FREE SHIPPING over $40
OVER 10000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Animals : an open access journal from MDPI2023; 13(13); doi: 10.3390/ani13132133

Hair Cortisol Concentrations in Feral Horses and the Influence of Physiological and Social Factors.

Abstract: Cortisol is a glucocorticoid hormone produced during activation of the hypothalamic-pituitary-adrenal axis (HPA) in response to psychological or physiological demands. High amounts of circulating cortisol can be found in individuals experiencing energetically demanding physiological events, such as pregnancy, lactation, injury, or starvation, but, also, in individuals who may have less obvious HPA activation from social situations. The feral horse population on Sable Island (Nova Scotia, Canada) provides an opportunity to look at hair cortisol concentration (HCC) as a proxy for circulating cortisol concentration to better understand physiological correlates. The horse's complex social structure also allows us to look at how the population and group structure may influence HPA activation. Hair samples (n = 282) were analyzed from 113 females and 135 males. Females with dependent offspring (foals) had higher HCC than those females without dependent offspring (p = 0.005). Horses in poor body condition were also more likely to have higher HCC (females: p < 0.001, males: p = 0.028); females had greater variation in the body condition index (BCI), which also correlated with foal production. In general, the top-ranked models describing female cortisol levels included age, BCI, presence of a foal, as well as social measures such as harem size and the number of bachelors in the vicinity. The top model describing male cortisol levels included age, BCI, and year of collection only, and the number of bachelors in the home range appeared in subsequent, though still high-ranked, models. Among the variables not of direct interest, we found some significant results relating to hair color and hair texture. Differences in HCC patterns between feral and domestically kept horses (e.g., age and sex) are likely linked to periods of resource limitations, particularly for individuals experiencing energetically demanding processes such as reproduction, illness/parasitism, or related to experiencing the full range of social and reproductive behaviors.
Get Full Text
Publication Date: 2023-06-27 PubMed ID: 37443930PubMed Central: PMC10339936DOI: 10.3390/ani13132133Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research paper discusses a study conducted on feral horses in Sable Island, Nova Scotia, Canada. The researchers studied the hair cortisol concentrations of these horses to understand how physiological and social factors influence their glucocorticoid hormone production.

Research Methodology and Objective

  • The researchers used hair cortisol concentration (HCC) as a measure for circulating cortisol concentration. Cortisol is a hormone produced in response to psychological or physiological stress.
  • A total of 282 hair samples were analyzed, collected from 113 female and 135 male horses.
  • The complex social structure of the feral horse populations was utilized to understand how population and group structures influence HPA activation.

Key Findings

  • Horses with dependent offspring or in poor body condition were more likely to have higher HCC. This might be due to the energetic demands of pregnancy, lactation, injury, or starvation.
  • In females, the top-ranked models for cortisol levels included age, body condition index, presence of a foal, harem size, and the number of bachelor horses in the vicinity.
  • On the other hand, the top model for male cortisol levels included age, body condition index, and year of collection, with the number of bachelor horses appearing in subsequent models.

Implications and Significance

  • The study provides insights into some of the influences on cortisol production in feral horses. This could have potential applications in understanding stress responses in other wild animal populations.
  • The authors suggest that differences in HCC patterns between feral and domestic horses, such as age and sex, could be linked to periods of resource limitations — in particular for reproduction and illness — or related to social and reproductive behaviors.

Additional Findings

  • The researchers also found significant results relating to hair color and hair texture, though these were not the primary focus of the study.

Cite This Article

APA
Medill SA, Janz DM, McLoughlin PD. (2023). Hair Cortisol Concentrations in Feral Horses and the Influence of Physiological and Social Factors. Animals (Basel), 13(13). https://doi.org/10.3390/ani13132133

Publication

Animals : an open access journal from MDPI
ISSN: 2076-2615
NlmUniqueID: 101635614
Country: Switzerland
Language: English
Volume: 13
Issue: 13

Researcher Affiliations

Medill, Sarah A
  • Department of Biology, University of Saskatchewan, Saskatoon, SK S7N 5C8, Canada.
Janz, David M
  • Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.
McLoughlin, Philip D
  • Department of Biology, University of Saskatchewan, Saskatoon, SK S7N 5C8, Canada.

Grant Funding

  • 371535-2009 / Natural Sciences and Engineering Research Council
  • 25046 / Canada Foundation for Innovation

Conflict of Interest Statement

The authors declare no conflict of interest.

References

This article includes 109 references
  1. Sapolsky RM, Romero LM, Munck AU. How do glucocorticoids influence stress responses? Integrating permissive, suppressive, stimulatory, and preparative actions.. Endocr Rev 2000 Feb;21(1):55-89.
    doi: 10.1210/edrv.21.1.0389pubmed: 10696570google scholar: lookup
  2. Boonstra R. Reality as the Leading Cause of Stress: Rethinking the Impact of Chronic Stress in Nature. Funct. Ecol. 2013;27:11–23.
    doi: 10.1111/1365-2435.12008google scholar: lookup
  3. Sapolsky RM. Why Zebras Don’t Get Ulcers: The Acclaimed Guide to Stress, Stress-Related Diseases, and Coping. 3rd ed. Henry Holt and Company; New York, NY, USA: 2004.
  4. Koren L, Mokady O, Geffen E. Social status and cortisol levels in singing rock hyraxes.. Horm Behav 2008 Jun;54(1):212-6.
    doi: 10.1016/j.yhbeh.2008.02.020pubmed: 18423638google scholar: lookup
  5. Creel S, Dantzer B, Goymann W, Rubenstein DR. The Ecology of Stress: Effects of the Social Environment. Funct. Ecol. 2013;27:66–80.
    doi: 10.1111/j.1365-2435.2012.02029.xgoogle scholar: lookup
  6. Dantzer B, Fletcher QE, Boonstra R, Sheriff MJ. Measures of physiological stress: a transparent or opaque window into the status, management and conservation of species?. Conserv Physiol 2014;2(1):cou023.
    doi: 10.1093/conphys/cou023pmc: PMC4732472pubmed: 27293644google scholar: lookup
  7. Kersey DC, Dehnhard M. The use of noninvasive and minimally invasive methods in endocrinology for threatened mammalian species conservation.. Gen Comp Endocrinol 2014 Jul 1;203:296-306.
    doi: 10.1016/j.ygcen.2014.04.022pubmed: 24798579google scholar: lookup
  8. Cattet M, Stenhouse GB, Boulanger J, Janz DM, Kapronczai L, Swenson JE, Zedrosser A. Can concentrations of steroid hormones in brown bear hair reveal age class?. Conserv Physiol 2018;6(1):coy001.
    doi: 10.1093/conphys/coy001pmc: PMC5788069pubmed: 29399362google scholar: lookup
  9. Sheriff MJ, Dantzer B, Delehanty B, Palme R, Boonstra R. Measuring stress in wildlife: techniques for quantifying glucocorticoids.. Oecologia 2011 Aug;166(4):869-87.
    doi: 10.1007/s00442-011-1943-ypubmed: 21344254google scholar: lookup
  10. Meyer JS, Novak MA. Minireview: Hair cortisol: a novel biomarker of hypothalamic-pituitary-adrenocortical activity.. Endocrinology 2012 Sep;153(9):4120-7.
    doi: 10.1210/en.2012-1226pmc: PMC3423616pubmed: 22778226google scholar: lookup
  11. Russell E, Koren G, Rieder M, Van Uum S. Hair cortisol as a biological marker of chronic stress: current status, future directions and unanswered questions.. Psychoneuroendocrinology 2012 May;37(5):589-601.
    doi: 10.1016/j.psyneuen.2011.09.009pubmed: 21974976google scholar: lookup
  12. Novak MA, Hamel AF, Kelly BJ, Dettmer AM, Meyer JS. Stress, the HPA axis, and nonhuman primate well-being: A review.. Appl Anim Behav Sci 2013 Jan 31;143(2-4):135-149.
    doi: 10.1016/j.applanim.2012.10.012pmc: PMC3580872pubmed: 23459687google scholar: lookup
  13. Macbeth BJ, Cattet MRL, Stenhouse GB, Gibeau ML, Janz DM. Hair Cortisol Concentration as a Noninvasive Measure of Long-Term Stress in Free-Ranging Grizzly Bears (Ursus Arctos): Considerations with Implications for Other Wildlife. Can. J. Zool. 2010;88:935–949.
    doi: 10.1139/Z10-057google scholar: lookup
  14. González-de-la-Vara Mdel R, Valdez RA, Lemus-Ramirez V, Vázquez-Chagoyán JC, Villa-Godoy A, Romano MC. Effects of adrenocorticotropic hormone challenge and age on hair cortisol concentrations in dairy cattle.. Can J Vet Res 2011 Jul;75(3):216-21.
    pmc: PMC3122973pubmed: 22210998
  15. Kirschbaum C, Tietze A, Skoluda N, Dettenborn L. Hair as a retrospective calendar of cortisol production-Increased cortisol incorporation into hair in the third trimester of pregnancy.. Psychoneuroendocrinology 2009 Jan;34(1):32-7.
    doi: 10.1016/j.psyneuen.2008.08.024pubmed: 18947933google scholar: lookup
  16. Carlitz EH, Kirschbaum C, Stalder T, van Schaik CP. Hair as a long-term retrospective cortisol calendar in orang-utans (Pongo spp.): new perspectives for stress monitoring in captive management and conservation.. Gen Comp Endocrinol 2014 Jan 1;195:151-6.
    doi: 10.1016/j.ygcen.2013.11.002pubmed: 24239791google scholar: lookup
  17. Stalder T, Steudte S, Miller R, Skoluda N, Dettenborn L, Kirschbaum C. Intraindividual stability of hair cortisol concentrations.. Psychoneuroendocrinology 2012 May;37(5):602-10.
    doi: 10.1016/j.psyneuen.2011.08.007pubmed: 21917384google scholar: lookup
  18. Bechshøft TØ, Sonne C, Dietz R, Born EW, Novak MA, Henchey E, Meyer JS. Cortisol levels in hair of East Greenland polar bears.. Sci Total Environ 2011 Jan 15;409(4):831-4.
    doi: 10.1016/j.scitotenv.2010.10.047pmc: PMC3019279pubmed: 21144554google scholar: lookup
  19. Fourie NH, Bernstein RM. Hair cortisol levels track phylogenetic and age related differences in hypothalamic-pituitary-adrenal (HPA) axis activity in non-human primates.. Gen Comp Endocrinol 2011 Nov 1;174(2):150-5.
    doi: 10.1016/j.ygcen.2011.08.013pubmed: 21893059google scholar: lookup
  20. Fourie NH, Turner TR, Brown JL, Pampush JD, Lorenz JG, Bernstein RM. Variation in vervet (Chlorocebus aethiops) hair cortisol concentrations reflects ecological disturbance by humans.. Primates 2015 Oct;56(4):365-73.
    doi: 10.1007/s10329-015-0486-ypubmed: 26318176google scholar: lookup
  21. Laudenslager ML, Jorgensen MJ, Fairbanks LA. Developmental patterns of hair cortisol in male and female nonhuman primates: lower hair cortisol levels in vervet males emerge at puberty.. Psychoneuroendocrinology 2012 Oct;37(10):1736-9.
    doi: 10.1016/j.psyneuen.2012.03.015pmc: PMC3398229pubmed: 22497987google scholar: lookup
  22. Dettmer AM, Novak MA, Meyer JS, Suomi SJ. Population density-dependent hair cortisol concentrations in rhesus monkeys (Macaca mulatta).. Psychoneuroendocrinology 2014 Apr;42:59-67.
    doi: 10.1016/j.psyneuen.2014.01.002pmc: PMC3959662pubmed: 24636502google scholar: lookup
  23. Fourie NH, Jolly CJ, Phillips-Conroy JE, Brown JL, Bernstein RM. Variation of hair cortisol concentrations among wild populations of two baboon species (Papio anubis, P. hamadryas) and a population of their natural hybrids.. Primates 2015 Jul;56(3):259-72.
    doi: 10.1007/s10329-015-0469-zpubmed: 25903227google scholar: lookup
  24. Macbeth BJ, Cattet MRL, Obbard ME, Middel K, Janz DM. Evaluation of Hair Cortisol Concentration as a Biomarker of Long-Term Stress in Free-Ranging Polar Bears. Wildl. Soc. Bull. 2012;36:747–758.
    doi: 10.1002/wsb.219google scholar: lookup
  25. Bechshøft TØ, Sonne C, Rigét FF, Letcher RJ, Novak MA, Henchey E, Meyer JS, Eulaers I, Jaspers VLB, Covaci A. Polar Bear Stress Hormone Cortisol Fluctuates with the North Atlantic Oscillation Climate Index. Polar Biol. 2013;36:1525–1529.
    doi: 10.1007/s00300-013-1364-ygoogle scholar: lookup
  26. Olvera-Maneu S, Carbajal A, Gardela J, Lopez-Bejar M. Hair Cortisol, Testosterone, Dehydroepiandrosterone Sulfate and Their Ratios in Stallions as a Retrospective Measure of Hypothalamic-Pituitary-Adrenal and Hypothalamic-Pituitary-Gonadal Axes Activity: Exploring the Influence of Seasonality.. Animals (Basel) 2021 Jul 25;11(8).
    doi: 10.3390/ani11082202pmc: PMC8388521pubmed: 34438659google scholar: lookup
  27. Bryan HM, Darimont CT, Paquet PC, Wynne-Edwards KE, Smits JE. Stress and reproductive hormones in grizzly bears reflect nutritional benefits and social consequences of a salmon foraging niche.. PLoS One 2013;8(11):e80537.
    doi: 10.1371/journal.pone.0080537pmc: PMC3842319pubmed: 24312230google scholar: lookup
  28. Dettmer AM, Rosenberg KL, Suomi SJ, Meyer JS, Novak MA. Associations between Parity, Hair Hormone Profiles during Pregnancy and Lactation, and Infant Development in Rhesus Monkeys (Macaca mulatta).. PLoS One 2015;10(7):e0131692.
    doi: 10.1371/journal.pone.0131692pmc: PMC4501543pubmed: 26172048google scholar: lookup
  29. Malcolm KD, McShea WJ, Van Deelen TR, Bacon HJ, Liu F, Putman S, Zhu X, Brown JL. Analyses of fecal and hair glucocorticoids to evaluate short- and long-term stress and recovery of Asiatic black bears (Ursus thibetanus) removed from bile farms in China.. Gen Comp Endocrinol 2013 May 1;185:97-106.
    doi: 10.1016/j.ygcen.2013.01.014pubmed: 23416358google scholar: lookup
  30. Nuñez CM, Adelman JS, Smith J, Gesquiere LR, Rubenstein DI. Linking social environment and stress physiology in feral mares (Equus caballus): group transfers elevate fecal cortisol levels.. Gen Comp Endocrinol 2014 Jan 15;196:26-33.
    doi: 10.1016/j.ygcen.2013.11.012pubmed: 24275609google scholar: lookup
  31. Laudenslager ML, Natvig C, Corcoran CA, Blevins MW, Pierre PJ, Bennett AJ. The influences of perinatal challenge persist into the adolescent period in socially housed bonnet macaques (Macaca radiata).. Dev Psychobiol 2013 Apr;55(3):316-22.
    doi: 10.1002/dev.21030pmc: PMC3404189pubmed: 22488164google scholar: lookup
  32. Yamanashi Y, Morimura N, Mori Y, Hayashi M, Suzuki J. Cortisol analysis of hair of captive chimpanzees (Pan troglodytes).. Gen Comp Endocrinol 2013 Dec 1;194:55-63.
    doi: 10.1016/j.ygcen.2013.08.013pubmed: 24013009google scholar: lookup
  33. Yu T, Xu H, Wang W, Li S, Chen Z, Deng H. Determination of endogenous corticosterone in rodent's blood, brain and hair with LC-APCI-MS/MS.. J Chromatogr B Analyt Technol Biomed Life Sci 2015 Oct 1;1002:267-76.
    doi: 10.1016/j.jchromb.2015.08.035pubmed: 26343018google scholar: lookup
  34. Brearley G, McAlpine C, Bell S, Bradley A. Influence of Urban Edges on Stress in an Arboreal Mammal: A Case Study of Squirrel Gliders in Southeast Queensland, Australia. Landsc. Ecol. 2012;27:1407–1419.
    doi: 10.1007/s10980-012-9790-8google scholar: lookup
  35. Bourbonnais ML, Nelson TA, Cattet MR, Darimont CT, Stenhouse GB. Spatial analysis of factors influencing long-term stress in the grizzly bear (Ursus arctos) population of Alberta, Canada.. PLoS One 2013;8(12):e83768.
    doi: 10.1371/journal.pone.0083768pmc: PMC3873976pubmed: 24386273google scholar: lookup
  36. Bryan HM, Smits JEG, Koren L, Paquet PC, Wynne-Edwards KE, Musiani M. Heavily Hunted Wolves Have Higher Stress and Reproductive Steroids than Wolves with Lower Hunting Pressure. Funct. Ecol. 2015;29:347–356.
    doi: 10.1111/1365-2435.12354google scholar: lookup
  37. Potratz EJ, Brown JS, Gallo T, Anchor C, Santymire RM. Effects of Demography and Urbanization on Stress and Body Condition in Urban White-Tailed Deer. Urban Ecosyst. 2019;22:807–816.
    doi: 10.1007/s11252-019-00856-8google scholar: lookup
  38. Mazzola SM, Colombani C, Pizzamiglio G, Cannas S, Palestrini C, Costa ED, Gazzonis AL, Bionda A, Crepaldi P. Do You Think I Am Living Well? A Four-Season Hair Cortisol Analysis on Leisure Horses in Different Housing and Management Conditions.. Animals (Basel) 2021 Jul 20;11(7).
    doi: 10.3390/ani11072141pmc: PMC8300697pubmed: 34359269google scholar: lookup
  39. Sauveroche M, Henriksson J, Theodorsson E, Svensson Holm AC, Roth LSV. Hair Cortisol in Horses (Equus caballus) in Relation to Management Regimes, Personality, and Breed. J. Vet. Behav. 2020;37:1–7.
    doi: 10.1016/j.jveb.2019.12.002google scholar: lookup
  40. Duran MC, Janz DM, Waldner CL, Campbell JR, Marques FJ. Hair Cortisol Concentration as a Stress Biomarker in Horses: Associations with Body Location and Surgical Castration. J. Equine Vet. Sci. 2017;55:27–33.
    doi: 10.1016/j.jevs.2017.03.220google scholar: lookup
  41. Cerasoli F, Podaliri Vulpiani M, Saluti G, Conte A, Ricci M, Savini G, D'Alterio N. Assessment of Welfare in Groups of Horses with Different Management, Environments and Activities by Measuring Cortisol in Horsehair, Using Liquid Chromatography Coupled to Hybrid Orbitrap High-Resolution Mass Spectrometry.. Animals (Basel) 2022 Jul 6;12(14).
    doi: 10.3390/ani12141739pmc: PMC9312200pubmed: 35883286google scholar: lookup
  42. Kirkpatrick JF, Baker CB, Turner JW, Kenney RM, Ganjam VK. Plasma Corticosteroids as an Index of Stress in Captive Feral Horses. J. Wildl. Manag. 1979;43:801.
    doi: 10.2307/3808770google scholar: lookup
  43. Rietmann TR, Staﾬher M, Bernasconi P, Auer JA, Weishaupt MA. The association between heart rate, heart rate variability, endocrine and behavioural pain measures in horses suffering from laminitis.. J Vet Med A Physiol Pathol Clin Med 2004 Jun;51(5):218-25.
    doi: 10.1111/j.1439-0442.2004.00627.xpubmed: 15315700google scholar: lookup
  44. Zandoná Meleiro MC, de Carvalho HJC, Ribeiro RR, da Silva MD, Salles Gomes CM, Miglino MA, de Santis Prada IL. Immune Functions Alterations Due to Racing Stress in Thoroughbred Horses.. Animals (Basel) 2022 May 7;12(9).
    doi: 10.3390/ani12091203pmc: PMC9104563pubmed: 35565629google scholar: lookup
  45. Holtby AR, McGivney BA, Browne JA, Katz LM, Murphy KJ, Hill EW. Variation in salivary cortisol responses in yearling Thoroughbred racehorses during their first year of training.. PLoS One 2023;18(4):e0284102.
    doi: 10.1371/journal.pone.0284102pmc: PMC10079128pubmed: 37023093google scholar: lookup
  46. Sinderbrand CA. The Relationship of Dominance, Reproductive State and Stress in a Non-Cooperative Breeder, the Domestic Horse (Equus caballus). Western Kentucky University; Bowling Green, KY, USA: 2011.
  47. Aurich J, Wulf M, Ille N, Erber R, von Lewinski M, Palme R, Aurich C. Effects of season, age, sex, and housing on salivary cortisol concentrations in horses.. Domest Anim Endocrinol 2015 Jul;52:11-6.
    doi: 10.1016/j.domaniend.2015.01.003pubmed: 25700267google scholar: lookup
  48. Nagel C, Erber R, Bergmaier C, Wulf M, Aurich J, Möstl E, Aurich C. Cortisol and progestin release, heart rate and heart rate variability in the pregnant and postpartum mare, fetus and newborn foal.. Theriogenology 2012 Sep 1;78(4):759-67.
    doi: 10.1016/j.theriogenology.2012.03.023pubmed: 22626780google scholar: lookup
  49. Comin A, Veronesi MC, Montillo M, Faustini M, Valentini S, Cairoli F, Prandi A. Hair cortisol level as a retrospective marker of hypothalamic-pituitary-adrenal axis activity in horse foals.. Vet J 2012 Oct;194(1):131-2.
    doi: 10.1016/j.tvjl.2012.04.006pubmed: 22633175google scholar: lookup
  50. Alexander SL, Irvine CH. The effect of social stress on adrenal axis activity in horses: the importance of monitoring corticosteroid-binding globulin capacity.. J Endocrinol 1998 Jun;157(3):425-32.
    doi: 10.1677/joe.0.1570425pubmed: 9691975google scholar: lookup
  51. Anderson MK, Friend TH, Evans JW, Bushong DM. Behavioral Assessment of Horses in Therapeutic Riding Programs. Appl. Anim. Behav. Sci. 1999;63:11–24.
    doi: 10.1016/S0168-1591(98)00237-8google scholar: lookup
  52. Erber R, Wulf M, Rose-Meierhöfer S, Becker-Birck M, Möstl E, Aurich J, Hoffmann G, Aurich C. Behavioral and physiological responses of young horses to different weaning protocols: a pilot study.. Stress 2012 Mar;15(2):184-94.
    doi: 10.3109/10253890.2011.606855pubmed: 21875302google scholar: lookup
  53. Plotka ED, Eagle TC, Gaulke SJ, Tester JR, Siniff DB. Hematologic and blood chemical characteristics of feral horses from three management areas.. J Wildl Dis 1988 Apr;24(2):231-9.
    doi: 10.7589/0090-3558-24.2.231pubmed: 3373630google scholar: lookup
  54. Seal US, Siniff DB, Tester JR, Williams TD. Chemical immobilization and blood analysis of feral horses (Equus caballus).. J Wildl Dis 1985 Oct;21(4):411-6.
    doi: 10.7589/0090-3558-21.4.411pubmed: 4078978google scholar: lookup
  55. Jones MM, Nuñez CMV. Laissez-Faire Stallions? Males' Fecal Cortisol Metabolite Concentrations Do Not Vary with Increased Female Turnover in Feral Horses (Equus caballus).. Animals (Basel) 2023 Jan 3;13(1).
    doi: 10.3390/ani13010176pmc: PMC9817692pubmed: 36611784google scholar: lookup
  56. Laforge MP, Uzal A, Medill SA, Mcloughlin PD. Scale-dependent Effects of Density and Habitat on Foal Survival. J. Wildl. Manag. 2016;80:347–354.
    doi: 10.1002/jwmg.1015google scholar: lookup
  57. Manning JA, Medill SA, McLoughlin PD. Climate Fluctuations Interact with Local Demography and Resources to Predict Spatially Dynamic Adult Sex Ratios in a Megaherbivore. Oikos. 2015;124:1132–1141.
    doi: 10.1111/oik.02273google scholar: lookup
  58. McLoughlin PD, Lysak K, Debeffe L, Perry T, Hobson KA. Density-dependent resource selection by a terrestrial herbivore in response to sea-to-land nutrient transfer by seals.. Ecology 2016 Aug;97(8):1929-1937.
    doi: 10.1002/ecy.1451pubmed: 27859192google scholar: lookup
  59. Debeffe L, Richard E, Medill SA, Weisgerber JN, McLoughlin PD. Costs of Social Dispersal in a Polygynous Mammal. Behav. Ecol. 2015;26:1476–1485.
    doi: 10.1093/beheco/arv092google scholar: lookup
  60. Regan CE, Medill SA, Poissant J, McLoughlin PD. Causes and consequences of an unusually male-biased adult sex ratio in an unmanaged feral horse population.. J Anim Ecol 2020 Dec;89(12):2909-2921.
    doi: 10.1111/1365-2656.13349pubmed: 32996590google scholar: lookup
  61. Richard E, Simpson SE, Medill SA, McLoughlin PD. Interacting effects of age, density, and weather on survival and current reproduction for a large mammal.. Ecol Evol 2014 Oct;4(19):3851-60.
    doi: 10.1002/ece3.1250pmc: PMC4301048pubmed: 25614799google scholar: lookup
  62. Jenkins E, Backwell AL, Bellaw J, Colpitts J, Liboiron A, McRuer D, Medill S, Parker S, Shury T, Smith M, Tschritter C, Wagner B, Poissant J, McLoughlin P. Not playing by the rules: Unusual patterns in the epidemiology of parasites in a natural population of feral horses (Equus caballus) on Sable Island, Canada.. Int J Parasitol Parasites Wildl 2020 Apr;11:183-190.
    doi: 10.1016/j.ijppaw.2020.02.002pmc: PMC7033351pubmed: 32095427google scholar: lookup
  63. Medill SA. Sociality of Sable Island Horses: Population, Group, and Individual Interactions. Ph.D. Thesis. University of Saskatchewan; Saskatoon, SK, Canada: 2018.
  64. Linklater WL, Cameron EZ, Minot EO, Stafford KJ. Stallion harassment and the mating system of horses.. Anim Behav 1999 Aug;58(2):295-306.
    doi: 10.1006/anbe.1999.1155pubmed: 10458881google scholar: lookup
  65. Berger J. Wild Horses of the Great Basin. University of Chicago Press; Chicago, IL, USA: 1986.
  66. Feh C. Alliances and reproductive success in Camargue stallions.. Anim Behav 1999 Mar;57(3):705-713.
    doi: 10.1006/anbe.1998.1009pubmed: 10196062google scholar: lookup
  67. Bennett D, Hoffmann RS. Equus Caballus. Mamm. Spec. 1999;1:1–14.
    doi: 10.2307/3504442google scholar: lookup
  68. Asa CS. Male Reproductive Success in Free-Ranging Feral Horses. Behav. Ecol. Sociobiol. 1999;47:89–93.
    doi: 10.1007/s002650050653google scholar: lookup
  69. Carroll CL, Huntington PJ. Body condition scoring and weight estimation of horses.. Equine Vet J 1988 Jan;20(1):41-5.
    doi: 10.1111/j.2042-3306.1988.tb01451.xpubmed: 3366105google scholar: lookup
  70. Tracey S, Dunnett M, Readmead M, Langridge K, Mood A, Kennedy M, Lees P. Effect of Breed and Environment on Mane and Tail Growth in a Mixed Group of Horses. Proceedings of the British Equine Veterinary Association 41st Congress Handbook of Presentations; Glasgow, UK. 11–14 September 2002.
  71. Dunnett M, Lees P. Trace element, toxin and drug elimination in hair with particular reference to the horse.. Res Vet Sci 2003 Oct;75(2):89-101.
    doi: 10.1016/S0034-5288(03)00074-2pubmed: 12893157google scholar: lookup
  72. Schlupp A, Anielski P, Thieme D, Müller RK, Meyer H, Ellendorff F. The beta-agonist clenbuterol in mane and tail hair of horses.. Equine Vet J 2004 Mar;36(2):118-22.
    doi: 10.2746/0425164044868620pubmed: 15038433google scholar: lookup
  73. West AG, Ayliffe LK, Cerling TE, Robinson TF, Karren B, Dearing MD, Ehleringer JR. Short-Term Diet Changes Revealed Using Stable Carbon Isotopes in Horse Tail-Hair. Funct. Ecol. 2004;18:616–624.
    doi: 10.1111/j.0269-8463.2004.00862.xgoogle scholar: lookup
  74. Boyer S, Garcia P, Popot MA, Steiner V, Lesieur M. Detection of testosterone propionate administration in horse hair samples.. J Chromatogr B Analyt Technol Biomed Life Sci 2007 Jun 1;852(1-2):684-8.
    doi: 10.1016/j.jchromb.2007.02.046pubmed: 17383946google scholar: lookup
  75. Burnik Šturm M, Pukazhenthi B, Reed D, Ganbaatar O, Sušnik S, Haymerle A, Voigt CC, Kaczensky P. A protocol to correct for intra- and interspecific variation in tail hair growth to align isotope signatures of segmentally cut tail hair to a common time line.. Rapid Commun Mass Spectrom 2015 Jun 15;29(11):1047-54.
    doi: 10.1002/rcm.7196pmc: PMC4437015pubmed: 26044272google scholar: lookup
  76. Welsh DA. Population, Behavioural and Grazing Ecology of the Horses of Sable Island, Nova Scotia. Ph.D. Thesis. Dalhousie University; Halifax, NS, Canada: 1975.
  77. Lucas Z, Raeside JI, Betteridge KJ. Non-invasive assessment of the incidences of pregnancy and pregnancy loss in the feral horses of Sable Island.. J Reprod Fertil Suppl 1991;44:479-88.
    pubmed: 1795292
  78. . R: A Language and Environment for Statistical Computing. Vienna, Austria: R Foundation for Statistical Computing. 2022.
  79. Komsta L. Outliers: Test for Outliers. R Package Version 0.15. 2022.
  80. Bates D, Mächler M, Bolker B, Walker S. Fitting Linear Mixed-Effects Models Using lme4. J. Stat. Softw. 2015;67:1–48.
    doi: 10.18637/jss.v067.i01google scholar: lookup
  81. Kuznetsova A, Brockhoff PB, Christensen RHB. LmerTest Package: Tests in Linear Mixed Effects Models. J. Stat. Softw. 2017;82:1–31.
    doi: 10.18637/jss.v082.i13google scholar: lookup
  82. Wickham H, Averick M, Bryan J, Chang W, McGowan LD, François R, Grolemund G, Hayes A, Henry L, Hester J. Welcome to the Tidyverse. J. Open Source Softw. 2019;4:1686.
    doi: 10.21105/joss.01686google scholar: lookup
  83. Robin X, Turck N, Hainard A, Tiberti N, Lisacek F, Sanchez JC, Müller M. pROC: an open-source package for R and S+ to analyze and compare ROC curves.. BMC Bioinformatics 2011 Mar 17;12:77.
    doi: 10.1186/1471-2105-12-77pmc: PMC3068975pubmed: 21414208google scholar: lookup
  84. Lenth R. Emmeans: Estimated Marginal Means, Aka Least-Squares Means. R Package Version 1.8.5. 2023.
  85. Burnham KP, Anderson DR, Huyvaert KP. AIC Model Selection and Multimodel Inference in Behavioral Ecology: Some Background, Observations, and Comparisons. Behav. Ecol. Sociobiol. 2011;65:23–35.
    doi: 10.1007/s00265-010-1029-6google scholar: lookup
  86. Zuur AF, Ieno EN, Elphick CS. A Protocol for Data Exploration to Avoid Common Statistical Problems. Methods Ecol. Evol. 2010;1:3–14.
    doi: 10.1111/j.2041-210X.2009.00001.xgoogle scholar: lookup
  87. Bartoń K. MuMIn: Multi-Model Inference. R Package Version 1.47.5. 2023.
  88. Bennett A, Hayssen V. Measuring cortisol in hair and saliva from dogs: coat color and pigment differences.. Domest Anim Endocrinol 2010 Oct;39(3):171-80.
    doi: 10.1016/j.domaniend.2010.04.003pubmed: 20705413google scholar: lookup
  89. Rusticus SA, Lovato CY. Impact of Sample Size and Variability on the Power and Type I Error Rates of Equivalence Tests: A Simulation Study. Pract. Eval. 2014;19:11.
    doi: 10.7275/4S9M-4E81google scholar: lookup
  90. Jolivald A, Ijichi C, Hall C, Yarnell K. The Mane Factor: Compliance is Associated with Increased Hair Cortisol in the Horse. Appl. Anim. Behav. Sci. 2023;258:105819.
    doi: 10.1016/j.applanim.2022.105819google scholar: lookup
  91. Miller R. Male Aggression, Dominance and Breeding Behavior in Red Desert Feral Horses. Z. Für Tierpsychol. 1981;57:340–351.
    doi: 10.1111/j.1439-0310.1981.tb01930.xgoogle scholar: lookup
  92. Stevens EF. Instability of Harems of Feral Horses in Relation to Season and Presence of Subordinate Stallions. Behaviour. 1990;112:149–161.
    doi: 10.1163/156853990X00167google scholar: lookup
  93. Linklater WL, Cameron EZ. Tests for cooperative behaviour between stallions.. Anim Behav 2000 Dec;60(6):731-743.
    doi: 10.1006/anbe.2000.1525pubmed: 11124871google scholar: lookup
  94. Medill SA, Janz DM, McLoughlin PD. Hair Cortisol and Testosterone Concentrations in Relation to Maturity and Breeding Status of Male Feral Horses. Animals. 2023;13:2129.
  95. Trivers RL, Willard DE. Natural selection of parental ability to vary the sex ratio of offspring.. Science 1973 Jan 5;179(4068):90-2.
    doi: 10.1126/science.179.4068.90pubmed: 4682135google scholar: lookup
  96. Cameron EZ, Linklater WL. Individual mares bias investment in sons and daughters in relation to their condition.. Anim Behav 2000 Sep;60(3):359-367.
    doi: 10.1006/anbe.2000.1480pubmed: 11007645google scholar: lookup
  97. Grange S, Duncan P, Gaillard JM. Poor horse traders: large mammals trade survival for reproduction during the process of feralization.. Proc Biol Sci 2009 May 22;276(1663):1911-9.
    doi: 10.1098/rspb.2008.1828pmc: PMC2674491pubmed: 19324787google scholar: lookup
  98. Boonstra R. Equipped for Life: The Adaptive Role of the Stress Axis in Male Mammals. J. Mammal. 2005;86:236–247.
    doi: 10.1644/BHE-001.1google scholar: lookup
  99. Debeffe L, McLoughlin PD, Medill SA, Stewart K, Andres D, Shury T, Wagner B, Jenkins E, Gilleard JS, Poissant J. Negative covariance between parasite load and body condition in a population of feral horses.. Parasitology 2016 Jul;143(8):983-97.
    doi: 10.1017/S0031182016000408pubmed: 27046508google scholar: lookup
  100. Hart KA, Wochele DM, Norton NA, McFarlane D, Wooldridge AA, Frank N. Effect of Age, Season, Body Condition, and Endocrine Status on Serum Free Cortisol Fraction and Insulin Concentration in Horses.. J Vet Intern Med 2016 Mar-Apr;30(2):653-63.
    doi: 10.1111/jvim.13839pmc: PMC4913614pubmed: 26860336google scholar: lookup
  101. Alberts SC, Sapolsky RM, Altmann J. Behavioral, endocrine, and immunological correlates of immigration by an aggressive male into a natural primate group.. Horm Behav 1992 Jun;26(2):167-78.
    doi: 10.1016/0018-506X(92)90040-3pubmed: 1612563google scholar: lookup
  102. Engh AL, Beehner JC, Bergman TJ, Whitten PL, Hoffmeier RR, Seyfarth RM, Cheney DL. Female Hierarchy Instability, Male Immigration and Infanticide Increase Glucocorticoid Levels in Female Chacma Baboons. Anim. Behav. 2006;71:1227–1237.
    doi: 10.1016/j.anbehav.2005.11.009google scholar: lookup
  103. Sapolsky RM. Behavior. Sympathy for the CEO.. Science 2011 Jul 15;333(6040):293-4.
    doi: 10.1126/science.1209620pubmed: 21764734google scholar: lookup
  104. Engh AL, Beehner JC, Bergman TJ, Whitten PL, Hoffmeier RR, Seyfarth RM, Cheney DL. Behavioural and hormonal responses to predation in female chacma baboons (Papio hamadryas ursinus).. Proc Biol Sci 2006 Mar 22;273(1587):707-12.
    doi: 10.1098/rspb.2005.3378pmc: PMC1560071pubmed: 16608690google scholar: lookup
  105. Monard AM, Duncan P. The Proximate Mechanisms of Natal Dispersal in Female Horses. Behaviour. 1996;133:1095–1124.
    doi: 10.1163/156853996X00611google scholar: lookup
  106. Marjamäki PH, Contasti AL, Coulson TN, McLoughlin PD. Local density and group size interacts with age and sex to determine direction and rate of social dispersal in a polygynous mammal.. Ecol Evol 2013 Sep;3(9):3073-82.
    doi: 10.1002/ece3.694pmc: PMC3790552pubmed: 24101995google scholar: lookup
  107. Ashley NT, Barboza PS, Macbeth BJ, Janz DM, Cattet MR, Booth RK, Wasser SK. Glucocorticosteroid concentrations in feces and hair of captive caribou and reindeer following adrenocorticotropic hormone challenge.. Gen Comp Endocrinol 2011 Jul 1;172(3):382-91.
    doi: 10.1016/j.ygcen.2011.03.029pubmed: 21501613google scholar: lookup
  108. Terwissen CV, Mastromonaco GF, Murray DL. Influence of adrenocorticotrophin hormone challenge and external factors (age, sex, and body region) on hair cortisol concentration in Canada lynx (Lynx canadensis).. Gen Comp Endocrinol 2013 Dec 1;194:162-7.
    doi: 10.1016/j.ygcen.2013.09.010pubmed: 24080086google scholar: lookup
  109. Wester VL, van der Wulp NR, Koper JW, de Rijke YB, van Rossum EF. Hair cortisol and cortisone are decreased by natural sunlight.. Psychoneuroendocrinology 2016 Oct;72:94-6.
    doi: 10.1016/j.psyneuen.2016.06.016pubmed: 27392216google scholar: lookup

Citations

This article has been cited 1 times.
  1. Medill SA, Janz DM, McLoughlin PD. Hair Cortisol and Testosterone Concentrations in Relation to Maturity and Breeding Status of Male Feral Horses. Animals (Basel) 2023 Jun 27;13(13).
    doi: 10.3390/ani13132129pubmed: 37443926google scholar: lookup
Subscribe to our newsletter
Join 99,780 horse owners like you who receive our email updates on horse health and nutrition.