Foals may need to be restrained for physical exams, treatments, diagnostic procedures, and sometimes for minor interventions. The veterinarian can use standing restraint while completing a physical exam or a handler can hold the foal while treatment is administered. Placing a foal in lateral recumbency is often used to perform abdominal ultrasound, to place a catheter, or to complete other procedures under sedation. Veterinarians can also help owners learn proper restraint and care. In addition, they can guide owners in the use of imprinting techniques which can facilitate socialization of the foal with humans, learning to halter and lead, and getting used to several routine procedures including picking up feet, tolerating touch during a physical exam, and accepting use of clippers. Foals that have undergone imprint training get used to common procedures and may become easier to handle and less fractious compared to untrained foals.
The natural or physiological breeding season of mares extends from April to October in the northern hemisphere. A majority of mares enter a state of ovarian inactivity, or seasonal anestrus, during the winter months. This chapter gives step-by-step instructions with interpretative information, as well as useful equipment lists for management of seasonal anestrus. Mares housed under a stimulatory artificial photoperiod will ovulate earlier in the year and potentially cycle and ovulate more often during the breeding season than mares maintained under ambient light conditions. The physiological mechanism by which artificial photoperiod works is through interruption of the normal pattern of melatonin secretion from the pineal gland. Melatonin is secreted during the hours of darkness. Extending the duration of light exposure will reduce the duration of melatonin secretion, which will subsequently stimulate hypothalamic production of gonadotropin-releasing hormone.
Centrifugation is a processing technique that can be utilized if an ejaculate has a low initial concentration (less than 100 million sperm/ml) or if the stallion's seminal plasma has a detrimental effect on spermatozoal viability. It is also utilized when processing semen for freezing or to remove seminal plasma that has been contaminated with urine during semen collection. Centrifugation will concentrate spermatozoa into a pellet. Subsequently, a majority or all of the seminal plasma can be removed and the sperm pellet re-suspended in an appropriate extender to the desired concentration. It is a necessary process for preparing cooled-shipped semen when a dilute ejaculate is obtained or when urine is present in the ejaculate.
In order to determine issues surrounding foaling, it is important to recognize normal parturition events. This chapter gives step-by-step instructions with interpretative information, as well as useful equipment lists for normal foaling. The mare should be properly prepared and monitored for foaling. The personnel monitoring the mare must be able to recognize the signs of dystocia so that an intervention plan can be implemented quickly. The mare should develop impending signs of parturition in accordance with her expected due date. Premature sign development may indicate an impending abortion or premature delivery. The gestation period for a mare is approximately 340 days, with a range of 320–360 days.
There are a number of management and therapeutic interventions that typically can improve sexual arousal, response, breeding efficiency, and/or endurance of breeding stallions. This chapter outlines a variety of management factors and interventions to be considered for stallions presenting for inadequate interest in breeding. Poor health, regardless the cause, can affect a stallion's interest in breeding, sexual arousal, and response. Some stallions do much better when breeding or when semen collection is done in a "private" area, as in their own paddock or in a breeding area used by no other stallions, and out of sight, smell, or sound of other stallions. Sexual arousal is greatly affected by the handling style and breeding environment. The stimulus mare, and the manner in which she is presented, can greatly affect sexual interest and response. A number of endocrine approaches have been useful for boosting stallion sexual arousal and response.
Gonadotropin-releasing hormone (GnRH) produced in the hypothalamus stimulates the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary. Pulses of GnRH induce pulsatile secretion of LH and FSH which, in turn, regulate testicular function. Administration of GnRH to a stallion will stimulate the synthesis and secretion of LH and FSH and may be used as a test of pituitary function. Test strategies include the administration of a physiological dose of GnRH to measure pituitary function and the administration of a pharmacological dose of GnRH to measure pituitary content of LH and FSH. In either situation, it is recommended that a normal fertile stallion be tested along with a subfertile stallion to evaluate and compare pituitary responses. The low dose, single pulse GnRH stimulation test is used to assess pituitary and potentially testicular responsiveness.
Plasma therapy in foals is most frequently administered as a treatment for failure of passive transfer (FPT). In addition, plasma therapy is used to treat other neonatal diseases such as septicemia, to provide immunoprohylaxis against specific infectious diseases, and for the management for coagulopathies. FPT is common in neonatal foals since the transfer of immunoglobulins must occur through ingestion of colostrum soon after birth. Intravenous plasma administration is strongly recommended in foals older than 12 hours with complete FPT. The benefits of hyperimmune plasma administration are still controversial and the amount of pathogen-specific IgG may be variable between lots of the same hyperimmune plasma product.
Training a stallion to use a phantom, breeding dummy, or breeding mount can take just a couple of training sessions or may require many sessions over several days or weeks depending on the nature of a particular stallion. A stallion that has never been allowed to interact with a mare or has never bred a mare previously may be more challenging to train. The key to training a stallion is to have excellent assistants, a mare in good estrus, proper facilities, and to titrate the exposure to stimuli properly. This chapter presents steps in training the stallion to how use a phantom. If a stallion does not ejaculate during multiple mount attempts on the phantom, the training session should be terminated for that day and all procedures evaluated to determine any improvements in technique.
This chapter describes the methods that are used for clinical cytogenetic analysis in horses. This includes a list of the basic required equipment and supplies for an equine cytogenetics laboratory, a detailed step-wise methodology for the preparation of metaphase chromosome spreads from different tissues, and a description of the main principles and methods of chromosome analysis. Chromosomal analysis includes counting the diploid (2n) chromosome number, arranging chromosomes into a karyotype, and evaluating chromosome morphology according to their banding patterns following the international system of chromosomal nomenclature for the horse. Changes in chromosome number and morphology directly affect the viability of zygotes and embryos, normal development, and the formation of gametes. Finally, advanced chromosome analysis approaches and future perspectives of equine clinical cytogenetics are briefly discussed.
Transvaginal ovarian biopsy (TVOB) is one method to determine the nature of an ovarian abnormality. The TVOB technique requires specialized equipment including a transvaginal ultrasound unit, a modified spring-loaded biopsy instrument, and personnel trained to perform the procedure. This chapter discusses the processes involved in TVOB. It is recommended that a physical examination is performed on the mare daily for 3 days post-procedure to monitor for any complications. There is a slight risk of rectal puncture arising from overzealous penetration of the ovary, failure to position the biopsy instrument accurately, accidentally firing the biopsy instrument, or mare movement. If a rectal puncture has occurred then non-steroidal anti-inflammatory therapy for 3 days and trimethoprim sulfa twice daily for 7–10 days, or other broad-spectrum antibiotic therapy may be indicated.
Chapter 104 Evaluation of Colostrum Quality Brix Refractometry Patrick M. McCue, Patrick M. McCue Equine Reproduction Laboratory, Colorado State University, USASearch for more papers by this author Patrick M. McCue, Patrick M. McCue Equine Reproduction Laboratory, Colorado State University, USASearch for more papers by this author Book Editor(s):John Dascanio VMD, John Dascanio VMD Diplomate ACT and ABVP (Equine) Senior Associate Dean for Academic and Student Affairs Professor of Theriogenology School of Veterinary Medicine, Texas Tech University, Amarillo, Texas, United StatesSearch for more papers by this authorPatrick McCue DVM, PhD, Patrick McCue DVM, PhD Diplomate ACT Iron Rose Ranch Professor of Equine Reproduction Colorado State University, Equine Reproduction Laboratory, Fort Collins, Colorado, United StatesSearch for more papers by this author First published: 19 February 2021 https://doi.org/10.1002/9781119556015.ch104 AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onFacebookTwitterLinked InRedditWechat Summary The evaluation of mare colostrum immediately after foaling and prior to nursing can be helpful in predicting if adequate passive transfer or failure of passive transfer is likely to occur. The evaluation of colostrum is also valuable in determining the quality of colostrum to be harvested and stored in a colostrum bank. Quantitative measurement of IgG levels in colostrum can be obtained by a radial immunodiffusion (RID) assay at a diagnostic laboratory. Qualitative assessment of colostrum can be performed using a sugar (Brix) refractometer, which measures the concentration of dissolved solids in a solution. Brix refractometer evaluation of equine colostrum has been shown to be highly repeatable and highly correlated with IgG levels as measured by RID assay. Equine Reproductive Procedures, Second Edition RelatedInformation
