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Topic:Cortisol

Cortisol is a steroid hormone produced by the adrenal glands in horses, playing a significant role in the regulation of metabolism, immune response, and stress management. As a glucocorticoid, cortisol influences various physiological processes, including glucose metabolism, inflammation modulation, and the maintenance of homeostasis during stress. Its levels in horses can vary due to factors such as exercise, environmental changes, and psychological stressors. Cortisol is often measured to assess stress responses and overall well-being in equine health management. This page compiles peer-reviewed research studies and scholarly articles that explore the production, regulation, and implications of cortisol in equine physiology and health.
The Effects of Human-Horse Interactions on Oxytocin and Cortisol Levels in Humans and Horses.
Animals : an open access journal from MDPI    March 21, 2025   Volume 15, Issue 7 905 doi: 10.3390/ani15070905
Jung Y, Yoon M.Therapeutic programs involving human-horse interactions are gaining popularity as a means of enhancing human well-being. Understanding the physiological responses of both humans and horses during these interactions is essential for evaluating the effectiveness of such programs. This study examined the effects of specific interactive activities on both humans and horses by monitoring changes in oxytocin and cortisol levels. Six participants and six horses took part in the study. The participants engaged in three distinct activities, each lasting 15 min: (1) resting alone without the horse (rest...
The power of interspecific sociality: how humans provide social buffering for horses.
Animal cognition    March 12, 2025   Volume 28, Issue 1 20 doi: 10.1007/s10071-025-01942-5
Di Lucrezia A, Scandurra A, Lotito D, Iervolino V, D'Aniello B, Mastellone V, Lombardi P, Pinelli C.In this study, we assessed the interspecific "social buffering effect" of humans on horses, exploring how human presence influences stress responses in horses in an unfamiliar environment using the "isolation paradigm." We examined nine Haflinger horses under two counterbalanced conditions: with a passive human stranger (social condition) or alone (isolation condition). Stress responses were assessed through cortisol measurements, heart rate monitoring, and behavioral observations. While cortisol levels significantly increased in both conditions, with no notable differences before and after th...
Effect of Massage on Stress Indicators in Recreational Horses-A Pilot Study.
Animals : an open access journal from MDPI    March 11, 2025   Volume 15, Issue 6 doi: 10.3390/ani15060789
Jastrzębska E, Górecka-Bruzda A, Ogłuszka M, Lipka MS, Pawłowska A.This pilot study investigated the effects of massage therapy on stress indicators in recreational horses, focusing on salivary cortisol levels, heart rate and conflict behaviors. Five recreational horses were analyzed under two experimental conditions: without and with massage treatments before riding sessions. Saliva samples were collected at four specific intervals in each condition to measure cortisol concentrations using an ELISA test. Observations of behavioral indicators and heart-rate monitoring complemented the physiological data. The results revealed that massage significantly reduced...
Initial investigation into the metabolic effects of intra-articular betamethasone on normal and insulin dysregulated horses.
Journal of equine veterinary science    February 22, 2025   Volume 147 105404 doi: 10.1016/j.jevs.2025.105404
Page AE, Rauber-Ramos AM, Humiston M, McPeek JL, Adam EN.Given the metabolic effects of intra-articular (IA) corticosteroids, the goal of this project was to monitor the effects of IA betamethasone in both insulin dysregulated (ID)(n = 3) and non-ID (n = 5) horses. A cross-over design was used where eight geldings were injected with either 9 mg of betamethasone or saline into both metacarpophalangeal joints, followed by regular blood collections for adrenocorticotropin releasing hormone (ACTH), cortisol, insulin, and glucose, as well as pre- and post-administration oral sugar testing. Results were analyzed via two-way repeated measures analysis of v...
Seasonal Pattern of Cortisol Fluctuation in Horsehair Samples from Three Different Body Areas: A Year Long Study.
Journal of equine veterinary science    February 17, 2025   105387 doi: 10.1016/j.jevs.2025.105387
Skurková L, Matulníková L, Peťková B, Florian M, Slivková M, Lešková L, Mesarčová L, Kottferová J.This study aimed to assess the seasonal changes of the cortisol concentrations in horsehair (HCC), as an indicator of long-term or chronic stress. Hair samples were taken four times throughout one year from 12 horses (aged from 1.5 to 30 years), and analysed by the ELISA method. The sampling interval (interval between two collections of the samples representing two different seasons) ranged between 102-115 days. Seasonal dynamics have been confirmed with a pattern: August ˃ November ˃ January ˃ April (F (3.93) = 50.28, P < 0.001). The lowest cortisol concentrations were detected in A...
Effect of an adjustable ceiling to prevent premature rising attempts after general anesthesia in healthy ponies and horses: A pilot study.
Veterinary surgery : VS    January 30, 2025   Volume 54, Issue 5 851-859 doi: 10.1111/vsu.14181
Lindqvist A, Nyman G, Rydén A, Wattle O.This study aimed to assess and compare the recovery of ponies and horses following general anesthesia in two different settings: a recovery box with an inflexible, adjustable ceiling, and free recovery without restraints. Our primary objective was to evaluate the effect of adjustable ceilings on the prevention of premature attempts to rise during recovery. The secondary aim was to compare the physiological stress indicators during recovery. Methods: Prospective, randomized, experimental study. Methods: Six healthy ponies and 10 healthy horses. Methods: This study used a crossover design with t...
From Pre-Foaling to Late Pregnancy: Cortisol, DHEA(S), Progesterone, 17-β-Estradiol, and Allopregnanolone Hair Concentration Profiles in Standardbred Mares.
Animals : an open access journal from MDPI    January 23, 2025   Volume 15, Issue 3 324 doi: 10.3390/ani15030324
Veronesi MC, Cotticelli A, Pividori I, Giombolini M, Corazzin M, Ellero L, Peric T.Pregnancy and parturition represent two important physiologic phases in female mammals, in which metabolic, behavioral, and endocrinologic changes should occur in perfect timing and interaction, leading to a normal course of gestation and the occurrence of parturition at term, allowing the birth of mature and viable offspring. The present study aimed to describe the hormonal changes recorded in the hair occurring in mares from pre-foaling to late pregnancy. The hair cortisol (C) concentrations did not show any significant variations throughout the study, while dehydroepiandrosterone (sulfate) ...
Soybean oil supplement induces increased approaching behavior to humans and alters serotonin concentrations in horses.
Journal of equine veterinary science    January 16, 2025   Volume 146 105361 doi: 10.1016/j.jevs.2025.105361
Kim S, Choi Y, Kim J, Wickens CL, Yoon M.Enhancement of human-horse interaction is crucial for safety in equine management, as poor relationships between humans and horses can lead to accidents. Serotonin is a neurotransmitter that is highly related to social affinity in animals and several studies have been documented that supplementation of tryptophan, which is a precursor of serotonin, can increase calmness of horses. This study aimed to assess the effect of tryptophan through soybean oil supplementation on serotonin concentrations and the behavior of horses. Six horses participated and the horses were treated with or without soyb...
Heart rate and salivary cortisol as indicators of arousal and synchrony in clients, therapy horses and therapist in equine-assisted therapy.
Complementary therapies in clinical practice    January 9, 2025   Volume 59 101937 doi: 10.1016/j.ctcp.2025.101937
Naber A, Kreuzer L, Zink R, Millesi E, Palme R, Hediger K, Glenk LM.This exploratory study aimed to analyse physiological interaction processes in equine-assisted-therapy (EAT) between client, therapy horse and therapist. Methods: We measured heart rate (HR), heart rate variability (HRV) and cortisol levels before, during and after a standardized therapy session and a control condition in one therapist, four therapy horses and ten female clients in emerging adulthood (Mn = 21.8 years, SD = 3.39). The clients were diagnosed with mild (N = 5) to moderate (N = 5) intellectual disability (ID). Results: There was no significant change in the client's HR, HR...
Stress, lipid profile and inflammatory responses to flunixin meglumine administration in surgical and non-surgical castration in donkeys.
Veterinary and animal science    December 22, 2024   Volume 27 100423 doi: 10.1016/j.vas.2024.100423
Alipour-Khairkhah H, Azizi S, Asri-Rezaei S.Donkeys are in the Equidae family but have several differences from horses. There are many studies on the pathophysiology of pain and its clinical signs in horses, but data are limited for donkeys. Therefore, the present study aimed to investigate biochemical effects of flunixin meglumine in donkeys subjected to pain induced by bloodless and surgical castration. Twenty healthy male donkeys were randomly divided into four groups: 1- Surgical castration with flunixin injection, 2- Surgical castration without flunixin injection, 3- Non-surgical castration with flunixin injection, and 4- Non-surgi...
Analgesic efficacy of tapentadol in chronic joint disorders in horses: plasma serotonin concentration and adrenocortical response as biomarkers of pain-induced stress.
Frontiers in veterinary science    December 17, 2024   Volume 11 1505398 doi: 10.3389/fvets.2024.1505398
Costa GL, Tabbì M, Bruschetta G, Spadola F, Leonardi F, Bruno F, Iannelli NM, Licata P, Macrì F, Passino ES, Macrì D, Interlandi C.The study aimed to evaluate the analgesic efficacy of tapentadol in horses, by determining plasma serotonin concentration and adrenocortical response, as biomarkers of pain stress in chronic joint disorders. Thirty-six horses (20 females and 16 males) were divided into three groups of 12 subjects each: group A, osteoarthritis (OA), grade 3-4 lameness; group B, OA, grade 5 lameness; and group C, no OA, no lameness, were enrolled. The orthopedic examination included flexion tests, and radiological and ultrasound examinations. The degree of lameness has been estimated from 0 to 5 according to the...
Effects of a Gastroscopic Procedure on Salivary Cortisol Release and Fecal Cortisol Metabolites in Young Racehorses.
Animals : an open access journal from MDPI    November 19, 2024   Volume 14, Issue 22 3332 doi: 10.3390/ani14223332
Ostermeier S, Palme R, Vervuert I, Glomm B, Feige K, Macho-Maschler S, König von Borstel U, Venner M.In this study, gastroscopy was performed twice in 31 two-year-old Thoroughbred racehorses in training. Salivary cortisol (SC) and fecal cortisol metabolite (FCM) concentrations were determined to measure the stress impact. One gastroscopy was performed at the beginning and one six months later at the end of the horses' first training season. According to the Wilcoxon signed rank test, a mild but significant increase of SC (1st gastroscopy: = 0.0045, 2nd gastroscopy: < 0.0001) and FCM (1st gastroscopy: < 0.0001, 2nd gastroscopy: = 0.0006) values after gastroscopy compared to basal val...
Stress response of 18-, 24- and 30-month-old sport horse stallions to a pretraining programme.
Animal : an international journal of animal bioscience    November 13, 2024   Volume 18, Issue 12 101373 doi: 10.1016/j.animal.2024.101373
Pilger F, Kroschel L, Aurich J, Nagel C, Hoffmann G, Hartmann U, Aurich C.Warmblood sires traditionally have been presented for stallion licencing at 2 years of age, but the age at which horses are mentally fit for training is a point of controversy. We have therefore investigated the stress response of young stallions to pretraining for licencing. Salivary cortisol concentration, heart rate and heart rate variability (HRV) were determined repeatedly over 12 weeks. Stallions were 24 and 30 months old and either housed in groups or individual boxes (Group 24, n = 9; Box 24, n = 10; Box 30, n = 10). Pretraining included free movement in an indoor arena, train...
Stress levels, hematological condition, and productivity of plasma-producing horses used for snake antivenom manufacture: A comparison of two industrial bleeding methods.
Toxicon: X    October 21, 2024   Volume 24 100212 doi: 10.1016/j.toxcx.2024.100212
Arias-Esquivel AM, Moscoso E, Umaña D, Arguedas M, Solano D, Durán G, Gómez A, Gutiérrez JM, León G.The immunization and industrial bleeding of horses are essential stages for producing snake antivenoms. In Costa Rica, the traditional method involves stimulating the antibody response of horses by periodically injecting venoms, collecting hyperimmune plasma over three consecutive bleeding days, and repeating this process every eight weeks. While this method does not cause major physical or hematological issues in horses, the associated stress has not been evaluated. We compared this traditional method with an alternative method that involves injecting venoms, collecting hyperimmune plasma in ...
Validation of a Commercial ELISA Kit for Non-Invasive Measurement of Biologically Relevant Changes in Equine Cortisol Concentrations.
Animals : an open access journal from MDPI    October 1, 2024   Volume 14, Issue 19 2831 doi: 10.3390/ani14192831
Share ER, Mastellar SL, Suagee-Bedore JK, Eastridge ML.The measurement of fecal cortisol/corticosterone metabolites (FCMs) is often used to quantify the stress response. The sampling method is relatively non-invasive, reduces concern for elevation of cortisol from the sampling method, and has been shown to measure cortisol more consistently without the daily diurnal rhythm observed in blood. Commercial ELISA (enzyme-linked immunoassay) kits offer benefits over previously validated immunoassay methods but lack validation. The objective of this study was to evaluate a commercial ELISA kit (Arbor Assays DetectX Cortisol ELISA kit, K003-H1, Ann Arbor,...
Cortisol levels, heart rate, and autonomic responses in horses during repeated road transport with differently conditioned trucks in a tropical environment.
PloS one    September 6, 2024   Volume 19, Issue 9 e0301885 doi: 10.1371/journal.pone.0301885
Lertratanachai S, Poochipakorn C, Sanigavatee K, Huangsaksri O, Wonghanchao T, Charoenchanikran P, Lawsirirat C, Chanda M.Horse's stress responses have been reported during road transport in temperate but not tropical environments. Therefore, this study measured cortisol levels, heart rate (HR), and heart rate variability (HRV) in horses during medium-distance road transport with different truck conditions in a tropical environment. Six horses were repeatedly transported in either air-conditioned trucks with full (ATF) or space (ATS) loads or non-air-conditioned trucks with full (N-ATF) and space (N-ATS) loads. Blood cortisol was determined beforehand and 5, 30, and 90 minutes post-transport. HR and HRV were asse...
The impact of short-term transportation stress on insulin and oral sugar responses in insulin dysregulated and non-insulin dysregulated horses.
Equine veterinary journal    September 4, 2024   doi: 10.1111/evj.14403
Jacquay ET, Harris PA, Adams AA.It is unknown whether short-term transportation affects endocrine responses similarly in horses with and without insulin dysregulation (ID). Objective: To characterise the effect of short-term transportation on stress parameters and insulin responses to an oral sugar test (OST) in horses with and without ID. Methods: Longitudinal cohort study. Methods: Fourteen adult non-pregnant, non-PPID mares of mixed light breeds were grouped as either ID (n = 7) or non-ID (n = 7) based on endocrine testing. Over 2 weeks, horses were transported once, in groups of 3-4 in a horse trailer on a roun...
Horses’ Cardiovascular and Glucocorticoid Responses to Equine-Assisted Therapy with Women with Intellectual Disability: An Exploratory Study.
Journal of applied animal welfare science : JAAWS    August 29, 2024   1-16 doi: 10.1080/10888705.2024.2396968
Kreuzer L, Naber A, Zink R, Millesi E, Palme R, Hediger K, Glenk LM.Research on equine-assisted therapy (EAT) has primarily been centered on human health. Relatively few studies have addressed the impact of EAT on horses. This study sought to monitor four experienced therapy horses' cardiovascular and glucocorticoid activity over the course of standardized EAT sessions designed to support women with intellectual disability. In the control condition, horses completed the EAT protocol solely with the therapist, thereby resembling a training session. Descriptive data analysis revealed higher levels of heart rate during an experimental EAT session and increased sa...
Eye Temperature Measured with Infrared Thermography to Assess Stress Responses to Road Transport in Horses.
Animals : an open access journal from MDPI    June 26, 2024   Volume 14, Issue 13 1877 doi: 10.3390/ani14131877
Aragona F, Rizzo M, Arfuso F, Acri G, Fazio F, Piccione G, Giannetto C.The aim of the present study was to investigate eye temperature modifications after road transport in athletic horses habituated to travel. Eight adult Italian saddle horses traveled 100 km and, two weeks later, 300 km. Eye temperature (ET), rectal temperature (RT) and serum cortisol concentration were assessed before (T1), after (T2) and 60 min (T3) after the road transport. ET was evaluated with infrared thermography (IRT) in three regions of interest: EL1 (medial canthus), EL2 (central cornea) and EL3 (lateral canthus). Two-way analysis of variance (ANOVA) for repeated measures showed stati...
Welfare and stress assessment of tourism carriage horses under real working conditions in Sicily.
Journal of equine veterinary science    June 21, 2024   105136 doi: 10.1016/j.jevs.2024.105136
Animal welfare has become an increasingly important concern regarding equids working as carriage animals. In the present study, the changes in the markers of stress and inflammatory responses as a result of the work performed by tourism carriage horses under real working conditions in Sicily (Italy) were investigated. Twenty-two Standardbreds performed a normal working day in the carriage tourism business during the months of May, June and July 2022, consisting of one day of work for each month. Blood samples were collected in the stables at rest before the tour route (Pre; 07.00 AM) and withi...
Ground-based adaptive horsemanship lessons for veterans with post-traumatic stress disorder: a randomized controlled pilot study.
Frontiers in psychiatry    May 28, 2024   Volume 15 1390212 doi: 10.3389/fpsyt.2024.1390212
Rankins EM, Quinn A, McKeever KH, Malinowski K.Equine-assisted services (EAS) has received attention as a potential treatment strategy for post-traumatic stress disorder (PTSD), as existing literature indicates that symptoms may decrease following EAS. Relatively little is known about the mechanisms at play during lessons and if physiological measures are impacted. The objectives of this pilot study were to 1) explore the effects of adaptive horsemanship (AH) lessons on symptoms of PTSD, hormone concentrations, and social motor synchrony; 2) determine if physiological changes occur as veterans interact with horses; and 3) explore if the in...
Effects of different winter paddock management of Thoroughbred weanlings and yearlings in the cold region of Japan on physiological function, endocrine function and growth.
The Journal of veterinary medical science    May 23, 2024   doi: 10.1292/jvms.24-0083
Ishimaru M, Tsuchiya T, Endo Y, Matsui A, Ohmura H, Murase H, Korosue K, Sato F, Taya K.Effects of different winter paddock management of Thoroughbred weanlings and yearlings in Hokkaido, Japan, which is extremely cold in winter, on physiological function, endocrine function and growth were investigated. They were divided into two groups; those kept outdoors for 22 hr in the paddock (22hr group) and those kept outdoors for 7 hr in daytime with walking exercise for 1 hr using the horse-walker (7hr +W group), and the changes in daily distance travelled, body temperature (BT), heart rate (HR), HR variability (HRV), endocrine function and growth parameters were compared between the t...
Hematological and physiological responses in polo ponies with different field-play positions during low-goal polo matches.
PloS one    May 16, 2024   Volume 19, Issue 5 e0303092 doi: 10.1371/journal.pone.0303092
Sanigavatee K, Poochipakorn C, Huangsaksri O, Wonghanchao T, Yalong M, Poungpuk K, Thanaudom K, Chanda M.Strenuous exercise in traditional polo matches creates enormous stress on horses. Hematological and physiological measures may vary across different field-play positions. This study aimed to investigate the effort intensity and the impact of exertion on hematology and heart rate variability (HRV) in polo ponies with different positions. Thirty-two ponies, divided equally into eight teams, were studied. Each comprises forwards (number 1), midfielders (numbers 2 and 3), and defenders (number 4). Team pairs played the first chukka in four low-goal polo matches. Percent maximum heart rate (%HRmax)...
Effect of pregnancy on isolation efficiency and in vitro proliferation of equine peripheral-blood derived mesenchymal stromal cells.
Theriogenology    May 14, 2024   Volume 224 107-118 doi: 10.1016/j.theriogenology.2024.05.015
Mattei DN, Harman RM, Van de Walle GR, Smith R, Grivel JC, Abdelalim EM, Vinardell T.Mesenchymal stromal cells (MSCs) have regenerative and immunomodulatory potential and may be used to treat injured tissues. Pregnancy has been associated with increased MSCs in the peripheral circulation in multiple species, but to date, there are no reports on this matter in horses. This study aimed to evaluate the effect of pregnancy on isolation efficiency and proliferation capacity of equine MSCs derived from the peripheral blood (PB) of mares. Venous blood samples were collected at the 11th month of gestation and 1 month after delivery from clinically healthy Arabian mares that presented ...
Physiological and metabolic responses in Kök-Börü horses: Correlations with game outcomes.
Veterinary medicine and science    April 30, 2024   Volume 10, Issue 3 e1457 doi: 10.1002/vms3.1457
Rişvanlı A, Şen İ, Canuzakov K, Tülöbayev A, Taş A, Saklykov R, Ceylan N, Türkçapar Ü, Alimov U, Kazakbayeva A, Cunuşova A, Uulu NA....The aim of this study was to examine variations in stress, metabolic, and physiological parameters of horses used in the traditional equestrian team sport of Kök-Börü in relation to winning and losing outcomes. Methods: To accomplish this, blood samples were taken from horses on four different teams who participated in two separate games, both before and after game. These samples were used to measure levels of cortisol, ACTH, beta-endorphin, adrenaline, noradrenaline, triiodothyronine (T3), and thyroxine (T4) via species-specific commercial ELISA kits. The autoanalyzer tested biochemical an...
Effect of hospitalization on equine local intestinal immunoglobulin A (IgA) concentration measured in feces.
Journal of equine veterinary science    April 30, 2024   Volume 137 105078 doi: 10.1016/j.jevs.2024.105078
May A, Gerhards H, Wollanke B.During hospitalization horses may develop gastrointestinal conditions triggered by a stress-associated weak local immune system. The prospective, clinical trial was conducted to find out whether fecal immunoglobulin A (IgA) concentrations could be determined in hospitalized horses and how they changed during hospitalization and in response to various stressors. Samples were obtained from 110 horses and a control group (n = 14). At arrival in the hospital, horses were categorized into pain grades (1-5), and elective versus strenuous surgery (> 2 hours, traumatic and emergency procedures). Feces...
Differences in bone turnover markers and injury risks between local and international horses: A Victorian Spring Racing Carnival study.
Equine veterinary journal    April 18, 2024   Volume 57, Issue 2 333-346 doi: 10.1111/evj.14098
Ayodele BA, Pagel CN, Mackie EJ, Armour F, Yamada S, Zahra P, Courtman N, Whitton RC, Hitchens PL.Musculoskeletal injuries (MSI) are common in racehorses and have been of increasing concern in horses travelling internationally to compete. Understanding the differences in bone turnover between local horses and international horses following long-distance air transportation may inform MSI prevention strategies. Objective: To understand the differences in bone turnover markers and risk of MSI between local horses and international horses following long-distance air transportation. Methods: Prospective cohort. Methods: The concentrations of bone turnover markers (OCN and CTXI), markers of stre...
Validation of a commercial ELISA kit to measure 11-oxoetiocholanolone in equine and bovine feces. Zoratti A, Pividori I, Comin A, Prandi A, Peric T.Feces are a noninvasive and easily collectible matrix that may help determine cumulative hormone metabolite concentrations over medium-to-long times. To date, 11-oxoetiocholanolone, an important metabolite of cortisol, has been measured in equine and bovine feces solely by an in-house enzyme immunoassay (EIA). Therefore, we validated the use of a commercial ELISA kit (11-oxoetiocholanolone ELISA kit; Cayman Chemical), which had been validated on sheep feces and human urine, to measure 11-oxoetiocholanolone in feces from 42 horses and 32 bulls. The ELISA kit had good precision (intra- and inter...
Blood-based assessment of oxidative stress, inflammation, endocrine and metabolic adaptations in eventing horses accounting for plasma volume shift after exercise.
Veterinary medicine and science    March 22, 2024   Volume 10, Issue 3 e1409 doi: 10.1002/vms3.1409
Giers J, Bartel A, Kirsch K, Müller SF, Horstmann S, Gehlen H.After submaximal exercise, blood values of eventing horses show physiological reactions. This prospective longitudinal study investigated blood parameters in 20 elite eventing horses before and after two-four-star cross-country rides. Using a mixed model adjusting for plasma volume shift, we assessed exercise-dependent parameters and compared blood values with reference ranges for healthy horses at rest. Following exercise, cortisol, triiodothyronine (T3) and thyroxine (T4) showed short-term increases, and superoxide-dismutase showed a small short-term increase. Hepatic values showed short-ter...
Behavioral and physiological responses of horses to ground-based adaptive horsemanship lessons for veterans with post-traumatic stress disorder (PTSD).
Journal of equine veterinary science    March 20, 2024   Volume 135 105049 doi: 10.1016/j.jevs.2024.105049
Rankins EM, McKeever KH, Malinowski K.Little literature exists on horses in adaptive horsemanship (AH) despite concerns about their well-being. The study objective was to evaluate behavioral and physiological responses of horses to ground-based AH lessons for veterans with post-traumatic stress disorder (PTSD). Lessons were expected to alter horses' hormone concentrations, behavior, and muscle activity. Geldings were assigned to AH (n=6; 20.3 ± 1.9 yrs., mean ± SE) or control (CON; stall in arena, n=6; 13.8 ± 1.7 yrs.) conditions for 8-week sessions based on current occupation (AH = equine-assisted services; CON = recreational ...