Effects of physiological changes and social life events on adrenal glucocorticoid activity in female zoo-housed Asian elephants (Elephas maximus)

Ensuring good health and welfare is an increasingly important consideration for conservation of endangered species and includes breeding of individuals managed under human care. Understanding how factors in the captive environment affect individual animal wellbeing can be aided by long-term monitoring of biological functioning. This study involved longitudinal assessments (4 to 28 years) of reproductive and adrenal hormones in zoo-housed female Asian elephants (Elephas maximus) (age range 4 to ~71 years) to elucidate patterns in adrenal glucocorticoid (GC) activity in association with reproductive and demographic factors, and examine individual response to major social changes. Concentrations of serum and urinary cortisol covaried more consistently with physiological changes (ovarian cycle phase, puberty, pregnancy, lactational anestrus, and age) than with social life events (births, deaths, and facility transfers). Cortisol fluctuated across the ovarian cycle with mean concentrations being higher in the follicular than in the luteal phase, and concentrations were highest in lactational anestrous compared to all other reproductive states. The elephants in this study exhibited substantial individuality in adrenal GC response to major social change, reinforcing the need to assess welfare on an individual basis and to consider factors influencing the impact of perceived stressors, such as social relationships, social support, temperament, and life history. Outcomes from this study deepen our understanding of Asian elephant physiology and highlight the importance of taking intrinsic patterns of hormone secretion into account when evaluating the impact of external factors. Finally, a better understanding of the impact of social change and resiliency in response to real and perceived stressors allows us to improve social management to enhance welfare in both captive settings and free-ranging environments.

Assessment of luteinizing hormone and prolactin immunoactivity in Asian and African elephant urine using assays validated for serum

Analysis of serum hormones is useful for timing artificial insemination (Luteinizing hormone) and diagnosing pregnancy (prolactin) in elephants. However, these tests require blood collection, which is not tolerated by all animals, and is impractical for field studies. Thus, developing a means to obtain these measures noninvasively could improve species management. Matched urine and serum was collected from Asian and African elephants daily throughout the follicular phase and after administration of a GnRH analogue for LH determination, and in pregnant and nonpregnant females for prolactin analyses using immunoassays validated for elephant serum. Despite identifying robust increases in circulating hormone concentrations, no concomitant changes in urinary LH or prolactin immunoactivity was detected. Concentration of samples by centrifugal filtration or ethanol precipitation did not increase the ability to measure biologically relevant changes in endogenous urinary LH or prolactin immunoactivity. Sample matrix interference was ruled out following sufficient recovery of exogenous LH or prolactin added to samples, except for samples concentrated >35-fold where some interference was suspected. These results suggest that elephants either do not excrete native LH or prolactin in urine, or concentrations are too low to be measured accurately by standard immunoassay techniques that are valid for serum analyses. Thus, it does not appear feasible or economically viable to use these noninvasive tests for ovulation detection or for pregnancy diagnosis in elephants.

Insect pheromones and precursors in female African elephant urine

Using automated solid-phase dynamic extraction and gas chromatography-mass spectrometry, our search for urinary chemical signals from ovulatory female African elephants (Loxodonta africana) has revealed the bark beetle aggregation pheromones frontalin, exo-brevicomin, and endo-brevicomin, as well as their precursors and the aphid alarm pheromones (E,E)-alpha-farnesene and (E)-beta-farnesene. Enantiomeric ratios for brevicomins have been determined. Prior discovery of common insect/elephant pheromones in Asian elephants, namely, (Z)-7-dodecenyl acetate and frontalin, suggests that the present findings may yield valuable insights into chemical communication among African elephants.

Relaxin concentrations in serum and urine of endangered species: correlations with physiologic events and use as a marker of pregnancy

Many mammalian species are facing extinction due to problems created by human encroachment, agriculture, pollution, and willful slaughter. Among those at risk are the Asian and African elephant, Sumatran rhinoceros, and giant panda. Conservation groups try to save species in the wild by preserving habitat and limiting animal-human conflicts, often with limited success. Another alternative is to preserve the extant gene pool through captive breeding as a hedge against extinction. Measurement of circulating reproductive hormones is impractical for most wildlife species; determination of urinary or fecal hormone metabolites provides a more viable approach. To aid breeding management, one important tool is the ability to diagnose and monitor pregnancy, especially in species with long gestations (e.g., rhinos over 15 mo and elephants over 20 mo). Unfortunately, measuring progestins often is not useful diagnostically, because concentrations are similar during at least part of the pregnancy and the nonpregnant luteal phase in some species (e.g., elephants, rhinoceroses, and giant pandas). As serum relaxin reliably distinguishes between pregnancy and pseudopregnancy in bitches, relaxin measurement might also provide a method for detecting a successful pregnancy in endangered species. Appropriate immunoassay reagents have enabled the estimation of relaxin concentrations in the serum of elephants and rhinos and the determination of pregnancy establishment and the outcome. Relaxin was also detected in panda serum and urine. However, the extreme variability of the time between observed mating and parturition and the confounding factors of delayed implantation, pseudopregnancy, and frequent fetal resorptions made it impossible to use the panda relaxin data as a specific marker of pregnancy.

Diagnosis and treatment of presumptive pyelonephritis in an Asian elephant (Elephas maximus)

A 37-yr-old female Asian elephant (Elephas maximus) presented with anorexia, restlessness, and dark-colored urine. Urinalyses showed hematuria, leukocyturia, isosthenuria, proteinuria, granular casts, and no calcium oxalate crystals. Bloodwork revealed azotemia. Urine culture revealed a pure growth of Streptococcus zooepidemicus resistant to sulfamethoxazole-trimethoprim but susceptible to cephalosporins. A presumptive diagnosis of pyelonephritis was made based on bloodwork, urinalysis, and urine culture. The animal was treated with intravenous ceftiofur, and intravenous and per rectum fluids were given for hydration. The elephant's attitude and appetite returned to normal, the abnormal blood parameters resolved, and urinary calcium oxalate crystals reappeared after treatment, supporting presumptive diagnosis. Follow-up ultrasonography revealed an abnormal outline of both kidneys with parenchymal hyperechogenicity and multiple uterine leiomyomas.

Non-invasive assessment of adrenocortical function in the male African elephant (Loxodonta africana) and its relation to musth

Adult male elephants periodically show the phenomenon of musth, a condition associated with increased aggressiveness, restlessness, significant weight reduction and markedly elevated androgen levels. It has been suggested that musth-related behaviours are costly and that therefore musth may represent a form of physiological stress. In order to provide data on this largely unanswered question, the first aim of this study was to evaluate different assays for non-invasive assessment of adrenocortical function in the male African elephant by (i) characterizing the metabolism and excretion of [3H]cortisol (3H-C) and [14C]testosterone (14C-T) and (ii) using this information to evaluate the specificity of four antibodies for determination of excreted cortisol metabolites, particularly with respect to possible cross-reactions with androgen metabolites, and to assess their biological validity using an ACTH challenge test. Based on the methodology established, the second objective was to provide data on fecal cortisol metabolite concentrations in bulls during the musth and non-musth condition. 3H-C (1 mCi) and 14C-T (100 microCi) were injected simultaneously into a 16 year old male and all urine and feces collected for 30 and 86 h, respectively. The majority (82%) of cortisol metabolites was excreted into the urine, whereas testosterone metabolites were mainly (57%) excreted into the feces. Almost all radioactive metabolites recovered from urine were conjugated (86% 3H-C and 97% 14C-T). In contrast, 86% and >99% of the 3H-C and 14C-T metabolites recovered from feces consisted of unconjugated forms. HPLC separations indicated the presence of various metabolites of cortisol in both urine and feces, with cortisol being abundant in hydrolysed urine, but virtually absent in feces. Although all antibodies measured substantial amounts of immunoreactivity after HPLC separation of peak radioactive samples and detected an increase in glucocorticoid output following the ACTH challenge, only two (in feces against 3alpha,11-oxo-cortisol metabolites, measured by an 11-oxo-etiocholanolone-EIA and in urine against cortisol, measured by a cortisol-EIA) did not show substantial cross-reactivity with excreted 14C-T metabolites and could provide an acceptable degree of specificity for reliable assessment of glucocorticoid output from urine and feces. Based on these findings, concentrations of immunoreactive 3alpha,11-oxo-cortisol metabolites were determined in weekly fecal samples collected from four adult bulls over periods of 11-20 months to examine whether musth is associated with increased adrenal activity. Results showed that in each male levels of these cortisol metabolites were not elevated during periods of musth, suggesting that in the African elephant musth is generally not associated with marked elevations in glucocorticoid output. Given the complex nature of musth and the variety of factors that are likely to influence its manifestation, it is clear, however, that further studies, particularly on free-ranging animals, are needed before a possible relationship between musth and adrenal function can be resolved. This study also clearly illustrates the potential problems associated with cross-reacting metabolites of gonadal steroids in EIAs measuring glucocorticoid metabolites. This has to be taken into account when selecting assays and interpreting results of glucocorticoid metabolite analysis, not only for studies in the elephant but also in other species.

Frontalin: a chemical message of musth in Asian elephants (Elephas maximus)

Musth is an important male phenomenon affecting many aspects of elephant society including reproduction. During musth, the temporal gland secretions (as well as the urine and breath) of adult male Asian elephants (Elephas maximus) discharge a variety of malodorous compounds together with the bicyclic ketal, frontalin. In contrast, teenage male elephants in musth release a sweet-smelling exudate from their facial temporal gland. We recently demonstrated that the concentration of frontalin becomes increasingly evident as male elephants mature. In the present study, we demonstrate that behaviors exhibited towards frontalin are consistent and dependent on the sex, developmental stage and physiological status of the responding conspecific individual. To examine whether frontalin functions as a chemical signal, perhaps even a pheromone, we bioassayed older and younger adult males, and luteal- and follicular-phase and pregnant females for their chemosensory and behavioral responses to frontalin. Adult males were mostly indifferent to frontalin, whereas subadult males were highly reactive, often exhibiting repulsion or avoidance. Female chemosensory responses to frontalin varied with hormonal state. Females in the luteal phase demonstrated low frequencies of responses, whereas pregnant females responded significantly more frequently, with varied types of responses including those to the palatal pits. Females in the follicular phase were the most responsive and often demonstrated mating-related behaviors subsequent to high chemosensory responses to frontalin. Our evidence strongly suggests that frontalin, a well-studied pheromone in insects, also functions as a pheromone in the Asian elephant: it exhibits all of the determinants that define a pheromone and evidently conveys some of the messages underlying the phenomenon of musth.

Chemosignalling of musth by individual wild African elephants (Loxodonta africana): implications for conservation and management

Elephants have extraordinary olfactory receptive equipment, yet this sensory system has been only minimally investigated in wild elephants. We present an in-depth study of urinary chemical signals emitted by individual, behaviourally characterized, wild male African elephants, investigating whether these compounds were the same, accentuated, or diminished in comparison with captive individuals. Remarkably, most emitted chemicals were similar in captive and wild elephants with an exception traced to drought-induced dietary cyanates among wild males. We observed developmental changes predominated by the transition from acids and esters emitted by young males to alcohols and ketones released by older males. We determined that the ketones (2-butanone, acetone and 2-pentanone, and 2-nonanone) were considerably elevated during early musth, musth and late musth, respectively, suggesting that males communicate their condition via these compounds. The similarity to compounds released during musth by Asian male elephants that evoke conspecific bioresponses suggests the existence of species-free 'musth' signals. Our innovative techniques, which allow the recognition of precise sexual and musth states of individual elephants, can be helpful to managers of both wild and captive elephants. Such sampling may allow the more accurate categorization of the social and reproductive status of individual male elephants.

Demonstration of 2-unsaturated C19-steroids in the urine of female Asian elephants, Elephas maximus, and their dependence on ovarian activity

Air-borne volatile substances have been demonstrated to signal oestrus, induce ovulation and synchronize ovarian activity in different mammals. An oestrous-related pheromone of the female Asian elephant (Elephas maximus) is known to induce behavioural responses in elephant bulls. Additional data revealed that timing of oestrus in females with close social relationships tends to be synchronized. Therefore, urine from female Asian elephants might be expected to contain luteal phase-dependent volatile substances, which may function as additional chemical signals in this species. The aim of the present study was to identify such compounds and to investigate their pattern of excretion throughout the ovarian cycle. Urine samples were collected three times a week during the follicular phase and one to three times a week during the luteal phase from five adult female Asian elephants from a total of 13 non-conception cycles and one conception cycle, including the first 72 weeks of pregnancy. A simple headspace solid-phase microextraction method has been developed for quantification of urinary volatile substances and analysis was performed by gas chromatography. The comparison of urine collected during the follicular and the luteal phase indicated the presence of two luteal phase-dependent substances. Mass spectrometry was used to identify one substance as 5alpha-androst-2-en-17-one and a second substance as the corresponding alcoholic compound 5alpha-androst-2-en-17beta-ol. The 5alpha-androst-2-en-17beta-ol and -17-one profiles reflected cyclic ovarian activity with clear (10-20-fold) luteal phase increases. Furthermore, measurements of both compounds were correlated positively with the concentration of urinary pregnanetriol and indicated cycle duration (15.1 +/- 1.2 weeks) similar to that obtained from pregnanetriol measurements (15.2 +/- 1.6 weeks). The results demonstrate the presence of two luteal phase-specific steroidal volatile compounds in elephant urine. One of the substances, 5alpha-androst-2-en-17-one, has been demonstrated in human axillary bacterial isolates. The measurement of both volatile substances in elephant urine can be used for rapid detection of the stage of the ovarian cycle, as the analysis can be completed within 2 h.

Patterns of urinary and fecal steroid excretion during the ovarian cycle and pregnancy in the African elephant (Loxodonta africana)

The aims of the present study were to (i) determine the relative abundance of the 5alpha-reduced progestins 5alpha-pregnane-3-ol-20-one (5alpha-P-3OH) and 5alpha-dihydroprogesterone (5alpha-DHP) and progesterone (P4) in African elephant feces and to establish improved fecal progestin assays for monitoring ovarian function; and (ii) describe longitudinal profiles of urinary and fecal progestin and estrogen metabolites during pregnancy. Matched urine and fecal samples were collected weekly from six adult females throughout 18 nonfertile cycles and two complete pregnancies (89 and 93 weeks duration). Fecal samples were lyophilized and extracted with 80% methanol in water and immunoreactive 5alpha-P-3OH, 5alpha-DHP, and P4 and (for pregnant females only) estrone (E1) and estradiol (E2) determined by enzyme immunoassay. Urine samples were hydrolyzed, ether-extracted, and assayed for 5alpha-P-3OH, E1, and E2. HPLC cochromatography of fecal extracts with various radioactive progestin tracers confirmed the presence of large amounts of both 5-reduced progestins (5alpha-P-3OH > 5alpha-DHP) but not of P4. 5-Reduced progestins (but not P4) were excreted in a cyclic pattern and levels were significantly correlated with urinary 5alpha-P-3OH. Fecal 5alpha-P-3OH showed the more pronounced and consistent luteal-phase elevation and a better correspondence to urine with respect to timing of the luteal-phase rise. Fecal and urinary 5-reduced progestins increased gradually during early pregnancy to maximum values around week 40-45. Levels gradually declined during the second half of pregnancy, reaching baseline values 2 days before parturition. Urinary estrogens did not show any cyclic pattern during the preconception period and levels remained low during the first 30 weeks of gestation. Thereafter, there was a rapid 10- to 20-fold increase to maximum values at mid-pregnancy, followed by a gradual decline to birth. There was no mid-pregnancy elevation in fecal estrogens, but there was a modest increase in E1 during the second half of gestation.

Musth and urinary testosterone concentrations in the African elephant (Loxodonta africana)

Urine samples were obtained from free-ranging African elephants that were considered to be in and out of musth. Testosterone concentrations, measured by radioimmunoassay were significantly greater in males that were in or around the time of behavioural musth. This study supports a correlation between the observed behavioural characteristics of musth and urinary testosterone levels.

Monitoring the estrous cycle of the Asian elephant (Elephas maximus), using urinary estrogens

The estrous cycle of the Asian elephant (Elephas maximus) was monitored by analysis of urinary estrogens. Daily morning urine samples were analyzed for estrone (E1), estradiol (E2), and total immunoreactive estrogen (ET). The ET values were shown to correlate poorly with E1 and E2 values and failed to reveal any patterns of reproductive cycling. Daily E1 and E2 values, indexed by creatinine concentrations, demonstrated cyclic profiles in those samples of sufficient concentration. The technique offered a simple, noninvasive method of documenting ovarian function in the elephant.