Analytical and physiological validation of an enzyme immunoassay to measure oxytocin in dog, wolf, and human urine samples.

Oxytocin (OT) promotes pro-sociality, bonding, and cooperation in a variety of species. Measuring oxytocin metabolite (OTM) concentrations in urine or saliva provides intriguing opportunities to study human and animal behaviour with minimal disturbance. However, a thorough validation of analytical methods and an assessment of the physiological significance of these measures are essential. We conducted an analytical validation of a commercial Enzyme Immunoassay (EIA; Arbor OT assay kit) to measure OTM concentrations in dog, wolf, and human urine samples. To test the assay's ability to detect changes in OTM concentrations, we administered oxytocin intranasally to 14 dogs. Assay performance with regard to parallelism was acceptable. Assay accuracy and extraction efficiency for dog and wolf samples were comparable to a previously validated assay (Enzo OT assay kit) but variation was smaller for human samples. Binding sensitivity and antibody specificity were better in the Arbor assay. Average OTM concentrations were more than twice as high as in comparable samples measured with the Enzo assay, highlighting a lack of comparability of absolute values between different assays. Changes in OTM concentrations after intranasal treatment were detected reliably. The Arbor assay met requirements of a "fit-for-purpose" validation with improvement of several parameters compared to the Enzo assay.

Endocrine changes related to dog domestication: Comparing urinary cortisol and oxytocin in hand-raised, pack-living dogs and wolves.

Dogs are exceptionally well adapted to life close to humans, and alterations in their endocrine system during the domestication process may be an underlying mechanism. In particular, it has been suggested that low circulating cortisol concentrations in conjunction with simultaneously high oxytocin concentrations may have resulted in dogs' increased docility ('selection for tameness' hypothesis) and heightened propensity to interact and form relationships with humans ('hypersociability' hypothesis) compared to wolves. To investigate this, we analyzed cortisol and oxytocin metabolite concentrations from urine samples of hand-raised, pack-living domestic dogs and their non-domestic relatives, grey wolves. Based on the hypotheses outlined above, we predicted lower cortisol but higher oxytocin concentrations in dogs than wolves. In contrast to our prediction, we found higher cortisol concentrations in dogs than wolves. However, oxytocin concentrations were higher in dogs compared to wolves although the effect was relatively small. Indeed, male dogs had the highest oxytocin concentrations while female dogs' oxytocin concentrations were comparable to wolves'. Feeding status, reproductive phase, and conspecific social interactions also significantly affected cortisol and oxytocin concentrations. Furthermore, we compared two methods of correcting for variable water content of urine samples. We discuss our results in light of physiological and behavioral changes during domestication and highlight the importance of accounting for confounding variables in future studies.

Consistency and efficacy of two methods of intranasal oxytocin application in dogs.

Over the last few years, oxytocin (OT) administration to investigate the role of the oxytocinergic system in the social behavior of dogs has become of more and more interest. To date, the most common OT administration method for dogs is the intranasal spray commonly used for humans. Due to the different nasal conformation of dogs and the unpleasantness of the procedure, most dogs need to be restrained to allow administration. This has 2 main drawbacks-it may hinder reliable administration, which might lead to tremendous variance in the uptake of OT across individuals and it is likely to be stressful for the dogs. Alternatively, a vaporizer mask can be used to administer aerolized OT and dogs can be trained to voluntarily enter the mask, which might enable a more reliable administration without having to restrain the dogs. The aim of this study was to compare the efficacy of these 2 methods to identify a reliable non-invasive method for exogenous OT administration, thereby assisting future research on the role of OT in canines. We administered OT to pet dogs using either an intranasal spray bottle or a vaporizer mask and assessed urinary OT concentrations as a measure of OT uptake. We found that only when administered using a vaporizer mask, OT significantly increased in all subjects, while using a spray bottle led to considerable variance in OT uptake and an inconsistent increase in urinary OT concentrations across individuals. These results suggest that using a vaporizer mask should be preferred over using an intranasal spray bottle for OT administration in dogs. If not available, experimenters should at least monitor OT uptake after administration using spray bottles, to evaluate the success of the method.

Applications for non-invasive thyroid hormone measurements in mammalian ecology, growth, and maintenance.

Thyroid hormones (THs) play a pivotal role in the regulation of metabolic activity throughout all life stages. Cross-talk with other hormone systems permits THs to coordinate metabolic changes as well as modifications in growth and maintenance in response to changing environmental conditions. The scope of this review is to explain the relevant basics of TH endocrinology, highlight pertinent topics that have been investigated so far, and offer guidance on measuring THs in non-invasively collected matrices. The first part of the review provides an overview of TH biochemistry, which is necessary to understand and interpret the findings of existing studies and to apply non-invasive TH monitoring. The second part focuses on the role of THs in mammalian ecology, and the third part highlights the role of THs in growth and maintenance. The fourth part deals with the advantages and difficulties of measuring THs in non-invasively collected samples. This review concludes with a summary that considers future directions in the study of THs.

Age and socially related changes in fecal androgen metabolite concentrations in free-ranging male giraffes.

In many mammal species, androgen levels in males are elevated during periods of mating activity, often to facilitate aggressive behavior between males over access to fertile females. However, this pattern might be less obvious in species with a rather low male-male aggression rate, or in those that are not strictly seasonal breeders. A complex social structure, as well as additional social and environmental factors, might add more to the complexity. Here, we applied a non-invasive method to monitor fecal androgen metabolite (fAM) levels in free-ranging giraffe bulls over a period of months to examine longitudinal patterns of androgen metabolite concentrations in relation to observed male sexual behavior in different age classes. Giraffes are non-seasonal breeders, living in a fission-fusion social system and males show a roaming strategy to search for fertile females. Our results show that season has an impact on fAM levels in free-ranging giraffes, with respective steroid concentrations being higher in summer. In the presence of females, fAM levels of bulls are significantly higher compared to when found in all-male groups, with old adult bulls showing the highest fAM levels. In contrast, young adult bulls have overall slightly higher fAM levels compared to old adult bulls when residing in all male groups. Sexual behavior increases fAM levels only in old adult bulls.