A novel method for assessing chronic cortisol concentrations in dogs using the nail as a source

Validating a Non-Invasive Method for Assessing Cortisol Concentrations in Scraped Epidermal Skin from Common Bottlenose Dolphins and Belugas

Society is showing a growing concern about the welfare of cetaceans in captivity as well as cetaceans in the wild threatened by anthropogenic disturbances. The study of the physiological stress response is increasingly being used to address cetacean conservation and welfare issues. Within it, a newly described technique of extracting cortisol from epidermal desquamation may serve as a non-invasive, more integrated measure of a cetacean's stress response and welfare. However, confounding factors are common when measuring glucocorticoid hormones. In this study, we validated a steroid hormone extraction protocol and the use of a commercial enzyme immunoassay (EIA) test to measure cortisol concentrations in common bottlenose dolphin (Tursiops truncatus) and beluga (Delphinapterus leucas) epidermal samples. Moreover, we examined the effect of sample mass and body location on cortisol concentrations. Validation tests (i.e., assay specificity, accuracy, precision, and sensitivity) suggested that the method was suitable for the quantification of cortisol concentrations. Cortisol was extracted from small samples (0.01 g), but the amount of cortisol detected and the variability between duplicate extractions increased as the sample mass decreased. In common bottlenose dolphins, epidermal skin cortisol concentrations did not vary significantly across body locations while there was a significant effect of the individual. Overall, we present a contribution towards advancing and standardizing epidermis hormone assessments in cetaceans.

Peripubertal Testosterone, 17β-Estradiol and Progesterone Concentrations in Hair and Nails in Dobermann Dogs

Studies about puberty in dogs are few, probably because many factors are involved in the delicate process of puberty onset, leading to difficulties in the proper enrollment of subjects. Moreover, the use of blood for monitoring hormonal changes can be problematic, and not feasible for long-term studies. Hair and nails proved to be suitable matrices for the retrospective evaluation of hormones' long-term accumulation. This study was performed using hair and nails for the evaluation of testosterone (T), 17β-estradiol (E2) and progesterone (P4) concentrations to assess possible sexual steroid changes during the peripubertal period in dogs. The results, obtained on five males and five females, showed a significant increase in T in hair and nails of males immediately before puberty. In females, a significant increase in E2 at puberty and a marked increase in P4 after puberty was found in both biological specimens. Sex-related differences were detected only for T hair concentrations, but when the sex and sampling time were considered together, hair and nails T and nails P4 concentrations allowed us to discern between male and female dogs at specific sampling times. The results from this study showed that hair and nails are useful biological specimens for the retrospective evaluation of changes in T, E2 and P4 concentrations in peripubertal dogs.

Coat, Claw and Dewclaw 17-β-Estradiol and Testosterone Concentrations in Male and Female Postpubertal Cats: Preliminary Results

In the recent past, tissue materials such as hair/coat and nails/claws have proved to be useful for the study of long-term hormonal changes in humans and animals and shown to be advantageous in terms of being collectable without invasiveness, with a benefit in terms of animal welfare. However, studies using these tissue materials in cats are scarce, especially on sexual hormone measurement. In this study, the concentrations of 17-β-estradiol (E2) and testosterone (T) were assessed in 20 male and 18 female domestic postpubertal cats at the time of neutering/spaying during the breeding season. Hormones were measured in coat shaved from the forearm (ACOAT) and from the surgical area (SCOAT); claws were collected from the forearms (CLAWS) and the dewclaws (DCLAWS). Although all these tissue materials were shown to be useful for E2 and T long-term measurement, only T concentrations were higher (p < 0.001) in males from both ACOAT and SCOAT samples when compared to females and therefore useful for distinguishing between the two sexes. Within each sex, E2 and T concentrations can be assessed on coat, but also on the dewclaws, providing an alternative, practical, matrix for sexual steroid measurement in postpubertal cats during the breeding season.

Assessing chronic stress in wild mammals using claw-derived cortisol: a validation using European badgers (Meles meles)

Measuring stress experienced by wild mammals is increasingly important in the context of human-induced rapid environmental change and initiatives to mitigate human-wildlife conflicts. Glucocorticoids (GC), such as cortisol, mediate responses by promoting physiological adjustments during environmental perturbations. Measuring cortisol is a popular technique; however, this often reveals only recent short-term stress such as that incurred by restraining the animal to sample blood, corrupting the veracity of this approach. Here we present a protocol using claw cortisol, compared with hair cortisol, as a long-term stress bio-indicator, which circumvents this constraint, where claw tissue archives the individual's GC concentration over preceding weeks. We then correlate our findings against detailed knowledge of European badger life history stressors. Based on a solid-phase extraction method, we assessed how claw cortisol concentrations related to season and badger sex, age and body-condition using a combination of generalized linear mixed models (GLMM) (n = 668 samples from 273 unique individuals) followed by finer scale mixed models for repeated measures (MMRM) (n = 152 re-captured individuals). Claw and hair cortisol assays achieved high accuracy, precision and repeatability, with similar sensitivity. The top GLMM model for claw cortisol included age, sex, season and the sex*season interaction. Overall, claw cortisol levels were significantly higher among males than females, but strongly influenced by season, where females had higher levels than males in autumn. The top fine scale MMRM model included sex, age and body condition, with claw cortisol significantly higher in males, older and thinner individuals. Hair cortisol was more variable than claw; nevertheless, there was a positive correlation after removing 34 outliers. We discuss strong support for these stress-related claw cortisol patterns from previous studies of badger biology. Given the potential of this technique, we conclude that it has broad application in conservation biology.

Stress Concepts and Applications in Various Matrices with a Focus on Hair Cortisol and Analytical Methods

When studying stress in animals, it is important to understand the types of stress and their classification, and how to assess the stress levels in different animal species using different matrices accurately and precisely. The classification of stress types helps to distinguish between good stress (eustress) and bad stress (distress). Hence, first, it is crucial to assess the animal's level of stress in a non-intrusive manner and second to identify the type of stress that is best suited to its environment. Third, it is also important to analyze the obtained samples using a suitable method to increase the validity of stress hormone measurements. Therefore, in this review, we aim to: (1) explain the classification of stress, (2) discuss the wide range of body matrices (e.g., saliva, milk, hair, urine, feces, sweat, fins, etc.) that can be used as samples to evaluate stress levels, as well as their comparisons and limitations, and present the reliable matrices for measuring stress hormones with special emphasis on hair, (3) compare the analytical methods for measuring stress hormones after sample preparation. Despite some literature that does not include hair as a reliable matrix for evaluating stress levels, hair is one of the matrices for measuring long-term stress hormone accumulations. This review discusses some factors that influence the level of stress hormones in the hair. By understanding these issues, the scientific community will not only be able to improve the understanding of stress and biomarker evaluation but also suggest how to deal with the consequences of stress in future research.

Dam (Canis familiaris) Welfare throughout the Peri-Parturient Period in Commercial Breeding Kennels

Simple Summary

Welfare problems experienced during gestation and lactation may negatively affect dams and their puppies. However, the welfare states of dams in commercial breeding (CB) kennels during this period have not been well examined. Therefore, we examined a range of behavioral, physical, and physiological metrics throughout the period around parturition to identify if changes indicative of impaired welfare were present. We tested 74 dams from eight CB kennels at 6 and 1 week prepartum, and 4 and 8 weeks postpartum. At each time point we measured their responses to a stranger approaching, their physical health, and indicators of their stress response, immune function, and parasite burden. Findings did not reveal major changes in dam welfare. Most changes observed were likely because of natural biological changes resulting from pregnancy, lactation, and weaning. However, as some changes in metrics deviated from what was expected and there were changes in environmental and management factors during this time, future research should identify how they affect dam welfare.

Abstract

Poor dam welfare throughout the peri-parturient period can also negatively affect that of their offspring. This study aimed to identify changes in physical, physiological, and behavioral metrics indicative of dam welfare throughout the peri-parturient period. Dams (n = 74) from eight U.S. Midwest commercial breeding (CB) kennels were tested at 6 and 1 week prepartum, and 4 and 8 weeks postpartum. At each time point dams underwent a stranger approach test, physical health assessment, hair collection for hair cortisol concentration (HCC) and fecal collection for fecal glucocorticoid metabolites (FGM), fecal secretory immunoglobulin A (sIgA) and parasite detection. Linear mixed-effects models indicated dams exhibited more affiliative behaviors towards the stranger at 4 weeks postpartum than 6 weeks prepartum (p = 0.03), increased HCC from 4-weeks to 8 weeks postpartum (p = 0.02), and increased FGM from 1 week prepartum to 8 weeks postpartum (p = 0.04). At each respective time point, the percentage of dams with intestinal parasites was 11%, 4%, 23%, and 15%. Most changes are likely due to increased energy requirements and hormonal variations. However, deviations from expected changes may have resulted from changes in environment and/ or management, which should be explored in future studies.

Evaluation of hair cortisol as an indicator of long-term stress responses in dogs in an animal shelter and after subsequent adoption

Shelter dogs are exposed to a variety of stressors. Among non-invasive techniques, hair cortisol concentration (HCC) is suggested an easy to collect biomarker for giving insight into long-term stress responses. We evaluated HCC as an indicator of long-term cortisol responses in dogs in an animal shelter over different chronological time points during sheltering and after adoption. Hair samples were collected from the neck region following a shave/re-shave protocol of shelter dogs (total n = 52) at four different time periods: T1 intake at shelter (pre-shelter period, n = 51); T2 after 6 weeks in the shelter (n = 23); T3 6 weeks after adoption (n = 24); T4 6 months after adoption (n = 22). HCC at T2 was significantly higher than HCC at T1, T3 and T4 (effect of sample collection moment: F_3,41 = 12.78, p < 0.0001). The dog’s weight class, age class, sex, reason for admission, kennel history and melanin type also explained HCC variability. No significant difference in HCC was found between shelter dogs T1 and control pet dogs in their own homes (n = 20, one sample, t = − 1.24, p = 0.219). A significant but moderate positive correlation between HCC and urinary cortisol:creatinine ratios was found (т = 0.3, p < 0.001). As HCC increased in the shelter, the use of this non-invasive parameter appears a useful additional tool in dog welfare research.

Evaluation of hair and nail cortisol concentrations and associations with behavioral, physical, and environmental indicators of chronic stress in cats

Background

Chronic stress is implicated in behavioral and health issues in cats, but methods for recognition, evaluation, and measurement of stress are lacking. Cortisol concentration is typically used as an indicator of stress.

Objectives

To evaluate use of an enzyme immunoassay to quantitate hair and nail cortisol concentrations (HCC and NCC) in cats and evaluate associations between HCC and NCC and behavioral, physical, and environmental correlates of chronic stress in cats.

Animals

Forty‐eight adult, owned or community cats.

Methods

Cross‐sectional study. Nail clippings and hair were collected from cats. Medical history and cat daily lifestyle questionnaires were completed by owners or caretakers. A commercial laboratory performed cortisol extraction and quantification using a validated enzyme immunoassay kit. Correlational and regression analyses were used to evaluate associations between HCC and NCC and behavioral, environmental, and medical factors.

Results

Hair and nail cortisol concentrations were significantly associated (r_s = 0.70; P < .001), but HCCs varied widely within and among cats. Cats with litterbox issues had significantly increased HCC (P = .02) and NCC (P = .001) as compared to cats without litterbox issues. Cats with groomed coats had lower HCCs (P = .02) as compared to cats without groomed coats, whereas cats with dander and mats had higher NCCs (P = .01) as compared to cats without dander and mats.

Conclusions and Clinical Importance

The quantification of NCCs might improve identification and evaluation of chronic stress in cats. The variability of HCCs in individual cats warrants caution using this measurement in chronic stress studies.

Salivary stress markers in dogs: Potential markers of acute stress

Along with the growing awareness of psychological stress in companion animals, several treatments have become available to address fear- and anxiety-related behaviors in dogs. To detect vulnerable individuals and apply effective treatments, reliable evaluations that can quantify individual stress responses are in high demand. To develop measurable variables that have clinical applications, more investigations are needed to increase our knowledge. When stress responses are activated by the sympathetic-adrenal-medullary (SAM) and hypothalamic-pituitary-adrenal (HPA) axes, the immune system is also activated. Although the peripheral cortisol level is commonly used as a stress biomarker, it primarily reflects the HPA axis response and does not sufficiently reflect the complexity of the stress response. Thus, this review primarily focuses on the available salivary biomarkers that mainly reflect the acute stress response through the activity of the SAM axis and the immune system in dogs. We hope that this review will promote the validation of these biomarkers in dogs and aid in the development of future studies to evaluate stress responses in dogs.

Urban bat pups take after their mothers and are bolder and faster learners than rural pups

BACKGROUND

Urbanization is rapidly changing our planet and animals that live in urban environments must quickly adjust their behavior. One of the most prevalent behavioral characteristics of urban dwelling animals is an increased level of risk-taking. Here, we aimed to reveal how urban fruitbats become risk-takers, and how they differ behaviorally from rural bats, studying both genetic and non-genetic factors that might play a role in the process. We assessed the personality of newborn pups from both rural and urban colonies before they acquired experience outdoors, examining risk-taking, exploration, and learning rates.

RESULTS

Urban pups exhibited significantly higher risk-taking levels, they were faster learners, but less exploratory than their rural counterparts. A cross-fostering experiment revealed that pups were more similar to their adoptive mothers, thus suggesting a non-genetic mechanism and pointing towards a maternal effect. We moreover found that lactating urban mothers have higher cortisol levels in their milk, which could potentially explain the transmission of some personality traits from mother to pup.

CONCLUSIONS

Young bats seem to acquire environment suitable traits via post-birth non-genetic maternal effects. We offer a potential mechanism for how urban pups can acquire urban-suitable behavioral traits through hormonal transfer from their mothers.

A non-invasive method to assess the reproductive status of the European badger (Meles meles) from urinary sex-steroid metabolites

Due to their unique reproductive physiology and behaviour, European badgers (Meles meles) are often used as a model to study mammalian reproduction. For reproductive endocrinology, circulating hormone levels are conventionally measured directly from blood samples. However, routine blood sampling is often not practical for wild animals and may induce stress affecting measurement accuracy. Non-invasive alternatives are thus of interest. Circulating hormones are metabolized through different routes, either by the kidneys, to be excreted through urine, or by the liver, to be excreted through faeces. These metabolites can thus be used as a proxy of hormone measurements, provided the species-specific metabolic characteristics are known. Here we tested the suitability of measuring urinary metabolites of circulating plasma sex-steroid hormones (testosterone in males and oestrogen in females) with enzyme immunoassays to assess the reproductive status of the European badger (Meles meles). Biological validation evidenced that urinary testosterone metabolite (UTM) and urinary total oestrogen metabolite (UEM) excretion patterns both corresponded with seasonal badger reproductive patterns on a population level, signaling correlation over a broad time frame. On an individual level, concurrent sampling of urine and plasma showed that male plasma testosterone and UTM levels correlated significantly across seasons, but no short term correlation was evident for total oestrogen and UEM in females. Thus, in badgers, urinary sex-steroid metabolites can be used reliably in the short term to assess male reproductive status at the individual level, but only at the broader population level for females.

Is ECLIA Serum Cortisol Concentration Measurement, an Accurate Indicator of Pain Severity in Dogs with Locomotor Pain?

Simple Summary

Serum cortisol level reflects the activity of stress axis, ethological alterations, acute and chronic pain, life quality, or psychogenic stress. Although it is stated that stress can produce a measurable influence on the cortisol level, a certified value of this pain biomarker in dogs was not generally accepted yet. This interdisciplinary research emerged from the need for information in this field since not many studies were focused mainly on comparative analysis. We consider this field as a hot topic with various possible applications. Our survey is a methodological study within the fields of behavior and veterinary sciences, being relevant for the dog’s pain assessment. Results are having the guarantee of the high standard analysis of serum specimens, and using the updated Cortisol assay, with serum cortisol determined by Electrochemiluminescence immunoassay. We consider that our work could refresh the information in this field. Yet, an area of interest, specific pathology and pain particularities in a dog, being studied more and more in the last decade. What we can say is that serum cortisol limits cannot be adopted as a single and accurate pain marker in dog species, our study confirming these values, as non-conclusive for the assessment of the real pain levels in the dogs.

Abstract

The purpose of determining serum cortisol level is to reflect the activity of stress axis, ethological alterations, acute and chronic pain, life quality, or psychogenic stress. Although it is stated that stress can produce a measurable influence on the cortisol level, a certified value of this pain biomarker in dogs was not generally accepted yet. This study aimed to investigate if serum cortisol measured follows allopathic treatments only, or it is associated with physiotherapy, point out pain level in dogs with orthopedic disease, which could reveal the healing progress. The diagnostic identified: hip dysplasia, cranial cruciate ligament rupture, or intervertebral disc disease. Ortolani and Barden tests, together with clinical examination, drawer sign, and tibia compression test, were done in dogs exhibiting postures, and motion alteration, and X-Ray confirmed. A total of 30 dogs were grouped in healthy (n = 10) and pain groups (n = 20), the blood sampling is done at the beginning of the investigation, and after ten days of the study. Dogs were handled in two ways: G1—treated with Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) only and respectively, G2—by therapy and physiotherapy. The analysis was performed on a Roche Cobas Analyzer (Roche, USA), serum cortisol being determined by Electrochemiluminescence immunoassay (ECLIA), and statistics using ANOVA, following Tukey’s Multiple Comparison Test. The results revealed that, out of ten specimens in the Control group, nine were within the normal limits: 5–65 ng × mL⁻¹ (24.76 ± 19.48678), and one sample under the set limit. In G1, it was observed that the plasmatic P1 values were below the levels of P2, in six situations. In G2, although the status of all subjects improved radically with the removal or evident reduction of pain, confirmed clinically and imagistically, the P2 values in five dogs were higher than the initial P1 values, and in contradiction with the observed clinical reality. Comparing results, the mean difference in G1 was 0.41, and in G2 = 2.54, with an SD for G1 = 13.38, and G2 = 16.66, registering moderate development. Standard deviation illustrated that the values of treated groups were highly spread throughout the interval, and the serum cortisol assay did not generate significant statistical differences between groups in our case. This inferred the doubt whether the used detection method or values registered correctly indicates the pain levels in dog species.

Effect of time and temperature on stability of progestagens, testosterone and cortisol in Asian elephant blood stored with and without anticoagulant

The value of biological samples collected in the field is compromised if storage conditions result in analyte degradation, especially in warmer climates like Thailand. We evaluated the effects of time and temperature on immunoactive steroid hormone stability in Asian elephant (Elephas maximus) blood stored with and without an anti-coagulant before centrifugation. For each elephant (5 male, 5 female), whole blood was aliquoted (n = 2 ml each) into 13 red top (without anticoagulant) or purple top (with anticoagulant) tubes. One tube from each treatment was centrifuged immediately and the serum or plasma frozen at -20°C (Time 0, T0). The remaining 12 aliquots were divided into stored temperature groups: 4°C, room temperature (RT, ~22°C), and 37°C, and centrifuged after 6, 24, 48 and 62 h of storage. Serum and plasma concentrations of progestagens in females, testosterone in males and cortisol in both sexes were quantified by validated enzyme immunoassays. Steroid concentration differences from T0 were determined by a randomized complete block ANOVA and Dunnett's tests. The only evidence of hormone degradation was cortisol and testosterone concentrations in serum stored at 37°C. Testosterone concentrations declined by 34% at 48 h and 52% at 62 h, cortisol was decreased by 19% after 48 h and 27% after 62 h at 37°C, respectively. None of the other aliquots displayed significant changes over time at any temperature. In conclusion, steroids appear to be stable in blood for nearly 3 days at room or refrigeration temperatures before centrifugation; steroids in samples with ethylenediaminetetraacetic acid were particularly stable. However, warmer temperatures may negatively affect steroids stored without anti-coagulant, perhaps due to red blood cell metabolism. Thus, under field conditions with no access to cold or freezer temperatures, collection of plasma is a better choice for elephants up to at least 62 h before centrifugation.

Multi-year longitudinal profiles of cortisol and corticosterone recovered from baleen of North Atlantic right whales (Eubalaena glacialis)

Research into stress physiology of mysticete whales has been hampered by difficulty in obtaining repeated physiological samples from individuals over time. We investigated whether multi-year longitudinal records of glucocorticoids can be reconstructed from serial sampling along full-length baleen plates (representing ∼10years of baleen growth), using baleen recovered from two female North Atlantic right whales (Eubalaena glacialis) of known reproductive history. Cortisol and corticosterone were quantified with immunoassay of subsamples taken every 4cm (representing ∼60d time intervals) along a full-length baleen plate from each female. In both whales, corticosterone was significantly elevated during known pregnancies (inferred from calf sightings and necropsy data) as compared to intercalving intervals; cortisol was significantly elevated during pregnancies in one female but not the other. Within intercalving intervals, corticosterone was significantly elevated during the first year (lactation year) and/or the second year (post-lactation year) as compared to later years of the intercalving interval, while cortisol showed more variable patterns. Cortisol occasionally showed brief high elevations ("spikes") not paralleled by corticosterone, suggesting that the two glucocorticoids might be differentially responsive to certain stressors. Generally, immunoreactive corticosterone was present in higher concentration in baleen than immunoreactive cortisol; corticosterone:cortisol ratio was usually >4 and was highly variable in both individuals. Further investigation of baleen cortisol and corticosterone profiles could prove fruitful for elucidating long-term, multi-year patterns in stress physiology of large whales, determined retrospectively from stranded or archived specimens.

Fingernail and toenail clippings as a non-invasive measure of chronic cortisol levels in adult cancer survivors

PURPOSE

Cancer survivors are at greater risk of comorbidities and functional decline due to physiological and psychological stress which can be measured by salivary cortisol. If saliva is used, multiple samples must be collected to accurately quantify long-term stress; however, fingernail (FN) and toenail (TN) clippings offer an opportunity to measure retrospective cortisol levels in a non-invasive manner.

METHODS

Three sets of FN and TN clippings were collected at 12-month intervals in conjunction with saliva samples from cancer survivors (n = 109) participating in two clinical trials. FN and TN samples were stored at room temperature (RT); a subset underwent additional processing and freezing before analysis. Cortisol levels were determined via enzyme immunoassay, and correlation coefficients were generated to determine overall correspondence of the individual measures.

RESULTS

Matched RT and frozen samples were highly correlated for TN (r = 0.950, p = 5.44 × 10^-37) and FN (r = 0.784, p = 1.05 × 10^-10). Correlations between RT FN and TN were statistically significant (r = 0.621, p = 3.61 × 10^- 17), as were frozen FN and TN (r = 0.310, p = 0.0283). RT, but not frozen TN and FN correlated with salivary cortisol (r = 0.580, p = 1.65 × 10^- 16 and r = 0.287, p = 0.00042 for TN and FN, respectively).

CONCLUSIONS

FN and TN cortisol levels correlate with salivary cortisol in adult cancer survivors and may offer a less invasive and convenient means for measuring chronic cortisol levels.

Evaluating pair versus solitary housing in kennelled domestic dogs (Canis familiaris) using behaviour and hair cortisol: a pilot study

Numerous studies conducted to assess welfare of domestic dogs housed in kennel facilities have reported that these dogs experience suboptimal living conditions. One important goal of improving welfare of kennelled dogs is to reduce their stress levels, and one recommended approach for improving welfare of kennelled dogs is group or social housing. The beneficial effects of management changes designed to achieve this goal should be measurable in individual animals. Stress is evident through behaviours exhibited, as well as via the concentration of cortisol, a key hormone reflecting stress. Using behavioural and hair cortisol measures, we conducted a pilot study to measure the impact of switching dogs housed in a long-term kennels facility from solitary to pair housing, using both within-subjects and between-groups comparisons. Considerable individual variation in dog responses was noted, with only two of eight pair-housed dogs showing significant declines in multiple stress-related behaviours once in pair housing. The most sensitive behaviours were active vigilance and repetitive movements (such as jumping and pacing). Barking was reduced overall in the facility following the housing change, even among dogs still in solitary housing. The long-term stress as reflected in hormone deposition in hair also provided encouraging indications that the dogs experienced lower stress levels when in paired housing; dogs showed a significant decline in hair cortisol levels from the first (prehousing change) to second (postintervention) samples. Domestic dogs are social animals, and numerous indications of potential benefit were recorded with no negative impacts seen. Based on our findings, we recommend pair or group housing of compatible dogs as a promising addition to the strategies available to those seeking to improve welfare of kennelled dogs. Future studies using higher numbers of animals and that include tracking of hair cortisol, vigilance behaviour, repetitive movements and barking would be desirable.