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Topic:Stallion
Stallions are adult male horses that have not been gelded and are often used for breeding purposes. They exhibit distinct behavioral and physiological characteristics compared to mares and geldings. Stallions are known for their strong musculature, prominent neck, and often more pronounced mane and tail. Their behavior can be more aggressive and territorial, especially during the breeding season, as they naturally compete for mating opportunities. This topic explores the anatomy, behavior, and management practices specific to stallions, as well as their role in equine reproduction. The page provides access to peer-reviewed research studies and scholarly articles that investigate various aspects of stallion health, fertility, and behavior, contributing to the understanding and management of these horses in equine science.
Factors associated with the risk of developing sarcoid tumours in horses. A retrospective case-control study was conducted to identify risk factors in horses associated with the development of the common skin tumours known as sarcoids. The study involved 503 sarcoid cases diagnosed (January 1980-December 1989) at New York State College of Veterinary Medicine and a similar number of controls (non-sarcoid cases). Data on age, breed and sex of cases and controls were obtained from computerised records. Multiple logistic regression analysis was used to identify risk factors. Separate data were obtained for the same 10-year period from the Veterinary Medical Data Program...
Skeletal muscle fiber size in untrained and endurance-trained horses. The mean area and minimal diameter of 3 histochemically determined myofiber types (1, 2A, and 2B; myosin ATPase in acid buffer) were calculated in middle gluteal muscle biopsy specimens from 62 stallions, 47 Andalusians and 15 Arabians, ranging in age from 6 to 12 years. Fourteen Andalusians and 7 Arabians were untrained, and the remainder were actively endurance-trained. The 6-month training schedules involved walking, slow trotting, and cantering. Fourteen Andalusians were moderately endurance-trained, whereas the other 19 Andalusians and 8 Arabians were strongly endurance-trained. Significa...
Growth hormone in mares and stallions: pulsatile secretion, response to growth hormone-releasing hormone, and effects of exercise, sexual stimulation, and pharmacological agents. Short-term patterns of growth hormone (GH) secretion and factors affecting it were studied in mares and stallions. In Exp. 1, hourly blood samples were collected from three mares and three stallions in summer and winter. Although GH concentrations varied in a pulsatile manner in all horses, there was no effect of sex or season (P greater than .1) on plasma GH concentrations and no indication of a diurnal pattern of GH secretion. In Exp. 2, 10-min blood samples were drawn for 8 h from 12 mares; after 6 h, porcine GH-releasing hormone (GHRH) was administered i.v. at 0, 45, 90, or 180 micrograms/...
Comparison of spermatozoal movement and semen characteristics with fertility in stallions: 64 cases (1987-1988). Information pertaining to evaluation of single ejaculates of semen and records for 2 consecutive breeding seasons were obtained. In all, data for 99 individual breeding seasons (n = 43 Standardbreds and 56 Thoroughbreds) were evaluated. Included in each semen evaluation was examination of semen characteristics and computer-aided analysis of spermatozoal movement characteristics. On the basis of the analysis of breeding records for 4,175 mares (7,017 estrous cycles), a per-estrous cycle fertility rate was calculated from data for 96 of the breeding seasons. Stallions with lower fertility than t...
Normal and abnormal sexual behavior. This article includes a brief description of the reproductive patterns and specific behaviors comprising courtship and copulation in equids. The author then focuses on breeding behavior of the domestic stallion. Descriptions of normal breeding behavior under a variety of domestic management systems, comments on sexual behavior of donkeys and exotic equids, and the most common types and treatments of sexual behavior dysfunction are included.
Ultrasonographic evaluation of the testis, epididymis, and spermatic cord of the stallion. Ultrasonographic examination of the testis, epididymis, and spermatic cord of the stallion can be used to enhance the routine breeding soundness evaluation of the stallion. Normal ultrasonographic anatomy of the testes and associated structures are presented to aid the clinician in differentiating abnormalities of these structures.
Reproductive anatomy and physiology of the stallion. Examination of the stallion's reproductive tract involves assessments of external and internal anatomy. External examinations are performed by visual inspection, palpation, or ultrasonography and include the scrotum, testes, epididymides, penis, and prepuce. Internal examinations may be performed by rectal palpation, transrectal ultrasonography, or endoscopy and include the accessory sex glands, pelvic urethra, and inguinal rings. A fertile stallion must produce, transport, store, and deliver viable spermatozoa to the mare. The physiologic processes involved include neuroendocrine control, spe...
Ejaculation. Physiology and dysfunction. In summary, important events of ejaculation include emission of sperm and the accessory gland fluids into the urethra, simultaneous closure of the bladder neck, and forceful ejaculation of the combined semen through the urethra. Emission and bladder neck closure are primarily alpha-adrenergically mediated thoracolumbar sympathetic reflex events with supraspinal modulation. Ejaculation is a sacralspinal reflex mediated by the pudendal nerve. In stallions, the most common ejaculation disorders are emission and ejaculation failure, and urine contamination of semen. Rare disorders are azoospermia ...
Training the novice stallion for artificial breeding. Although the act of breeding is instinctive to the stallion, the use of a phantom mare and AV represent an unnatural element to this act. The use of these devices, as well as proper breeding manners and etiquette, must be taught to the stallion. The novice stallion usually learns these techniques rapidly and is quite manageable if proper restraint is used during training. Positive reinforcement for good behavior is essential. The ultimate goal in training the novice stallion is to develop an individual that will enter the breeding area with controlled enthusiasm, develop an erection and gracef...
Management of stallions on large breeding farms. Often, there is an adversarial relationship between senior management and livestock managers. It is important that the veterinarian responsible for breeding management and health care maintain open communications with senior managers. Although the veterinarian may recognize livestock-management deficiencies that need changing, he or she must remain flexible within the constraints provided on the breeding farm. Years may be required to solidify this give-and-take relationship, and opinions on the value of many management procedures will change. The underpinnings of a successful stallion manager...
Training the novice stallion for natural breeding. There are myriad problems that can arise when training the novice stallion for natural service. Many problems can be avoided by proper early training of the novice stallion. In the final analysis, common sense should prevail. The major ally of common sense is patience. One should keep in mind that the goal is to have a stallion behave in a disciplined manner, allowing for his expression of libido and effective mounting, intromission, and ejaculation. This is accomplished through judicious training and, as with any training process, takes some time and work. Proper training will help circumvent...
Evaluation of the stallion for breeding soundness. The breeding soundness evaluation of a stallion is a thorough investigation of a stallion's libido, mating ability, and semen quality. The evaluation should include historical data about the medical aspects of the horse's performance and breeding career, observations and breeding behavior characteristics, collection and evaluation of semen, tests to determine freedom from infectious or contagious disease, and production of foals free of genetic defects. This information should allow the examiner to anticipate the impact of the stallion on the reproductive efficiency of a group of mares. The br...
Endocrine abnormalities and hormonal therapy. Routine measurement of estrogens, testosterone, T4, insulin, FSH, and LH at least four times per year (e.g., during each of the four seasons) may improve the efficiency of stallion management. Benefits may not be realized in the short term but will provide valuable historical data on individual stallions that, when added to other data, will improve ability of management personnel to initiate early treatment and delay or slow declining fertility. This ability will be greatly improved as more data and products become available. There appears to be a relationship between low total estrogen concen...
Venereal disease. Equine venereal infections of concern in the United States include EHV-3, T. equigenitalis, P. aeruginosa, and K. pneumoniae. Stallions may also harbor EAV in the genital tract and transmit the virus to mares during coitus. With the exception of EHV-3, the stallion generally remains asymptomatic while transmitting infections to mares during breeding. Methods for diagnosis, treatment, and control of these infections are discussed.
Transrectal ultrasonography for the evaluation of stallion accessory sex glands. This article reviews the capabilities of transrectal ultrasonography for determining the distribution of fluid and tissue within stallion accessory sex glands. Emphasis is placed on describing the normal ultrasonographic appearance of the accessory sex glands, excurrent ducts, and pelvic urethra of stallions during rest, after teasing, and after ejaculation and using this information to detect glandular abnormalities.
Semen collection techniques. Semen collection techniques in the stallion have evolved considerably over the last 70 to 80 years and are used today primarily for artificial insemination. Semen can be collected from stallions that are otherwise unable to breed, allowing continued use of valuable animals. There are many options for collection of semen from stallions that present with ejaculatory dysfunction (see the article by McDonnell elsewhere in this issue.) Although there are many advantages to the use of artificial breeding, the collector must understand each step of the collection procedure as well as stallion prefere...
Lipid composition and thermotropic phase behavior of boar, bull, stallion, and rooster sperm membranes. Composition and thermotropic phase behavior of sperm membrane lipids from species ranging in sensitivity to cold shock were determined. Lipids from whole sperm and sperm plasma membrane were fractionated into neutral lipid, glycolipid, and phospholipid fractions. Compositional analyses were completed for free sterols, phospholipids and phospholipid-bound fatty acids. Phase transition temperatures were determined for phospholipid and glycolipid fractions using differential scanning calorimetry. Cholesterol was the major sterol in sperm lipids of all species. Cholesterol to phospholipid molar ra...
Evaluation of stallion semen. This article outlines a basic method for conducting a stallion semen evaluation. After the removal of the gel fraction of the ejaculate, semen gel-free volume is determined, and any abnormality in appearance is noted. Concentration of sperm cells in semen can be determined with the use of either a hemacytometer or spectrophotometer after appropriate dilution of raw semen. The percentage of progressively motile sperm is evaluated promptly after collection of semen with the use of a phase-contrast microscope. The total numbers of sperm and progressively motile sperm in the ejaculate are calculat...
Ejaculatory failure associated with aortic-iliac thrombosis in two stallions. Two mature breeding stallions were evaluated because of specific ejaculatory dysfunction, and each was found to have aortic-iliac thrombosis occluding 60 to 70% of the aortic lumen. In each case, the stallion had strong libido, normal mounting, and vigorous initial thrusting. With continued exertion, thrusting became weak and dismount was awkward. Treatment aimed at maximizing sexual arousal before mounting and reducing hind limb pain and exertion during breeding allowed these stallions to continue breeding. A program of gradually increasing daily exercise also was associated with improved bre...
Endocrine and testicular changes associated with season, artificial photoperiod, and the peri-pubertal period in stallions. The seasonal reproductive cycle of stallions is characterized by an annual regression and recrudescence in testicular function and concentrations of LH, FSH, and testosterone in serum. Maximum reproductive capacity occurs during the increasing day lengths of spring and summer. The annual cycle in LH secretion may reflect a seasonally associated and photosensitive reduction and replenishment in pituitary content of LH. Similar to other seasonal breeders, it appears that stallions may possess an endogenous circannual rhythm in reproductive function that is subject to manipulation by altering the...
Artificial insemination and preservation of semen. Artificial insemination is an effective technique for improving utilization of stallions in breeding programs. When proper semen handling and insemination procedures are used, optimal pregnancy rates are attainable. When AI techniques are employed for mares and stallions with marginal fertility, pregnancy rates may be improved in comparison with natural mating. Preservation of stallion semen in the liquid or frozen state reduces the costs and potential health hazards incurred by transporting mares and provides easier access to genetic material that may otherwise be unavailable. Acceptable preg...
A two year, prospective survey of equine colic in general practice. The records of 200 colic episodes, collected prospectively, over a two year period, from first opinion cases, were analysed and compared with a control sample selected at random from the same population. Analysis by colic type revealed 72% spasmodic/undiagnosed; 7% surgical; 5.5% flatulent; 5% pelvic flexure impactions; 9.5% other implications and 1% colitis. A possible predisposing cause was identified in 43% of the spasmodic/undiagnosed cases. The total incidence of colic in each age group showed no statistically significant differences from the control population. Stallions were significant...
On the genetic basis of equine allergic diseases: II. Insect bite dermal hypersensitivity. The horses studied were of the Swiss Warmblood breed and most were ELA-typed to assess a possible association of dermal hypersensitivity to insect bites with the major histocompatibility complex. Firstly, the occurrence of the condition was examined in 304 half-siblings sired by six stallions (A to F). Fourteen cases of dermal hypersensitivity were recognized and all were in the 153 offspring of Stallions C, E and F. Most animals of this group were also investigated for chronic hypersensitivity bronchitis: none of the sires displayed clinical signs of dermal hypersensitivity, but Stallions D, ...
