Male horses, or stallions and geldings, are a significant focus of equine research due to their distinct physiological and behavioral characteristics. Stallions are intact male horses, known for their reproductive capabilities and often more pronounced secondary sexual traits. Geldings, on the other hand, are castrated males, typically exhibiting more docile behavior compared to stallions. Research in this area explores various aspects such as reproductive physiology, behavior, management practices, and the impact of castration on health and performance. Studies also examine hormonal influences, particularly testosterone, and their effects on behavior and physical development. This page compiles peer-reviewed research studies and scholarly articles that investigate the biology, behavior, and management of male horses, providing insights into their role in equine science and industry.
Auge BK, Preminger GM.The surgical management of urinary calculus disease has changed dramatically in the past two decades. Minimally invasive options have made open stone surgery nearly obsolete. The development of shock wave lithotripsy, percutaneous nephrostolithotomy techniques and intracorporeal lithotripsy devices has conferred unprecedented management tools for upper tract stones. Moreover, transfusion rates, hospital costs, and convalescence periods have been markedly reduced when compared to open surgery. Likewise, the advent of fiberoptic technology has resulted in miniaturization of ureteroscopes making ...
Whitehair KJ, Willits NH.To identify factors associated with various arterial partial pressures of oxygen (Pao2) in anesthetized horses. Methods: Retrospective study. Methods: 1,450 horses anesthetized a total of 1,610 times with isoflurane or halothane. Methods: Anesthesia records, particularly results of blood gas analyses, were reviewed, and horses were grouped on the basis of lowest Pao2. Results: For horses with lowest Pao2 < 120 mm Hg, those with low pulse pressure, that underwent anesthesia on an emergency basis, or that were males were more likely to have Pao2 < 80 mm Hg. For horses with lowest Pao2 <...
Gross DK, Morley PS, Hinchcliff KW, Wittum TE.To determine the effect of furosemide on performance of Thoroughbreds racing on dirt surfaces at tracks in the United States and Canada. Methods: Cross-sectional study. Methods: All Thoroughbreds (n = 22,589) that finished a race on dirt surfaces at tracks in the United States and Canada between June 28 and July 13, 1997 in jurisdictions that allowed the use of furosemide. Methods: Race records were analyzed by use of multivariable ANOVA procedures and logistic regression analyses to determine the effect of furosemide on estimated 6-furlong race time, estimated racing speed, race earnings, and...
Rivara FP.Examine the current magnitude of the injury problem to children and adolescents on farms, and to compare these data to that from 1978-83. Methods: US National Center for Health Statistics Mortality Multiple Cause of Death Tapes for the years 1991-3, and the US Consumer Product Safety Commission National Electronic Injury Surveillance System for data on emergency department visits for 1990-3. Methods: Children and adolescents 19 years and younger injured on farms. Results: There were an average of 104 deaths per year due to injuries occurring on farms. The rate of 8.0 deaths per 100,000 child f...
Dabareiner RM, White NA.Medical records from all horses with large colon impaction admitted between 1985 and 1991 were examined. Large colon impaction was diagnosed in 147 of 1,100 (13.4%) horses with colic. One hundred thirty horses were admitted for further evaluation of acute onset of abdominal pain after having been examined and treated by referring veterinarians, and 17 horses that were hospitalized for unrelated medical problems developed large colon impaction. Female horses (92/147; 62.6%) were more commonly affected than males. The age ranged from 1 to 29 years (median, 7.1 years). Mean duration of clinical s...
Hanie EA, Sullins KE, White NA.The results of 31 intracortical dorsal metacarpal stress fractures in 28 horses following unicortical osteostixis were reviewed. The incidence was predominately in the middle third of the lateral aspect of the left metacarpus, and males were affected more commonly. Approximately half of the surgical procedures were performed with the horse in the standing position. The mean times to return to training and racing were 4.25 and 6.9 months respectively. There was no correlation between time taken to return to racing and position of surgery. Complications experienced included lack of suture remova...
Power MM, Gustavsson I, Switoński M, Plöen L.Synaptonemal complex analysis by electron microscopy of a trisomy 28 in a male horse demonstrated a trivalent or a bivalent plus a univalent in primary spermatocytes. Two of the chromosomes making up the trivalent were, most often, completely paired with each other and only partially paired or associated with the third one. Half of the spermatocytes analysed demonstrated heterologous pairing or association between the free axis of the trivalent and the sex bivalent. The pairings remained, to a large extent, into diakinesis-metaphase I. In most pachytene cells one autosomal bivalent showed prox...
de Loës M.A prospective study of acute injuries from sports and physical exercise was carried out during 1 year in a total population of a municipality with 31,620 inhabitants. The medical treatment and the services required for the injuries have been calculated and related to the total consumption of medical care in the municipality. A total of 571 injuries (17% of all injuries) occurred in 28 different sports: 65% of the injured were males. Sports injuries accounted for 3% of all acute visits and there were altogether 1,083 outpatient visits, which yields a mean of 1.9 visits per injury. Related to th...
Koizumi N, Inoue Y, Ninomiya R, Fujita D, Tsukamoto T.The concentrations of Cd, Zn, Cu, and metallothionein (MT) in the liver, renal cortex, and renal medulla were determined in 24 male and 15 female younger thoroughbreds (age 27 to 97 months) and two old male horses (age 154 months and 190 months). High correlations were found between Zn and MT in the liver (partial correlation coefficient 0.836), between Cd and MT in the renal cortex (partial correlation coefficient 0.786), and between Cd and Zn in the renal cortex (partial correlation coefficient 0.675), while the correlation between Cd and MT in the liver was low (partial correlation coeffici...
Illera JC, Hamlin RL, Illera M.Bipolar and unipolar limb leads and unipolar thoracic lead ECG were obtained from 100 male crossbred horses. P-wave morphologic features were classified according to positivity negativity and monopolarity dipolarity, and the percentage of horses that had P waves of a given morphologic class in each lead was calculated. P-Wave morphologic features of 4 precordial leads were most uniform, with greater than 80% of the horses having a single configuration.
Illera JC, Illera M, Hamlin RL.Electrocardiograms were obtained from 100 male crossbred horses. In addition to standard limb leads, leads were taken from 12 points on the thorax. The QRS complexes were categorized into 1 of 8 forms on the basis of configuration and amplitudes of component deflections. Relative uniformity of QRS was determined for each lead, using the percentage of horses that possess a particular configuration. All unipolar thoracic leads, except those coplanar with the frontal plane, and lead aVR had great uniformity, with greater than 80% of the horses with a QRS of similar contour.
Dunlop CI, Steffey EP, Miller MF, Woliner MJ.Cardiopulmonary function was monitored in 6 non-medicated, healthy male horses, anesthetized with halothane or isoflurane in O2 at a constant dose (1.2 times the minimum alveolar concentration). Horses were exposed once to each anesthetic agent, and a minimum of 2 weeks separated anesthetic exposures. All horses were studied in left lateral recumbency, and ventilation was mechanically controlled to induce a PaCO2 of 35 to 45 mm of Hg and an inspiratory peak airway pressure of 18 to 22 cm of H2O. After 1 hour of horse preparation, constant conditions were begun. With duration of anesthesia, car...
Irvine CH, Alexander SL, Turner JE.The possibility of seasonal variation in the feedback effect of testosterone or oestradiol was investigated by giving replacement treatment to geldings for 2-3 weeks during breeding and non-breeding seasons. In the non-breeding season, testosterone suppressed LH values (mean +/- s.e.m., ng/ml) in all geldings (before treatment, 7.5 +/- 2.3; final treatment week, 1.8 +/- 0.2; P less than 0.05), whereas early in the breeding season, testosterone caused a prolonged rise in LH (before, 6.8 +/- 2.3; final week, 18.9 +/- 6.4; P less than 0.05). In all testosterone experiments, LH returned to pretrea...
Little CB, Hilbert BJ, McGill CA.The clinical features of 21 horses which sustained head fractures are reviewed. There was a higher incidence of fractures in males and Standardbred horses. Surgical treatment was practical and successful in most cases when the fractures involved the bones of the jaws and the face. Fractures which involved the cranial cavity or the cranial nerves were difficult to treat and usually held a poor prognosis.
Line SW, Hart BL, Sanders L.Males horses castrated prepubertally occasionally display stallion-like sexual and aggressive behavior as adults. A retrospective survey of 140 horse owners was undertaken to compare the effectiveness of prepubertal versus postpubertal castration on objectionable sexual and aggressive behavior. Of 94 geldings that had been castrated prepubertally (before 2 years of age), 20% to 30% displayed stallion-like sexual behavior and aggression toward horses, and 5% were aggressive toward people in a stallion-like manner. This occurrence of problem behavior was not significantly different from the occu...
Lindsell CE, Hilbert BJ, McGill CA.Osteochondrosis dissecans was diagnosed clinically and radiographically in 31 joints of 21 horses. The horses ranged in age from 8 months to 5 years at the time of presentation. The usual age of onset of clinical signs was 18 to 24 months. Presenting complaints included joint effusion and lameness of either gradual or sudden onset. In Thoroughbred horses, the stifle joint was the most common site of lesions and in Standardbred horses lesions occurred more commonly in the hock. In 16 of the 21 horses, the contralateral joint was radiographed and 9 of these horses had bilateral lesions. Thorough...
Mann T.Stallion semen has several chemical characteristics not commonly encountered in other animals. It contains very little fructose and the spermatozoa possess only limited fructolytic ability under anaerobic conditions. By determining some of the characteristic constituents such as ergothioneine, citric acid, glycerylphosphorylcholine and certain glycosidases, it is possible to obtain a quantitative measure of the secretory contribution of the ampulla, seminal vesicle and epididymis, respectively, towards the final composition of the whole ejaculate. By analysing separately the various fractions ...
Townsend J, Sneddon CL, Tortonese DJ.The intrapituitary mechanisms regulating gonadotrophin secretion in the horse remain unclear. Here, we examined seasonal and gonadal effects on the gonadotroph and lactotroph populations of male horses with the aim of defining a possible morphological basis for the differential release of gonadotrophins. Pituitaries were collected from: (i) gonadal-intact horses in the breeding season (GBS); (ii) orchidectomized horses in the breeding season (OBS); and (iii) orchidectomized horses in the nonbreeding season (ONBS). Immunohistochemistry was performed using antibodies to the luteinizing hormone (...
Vollmerhaus B, Roos H, Gerhards H, Knospe C.The canine teeth of the horse developed phylogenically from the simple, pointed, short-rooted tooth form of the leaf eating, in pairs living, Eocene horse Hyracotherium and served up to the Oligocene as a means of defense (self preservation). In the Miocene the living conditions of the Merychippus changed and they took to eating grass and adopted as a new behavior the life in a herd. The canine teeth possibly played an important role in fights for social ranking; they changed from a crown form to knife-like shape. In the Pliohippus the canine tooth usually remained in male horses and since the...
Merchan A, Barrett EJ, Rodgerson DH.A technique for hand-assisted laparoscopic removal of cystic calculi in male horses is described. Three cystic calculi ranging from 5 to 10 cm in diameter were removed successfully using bilateral para-inguinal laparoscopic portals assisted by a human hand within the abdomen, effectively sealing the midline incision. Long-term follow-up information obtained from referring veterinarians and owners indicated that the patients returned to their previous activity level and had no recurrence of clinical signs in the following 6 to 12 months. Key clinical message: Hand-assisted recumbent laparoscopy...
Lindsell CE, Hilbert BJ, McGill CA.Osteochondrosis dissecans was diagnosed clinically and radiographically in 31 joints of 21 horses. The horses ranged in age from 8 months to 5 years at the time of presentation. The usual age of onset of clinical signs was 18 to 24 months. Presenting complaints included joint effusion and lameness of either gradual or sudden onset. In Thoroughbred horses, the stifle joint was the most common site of lesions and in Standardbred horses lesions occurred more commonly in the hock. In 16 of the 21 horses, the contralateral joint was radiographed and 9 of these horses had bilateral lesions. Thorough...
Irvine CH, Alexander SL, Turner JE.The possibility of seasonal variation in the feedback effect of testosterone or oestradiol was investigated by giving replacement treatment to geldings for 2-3 weeks during breeding and non-breeding seasons. In the non-breeding season, testosterone suppressed LH values (mean +/- s.e.m., ng/ml) in all geldings (before treatment, 7.5 +/- 2.3; final treatment week, 1.8 +/- 0.2; P less than 0.05), whereas early in the breeding season, testosterone caused a prolonged rise in LH (before, 6.8 +/- 2.3; final week, 18.9 +/- 6.4; P less than 0.05). In all testosterone experiments, LH returned to pretrea...
Choińska AM, Bajer W, Żurek A, Gieysztor E.Activities with horses cause many emotional reactions in their recipients, the measurement and analysis of which can provide information about positive or negative attitudes toward hippotherapy activities. The purpose of the study was to explore how horse contact affects the emotions of female and male students experiencing horseback riding during a three-day hippotherapy session. Unassigned: The study included 252 physiotherapy students from the Medical University of Wrocław who participated in hippotherapy classes during a three-day didactic and scientific course implemented in the years 20...
Illera JC, Hamlin RL, Illera M.Bipolar and unipolar limb leads and unipolar thoracic lead ECG were obtained from 100 male crossbred horses. P-wave morphologic features were classified according to positivity negativity and monopolarity dipolarity, and the percentage of horses that had P waves of a given morphologic class in each lead was calculated. P-Wave morphologic features of 4 precordial leads were most uniform, with greater than 80% of the horses having a single configuration.
Little CB, Hilbert BJ, McGill CA.The clinical features of 21 horses which sustained head fractures are reviewed. There was a higher incidence of fractures in males and Standardbred horses. Surgical treatment was practical and successful in most cases when the fractures involved the bones of the jaws and the face. Fractures which involved the cranial cavity or the cranial nerves were difficult to treat and usually held a poor prognosis.
Shojaei B, Kheirandish R, Azizi S.The present study describes the anatomical and microscopic features of a horseshoe kidney that was found in a 7-year-old male horse. The specimen consisted of two kidneys joined at their caudal poles by an isthmus composed of renal parenchyma and situated caudal to the caudal mesenteric artery. Six main renal arteries arose from the aorta and the external iliac arteries and ramified into 21 branches before entering the kidney. A hypoplastic and ectopic left testis, located in the inguinal canal, was observed as an associated anomaly.
Trumble TN, Hendrickson DA.Standing laparoscopy in the horse was used initially as a diagnostic tool to assist in the diagnosis of a cryptorchid testicle. Now, this technique is also used for treatment of cryptorchid testicles. The focus of this article is the standing laparoscopic cryptorchidectomy, the most common laparoscopic procedure performed on the male equine urogenital tract. Advantages, disadvantages, instrumentation, and general procedure are discussed.
Auge BK, Preminger GM.The surgical management of urinary calculus disease has changed dramatically in the past two decades. Minimally invasive options have made open stone surgery nearly obsolete. The development of shock wave lithotripsy, percutaneous nephrostolithotomy techniques and intracorporeal lithotripsy devices has conferred unprecedented management tools for upper tract stones. Moreover, transfusion rates, hospital costs, and convalescence periods have been markedly reduced when compared to open surgery. Likewise, the advent of fiberoptic technology has resulted in miniaturization of ureteroscopes making ...
Kondo T, Mashimo Y, Sato F, Tsuzuki N, Yamada K.Thoroughbred horses appear to be particularly predisposed to cervical vertebral stenotic myelopathy (CVSM), also known as wobbler syndrome. We hypothesized that variations in the cervical vertebral volumes can affect the dynamic instability of the cervical vertebrae. This observational study aimed to clarify whether cervical vertebral volume could be considered as a contributing factor in CVSM in Thoroughbred horses. Computed tomography (CT) was used to investigate a total of 21 male Thoroughbred horses (age range, 217-1,002 days; mean, 542.3 days). The study population comprised 17 CVSM horse...
Illera JC, Illera M, Hamlin RL.Electrocardiograms were obtained from 100 male crossbred horses. In addition to standard limb leads, leads were taken from 12 points on the thorax. The QRS complexes were categorized into 1 of 8 forms on the basis of configuration and amplitudes of component deflections. Relative uniformity of QRS was determined for each lead, using the percentage of horses that possess a particular configuration. All unipolar thoracic leads, except those coplanar with the frontal plane, and lead aVR had great uniformity, with greater than 80% of the horses with a QRS of similar contour.
Whishaw IQ, Kolb B.A human physical asymmetry is the near 90% clockwise occipitoparietal scalp hair-whorl direction in Europeans, an incidence that approximates the left lateralization of speech and right-handedness. Hair-whorl direction is also asymmetric in horses, Equus ferus caballus and placement is proposed to be related to temperament and lateralized skill in equitation manoeuvres. We describe a hair-whorl asymmetry in the horse, mane direction. Of 526, 3-year-old American Quarter horses, 69% of horses had mane directed to the right and 31% had mane directed to the left. The bias was larger in females, wi...
Hanie EA, Sullins KE, White NA.The results of 31 intracortical dorsal metacarpal stress fractures in 28 horses following unicortical osteostixis were reviewed. The incidence was predominately in the middle third of the lateral aspect of the left metacarpus, and males were affected more commonly. Approximately half of the surgical procedures were performed with the horse in the standing position. The mean times to return to training and racing were 4.25 and 6.9 months respectively. There was no correlation between time taken to return to racing and position of surgery. Complications experienced included lack of suture remova...
Giontella A, Cardinali I, Sarti FM, Silvestrelli M, Lancioni H.Horse domestication and breed selection processes have profoundly influenced the development and transformation of human society and civilization over time. Therefore, their origin and history have always attracted much attention. In Italy, several local breeds have won prestigious awards thanks to their unique traits and socio-cultural peculiarities. Here, for the first time, we report the genetic variation of three loci of the male-specific region of the Y chromosome (MSY) of four local breeds and another one (Lipizzan, UNESCO) well-represented in the Italian Peninsula. The analysis also inc...
Sassot LN, Ragle C, Pentzke-Lemus L, Jones ARE, Farnsworth K.This retrospective case series describes the use of progressive urethral dilation in 22 client-owned male horses undergoing perineal urethrotomy (PU) for cystolith removal. Medical records of horses undergoing PU and urethral dilation for treatment of cystolithiasis were reviewed. Dilation of the pelvic urethra was performed following PU and using customized dilators with the same length (30cm) and with various outer diameters (25 to 45mm). Analyzed data included: signalment, cystolith size, renal ultrasound findings, method used for cystolith removal, diameter of urethral dilators, intra- and...
Megerssa YC, Gari FR.Delays between blood collection and analysis are inevitable, and samples are always stored in the refrigerator. The current study aimed to evaluate the stability of serum total cholesterol (TC), triglycerides (TG), total protein (TP), albumin and urea (URA) in horses and oxen after storage at -20°C. Methods: Sera from apparently healthy 20 male horses and 20 oxen were obtained and aliquots of serum were divided into 3 portions. The first tube was used for baseline (T0) measurement of analyte values, whereas the other two tubes, T1 and T2, were stored at -20°C for 1 and 2 months, respectively...
