The study of diseases in horses encompasses a wide range of conditions affecting equine health, including infectious diseases, metabolic disorders, and genetic abnormalities. These diseases can impact various systems within the horse, such as respiratory, gastrointestinal, and musculoskeletal systems, and can lead to significant health challenges. Research in this area focuses on understanding the pathophysiology, diagnosis, prevention, and treatment of equine diseases. Common diseases studied include equine influenza, equine herpesvirus, and laminitis. This page provides access to peer-reviewed research studies and scholarly articles that explore the etiology, clinical presentation, and management strategies of diseases in horses, contributing to the advancement of equine veterinary medicine.
Pease AP, Schott HC, Howey EB, Patterson JS.Pituitary pars intermedia dysfunction (PPID) is the most common endocrinologic disorder of aged horses. Objective: Pituitary glands of PPID-affected horses are larger than those of aged horses without signs of PPID, and the size difference can be detected using computed tomography (CT) imaging. Methods: Eight horses with clinical signs of PPID and supportive endocrinologic test results and 3 aged control (PPID-negative) horses. Methods: Computed tomography examination of the brain and pituitary gland was performed twice in 10 of the 11 horses, approximately 6 months apart. Six PPID-affected ho...
Nemoto M, Yamanaka T, Bannai H, Tsujimura K, Kondo T, Matsumura T.Reverse transcription loop-mediated isothermal amplification (RT-LAMP) was applied to the detection of equine influenza virus (EIV). Because equine influenza is caused currently by EIV of the H3H8 subtype, the RT-LAMP primer set was designed to target the hemagglutinin gene of this subtype. The detection limit of the RT-LAMP assay was a virus dilution of 10(-5); which was 10(3) times more sensitive than the Espline Influenza A&B-N test and 10 times more sensitive than a reverse transcription polymerase chain reaction (RT-PCR) assay. The specificity of the RT-LAMP assay was examined by usin...
de Laat MA, Sillence MN, McGowan CM, Pollitt CC.Endocrinopathic laminitis is frequently associated with hyperinsulinaemia but the role of glucose in the pathogenesis of the disease has not been fully investigated. This study aimed to determine the endogenous insulin response to a quantity of glucose equivalent to that administered during a laminitis-inducing, euglycaemic, hyperinsulinaemic clamp, over 48 h in insulin-sensitive Standardbred racehorses. In addition, the study investigated whether glucose infusion, in the absence of exogenous insulin administration, would result in the development of clinical and histopathological evidence of ...
Waguespack RW, Taintor J.The paranasal sinus system of horses is complex, comprising six pairs of sinuses. Disease processes that can develop in the sinuses include ethmoid hematomas, cysts, neoplasia, and bacterial and fungal infections. Horses that develop paranasal sinus disease vary widely in age. A significant number of clinical conditions involving the paranasal sinuses require a combination of diagnostic tests to determine the specific pathologic process. Because of the anatomic location of the paranasal sinuses and associated chronic conditions that affect many patients, many disease processes involving the pa...
Curling A.Equine recurrent uveitis has traditionally been treated with medical management to reduce ocular inflammation and control pain during a single episode. Newer management methods include surgical options such as cyclosporine implantation and vitrectomy. These methods were developed not only to control inflammation but also to eliminate the underlying cause of uveitis in order to prevent recurrence.
Cocchia N, Paciello O, Auletta L, Uccello V, Silvestro L, Mallardo K, Paraggio G, Pasolini MP.Endometritis is the most important cause of infertility in barren mares. The quick method of endometrial cytology (EC) has a relatively high reliability in diagnosing endometrial inflammation in the mare. For reliable cytological results, a collection technique that yields many well-preserved cells representative of a large uterine surface area without causing harm to the reproductive tract is required. The aim of the study was to compare three usually employed techniques for collection of endometrial and inflammatory cells (guarded cotton swab, uterine lavage, and cytobrush) in chronically in...
Breuer J, Schmoll F, Uhlig A, Schusser GF.Equine proliferative enteropathy (EPE) caused by Lawsonia (L.) intracellularis is an emerging disease in foals, particularly in North America. Since a case report in Germany exists, the objective of this study was to examine the incidence of L. intracellularis-antibodies in healthy horses from two German breeding farms. In group 1, serum samples from 24 (year 1) and 16 (year 2) Haflinger mares and their foals were taken. In group 2, over a period of five months, serum samples of six warmblood mares and foals were collected monthly from birth until the foals became seronegative. Serum samples w...
Maddox TW, Pinchbeck GL, Clegg PD, Wedley AL, Dawson S, Williams NJ.The increasing prevalence of antimicrobial resistant bacteria such as antimicrobial-resistant and extended spectrum β-lactamase (ESBL)-producing Escherichia coli represents a significant problem for human and veterinary medicine. Despite this, the risk factors for faecal carriage of such bacteria by horses in the UK, particularly those in the wider community, have not been well described. Objective: To characterise the risk factors for faecal carriage of antimicrobial-resistant E. coli amongst horses in the mainland UK. Methods: A cross-sectional study of horses recruited by 65 randomly selec...
Major DA.This paper describes a protocol for hygiene practices that was devised by a practice in which all veterinarians were involved on a daily basis in visiting infected premises, including sampling, treatment of clinical cases and general veterinary work. This protocol was strictly followed when attending an infected or at risk property.
Carr E, Schott H, Pusterla N.Equid herpesvirus-1 (EHV-1) reactivation and shedding can occur in latently infected, asymptomatic animals. Risk factors for reactivation include stress and illness. The risk of asymptomatic shedding in hospitalized, critically ill horses with acute abdominal disease is unknown. This information is important to assess the need for additional biosecurity protocols to prevent spread of EHV-1 in hospitalized critically ill horses with acute abdominal disorders. Objective: To determine the frequency of reactivation and nasal shedding of EHV-1 in hospitalized critically ill horses. Methods: One hun...
Labelle AL, Hamor RE, Townsend WM, Mitchell MA, Zarfoss MK, Breaux CB, Thomasy SM, Hall T.To determine types and frequency of ophthalmic lesions detected in neonatal foals evaluated for nonophthalmic disease at 3 veterinary referral hospitals and to investigate associations between systemic and ophthalmic diseases in these foals. Methods: Prospective cross-sectional study. Methods: 70 foals < 30 days old. Methods: Complete ophthalmic examinations were performed. Signalment, clinical signs, mentation during ophthalmic examination, results of clinicopathologic tests, and diagnosis of systemic disease were recorded. Descriptive data analysis including a χ(2) test for associations was...
Richards MA, Clarke JD, Saravanan P, Voigt N, Dobrev D, Eisner DA, Trafford AW, Dibb KM.Transverse (t) tubules are surface membrane invaginations that are present in all mammalian cardiac ventricular cells. The apposition of L-type Ca(2+) channels on t tubules with the sarcoplasmic reticulum (SR) constitutes a "calcium release unit" and allows close coupling of excitation to the rise in systolic Ca(2+). T tubules are virtually absent in the atria of small mammals, and therefore Ca(2+) release from the SR occurs initially at the periphery of the cell and then propagates into the interior. Recent work has, however, shown the occurrence of t tubules in atrial myocytes from sheep. As...
Liu M, Bordin A, Liu T, Russell K, Cohen N.Focusing on the first 3 weeks of life, this study examined the mRNA transcript development of different Th-type cytokines in foals in response to Rhodococcus equi infection in vitro. Results demonstrated the significant up-regulation in expression of Th1-, Th2-, and Th17-type cytokines (IFN-γ, IL-4, IL-6, IL-8, IL-12p35, IL-12p40, IL-17, IL-23p19, and TNF-α) in R. equi infection of bronchial alveolar lavage (BAL) cells of 10-day-old foals. Consequently, signature cytokines of 3 Th cell types, IFN-γ (Th1), IL-4 (Th2), and IL-17 (Th17), were used to compare temporal response patterns of circu...
Leclere M, Lavoie-Lamoureux A, Lavoie JP.Animal models have been developed to investigate specific components of asthmatic airway inflammation, hyper-responsiveness or remodelling. However, all of these aspects are rarely observed in the same animal. Heaves is a naturally occurring disease of horses that combines these features. It is characterized by stable dust-induced inflammation, bronchospasm and remodelling. The evaluation of horses during well-controlled natural antigen exposure and avoidance in experimental settings allows the study of disease mechanisms in the asymptomatic and symptomatic stages, an approach rarely feasible ...
Tsujimura K, Oyama T, Katayama Y, Muranaka M, Bannai H, Nemoto M, Yamanaka T, Kondo T, Kato M, Matsumura T.A single non-synonymous nucleotide substitution of guanine (G) for adenine (A) at position 2254 in the viral DNA polymerase gene (encoded by open reading frame [ORF] 30) of equine herpesvirus type 1 (EHV-1) has been significantly associated with neuropathogenic potential in strains of this virus. To estimate the prevalence of EHV-1 strains with the neuropathogenic genotype (ORF30 G(2254)) in the Hidaka district--a major horse breeding area in Japan--we analyzed the ORF30 genomic region in cases of EHV-1 infection in this area during the years 2001-2010. Of the 113 cases analyzed, 3 (2.7%) were...
Piviani M, Segura D, Monreal L, Bach-Raich E, Mesalles M, Pastor J.Two neutrophilic indices reported by the ADVIA 120 Hematology Analyzer, neutrophilic myeloperoxidase index (MPXI), and mean light absorbance (neutrophil X mean [NXM]) have been proposed as indicators of systemic inflammatory disease in horses and of neutrophil activation in coronary ischemic syndromes in people. Objective: The aim of this study was to evaluate NXM and MPXI in healthy, sick nonseptic, and sick septic foals to determine whether conditions likely associated with neutrophil activation result in decreases in these variables. Methods: In this retrospective study, CBC data from 61 ne...
Iyer U, Kadambi VJ.Antibody drug conjugates (ADCs) consist of an antibody attached to a cytotoxic drug by means of a linker. ADCs provide a way to couple the specificity of a monoclonal antibody (mAb) to the cytotoxicity of a small-molecule drug and, therefore, are promising new therapies for cancer. ADCs are prodrugs that are inactive in circulation but exert their cytotoxicity upon binding to the target cancer cell. Earlier unsuccessful attempts to generate ADCs with therapeutic value have emphasized the important role each component plays in determining the efficacy and safety of the final ADC. Scientific adv...
Daly K, Proudman CJ, Duncan SH, Flint HJ, Dyer J, Shirazi-Beechey SP.We aimed to determine the effects of variations in dietary composition on equine gut microbiota and their fermentation products, and proposed that dietary modifications profoundly affect microbial ecosystems and their metabolites. Bacterial communities within the large intestine of three groups of horses were compared using oligonucleotide-RNA hybridisation methodology. Each group consisting of six horses was maintained on (1) a grass-only diet, (2) a concentrate diet (i.e. supplemented with hydrolysable carbohydrates) and (3) a concentrate diet but horses were affected by simple colonic obstr...
Muehlmann LA, Michelotto PV, Nunes EA, Grando FC, da Silva FT, Nishiyama A.Phagocytosis exerted by alveolar macrophages and neutrophils is crucial in the clearance of exogenous particles deposited in the airways. Therefore, substances that activate these phagocytes in the airways can exert important effects on the particle clearance rate. PAF, particularly, was proved to be a potent activator of several immune cells and was shown to be present in the equine lower airways in specific conditions, such as after exercise. The present study aimed to investigate if PAF is able to increase the phagocytic capacity and the production of superoxide anion in equine alveolar mac...
Grenager NS, Durham MG.This report describes the use of ultrasound to diagnose right dorsal displacement of the large colon (RDDLC) in 13 horses prior to surgery. Horses had ultrasonographic examinations performed of the right lateroventral aspect of the abdomen upon admission to the hospital with a 2-5 MHz broadband curvilinear sector scanning transducer after alcohol was used to wet the hair. First, the caecal vessels were identified in the right flank and followed medially and cranially. Next, each intercostal space, from caudal to cranial, was scanned from dorsal to ventral evaluating for abnormally-located mese...
Hopster-Iversen C, Hopster K, Staszyk C, Rohn K, Freeman D, Rötting AK.Large intestinal diseases in horses are characterised by inflammation, which could arise from the disease process with some contribution from intestinal manipulation. The effects of the latter are unknown but important to surgeons and could contribute to post operative complications. Objective: To characterise type and degree of intestinal inflammation induced by various mechanical stimuli in the equine ascending colon. Methods: Laparotomy was performed in 12 horses, the left dorsal colon exteriorised and 3 segments randomly exposed to different mechanical manipulations: 1) enterotomy, 2) ente...
Fog P, Vigre H, Nielsen MK.Strongyle worm burdens are assumed to subclinically affect equine performance. This assumption appears to be particularly pronounced in the equine racing industry. Objective: Race results of Standardbred trotters are negatively affected by high strongyle faecal egg count levels. Methods: Faecal samples were obtained from 213 racing Standardbred trotters, aged ≥ 2 years, and stabled at training facilities of 21 professional trainers with license at racecourses in Denmark. Strongyle egg counts were generated using a McMaster technique. Race results were recorded as the finishing position of th...
Morton AJ, Grosche A, Matyjaszek SA, Polyak MM, Freeman DE.The effects of prostaglandins and nonsteroidal anti-inflammatory drugs (NSAIDs) on repair of equine intestinal mucosa are important since most horses with gastrointestinal diseases are routinely treated with NSAIDs, such as flunixin meglumine (FM), and these drugs can be toxic to equine gastrointestinal mucosa. Objective: Flunixin meglumine would not affect recovery of equine colonic mucosa in vitro, 18 h after a reversible ischaemic injury. Methods: In 14 anaesthetised horses, a segment of pelvic flexure was subjected to 2 h of ischaemia and the horses were allowed to recover for 18 h. Seven ...
Parmar J, Winterbottom A, Cooke F, Lever AM, Gaunt M.Streptococcus equi is a common equine infectious disease, but transmission to man is rare and confined to those who commonly come into close contact with horses. Similarly, prosthetic stent graft infection is a rare complication of endovascular aortic aneurysm repair. We describe the first reported case of aortic stent graft with S. equi occurring in a professional racehorse trainer. Clinical presentation, investigations, imaging and management of this case are described. In conclusion, clinicians should consider infection with rare organisms in patients with prosthetic implants who regularly ...
Biggi M, Dyson S.The significance of distal border fragments of the navicular bone is not well understood. There are also no objective data about changes in thickness and proximal/distal extension of the palmar cortex of the navicular bone. Objective: To describe the distribution of distal border fragments and their association with other radiological abnormalities of the navicular bone and describe the shape of the navicular bone in sound horses and horses with foot-related lameness, including navicular pathology. Methods: Sound horses had radiographs acquired as part of a prepurchase examination. Lame horses...
Spencer JA, Deinnocentes P, Moyana EM, Guarino AJ, Ellison SE, Bird RC, Blagburn BL.Equine protozoal myeloencephalitis (EPM) is a neurologic syndrome seen in horses from the Americas and is mainly caused by Sarcocystis neurona. Recently, a 29-kDa surface antigen from S. neurona merozoites was identified as being highly immunodominant on a Western blot. This antigen has been sequenced and cloned, and the expressed protein has been named SnSAG1. In a previous study, cell-mediated immune responses to SnSAG1 were shown to be statistically significantly reduced in horses with EPM in comparison to EPM-negative control horses. It therefore appears as though the parasite is able to i...
Mitchell KJ, De Clercq D, Stirn M, van Loon G, Schwarzwald CC.Homocysteine (HCY) is an amino acid produced from methionine metabolism. Plasma homocysteine concentrations ([HCY]p) are elevated (>13 μmol/L) in people with atrial fibrillation (AF) and can predict the recurrence of AF after cardioversion. This study aimed to validate a commercially available human HCY assay for use in horses to develop reference intervals for [HCY]p and compare [HCY]p in healthy horses and horses with AF. Methods: Healthy horses (n = 27) and horses with AF (n = 55, 34 of which were cardioverted using transvenous electrical cardioversion). Methods: Blood samples were a...
Crafford JE, Guthrie AJ, Van Vuuren M, Mertens PP, Burroughs JN, Howell PG, Batten CA, Hamblin C.A polyclonal antibody-based, group-specific, competitive ELISA (C-ELISA) for the detection of antibodies to equine encephalosis virus (EEV) was developed. The assay measures the competition between a specific guinea pig antiserum and a test serum, for a pre-titrated EEV antigen. The C-ELISA detected antibodies to the seven known EEV serotypes. Reference antisera raised against other arboviruses did not cross react with EEV antigen. Negative sera from horses in the United Kingdom were used to establish the baseline for a negative population. Negative and positive populations of South African ho...
Nemoto M, Matsumura T.This review briefly describes the virus classification, clinical signs, epidemiology, diagnosis, disinfection, and vaccines related equine group A rotavirus (RVA) infection. Equine RVA is one of the most important pathogens causing diarrhoea in foals. The main transmission route is faecal-oral, and the clinical signs are diarrhoea, fever, lethargy, and anorexia (decreased suckling). Some human RVA rapid antigen detection kits based on the principles of the immunochromatographic assay are useful for the diagnosis of equine RVA infection. The kits are used in daily clinical practice because of t...
Borba LA, Nogueira CEW, Bruhn FRP, da Silva GC, Feijó LS, Canisso IF, Curcio BDR.Neonatal sepsis is a leading cause of neonatal death during the first-week postfoaling. Despite recent advancements in the diagnosis and treatment of sepsis in the newborn foal, the non-specific clinical signs and subtle nature of this disease may result in delayed diagnosis until severe progression of the disease; thus, early detection of sepsis remains critical for a favourable outcome. This study aimed to identify early blood markers as predictive of sepsis on foals. Thirty-five foals were allocated into three groups: healthy control foals (n=7) and foals born from mares with placentitis: s...
The Journal of parasitologyJanuary 23, 2003
Volume 88, Issue 6 1164-1170 doi: 10.1645/0022-3395(2002)088[1164:EIOEPM]2.0.CO;2
Sofaly CD, Reed SM, Gordon JC, Dubey JP, Ogleebee MJ, Njoku CJ, Grover DL, Saville WJ.The effect of inoculation dose of Sarcocystis neurona sporocysts on the development of clinical neurologic disease in horses was investigated. Twenty-four seronegative weanling horses were subjected to the natural stress of transport and then randomly assigned to 6 treatment groups of 4 horses each. Horses were then immediately inoculated with either 10(2), 10(3), 10(4), 10(5), or 10(6) S. neurona sporocysts or placebo using nasogastric tube and housed indoors. Weekly neurologic examinations were performed by a blinded observer. Blood was collected weekly for antibody determination by Western ...
Cray C, Perritt E, Hughes C, Belgrave RL.Encephalitozoon cuniculi is an obligate intracellular microsporidian parasite that can result in clinical and subclinical infection in many species. In the present study, a serological survey was conducted using samples from 105 horses in the state of New Jersey; 49 of the samples were obtained from clinically abnormal animals. Five or 4.8% of 105 serum samples were found to demonstrate reactivity by ELISA with titers of 1:64 to 1:1,024. One of the samples was obtained from a clinically normal horse. Clinical signs and diagnoses from the other animals included lameness, colic, osteochondritis ...
Crew CR, Brennan ML, Ireland JL.Biosecurity measures are designed to prevent the introduction and spread of pathogens, and play a vital role in the equine industry, controlling endemic diseases and reducing the threat of exotic disease incursion. Equestrian premises differ with respect to disease risks, biosecurity requirements and available facilities. This narrative review summarises reported frequency of implementation for selected biosecurity measures, as well as evidence relating to potential barriers to implementation of biosecurity on equestrian premises. Possible opportunities for improvement in the adoption of equin...
Boorman S, Scherrer NM, Stefanovski D, Johnson AL.Facial nerve paralysis (FNP) in equids is not well described in the veterinary literature. Objective: To investigate the causes of FNP and associations among clinical variables, diagnosis, and outcome. Methods: Sixty-four equids presenting with FNP between July 2000 and April 2019. Cases of postanesthetic FNP were excluded. Methods: Medical records were retrospectively reviewed. Variables were evaluated for associations with outcomes (diagnosis and case outcome) using logistic regression. Results: The most common cause of FNP was trauma (n = 20). Additional diagnoses included central nervous s...
Palmer JE, Benson CE.Eight normal ponies placed in direct contact with ponies experimentally infected with Ehrlichia risticii for 30 to 90 days did not develop signs of Potomac horse fever. They also did not seroconvert, and they remained susceptible to IV infection. One of 8 ponies that were force fed fresh feces from infected ponies while in direct contact with ponies experimentally infected with E. risticii developed Potomac horse fever and seroconverted. The other 7 remained asymptomatic, did not seroconvert, and were susceptible to IV infection. Six of 9 ponies inoculated with E. risticii via nasogastric intu...
van der Harst M, Bull S, Brama PA, Barneveld AB, van Weeren PR, van de Lest C.Osteoarthritis (OA) is a chronic debilitating joint disorder in which the importance of inflammation is increasingly recognized. In advanced cases, both the articular cartilage and the underlying bony layers are affected, but the exact sequence of events and their localization in the initial phase of pathogenesis remain uncertain. We measured nitric oxide (NO) end products in tissue layers that constitute the bearing surface of the joint, as possible indicators of physiological and pathological processes. Methods: Nitrite as a measure for NO and nitrotyrosine was measured in articular cartilag...
O'Niell FD, Issel CJ, Henk WG.Organ cultures of equine fetal tracheal and nasal turbinate epithelium were inoculated with equine influenza virus-A1 (EIV-A1), equine herpesvirus-1 (EHV-1), or equine rhinovirus-1 (ERV-1). Infected organ cultures were processed for scanning and transmission electron microscopy at various intervals and were compared with noninfected controls. Organ cultures inoculated with ERV-1 appeared normal with the exception of rare island-like lesions in infected nasal turbinate. Virus particles were not seen in thin sections of organ cultures infected with ERV-1. The EHV-1 caused extensive loss of the e...
Petersen JL, Coleman SJ.The sequencing and assembly of a reference genome for the horse has been revolutionary for investigation of horse health and performance. Next-generation sequencing (NGS) methods represent a second revolution in equine genomics. Researchers can align and compare DNA and RNA sequencing data to the reference genome to explore variation that may contribute or be attributed to disease. NGS has also facilitated the translation of research discovery to clinically relevant applications. This article discusses the history and development of NGS, details some of the available sequencing platforms, and ...
Kimura Y, Haneda S, Aoki T, Furuoka H, Miki W, Fukumoto N, Matsui M, Nambo Y.The combined thickness of the uterus and placenta (CTUP) and ultrasonographic images of uteroplacental tissues were investigated in 35 pregnant heavy draft horses in Months 7-12 of pregnancy. The mares were divided into three groups: those pathologically diagnosed as placentitis (placentitis group, n=3); those who had abortion, premature birth, or fetal malformation (abnormal group, n=7); and those who had no abnormal findings (normal group, n=25). In the normal group, CTUP increased as pregnancy progressed from Months 7 (median, 7.08 mm; range, 5.68-11.27) to 12 (13.31 mm; 7.44-16.31 mm) (P<0...