Salivary testosterone levels in normal and testosterone treated monkeys

Non-invasive monitoring of physiological markers in primates

The monitoring of endocrine markers that inform about an animal's physiological state has become an invaluable tool for studying the behavioral ecology of primates. While the collection of blood samples usually requires the animal to be caught and immobilized, non-invasively collected samples of saliva, urine, feces or hair can be obtained without any major disturbance of the subject of interest. Such samples enable repeated collection which is required for matching behavioral information over long time periods with detailed information on endocrine markers. We start our review by giving an overview of endocrine and immune markers that have been successfully monitored in relation to topics of interest in primate behavioral ecology. These topics include reproductive, nutritional and health status, changes during ontogeny, social behavior such as rank relationships, aggression and cooperation as well as welfare and conservation issues. We continue by explaining which hormones can be measured in which matrices, and potential problems with measurements. We then describe different methods of hormone measurements and address their advantages and disadvantages. We finally emphasize the importance of thorough validation procedures when measuring a specific hormone in a new species or matrix.

The effect of sex and time of day on testosterone concentrations in equine saliva and serum

In terms of exercise, testosterone is important for the growth and maintenance of skeletal muscle mass. Sampling saliva could be a non-invasive alternative to blood sampling for the quantification of testosterone levels in horses. The objective of this study was to compare testosterone concentrations in saliva and serum (sampled simultaneously) from horses of different sexes and at different times throughout the day. A total of 67 warmblood riding horses (21 geldings, 22 mares and 24 stallions) were included in the study. Saliva and blood samples were collected in the morning (06:00-08:00), at midday (11:00-13:00) and in the evening (17:00-19:00). The results demonstrated a weak correlation between saliva and serum testosterone concentrations (rs=0.25, P=0.04). Stallions had higher serum testosterone concentrations than mares and geldings (P<0.001), but there was no significant effect of sex on salivary testosterone concentrations. The time of day did not affect the concentration of testosterone in either saliva or serum. In conclusion, our results indicate that saliva samples cannot be recommended for measuring testosterone levels in horses. However, further research is needed to identify the disturbing factors.

Salivary cortisol and behaviour in an all-male group of western lowland gorillas (Gorilla g. gorilla)

While the use of salivary cortisol as an index of hypothalamic–pituitary–adrenal (HPA) axis activation has increased rapidly in human studies, few non-human primate studies have used saliva samples. Nearly 300 h of behavioural data and over 400 saliva samples were collected from three young adult, male western lowland gorillas to document the feasibility and effectiveness of using salivary cortisol as an index of HPA activation in gorillas. Cortisol concentrations were significantly higher in morning samples than in afternoon samples, and there was a significant decrease in morning cortisol concentrations across the study period. Additionally, acute increases, followed by a return to baseline concentrations of cortisol were observed. Salivary cortisol concentration was found to correlate across individuals, indicating potential psychological attunement to environmental and/or social variables in these animals. Although no clear relationship between behaviour and cortisol concentrations was established, these results indicate that salivary cortisol is an effective technique for documenting HPA activity over an extended period of time, as it allows for detection of diurnal variation as well as acute changes in salivary cortisol concentrations.