Annual variation in plasma cortisol levels in common marmosets, Callithrix jacchus

In contrast to numerous studies showing breeding seasonality for animals living in temperate zones, few have addressed the effect of annual environmental changes on hormones and behavior related to reproduction for animals living in tropical and equatorial regions. In order to expand information on other primates living near the equator, we used 13 adult common marmosets, eight males and five females living under natural climatic conditions in a colony located in North-Eastern Brazil. Blood samples were collected monthly from July 2002 to June 2004. Cortisol assays were performed by ELISA. Cortisol levels varied according to environmental temperature and rainfall but were not significantly affected by photoperiod. After separating out these environmental effects through an analysis of covariance for repeated measurements, a marginal significant difference in cortisol levels according to the seasons of the year was detected. A significant difference in cortisol levels between females and males was also observed. The results suggest that annual variation in cortisol in common marmosets is influenced by temperature and rainfall and might be associated with the mating season.     

On the mechanism of central effect of thyroxine on body temperature in dogs.

The effect of intraventricular injection of thyroxine 1 microgram/animal on body temperature was studied in dogs under resting conditions: at normal ambient temperature, at high ambient temperature (35 degrees C) and during administration of pyrogen. Besides, changes in body temperature were elucidated in dogs performing physical exercise following I.V. T4 injection in the same dose. Thyroxine exerted its central action on body temperature only in dogs performing physical exercise.     

Serum cortisol levels in goats exhibit seasonal but not daily rhythmicity

The aim of the study was to find out whether there is a daily rhythm in goat serum cortisol concentrations, whether the concentration profiles differ between normal light:dark and constant dark conditions, and whether any seasonal variations might be detected in daily cortisol secretion patterns. Seven Finnish landrace goats were kept at indoor temperature (18-23°C) under artficial lighting that approximately simulated the annual changes of daylength at 60°N. Blood samples were collected for cortisol measurements by radioimmunoassay at 2h intervals during six times of the year: winter (light:dark 6:18h), early spring (10:14h), late spring (14:10h), summer (18:6h), early fall (14:10h), and late fall (10:14h). Cortisol profiles were determined for two consecutive days, first in light:dark (LD) conditions and then in continuous darkness (DD). There was no significant daily rhythm in serum cortisol levels in any time of the year, nor did the profiles in LD and DD conditions show any differences. A significant seasonal variation was, however, detected among the overall cortisol levels. In winter, the concentrations were higher than in any other season, and from early spring to summer they were at their lowest. Under equal photoperiods, the cortisol levels were higher in fall than spring. The difference between winter and summer was confirmed in the following year in LD conditions. There was no correlation between the serum cortisol and progesterone levels. The results suggest that the possible circadian variation of cortisol secretion in goats is completely masked by external factors, and the lighting conditions do not have immediate effects on the daily secretion patterns. The seasonal variation in the overall cortisol levels is most probably related to the changes in photoperiod, because other conditions were relatively constant during the experiment.     

Urinary cortisol responses of longtailed macaques to five cage sizes,tethering, sedation,and room change

Urinary free cortisol responses to five cage sizes, cage level, room change, tethering adaptation, chronic catheterization, and ketamine sedation were measured in 14 female and 14 male wild-born adult Macaca fascicularis. Urinary free cortisol, a physiological measure of psychological well-being that can be collected unobtrusively, provided a measure of the animals' general adrenocortical response to various conditions over a time course of hours. Urinary free cortisol values in response to stimulation with adrenocorticotropic hormone (ACTH) validated the measure as a reflection of blood values. Cortisol values were expressed as a ratio to creatinine, which normalized for differences in urinary output and body weight (muscle mass). Cage size (20–140% of regulation floor area) and housing level (upper vs. lower cage) had no effect on stress, as measured by cortisol excretion. Room change elicited a slight increase in cortisol excretion for the first day, but not to a level suggesting stress. Sedation, surgery, some aspects of tethering adaptation, and chronic catheterization produced urinary cortisol evidence of stress. Even so, animals varied in their responses and all showed adaptation. Males and females did not differ in normal mean values but females tended to have higher cortisol levels in response to potential stressors investigated in this study. Cortisol levels continued to decline gradually throughout the study. © 1993 Wiley-Liss, Inc.     

Hospitalized dogs recovery from naturally occurring heatstroke; does serum heat shock protein 72 can provide prognostic biomarker?

Heatstroke is a serious illness in dogs characterized by core temperatures above 41 °C with central nervous system dysfunction. Experimental heatstroke models have tried to correlate biomarker levels with the severity of the syndrome. Serum heat shock protein (eHSP70) levels were recently evaluated as a biomarker of heat tolerance and acclimation, their role as a marker of heatstroke is inconclusive. Here, we monitored eHSP70 levels in correlation with systemic biomarkers in 30 naturally occurring canine heatstroke cases. Thirty dogs diagnosed with environmental (33 %) or exertional (66 %) heatstroke admitted to hospital (0–14 h post-injury) were tested for biomarkers of organ damage and coagulation parameters. eHSP70 levels were measured upon admission and 4, 12, and 24 h later (T1, T2, and T3, respectively). No differences were found between exertional and environmental heatstroke cases. The eHSP profile demonstrated an inverted bell shape, with the lowest levels at the 12 h time point. A positive correlation between eHSP70, lactate, and aPPT was also noted at T2 in all the dogs in the study. Twenty-four h after presentation, eHSP70 levels returned to those measured upon admission, this change was only significant in the survivors. The obtained results suggest that eHSP72 level profile may be predictive of survival.     

Behavior and cortisol levels of dogs in a public animal shelter, and an exploration of the ability of these measures to predict problem behavior after adoption

Behavior and plasma cortisol levels were examined in puppies and juvenile/adult dogs admitted to a public animal shelter. A behavioral test was developed to assess the responses of the dogs to novel or threatening conditions. Factor analysis of the behavioral responses of 166 dogs on day 3 in the shelter yielded six factors (locomotor activity, flight, sociability, timidity, solicitation, and wariness) that accounted for 68% of the total variance. Among those dogs remaining in the shelter for 9 days, plasma cortisol levels declined from day 2 to 9. Cortisol levels were weakly related to factor scores. In order to explore the relation of measures in the shelter to later behavior, questionnaires assessing problem behaviors were mailed to new owners of dogs 2 weeks and 6 months following adoption. Among puppies, wariness scores were negatively correlated with behavior problems at 2 weeks and cortisol levels were negatively correlated with behavior problems at 6 months. These results suggest how measures of behavior and endocrine activity obtained in shelters might prove useful for screening dogs for adoption or targeting dogs for behavioral intervention.     

Cortisol secretion following nomifensine administration in normal subjects

The effects of the oral administration of nomifensine, which inhibits endogenous cathecolamine re-uptake, on secretion of prolactin and cortisol were investigated in 12 normal subjects. In all the volunteers, a significant decrease of prolactin levels was observed following nomifensine administration. Cortisol levels were unaffected by this pharmacological treatment. The role of hypothalamic dopaminergic inhibitory system on ACTH-cortisol axis is discussed.     

Effects of weight, temperature and behaviour on the circadian rhythm of salivary cortisol in growing pigs

In farm animals, salivary cortisol has become a widely used parameter for measuring stress responses. However, only few studies have dealt with basal levels of concentration of cortisol in pigs and its circadian rhythm. The aim of this study was to examine the effects of ambient temperature and thermoregulatory behaviour on the circadian rhythm of salivary cortisol levels in fattening pigs. Subjects were 30 fattening pigs of different weight (60 to 100 kg), kept in six groups in an uninsulated building in pens with partly slatted floors. Saliva samples were taken every 2 h over periods of 24 h at different ambient temperatures at two times in winter and four times in summer. Thermoregulatory behaviour was recorded in the same 24-h time periods. The effect of time of day, body weight, ambient temperature and behaviour on the cortisol level was analysed using a mixed-effects model. Two peaks of cortisol levels per day were found. This circadian pattern became more pronounced with increasing weight and on days where thermoregulatory behaviour was shown. Mean cortisol levels per day were affected by weight but not by thermoregulatory behaviour. From our data, we conclude that long-term variations in cortisol concentration may be influenced by increasing age and weight more than by the respective experimental situation. In assessing animal welfare, it seems more reliable to consider the circadian pattern of cortisol concentration instead of only one value per day.     

The effect of transportation stress on circulating corticosteroids, enzyme activities and hematological values in laboratory dogs.

Stress during transportation was monitored in truck-transported Beagle dogs "IVTK HD". Cortisol (F), corticosterone (B), red and white blood cell parameters, and enzyme activities in plasma were estimated. Plasma levels of cortisol and corticosterone were increased significantly during transportation and returned to basal values overnight post arrival. Hematocrit, hemoglobin, erythrocytes and leukocytes increased moderately. No obvious differences in enzyme activities were observed. Only alpha-HBDH values dropped significantly at the end of the 9.5 h transport period. This study confirms, although individual reaction is remarkably different, transportation as a potent stressor for Beagle dogs.     

bFGF对热射病大鼠模型ET21, VWF, VEGF水平的影响

目的:研究碱性成纤维细胞生长因子(basic Fibroblast growth factor,bFGF)对热射病大鼠模型ET21、VWF、VEGF水平的影响。方法:选择SD大鼠36只随机分为6组,每组个6只,建立热射病大鼠模型后分为模型组、常温组、常温bFGF组、降温组、降温bFGF组,建模后0 h、2 h,比较不同级别生命征、血管功能因子。结果:建模后0 h,模型组Tr、HR、RR、MAP明显高于空白组(P0.05);建模后2 h,常温bFGF组、降温bFGF组明显低于常温组、降温组,降温组、降温bFGF组明显低于常温组、常温bFGF组(P0.05)。建模后0 h,模型组ET21、VWF的含量均明显高于空白组,VEGF含量明显低于热空白组(P0.05);建模后2 h,常温组ET21、VWF明显升高,VEGF明显降低,常温bFGF组、降温组、降温bFGF组ET21、VWF明显降低,VEGF明显升高(P0.05);降温组、降温bFGF组ET21、VWF明显低于常温组、常温bFGF组,VEGF明显高于常温组、常温bFGF组(P0.05);常温bFGF组、降温bFGF组ET21、VWF明显低于常温组与降温组,VEGF明显高于常温组与降温组(P0.05)。结论:碱性成纤维细胞生长因子有助于改善热射病大鼠生命体征,调节血管功能因子含量,提高热射病大鼠预后。     

Physiological arousal for companion dogs working with their owners in animal-assisted activities and animal-assisted therapy

This study investigated the physiological reactions of companion dogs (Canis familiaris) used in animal-assisted activities and animal-assisted therapy by measuring salivary cortisol concentrations. The dog caregivers (owners) collected saliva samples (a) at 3 control days without therapeutic work, (b) directly before and after each therapeutic session during 3 consecutive months, and (c) again at 3 control days without therapeutic work. The study used an enzyme immunoassay to analyze the samples. Cortisol concentrations were significantly higher during therapy days than on control days. Dogs working during the first half of the day produced higher cortisol concentrations after therapeutic sessions than before, whereas dogs working in the afternoon produced lower cortisol concentrations. Cortisol concentrations were higher in short sessions than in long ones and increased relative to the number of therapeutic sessions done during the sampling period. The results indicate that therapeutic work was physiologically arousing for the dogs in this study. Whether these physiological responses are indicative of potentially negative stress or of positive excitement remains an open question.     

Fecal cortisol levels in free-ranging female chacma baboons: relationship to dominance, reproductive state and environmental factors

Savannah baboons are one of the few mammalian species that do not exhibit seasonal reproduction patterns and are therefore ideally suited to study the effect of female reproductive states (cycling, pregnant, lactating) on cortisol levels independent of seasonal factors. Fecal samples from 10 free-ranging female chacma baboons (Papio hamadryas ursinus), collected during a period of 17 months, were analyzed using a steroid-extraction method. Reproductive state had a significant effect on fecal cortisol, with lowest levels found in estrous females. Fertility was not related to fecal cortisol levels; we found no significant differences between samples collected on conceptive and nonconceptive cycles. Environmental factors explained most of the variance of fecal cortisol levels. Cortisol measures were strongly correlated with seasonal differences such as daylight duration, temperature and the amount of time that baboons spent resting. We measured higher cortisol levels during winter months and suggest that this could be related to shorter resting periods and to the cold minimum ambient temperatures at this study site. Finally, we found no relationship between social rank nor the rate of agonistic interactions with basal fecal cortisol levels.     

Endocrine Effects of Heat Stress in Boars

The purpose of this study was to describe the temporal changes in peripheral plasma levels of testosterone and Cortisol in boars during and after heat stress. A total of 8 boars were utilized, 4 of them were exposed to 35°C, for 100 h in a climatic room, and 4 served as controls and were kept at 20 °C for 100 h in the climatic room. Blood samples were obtained via permanent vein catheters 3 times daily from 5 days before heat stress until 20 days after termination of heat stress. Testestorone levels were determined by radioimmunoassay and Cortisol by a competitive protein binding technique. For both hormones the pre-exposure levels were similar in both groups of boars. The control boars had significantly higher testosterone levels, while being in the climatic room, than during any other period. The experimental boars had slightly increased testosterone levels during the first day of heat stress and thereafter continuously decreased levels. In the control boars the testosterone levels returned to pre-exposure levels immediately after removal from the climatic room, whereas in the experimental boars the testosterone levels were dramatically increased during the first 5 days after exposure. The differences in Cortisol levels, between the 2 groups of boars were restricted to the period spent in the climatic room. During this period the experimental boars had significantly higher Cortisol levels.     

Combined effect of ambient temperature and solar radiation on maned sloths' behaviour and detectability

Changes in ambient temperature and solar radiation may affect sloths' metabolic rate and body temperature, with consequent changes in activities, postures and microhabitat selection. Although the separate effect of temperature and solar radiation on sloth's behaviour have been previously studied, the combined effect of these climatic factors on behavioural aspects of sloths has never been systematically evaluated in field conditions. Here we evaluated the influence of hourly ambient temperature variation on maned sloth (Bradypus torquatus) activities, postures and tree crown positions, under sunny and cloudy conditions; and tested if any of the animal posture and position increase their exposure to human detection. We performed 350 h of visual observation on eight maned sloths, equipped with radio-backpacks, in northern Bahia, Brazil, recording their activities, and their resting postures and positions on tree crowns. We also recorded the time taken to visualize the sloths on 58 days to analyse if sloths' detection is affected by posture and position. Higher ambient temperature, within a range of 21–33°C, increased the sloths' activity levels in cloudy conditions but reduced their activity in sunny conditions. Increasing ambient temperature also reduced the frequency of huddled posture and increased the frequency of extended posture and permanence in the inner tree crown. Lastly, the postures and positions did not influence sloths' detectability. Thus, the direction of the temperature–activity relationship depends on climatic conditions (sunny/cloudy), and individuals rely on resting postures and positions to thermoregulate. The warmer and drier future climate, expected to occur in the northern Atlantic Forest, may impose change in the diurnal activity levels and postural pattern for this threatened species, leading maned sloths to reduce its activity on sunny and warmer days and adopting an extended posture.     

Cortisol response of wild ungulates to trauma situations: hunting is not necessarily the worst stressor

Animal welfare concerns are becoming a central issue in wildlife management and conservation. Thus, we investigated stress response of wild ungulates to potentially traumatic situations (shooting injuries, vehicle collisions, entanglement, injuries or diseases) and hunting methods (stalking, battues and hunts with dogs) by means of serum cortisol concentrations from blood collected from killed animals. Cortisol levels in roe deer ranged below and in wild boar above levels for moose, red deer and fallow deer (hence, pooled as a group “deer”). Apart from species, cortisol concentration in trauma situations was mainly explained by trauma type and presence of disturbance after the trauma event. Effect of trauma type differed significantly for “deer”, with animals caught in fences and suffering vehicle collisions experiencing higher cortisol levels than animals injured by shooting. Differences between hunting methods were observed in the cervids (“deer” and roe deer), with stalking leading to lower cortisol levels than hunts with dogs (both groups) and battues (roe deer). Events both before and after the shot, such as duration of pursuit prior to shooting, location of injury, trauma length and presence of disturbance after the shot were relevant for cortisol levels in hunted cervids. Our results indicate that search teams tracking and euthanising wounded animals should behave in a calm way to minimise disturbance. Still, it is important to acknowledge that many situations described in the literature, i.e. reindeer handling, roe deer captures and red deer yarding, seem even more stressful, beside vehicle collisions, than most hunting methods.     

Interaction of cortisol with the neural retina of the chick embryo in culture.

The uptake of cortisol and the kinetics of hormone-receptor interaction in the cytosol and cell nucleus were investigated in the intact tissue in organ culture. Cortisol is concentrated by the neural retina. The accumulation of the free steroid is temperature dependent but the effect of temperature decreases with the increase of cortisol in medium. Cortisol binding to specific receptors in the cytosol shows a sigmoidal type of kinetics which correlates well with the kinetics of glutamine-synthetase induction by cortisol. The temperature dependent translocation of the receptor-hormone complexes to the nuclei and the effect of detergents on the binding to nuclei are presented.     

Theme D: The Refinement of Animal Procedures

This study investigated the physiological reactions of companion dogs (Canis familiaris) used in animal-assisted activities and animal-assisted therapy by measuring salivary cortisol concentrations. The dog caregivers (owners) collected saliva samples (a) at 3 control days without therapeutic work, (b) directly before and after each therapeutic session during 3 consecutive months, and (c) again at 3 control days without therapeutic work. The study used an enzyme immunoassay to analyze the samples. Cortisol concentrations were significantly higher during therapy days than on control days. Dogs working during the first half of the day produced higher cortisol concentrations after therapeutic sessions than before, whereas dogs working in the afternoon produced lower cortisol concentrations. Cortisol concentrations were higher in short sessions than in long ones and increased relative to the number of therapeutic sessions done during the sampling period. The results indicate that therapeutic work was physiologically arousing for the dogs in this study. Whether these physiological responses are indicative of potentially negative stress or of positive excitement remains an open question.     

Water homeostasis in desert-dwelling horses

This study set out to investigate tolerance of the body water pool to short-term water deprivation in horses and, in particular, to assess whether feral horses from the Namib Desert showed tolerance to dehydration superior to Transvaal. Hydration status was compared in six feral horses from the Namib Desert and in six Boerperd farm horses under conditions of normal hydration and after 72 h of dehydration. Under normal hydration, the two groups did not differ significantly in water intake, plasma sodium and potassium concentrations, plasma osmolality, hematocrit, total plasma protein, body water content, or water turnover (ml.kg-0.82.day-1). The Namib horses were significantly smaller (P less than 0.0001) and turned over 5 liters less water per day than the Boerperd during normal hydration and 4 liters less during dehydration. Increases in plasma sodium concentration after 72 h of dehydration were greater (P less than 0.05) in the Namib horses. It was concluded that horses can easily tolerate water deprivation that results in a 12% reductions in body mass. The feral horses of the Namib desert were not significantly different per unit mass from domestic horses with regard to indexes of total body water content under conditions of normal hydration and after 72 h of dehydration. Their smaller size and, hence, lower water turnover might be mechanisms they use for survival in the Namib Desert.     

A relationship between heat load and plasma enzyme concentration

1. 1. The sensitivity of serum enzyme levels as indicators of tissue damage is less well established in the prodromal period of heatstroke, especially for sub-lethal stress conditions.

2. 2. Anaesthetized rats were exposed to two different sets of thermal conditions.

3. 3. Plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase (CK) and lactate dehydrogenase (LD) were assayed in each group upon termination of stress, 6 h post-stress and 24 h post-stress.

4. 4. The tissue “damage” sustained was mild to moderate and completely reversible.

5. 5. The rate of rise in body temperature may constitute an important factor in the ultimate pathology.

6. 6. CK proved to be the most sensitive parameter of tissue “damage”.

A modified and cost-effective method for hair cortisol analysis

Hair cortisol may hold potential as a biomarker for assessment of chronic psychological stress. We report a modified and cost-effective method to prepare hair samples for cortisol assay. Hair samples were ground using an inexpensive ball grinder – ULTRA-TURRAX tube drive. Cortisol was extracted from the powder under various defined conditions. The data showed that the optimal conditions for this method include cortisol extraction at room temperature and evaporation using a stream of room air. These findings should allow more widespread research using economical technology to validate the utility of hair cortisol as a biomarker for assessing chronic stress status.