, the record of the elimination type and counting of urine spots and stools, exploration duration of each litter tray, and first and second choice of litter tray to eliminate. Across all parameters, cats urinated and defecated significantly less in the litter tray where the semiochemical composition was sprayed than in the litter tray where the control was sprayed (for example: elimination weight p < 0.0001; urine only weight p < 0.0001; exploration duration p < 0.0001, and first elimination choice p < 0.0001). These results demonstrate that a semiochemical composition-derived from cat anal glands significantly decreases elimination at the location where it is sprayed. Future research is warranted to explore the possibility to manage unwanted toileting using this semiochemical composition.

Is There a Link between Vomeronasalitis and Aggression in Stable Social Groups of Female Pigs?

The vomeronasal organ (VNO) is a bilateral chemosensory structure strongly involved in animal behaviour, thanks to its sensory epithelium (VNSE) that detects pheromones. Experimental VNO lesions can impair social, reproductive and maternal behaviour, while feline spontaneous vomeronasalitis has been associated with aggression. This study aimed to describe vomeronasalitis in farm pigs and explore its association with intraspecific behavioural alterations. Using 38 six-month-old pigs, the skin lesion score based on Welfare Quality® protocols was obtained during the fattening period. The seventy-six VNOs from these pigs were stained in haematoxylin-eosin for histological examinations. VNSE inflammation was classified considering its intensity. Skin lesions data were compared to vomeronasalitis. There were 34% of pigs that showed unilateral VNSE inflammation, while 66% were bilaterally affected. The mean ± SD number of skin lesions/animal was 4.4 ± 2.82, and 34% of pigs scored 1 (moderately wounded animals) at least once during the fattening period. Statistical analysis showed an association between bilateral vomeronasalitis and skin lesion score (p < 0.05) and between bilateral moderate vomeronasalitis and skin lesions number (p < 0.01). This is the first report linking vomeronasalitis to social life in farm animals. Considering the role of social life in animal welfare, our data opens a research field linking pathology to animal behaviour.

Sex Differences in Mouse Exploratory Behaviour to Fel d 1, a Cat ABP-Like Protein.

Fel d 1 is a cat protein abundantly released and found in their habitat and is closely related to mouse androgen-binding proteins (ABPs). We hypothesized that mice have developed chemical communication mechanisms to detect and avoid this protein. We tested purified natural Fel d 1, a fox faeces molecule (TMT) as a positive control, and a negative control (purified water) in three different mouse groups (n = 14 each) to evaluate exploratory behaviour and stress responses. The mice did not show clear avoidance or stress responses to Fel d 1. Our results demonstrated a sex-treatment interaction for Fel d 1, with males spending more time in the areas treated with Fel d 1 than in the untreated areas (p = 0.018). This sex-treated area interaction was also not observed for either the blank or TMT. These results suggest that Fel d 1 from domestic cats could be recognized differently by male and female mice. These sex differences could be linked to the sexual role of ABP proteins and the ABP-like characteristics of Fel d 1.

Neurohormonal Profiles of Assistance Dogs Compared to Pet Dogs: What Is the Impact of Different Lifestyles?

Assistance dogs must manage stress efficiently because they are involved in challenging tasks. Their welfare is currently a fundamental issue. This preliminary study aimed to compare assistance dogs (AD; n = 22) with pet dogs (PD; n = 24), using blood neuromodulator indicators to help find biomarkers that can improve the AD breeding, selection, training, and welfare monitoring. Both populations originated from different breeds, are of different ages, and had different lifestyles. Basal peripheral concentrations of prolactin (PRL), serotonin (5-HT), free (fOT) and total (tOT) oxytocin were measured by immunoassays. Multiple linear regressions were performed to assess the effect of activity, age, sex, and their interactions on these parameters. Correlations between neurohormonal levels were analyzed. No interactions were significant. fOT and tOT concentrations were significantly influenced by age (p < 0.0001 and p = 0.0002, respectively) and dogs' activity (p = 0.0006 and p = 0.0277, respectively). A tendency was observed for age effect on PRL (p = 0.0625) and 5-HT (p = 0.0548), as well as for sex effect on tOT (p = 0.0588). PRL concentrations were heterogenous among AD. fOT and tOT were significantly but weakly correlated (Pearson's r = 0.34; p = 0.04). Blood prolactin, serotonin, and oxytocin may represent biomarkers to assess workload and chronic stress-related responses in ADs and eventually improve their selection and training.

Effect of handling and crowding on the susceptibility of Atlantic salmon (Salmo salar L.) to Lepeophtheirus salmonis (Krøyer) copepodids.

Lepeophtheirus salmonis is an ectoparasite causing economic concerns in Atlantic salmon farming. Salmon lice infestation management methods can be stressful and impact fish welfare. This work investigated the stress effect on the attachment of L. salmonis copepodids to Atlantic salmon through two approaches: (a) handling by netting and air exposure (acute stress), and (b) crowding with restricted surface access in a tank (chronic stress). In the first experiment, we compared the number of attached L. salmonis and cortisol levels between a group of handled salmon and a control group. In the second experiment, a group of densely packed salmon was compared to a control group based on the number of attached copepodids, cortisol levels and neutrophil:lymphocyte ratios. Handled salmon showed significantly higher plasma cortisol levels (p < .001) and more attached copepodids (p = .01) than control salmon. Conversely, the cortisol level and number of attached copepodids were not significantly different between the densely packed and control salmon (p > .05). The neutrophil:lymphocyte ratio was significantly higher (p = .0014) in the densely packed salmon than in the control salmon. Handling salmon increased their risk of infestation by L. salmonis. This has implications for reinfestation rates following delousing treatments in commercial salmon aquaculture, which often involve crowding and handling salmon.

The provision of toys to pigs can improve the human-animal relationship.

It is now widely recognised that a positive human-animal relationship is beneficial not only for farm animals' welfare but also for productivity and the quality of products. A better understanding of animal emotions is an important goal in disciplines ranging from neuroscience to animal welfare science, but few reliable tools exist for measuring these emotions. In this study, whether the provision of toys to solicit play behaviour in pigs is associated with a change in the human-animal relationship and the emotional state of pigs was investigated. We involved a group of sixteen mini-pigs housed in an experimental setting and the use of a preliminary test called the 'strange person' test. After a Control and a Play session (with medium-sized dog toys, balls with ropes), the strange person test was performed. During the test, a person wearing a colourful overall, a hood, a mask, gloves and boots (unknown person with an odd appearance) entered the pen, where 2 mini-pigs were housed, for a 2-min video recording. The strange person test results after the Play and Control sessions were compared. The results showed that the latency to approach the person (duration in seconds) and the duration for which the pig was distant from the strange person (duration in seconds) were significantly lower after the Play session than after the Control session (Degrees of Freedom =30; Statistic of the F test =39.1; p < 0.0001 and Degrees of Freedom =15; Statistic of the F test =54.3; p < 0.0001, respectively). The duration of direct contact (duration in seconds) (Degrees of Freedom =15; Statistic of the F test =14.8; p = 0.002), the need to separate the pig from the strange person (frequency) (Degrees of Freedom =30; Statistic of the F test =9.3; p = 0.005) and the duration of tail movement (duration in seconds) (Degrees of Freedom =15; Statistic of the F test =12.6; p = 0.003) were all significantly higher after the Play sessions than after the Control sessions. Overall, the results suggest a change in the human-animal relationship after the Play sessions: the pigs seemed to be less fearful and more inclined to interact with the strange person, showing a more positive emotional state. This preliminary study suggests that the provision of toys, and more precisely, the opportunity to perform object play behaviour, and sometimes, spontaneously, social play behaviour, can improve the human-animal relationship. Additional research to explore this topic thoroughly may yield interesting results because a positive emotional state of the animals and a good human-animal relationship are essential to ensure good quality of life of farm animals.

Single fluff-spray application of mother hen uropygial secretion analogue positively influences bursa of Fabricius development and the heterophil-to-lymphocyte ratio in ROSS 308 chicks.

Stress is an important cause of illness and mortality in chick production. Stressors such as manipulation, absence of maternal care, transport, and housing can lead to welfare issues, immunodepression, and decreased productivity. The mother hen uropygial secretion analogue (MHUSA), a synthetic analog of a maternal semiochemical secretion, has been proven to protect chicks and broilers against stress, significantly reducing the heterophil-to-lymphocyte ratio. The aim of the present study was to test the effects of the MHUSA on chicks' stress when single-sprayed on their fluff at the age of 1 d. Two-hundred eighty ROSS 308 chicks were included in the study. At day 1, each chick received a spray of 200 µL of a 2% MHUSA aqueous solution (140 chicks) or the same amount of the excipient (control group, 140 chicks), and then chicks were housed in 2 separate rooms. To assess the persistence of the MHUSA after this single application, fluff was sampled from 10 chicks every day for 7 d and at day 13 and 19, weighed, placed in dichloromethane, and analyzed by gas chromatography. Blood smears and the bursa of Fabricius were collected every 3 d from 10 chicks of each group for 36 d to assess the heterophil-to-lymphocyte ratio and the bursa weight-to-BW ratio, respectively. Gas chromatography analysis showed that the MHUSA was present on chick fluff until day 5. The statistical analysis revealed that the heterophil-to-lymphocyte ratio was lower in the MHUSA group at day 4, 7, and 9 (P < 0.0001 for day 4 and 7; P = 0.0377 for day 9). The bursa weight-to-BW ratio was significantly higher in the MHUSA group than in the control group from day 4 until day 29. These results confirm the beneficial effects of the MHUSA on chicks' adaptation to the new environment and on bursa of Fabricius development, suggesting its potential role in improving chicks' immune response.

The Major Cat Allergen Fel d 1 Binds Steroid and Fatty Acid Semiochemicals: A Combined In Silico and In Vitro Study.

The major cat allergen Fel d 1 is a tetrameric glycoprotein of the secretoglobin superfamily. Structural aspects and allergenic properties of this protein have been investigated, but its physiological function remains unclear. Fel d 1 is assumed to bind lipids and steroids like the mouse androgen-binding protein, which is involved in chemical communication, either as a semiochemical carrier or a semiochemical itself. This study focused on the binding activity of a recombinant model of Fel d 1 (rFel d 1) towards semiochemical analogs, i.e., fatty acids and steroids, using both in silico calculations and fluorescence measurements. In silico analyses were first adopted to model the interactions of potential ligands, which were then tested in binding assays using the fluorescent reporter N-phenyl-1-naphthylamine. Good ligands were fatty acids, such as the lauric, oleic, linoleic, and myristic fatty acids, as well as steroids like androstenone, pregnenolone, and progesterone, that were predicted by in silico molecular models to bind into the central and surface cavities of rFel d 1, respectively. The lowest dissociation constants were shown by lauric acid (2.6 µM) and androstenone (2.4 µM). The specific affinity of rFel d 1 to semiochemicals supports a function of the protein in cat's chemical communication, and highlights a putative role of secretoglobins in protein semiochemistry.

Working Smarter Not Harder: Oxytocin Increases Domestic Dogs' (Canis familiaris) Accuracy, but Not Attempts, on an Object Choice Task.

The neuropeptide oxytocin (OT) has been shown to enhance dogs' ability to perform an object choice task (OCT) involving the use of human pointing cues, when delivered intranasally. This study aimed at further investigating whether OT enhances task performance by increasing choices made, or by increasing correctness of choices made, and to compare these treatment effects to dog appeasing pheromone (DAP), known to balance emotional activation in dogs. Hence, we compared OCT performance between three groups of dogs: (i) dogs administered OT and a sham collar, (ii) dogs administered a saline placebo and a DAP collar, and (iii) control dogs administered a saline placebo and a sham collar. All three groups consisted of a combination of male and female pet dogs and assistance-dogs-in-training currently living with a volunteer carer. The study also evaluated the effect of intranasal OT and/or DAP on plasma levels of OT, and prolactin; which has previously been linked with anxiety in dogs. The dogs' emotional state was measured using the Emotional Disorders Evaluation in Dogs (EDED) scale. The owners'/carers' degree of anxious- and avoidant-style attachment to their dogs was accessed using the Pet Attachment Questionnaire (PAQ). Interesting descriptive data appeared for both treatment groups. Particularly, in OT group, we obtained significant results demonstrating that intranasal OT enhances OCT performance in dogs compared to control, by increasing the percentage of correct choices, but not the number of choices, made. Results also support that the mode of action of intranasal OT is via direct access to the brain and not via the blood, since no elevation of plasma OT (or prolactin) levels were observed after intranasal administration in this study. Similarly, DAP application did not significantly alter OT or prolactin peripheral concentrations. Several differences were observed between fostered and pet dogs, namely: fostered dogs demonstrated higher levels of serum prolactin, made more choices on the OCT compared to pet dogs but were not more likely to be correct, and were fostered by carers with higher avoidant attachment scores than pet dog owners. These findings implicate consideration of potential carer and training consequences for assistance dogs.