Veterinary medicine for horses encompasses the study and application of medical practices to diagnose, treat, and prevent diseases in equine species. This field involves a comprehensive understanding of equine anatomy, physiology, pathology, and pharmacology. Veterinary practitioners employ a range of diagnostic tools and therapeutic interventions to address health issues in horses, including lameness, gastrointestinal disorders, respiratory conditions, and infectious diseases. Preventative care, such as vaccination and deworming programs, is also a significant aspect of equine veterinary medicine. This page gathers peer-reviewed research studies and scholarly articles that explore various aspects of veterinary medicine as it pertains to horses, including advancements in diagnostic techniques, treatment protocols, and preventive health strategies.
Wiemer P, Bergman HJ, van der Veen H, Pruissen L.In the period from January 1995 until December 2000, 272 horses underwent a laparotomy for gastrointestinal disorders. The results of these surgeries were evaluated. From these 272 patients 176 (= 65%) were discharged in good health from the hospital. When the patients that were euthanized immediately after the start of the surgery, because of a fatal deterioration, were not taken into account, the short time survival rate was 77%. Strangulated small and large intestinal obstructions (48%) had a lower short time survival rate than non-strangulated obstructions (87%). Fatal postoperative compli...
Kearns CF, McKeever KH.The purpose of this 8-wk study was to examine the effect of therapeutic levels of clenbuterol on aerobic performance and hemodynamics associated with exercise. Methods: Twenty-three unfit Standardbred mares were divided into four experimental groups, clenbuterol (2.4 microg x kg(-1) body weight twice daily) plus exercise (20 min at 50% O2max; CLENEX; N = 6), clenbuterol only (CLEN; N = 6), exercise only (EX; N = 5), and control (CON; N = 6). All horses performed an incremental exercise test (GXT) to measure maximal oxygen consumption (O2max), blood lactate concentration, total plasma protein c...
Sriprapat S, Aeksowan S, Sapsutthipas S, Chotwiwatthanakun C, Suttijitpaisal P, Pratanaphon R, Khow O, Sitprija V, Ratanabanangkoon K.Therapeutic antivenom against snakes was first produced by Albert Calmette in 1894. Since then antivenoms have saved the life of countless snakebite victims. However, there are still many problems associated with antivenom production, for example variable percentage of responder horses, low neutralizing potency of antivenom, the large amount of snake venom needed for immunization and the difficulties encountered in producing potent polyvalent antivenoms. These problems have led to shortage and high cost of antivenom and, in some cases, failure of treatment. In 1997, a new immunization protocol...
Brianceau P, Chevalier H, Karas A, Court MH, Bassage L, Kirker-Head C, Provost P, Paradis MR.Twenty-eight horses with the diagnosis of an intestinal disorder requiring surgical intervention were randomly assigned to lidocaine (n = 13) or saline (control, n = 15) treatment groups. After induction of anesthesia, treated horses received a loading dose of 2% lidocaine (0.65 mg/kg) intravenously, followed by a continuous rate of infusion of 1% lidocaine (0.025 mg/kg/min) until the discontinuation of anesthesia. Upon recovery from anesthesia, a 2nd loading dose of 2% lidocaine (1.3 mg/kg) was administered, followed by an infusion of 1% lidocaine (0.05 mg/kg/min) for 24 hours postoperatively...
Walker AM, Sellon DC, Cornelisse CJ, Hines MT, Ragle CA, Cohen N, Schott HC.A retrospective study of the medical records of 33 horses was performed to determine the clinical and diagnostic abnormalities associated with temporohyoid osteoarthropathy. Data collected from medical records included signalment, presenting complaints, history, physical examination findings, laboratory data, results of diagnostic imaging studies, and treatments. Follow-up information was obtained from a review of case records; by telephone conversation with the owner, veterinarian, or trainer; or by both methods. Of 33 horses with temporohyoid osteoarthropathy, 29 presented with facial nerve ...
Aurich C, Gerlach T, Aurich JE, Hoppen HO, Lange J, Parvizi N.In the non-breeding season, LH release is reduced via dopaminergic systems in the ram. On the other hand, our previous studies demonstrated an opioidergic inhibition of LH release in stallions outside the breeding season. Thus, in the present study we investigated the dopaminergic regulation of LH and prolactin secretion in stallions, considering interactions between dopamine and opioids. To achieve this, stallions (n=8) were treated with the dopamine antagonist sulpiride (0.6 mg/kg), the opioid antagonist naloxone (0.5 mg/kg), sulpiride plus naloxone or saline in December, March and June. Two...
Davis JL, Gilger BC, Spaulding K, Robertson ID, Jones SL.A 9-year-old Trakehner gelding was examined because of right exophthalmus. Clinical findings included a lack of menace response in the right eye, reduced direct and consensual right pupillary light reflexes, ventrolateral strabismus of the right eye, mild right-sided facial asymmetry, a head tilt to the left, and increased extensor tone in the right limbs. Findings were suggestive of a multifocal lesion affecting the right forebrain; right optic, oculomotor, and facial nerves; and left vestibulocochlear nerve. Ultrasonographic examination of the right eye revealed a vascular retrobulbar mass. ...
Giese A, Jude R, Kuiper H, Raudsepp T, Piumi F, Schambony A, Guérin G, Chowdhary BP, Distl O, Töpfer-Petersen E, Leeb T.The cysteine-rich secretory protein (CRISP) family consists of three members called acidic epididymal glycoprotein 1 (AEG1), AEG2, and testis-specific protein 1 (TPX1), which share 16 conserved cysteine residues at their C-termini. The CRISP proteins are primarily expressed in different sections of the male genital tract and are thought to mediate cell-cell interactions of male germ cells with other cells during sperm maturation or during fertilization. Therefore, their genes are of interest as candidate genes for inherited male fertility dysfunctions and as putative quantitative trait loci fo...
Lebis C, Bourdeau P, Marzin-Keller F.Allergic diseases are often diagnosed clinically in the horse without performing diagnostic tests. The purpose of this work was to contribute to the validation of intradermal skin tests in the horse. Eighty-three horses, 14 showing skin or respiratory signs of supposed allergic origin, were subjected to an intradermal skin test using 6 different allergens, positive and negative controls. The tests were read for all animals after 20 min, and for 29 horses after 1 and 4 h. Additionally, 19 horses were tested a few months apart. The comparison after 20 min of the cutaneous reactions to allergens ...
McGorum BC, Milne AJ, Tremaine WH, Sturgeon BP, McLaren M, Khan F.A combined laser Doppler flowmetry and iontophoresis (LDFI) technique, used routinely to assess human microvascular function, was evaluated as a noninvasive technique for assessment of equine microvascular function, to facilitate the study of diseases such as laminitis. Baseline and vasoactive agonist-induced (acetylcholine and nitroprusside) microvascular flux was quantified at 2 sites (on the dorsal pastern adjacent to the coronary band and over the gluteals) in 6 clinically normal horses on 5 or 6 separate occasions under standardised conditions. Both agonists significantly increased microv...
Goodwin S.Body temperature of goats, horses, and sheep was measured, using 3 methods. Tympanic temperature was measured with a tympanic infrared thermometer, subcutaneous temperature was measured with an implantable microchip transponder, and rectal temperature was measured with a digital thermometer. For goats, rectal and subcutaneous temperatures were significantly higher than tympanic temperatures, but rectal and subcutaneous temperatures did not differ significantly. For horses and sheep, rectal temperatures were significantly higher than tympanic and subcutaneous temperatures, and tympanic temperat...
Hultén C, Grönlund U, Hirvonen J, Tulamo RM, Suominen MM, Marhaug G, Forsberg M.Despite the importance of noninfectious joint diseases in equine medicine, little is known about the acute phase response which may be elicited if the local inflammatory process of noninfectious arthritis is sufficiently strong, Therefore the aim of this study was to monitor the systemic inflammatory response during experimentally-induced noninfectious arthritis by studying the dynamics in serum of the acute phase proteins serum amyloid A (SAA), haptoglobin, fibrinogen and alpha2-globulins. Twenty-four Standardbred horses, age 3-7 years, found healthy on thorough clinical, radiological, haemat...
Perkins GA, Lamb S, Erb HN, Schanbacher B, Nydam DV, Divers TJ.Plasma ACTH levels have been variable in horses with a positive clinical response for therapy for equine Cushing's Disease (ECD). Therefore, our purpose was to determine the value of monitoring plasma adrenocorticotropin (ACTH) levels during treatment of equine Cushing's disease (ECD) with either cyproheptadine (n = 32) or pergolide (n = 10). First, we validated the chemiluminescent ACTH assay (specificity, precision, accuracy, intra-assay and interassay variations) and tested methods of handling the whole blood from the time of collection to when the ACTH was assayed. The sensitivity and spec...
Hultén C, Demmers S.Differentiation between infectious and noninfectious disease and rapid initiation of accurate treatment are essential in managing diseases in the neonatal and young foal. Identification of useful inflammatory markers for these purposes is, therefore, of great importance. The aim of this study was to compare the responses of the acute phase protein serum amyloid A (SAA) with the responses of fibrinogen and total leucocyte and neutrophil counts in infectious diseases encountered in the young foal, and to assess whether SAA measurements give additional information useful in the management of thes...
Thomason JJ, McClinchey HL, Jofriet JC.Finite-element (FE) methods have great potential in equine biomechanics in evaluating mechanical stresses and strains in tissues deep within the hoof. In this study, we critically assessed that potential by comparing results of FE analyses of capsular strain with in vivo data. Nine FE models were developed, corresponding to the shape of hooves for which in vivo principal strain data are available. Each model had the wall, laminar junction, sole and distal phalanx (PIII). In a first loading condition (LC1), force is distributed uniformly to the bearing surface of the wall to determine reaction ...
Smith RK, McGuigan MP, Hyde JT, Daly AS, Pardoe CH, Lock AN, Wilson AM.Metacarpophalangeal (MCP) joint extension is primarily resisted by the digital flexor tendons and suspensory ligament. A variety of external support techniques are used to protect these supporting structures from or after injury by resisting MCP joint extension, although not all are effective and/or practical for use in an exercising horse. In this study, 7 forelimbs were loaded in vitro to determine the effect of a simple gamgee bandage, a 3-layered bandage with and without a contoured palmar splint, a neoprene exercise boot, and an innovative carbon fibre composite exercise boot (Dalmar tend...
Kirschvink N, Fiévez L, Bougnet V, Art T, Degand G, Smith N, Marlin D, Roberts C, Harris P, Lekeux P.An oxidant/antioxidant imbalance in favour of oxidants has been identified as playing a decisive role in the pathogenesis of chronic inflammatory airway diseases. Nutritional antioxidant supplementation might reduce oxidative damage by enhancement of the antioxidant defence, thereby modulating inflammatory processes. In a placebo-controlled, blind study, it was tested whether a dietary antioxidant supplement administered for 4 weeks would improve lung function and reduce airway inflammation in heaves-affected horses. Eight horses in clinical remission of heaves were investigated at rest and af...
Wagner B, Siebenkotten G, Leibold W, Radbruch A.Due to characteristic clinical signs, immunoglobulins of isotype E (IgE) are believed to be involved in several allergic diseases of the horse. To date, closer investigations have been hampered by the fact that neither purified equine IgE nor anti-equine IgE monoclonal antibodies were available for IgE isotype determination. As an approach to solve this problem, we constructed a stable cell line (EqE6) that expresses recombinant equi-murine IgE specific for 4-(hydroxy-3-nitro-phenyl) acetyl (NP). Biochemical analysis of the purified protein revealed a highly glycosilated IgE monomer of approxi...
Rosati I, Berlinguer F, Bogliolo L, Leoni G, Ledda S, Naitana S.It is clear that, in the horse, there are many weak links in the process of in vitro embryo production; an optimal culture system for equine oocytes does not exist, and related data are conflicting. Therefore, the ability of 3 different culture systems to support embryonic development of ICSI horse oocytes was examined. Oocytes (n = 261) suitable for culture were collected from 55 ovaries and divided, according to cumulus morphology, into 2 categories: expanded cumulus and compacted cumulus. Oocytes with expanded and compacted cumulus were cultured for in vitro maturation in TCM 199 + 10% FCS ...
Chotel F, Parot R, Durand JM, Garnier E, Hodgkinson I, Bérard J.The choice of first-line treatment for congenital varus equine clubfoot remains a controversial issue largely dependent on experience. In France, functional treatment predominates. In 1948, Ponseti proposed reducing the deformity with successive casts. Although cast treatment is a very old method, Ponseti's method is original because it is based on strict rules established from anatomic evidence. The goal is not to correct the apparent deformation, but on the contrary to impose a simultaneous supination and abduction of the foot. Once the calcaneopedal block has been derotated, percutaneous te...
Turner M, McCrory P, Halley W.Professional horse racing is an exciting and demanding sport with high injury rates. Surprisingly few epidemiological studies have been published and no prospective studies have been reported. This paper reviews the literature and provides a detailed breakdown of injuries in Great Britain and the Republic of Ireland for 1992-2000. The introduction of protective equipment is discussed and evidence for its effectiveness put forward.
Price J, Marques JM, Welsh EM, Waran NK.This preliminary study investigated the attitudes, and evaluated the current practice of a sample of the veterinary profession in the UK in relation to the management of pain in horses. In June 2001, a questionnaire was posted to 260 veterinarians in specialised equine practice, and 140 veterinarians in general practice with a significant equine caseload. There was a 25 per cent response rate to the questionnaire, which recorded information about the availability and prescription of analgesic drugs, the factors influencing the selection of analgesics and their administration, and estimates of ...
Hardy GW, Darbre A, Merrett M.3-Phosphoglycerate kinase was isolated from horse muscle and subjected to the action of cyanogen bromide. The resulting peptides were separated using gel filtration combined with either ion exchange chromatography on phosphocellulose in 6 M urea or high voltage paper electrophoresis. The sequence of the largest peptide, CB5, has been determined by a combination of automated and manual Edman degradation carried out on the intact peptide and derivatives obtained by proteolytic digestion. The isolation of two peptides derived from CB5 by cleavage of the bond between Asp109 and Pro110 facilitated ...
Valentine BA, Hintz HF, Freels KM, Reynolds AJ, Thompson KN.To determine whether feeding a low-carbohydrate, high-fat diet would decrease severity of exercise-induced muscle injury in horses with exertional rhabdomyolysis. Methods: 19 horses with a history of exertional rhabdomyolysis. Methods: Case series. Methods: Specimens of the semitendinosus or semimembranosus muscle were obtained for histologic examination, and serum creatine kinase (CK) and aspartate transaminase (AST) activities 4 hours after exercise were determined. Horses were then fed a low-carbohydrate, high-fat diet, and serum CK and AST activities 4 hours after exercise were reevaluated...
Johnson R.A review of the literature on intestinal atresia of domestic animal species and humans was done. The 5 types of intestinal occlusions described in human infants are atresia type 1, atresia type 2, atresia type 3, stenosis, and the "apple peel" or "Christmas tree" deformity. The intestinal defects described in domestic animal species such as the bovine, equine and porcine are similar to those of human infants. The "T-formation", an intestinal defect of the bovine resembling atresia type 3, and rectal stricture, an acquired intestinal defect of the porcine resembling stenosis, were described rec...
Sprayberry KA, Slovis NM.Pericarditis is a sporadic, but important cause of critical illness in horses of all ages. There is limited information on whether Thoroughbred horses that survive pericarditis are able to reach athletic potential. Objective: To determine how pericarditis affected horses that had the disease as young animals with regard to selling price in public sales and the ability to race successfully. Methods: Retrospective case series. Methods: Medical records were searched to identify pericarditis cases. Signalment and month of diagnosis were noted and Thoroughbreds with ultrasonographically confirmed p...
Joncas JH, Gilker JC, Chagnon A.The relative value of heterophil agglutinins (HA) and of specific EBV antibodies in the diagnosis of infectious mononucleosis (IM) was assessed in 108 cases of the disease and in 280 controls. Among the 108 cases 93 were HA-positive by sheep cells in at least one of their sera, while 15 were HA-negative by the same test. Among the 280 controls false-positive HA tests were not encountered except in eight cases with the horse cell microtitre tests. With one of the two slide tests at least two false-positive tests and 12 false-negative tests were also found but these sera had low titres in microt...
Frippiat T, Paindaveine C, Duprez JN, Delguste C, Mainil J, Art T.Antimicrobial resistance is increasing in both human and veterinary medicine. Bacteria can be part of the etiology of respiratory disorders in horses. Bactericidal activity of silver has been largely described and silver is currently used in veterinary therapeutic applications such as wound dressings. The aim of this study was to assess the in vitro bactericidal effects of nebulized silver nanoparticles (AgNP) on 2 common equine respiratory bacteria, Streptococcus equi subsp. zooepidemicus and Actinobacillus equuli subsp. equuli. Firstly, antimicrobial susceptibility of AgNP was determined ove...
Altamura G, Strazzullo M, Corteggio A, Francioso R, Roperto F, D'Esposito M, Borzacchiello G.Bovine papillomaviruses (BPVs) types 1 and 2 are the only known papillomaviruses able to jump the species. In fact, BPVs 1/2 induce neoplasia in their natural bovine host but infection is also associated to neoplastic skin lesions in equids termed sarcoids. The equine sarcoid is considered to be the most common equine cutaneous tumour worldwide for which no effective therapy is available. Very little is known about the molecular mechanisms underlying tumourigenesis, although genes contributing to sarcoid development have been identified. Several studies associate the development of cancer to t...
Hitchens PL, Ryan K, Koch SI, Scollay MC, Peterson ML.Jockey injuries in North American racing are not well understood. The types and severity of injuries as well as exposure need to be better characterized in order to reduce risk. We consider existing data sources and the opportunity to combine this data with a new data collection effort to better understand and potentially reduce risk to riders. Using a two-phase approach, data appears to be available which would allow useful information on jockey injuries that could inform efforts for risk reduction quickly and with modest resources. Initial successes can help to develop support for a more com...
Nakamura Y, Nishi H, Katayama Y, Niwa H, Matsumura T, Anzai T, Ohtsu Y, Tsukano K, Shimizu N, Takai S.An eight-year-old thoroughbred mare with no previous history of illness aborted a fetus at 196 days of gestation, and its internal tissues were examined immunohistologically and bacteriologically. The placenta was not examined, but specimens of the intrauterine fluids and the dam's faeces were collected four days after the abortion and examined bacteriologically. No significant histological lesions were found in the fetus but the amnion and the umbilical cord were oedematous and had petechial haemorrhages. Rhodococcus equi was isolated in pure culture from the lung, heart and stomach contents ...
Bird J, Herd RP.The ability of two species of nematophagous fungi, Arthrobotrys oligospora and Arthrobotrys flagrans (syn. Trichothecium flagrans, Duddingtonia flagrans), to control the development of infective larvae in feces from naturally infected horses was assessed in vitro. The horses were from a farm where it had been previously established that cyathostomes accounted for 100% of the strongyle egg output. The feces from these naturally infected horses were mixed with spores of each fungal species at four concentrations: 0 (control), 1, 10, and 100 spores per egg. Five replicates for each group were inc...
Lyons ET, Tolliver SC.Macrocyclic lactones (MLs) revolutionized parasite control in horses and other animals. They are unique in that they are effective against arthropods and nematodes. The first of the widely used avermectins was ivermectin. In 1983, it was marketed for use in horses as an injectable formulation but was withdrawn in 1984 after about a year and half on the market because of adverse problems. It was replaced by a paste formulation and an oral/stomach tube liquid formulation. Ivermectin is highly active on bots, ascarids, large and small strongyles, pinworms, strongyloides, stomach worms, and some o...
Schaaf KL, Kannegieter NJ, Lovell DK.Ten horses presented with severe distortion of the facial contour, crepitus on palpation and mild to moderate epistaxis. Individual horses also showed ocular damage, ptosis, severe dyspnoea and movement of the facial bones concurrent with respiration. The fracture fragments were exposed using a large curvilinear incision and elevated using a retractor, periosteal elevator, chisel or Steinmann pin. The fracture fragments were unstable following reduction and fixation was necessary. Stabilisation was achieved with polydioxanone sutures placed through holes drilled in opposing sides of the fractu...
Morris LH, Maclellan LJ.The increased commercialisation of intracytoplasmic sperm injection (ICSI) in horses creates more opportunities to incorporate advanced reproductive technologies, such as sex-sorted, refrozen and lyophilised spermatozoa, into a breeding program. This paper reviews the status of these semen-handling technologies in light of their use in equine ICSI programs. Pregnancies have been achieved from each of these advanced technologies when combined with ICSI in horses, but refinements in the semen-handling processes underpinning these technologies are currently being explored to produce more reliable...
Bahar S, Bolat D, Selcuk ML.Although the cervical spinal cord (CSC) of the horse has particular importance in diseases of CNS, there is very little information about its segmental morphometry. The objective of the present study was to determine the morphometric features of the CSC segments in the horse and possible relationships among the morphometric features. The segmented CSC from five mature animals was used. Length, weight, diameter, and volume measurements of the segments were performed macroscopically. Lengths and diameters of segments were measured histologically, and area and volume measurements were performed u...
Govaere J, Ducatelle R, Hoogewijs M, De Schauwer C, de Kruif A.This report describes a bilateral seminoma in a stallion. After slaughter, histological examination revealed that the tumour consisted predominantly of polyhedral tumour cells with large nuclei, obvious nucleoli and a small border of cytoplasm. The mitotic index was low and Ki67 staining revealed 4% nuclear staining. To our knowledge, this paper is the first using Ki67 staining as a method to evaluate the mitotic rate in a testicular seminoma in the stallion.
Ramseyer A, Sides R, Slinker B, Evans D, Bayly W.The ability to obtain breath-by-breath measures of ventilatory mechanics for the entirety of an exercise test, regardless of speed(s) or duration enables evaluations of equine ventilation during exercise that are necessary for assessments of performance. Objective: Evaluation of a new ergospirometer (Quadflow; QF) system's accuracy and repeatability for measuring pulmonary variables in contrast to the established pneumotachometer-based system (control) and assessment of its effects, if any, on exercise capacity at high speeds. Methods: Five Thoroughbred horses each performed 10 incremental exe...
Acker DA, Curran S, Bersu ET, Ginther OJ.To describe the gross and histologic changes that develop in the equine embryo proper (ie, the portion of the embryo that becomes the fetus) from days 17 to 40 after ovulation and to compare the external features of equine embryos with those of porcine, ovine, and human embryos. Methods: 34 embryos collected from mixed-breed pony mares. Methods: External features for each embryo proper, including length, number of branchial arches, growth of appendages, face and head features, and body features, were examined, using a dissecting microscope, for embryos collected on days 17 to 40. Internal feat...
Hiraga A, Sugano S.Although the total number of horses raised in Japan dramatically decreased after World War II, because draft horses were still used for farm work in paddy fields and on farms during the period of the 1950s and 1960s, a performance test for selecting better draft horses was needed. In order to determine the most suitable size of draft horses for Japanese farm conditions, the working power of horses weighing from 185 to 622 kg was evaluated by performing an endurance test, several kinds of working power tests, and maximum pulling power tests. Oxygen consumption during draft exercise was measured...
Russell JW, Hall MS, Kelly GM.A 3-year-old Thoroughbred gelding was presented with a grade 3/5 lameness of the right forelimb and effusion of the extensor carpi radialis tendon sheath (ECRTS). Radiographic and ultrasonographic examinations revealed an osteochondroma on the cranial aspect of the distal radius projecting into the fibrous lining of the ECRTS. An open surgical approach was used to remove the osteochondroma and some of the proliferative synovial tissue. Conclusions: Six months after surgery the clinical signs had resolved and the horse raced successfully.
Singha H, Malik P, Saini S, Khurana SK, Elschner MC, Mertens K, Barth SA, Tripathi BN, Singh RK.Burkholderia mallei is a Gram-negative coccobacillus which causes glanders-a fatal disease of equines that may occasionally be transmitted to humans. Several cases of outbreaks have been reported from India since 2006. This paper presents draft genome sequences of two B. mallei strains isolated from equines affected by glanders in India.
Dunay MP, Németh T, Makra Z, Izing S, Bodó G.In the present series of cases, 8 laparoscopic cryptorchidectomies and 4 laparoscopic ovariectomies were carried out in sedated standing horses. Sedation involved a lesser anaesthesiological risk than does general anaesthesia. As compared to laparotomic exposure, the minimally invasive laparoscopic intervention provided better visualisation, shorter operative time and faster recovery. The blood vessels supplying the testes and ovaries and the suspensory ligaments of the organs were sealed and cut with EnSeal®, an adaptive bipolar electrosurgical blood vessel- and tissue-sealing device. The cl...
de Lorenzi L, Molteni L, Zannotti M, Galli C, Parma P.This report concerns the cytogenetic analysis, using both C-banding and fluorescence in situ hybridisation techniques, of a sterile mare. Results obtained revealed a 2n = 65, XXX condition with no sign of mosaicism. The work supports the suggestion that X trisomy, rare in horse, causes infertility in mares and is not associated to other clearly visible phenotypic features.
