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.
Parker JT, McCoy MV.1. The serum of horses immunized with increasing doses of certain anaerobically produced autolysates of pneumococci contain potent neutralizing antibodies for the pneumotoxin. 2. The method for the in vitro titration of these horse antipneumotoxic serums is given.
Olitsky PK, Long PH.The virus of vesicular stomatitis is not readily killed by formalin. This chemical is one of a group which coagulates the proteins of the medium in which the virus is usually contained. It has already been found(7) that other reagents of the protein-coagulating group are not actively virucidal) and the effect of formalin in this instance is therefore characteristic of the group. The so called formalinized vaccines which give rise to immunity can be shown to have done so because of the presence of living virus. A single injection of such so called "vaccine," or of other material containing livi...
Friedlander M, Sobotka H, Banzhaf EJ.The precipitin indices for a number of monovalent and polyvalent antipneumococcus sera were determined under known conditions, and found to vary as did the number of protective units. The ratio precipitin index/protective units in monovalent sera was found to lie between 2.8 and 4.8 for Type I and to be about ten times greater for Type III. Lower values were found in polyvalent horses and when mixing heterologous monovalent sera with each other. The influence of the duration of treatment upon the quotient was studied. Several refined and concentrated preparations showed a relative increase in ...
Wadsworth AB, Sickles GM.IT HAS BEEN SHOWN THAT THE PNEUMOCOCCUS MULTIPLYING IN THE TISSUES OF THE IMMUNIZED ANIMAL (HORSE) BECOMES ATTENUATED: loses, in varying degrees, its virulence, capacity of capsule formation, susceptibility to phagocytosis, and type specificity. The antigenic activity as an immunizing agent and the production of "soluble specific substance" are also altered. In some instances, the typical pneumococcus characteristics may be quickly restored by one or two passages through a susceptible animal (mouse). In others, virulence is not recovered and the organism remains atypical. Whether these changes...
Reimann HA.It is conceivable that a change from the virulent, non-phagocytable S form of Pneumococcus to the avirulent phagocytable R form may take place in pneumococcus disease, but the experiments here reported do not settle the question whether or not this is an important factor in determining the outcome in natural infection. It has been shown experimentally that the degradation from the S form to the R form actually does take place in cultures of Pneumococcus growing in agar subcutaneously embedded in guinea pigs, in agar enclosed in vials subcutaneously embedded in rabbits, and spontaneously in the...
Jungeblut CW.1. A flocculation reaction has been described which occurs between alcoholic extracts of pneumococci and antipneumococcus serum. 2. The reaction appears to be species-specific. It is not strictly type-specific, as slight or moderate cross-reactions occurred between Type I serums and Type II and Type III extracts. 3. The flocculating power of the serum from five horses undergoing immunization with pneumococcus, Type I, did not develop to any extent before the end of the 4th or 5th month. 4. In the case of two of these horses in which it was possible to carry out parallel tests on a larger numbe...
Jones FS.The lower nasal mucosa and the pharynx of thirty eastern and twenty-three western horses have been examined for streptococci. Eight of the eastern horses carried non-hemolytic streptococci on the nasal mucosa. From the pharynx of six, non-hepiolytic streptococci were cultivated. The throats of eighteen contained strains of the hemolytic type. The nasal mucosa of the eastern horses failed to show hemolytic streptococci. Eight western horses carried non-hemolytic streptococci in the nasal passage; eight also harbored the hemolytic type. Twenty-two strains were isolated from the pharynx. Eleven w...
Amoss HL, Marsh P.Experiments were made for the purpose of testing the reaction of protection against infection as a measure of potency of antimeningococcic serum. The results of the experiments were extremely variable and bore no relation to the quality of the sera as determined by the period of immunization of the horses from which they were obtained, or the indications of efficiency based upon their employment in human cases of epidemic meningitis. The results also failed entirely to conform to the agglutination titer of the sera tested and to be affected by the different type forms of the meningococci. We r...
Hubbert WR.1. Better results in the production of diphtheria antitoxin can be obtained with greater experience in the selection of the most suitable type of horses to be used. Young animals are usually to be preferred. Over one-half of all such horses can be made to yield 300-unit serum, while a third will yield (5)oo-unit serum. 2. High-test horses require a shorter time to immunize and will yield a potent serum for a longer period than will low-test horses. 3. The period of usefulness of an antitoxin horse is short, and on an average endures only a few months. 4. A horse having attained a maximal antit...
Atkinson JP.1. The globulins of both normal and diphtheria antitoxic serum exhibit chemically toward reagents the same reactions, being precipitated by magnesium sulphate and split up into fractions in precisely the same way. 2. All of the diphtheric antitoxic power of both normal and immunized serum is always carried by the globulin and its fractional precipitates. 3. During the fractional precipitation of the serum globulin of horses immunized from diphtheria toxin and horses not immunized from diphtheria toxin, some of the globulin is lost, likewise at the same time some of the antitoxic power of the g...
Raftery AG, Gummery L, Garcia K, Mohite D, Capewell P, Sutton D.Equine trypanosomiasis is a neglected protozoal disease. Objective: To answer the study question: In equines what are the effects of disease management of trypanosomiasis on disease severity (individual level) and disease prevalence (population level) compared to no intervention? Methods: Systematic review. Methods: Studies were identified that described management of naturally occurring equine trypanosomiasis in any country following 'Preferred Reporting Items for Systematic Reviews and Meta-analyses' using eight international databases (1980-2022). Risk of bias was assessed using ROBINS-I. D...
Rossi TM, O'Sullivan TL, Greer AL.Competitions are an important source of entertainment and revenue in the horse industry but may contribute to disease introduction and spread. The objectives of this study were to, (i) describe the annual (2016 to 2018) contact networks of Equestrian Canada competitions in Ontario, Canada, and (ii) determine if the networks exhibit characteristics of 'small world' networks. Data on Equestrian Canada registered competitions in the province of Ontario, Canada between 2016 and 2018 were used to create three types of yearly contact networks: competition networks, horse networks, and venue networks...
Jager MC, Luethy D, Shallop S, Cathcart J, Divers TJ, Tan JY, Beasley EM, Johnson P, Leduc L, Smith C, Jamieson CA, Magdesian KG, Van de Walle GR....Equine hepacivirus (EqHV) is closely related to hepatitis C virus (HCV), which causes persistent infection and chronic hepatitis in people. Information on persistent EqHV infection and hepatitis is limited. Objective: To report 19 cases of chronic hepatitis and persistent EqHV infection. Methods: Mixed retrospective and prospective case series. Methods: Inclusion criteria were: (1) chronic hepatitis, defined as persistently increased serum liver biomarkers, increased serum liver biomarkers accompanied by histopathological evidence of chronicity, for example, fibrosis, or both; (2) positive ser...
Decoster C, Lefère L, Raes E, van Loon G, Dufourni A.Leptospirosis is a widespread zoonotic, infectious disease associated with abortion, stillbirth, as well as liver and kidney failure. Leptospiral Pulmonary Haemorrhage Syndrome (LPHS) has increasingly been reported in human and canine patients infected by Leptospira and is associated with a high fatality rate. In equine medicine, pulmonary haemorrhage has mainly been described in foals with leptospiral infections, but rarely in adult horses. Objective: To characterise the clinicopathological features of pulmonary haemorrhage as a distinct disease entity in adult horses with leptospirosis, term...
Rossi GAM, Sellera FP, Ferraz CM, Carvalho RS, Oliveira APL, Marques CA, Fávaro EBR, Rosa RDS, Silva LAM, Cardozo MV, Stehling EG, Furlan JPR. Infections caused by antimicrobial-resistant bacteria are difficult to treat and increase the risk of death in animals. This report describes a fatal case of diarrhea in a horse that, despite intensive treatment including surgery and broad-spectrum antimicrobials (ceftiofur and amikacin), experienced a worsening of its condition and subsequent death. A fecal swab sample was subjected to microbiological culture for the identification of bacteria and assessment of their phenotypical antimicrobial susceptibility profiles using the disk-diffusion and broth microdilution methods. The double-disk ...
Atasoy MO, Turan T, Özbek R, Işıdan H, Naggar RFE, Afify AF, Rohaim MA.The genus (HCV) has long been a dynamic group, increasing its number by myriads of species collectively referred to as non-primate hepaciviruses (NPHVs). NPHV exhibits a broad hepatotropism and is often attributed to chronic infection in horses and dogs. However, recent studies and meta-analyses on NPHV in horses have remained inconclusive regarding the determination of risk factors for infection. Therefore, our main goal was to investigate the frequencies and molecular characteristics of NPHV infection linked to geographical location, horse breeds, genders, and ages. For this purpose, we tes...
Sayre KC, Flores-Ahlschwede P, Wethington AB, Kahn SK, Bray JM, Volding DM, Ahlschwede S, Bordin AI, Cohen ND, Welsh TH.Transfusion of Rhodococcus equi hyperimmune plasma (REHIP) to neonatal foals is done to reduce the incidence of rhodococcal pneumonia. Objective: To determine effects in newborn foals of REHIP transfusion on serum cortisol concentrations; the association of serum cortisol concentrations with serum globulin concentration and anti-rhodococcal immunoglobulin activity; and cumulative incidence of rhodococcal pneumonia. Methods: Serum samples were collected from 356 newborn foals from 13 New York farms immediately before and after transfusion of 1 L or 2 L of REHIP. Serum samples were assayed for c...
Puccetti M, Beccati F, Pilati N.Femoral nerve neuropathy causes lameness, a condition clinically characterized by stifle's lack of extension with subsequent diminished lower limb function. This case report describes the ultrasonographic diagnosis of femoral neuropathy secondary to compression caused by myopathy of the iliopsoas muscle of an endurance horse during a competition. Transrectal ultrasonography played a pivotal role in diagnosis of the injury by assessment of the involved structures and monitoring of the healing process throughout the recovery period. The horse achieved complete recovery and successfully returned ...
Riquelme LF, de Araújo VO, da Silva TKF, de Sousa MS, da Silva MA, da Silva WDQ, Lucena RB.Malachra fasciata Jacq. (Malvaceae) is an invasive plant widely found in Northeastern Brazil and has been experimentally demonstrated to cause severe dermatitis in sheep. However, its toxic effects in horses have not previously been documented. This report describes primary photosensitization in four Quarter Horses grazing on a pasture heavily infested with M. fasciata in Paraíba, Brazil. Affected animals developed alopecic, erythematous, crusted, and ulcerated lesions on sun-exposed areas, accompanied by severe pruritus and behavioral signs of distress. Histopathology revealed epidermal ulce...
Souza LL, Lima AS, Martins AS, Silva TA, Borsanelli AC, Dutra IS, Pupin RC, Gomes DC, Lemos RA.An outbreak of botulism occurred in March 2024 among horses at a Quarter Horse stud farm in Central-West Brazil. After ingesting baleage, 22 of 26 (85%) horses housed in stables and fed baleage became ill. The affected horses had dysphagia, muscular weakness, fasciculations, and progressive recumbency; 13 of 22 (59%) died within a few days. The diagnosis of type C botulism was established based on clinical and epidemiologic findings and confirmed by mouse bioassays, which indicated botulinum toxin type C in liver samples and intestinal contents. Furthermore, PCR testing identified toxigenic i...
DiBello D, Cassel N, Granacka V, Beard L, Rosado SC, Hill-Thimmesch K, Avellar H.Equine sarcoidosis is an uncommon disease characterized by granulomatous inflammation presenting in a spectrum of body system involvement and severity. Musculoskeletal manifestations are sporadically reported but without correlation between imaging and pathologic findings. In a mature Quarter Horse mare eventually diagnosed with a progressive form of sarcoidosis, phalangeal osteolysis discovered on radiography prompted further evaluation, revealing diffuse, discrete osteolysis throughout the axial skeleton. Due to disease progression, humane euthanasia was elected, and computed tomography and ...
Sfraga H, Demeter EA, Pinn-Woodcock T, Guarino C, Young R, Cronk B, Cercone M.To investigate the presence of subclinical cranial nuchal bursitis and characterize its histopathologic features and association with Borrelia burgdorferi. Unassigned: This was a prospective descriptive cadaver study on a convenience population of horses in a B burgdorferi-endemic region (15 horses: 5 geldings and 10 mares of various breeds; 4 to 29 years old). Horses without history or clinical signs of cranial nuchal bursitis underwent euthanasia and tissue donation. Cranial nuchal bursa, synovial fluid, and nuchal ligament were collected postmortem. The bursa and ligament were evaluated via...
Veit M, Matczuk AK.Equine arteritis virus (EAV) is a positive-stranded RNA virus of the Arteriviridae family. Its GP5/M dimer, the principal component of the viral envelope, mediates virus budding and serves as a key target for neutralizing antibodies. Using AlphaFold3, we predicted the 3D structure of the EAV GP5/M dimer and compared it to its homolog in porcine reproductive and respiratory syndrome virus (PRRSV). Both complexes share a conserved architecture comprising a short ectodomain, three helical transmembrane regions, and a β-sheet-rich endodomain. EAV GP5 features a longer ectodomain with four α-heli...
Conrad NL, Mazzoleni I, Abreu MC, Costa AV, Di Giácomo CP, Zorzi VSG, Leite FPL.Equine proliferative enteropathy (EPE), caused by Lawsonia intracellularis induces intestinal epithelial hyperplasia, resulting in malabsorption, weight loss, colic, and diarrhea. Despite its clinical and economic importance, no equine-specific vaccine is commercially available. Recombinant subunit vaccines are a safe and scalable alternative; however, their immunogenicity often requires improvement. Probiotic supplementation with Bacillus toyonensis may act as an immunomodulatory strategy to potentiate vaccine efficacy. This study aimed to evaluate the immunogenicity of a recombinant protein ...
Rudeekiatthamrong A, Nguyen GT, Kamyingkird K. infection (Surra) remains a major constraint to equine health and productivity in Thailand. The only available trypanocidal drug, diminazene aceturate (DA), has limited efficacy, poor blood-brain barrier penetration, and toxicity in horses. This study aimed to investigate the inhibitory effects of commonly used equine antibiotics, gentamicin (GMC), ceftiofur (CTF), and trimethoprim-sulfamethoxazole (TS), against (Thai strain isolated from dairy cattle number 953; TEDC 953) to identify potential therapeutic alternatives or adjuncts for equine trypanosomosis. Unassigned: An growth inhibition...
Li Z, Yu T, Ge L, Lv S, Fu Q, Shi H.Equine herpesvirus type 1 (EHV-1) is a major veterinary pathogen causing significant economic losses in the livestock industry. Despite its impact, effective vaccines and targeted antiviral strategies remain limited, largely due to an incomplete understanding of host factors regulating viral replication and pathogenesis. Unassigned: To systematically identify host genes essential for EHV-1 infection, we established a BHK-21 cell line stably expressing Cas9 and performed a genome-wide CRISPR/Cas9 knockout screen using a pooled lentiviral single-guide RNA library. Significantly enriched candidat...
Zanacchi A, Fruscione F, Grasselli S, Razzuoli E, Pastorino L, Di Lisa D.Developing advanced preclinical in vitro cancer models is essential for understanding tumor biology, improving drug discovery, and enhancing the clinical translation of new therapies. Papillomaviruses (PVs) cause diverse lesions in humans and animals; notably, bovine papillomavirus (BPV) is the main cause of equine sarcoid, the most common skin tumor in horses. Its pathogenesis involves viral infection, fibroblast transformation, and extracellular matrix (ECM) remodeling. These processes highlight the limitations of conventional two-dimensional (2D) culture systems, which fail to replicate the...
Haussler KK.Congenital cervical vertebral anomalies in horses are structural changes in the neck vertebrae that develop during the fetal stage. These anomalies can vary in their severity and effects. Some horses may not show any clinical signs and can live normally, while others may develop serious problems such as spinal cord compression. This compression can lead to issues like ataxia or even paralysis, affecting the horse's mobility and quality of life. Recognizing and diagnosing these anomalies early are very important, as it helps guide decisions about the best treatment options and overall managemen...
Uprety T, Shaffer CL, Loynachan A, Janes J, Cassone L, Kennedy L, Bryant U, Ruby R, Swan M, Sponseller BT, Adam E, Lubbers B, Erol E.Salmonellosis is a highly contagious, zoonotic disease affecting both animal and human health. Early characterization of emerging Salmonella serotypes and associated antimicrobial resistance patterns are essential for outbreak controls in animals and humans. Between 2018 and 2025, 245 Salmonella enterica subsp. enterica were isolated from both ante-mortem and post-mortem equine cases. The predominant Salmonella serotypes were Typhimurium (83), Newport (28), 1,4,[5],12:i:- (26), Saintpaul (25), Hartford (15), and Mbandaka (12). S. Saintpaul, previously rare in horses, was detected in 21 cases i...
Penzhorn L, Crafford JE, Guthrie AJ.African horse sickness (AHS) is the only equine disease for which the World Organisation for Animal Health (WOAH) gives official disease-free status, given that it poses a major threat to the equine industry. The disease is caused by AHS virus (AHSV; family , taxon species ), which is endemic in sub-Saharan Africa. Reverse-transcription quantitative real-time PCR (RT-qPCR) is a rapid, sensitive detection method used in the diagnosis of AHS and the certification of animals as negative for AHSV for the purpose of movement. Genetic variability of AHSV may influence the accuracy of RT-qPCR detecti...
The research aims to study the dynamics of reproductive system pathologies in mares of Kazakh and Mugalzhar horse breeds and their impact on the reproductive traits of the breeding stock. The object of the research was horses of the Kazakh and Mugalzhar breeds. The formation of experimental groups was carried out using the pair-analog method. It was found that the frequency of detection of infertile mares is 13.8-25.0%. Subinvolution of the uterus from the total number of infertile mares is 8.3-10.7%, endometritis - 16.6-23.3%, atony and hypotonia of the uterus - 8.3-13.3%, ovarian diseases - ...
Valberg SJ, Williams ZJ, Ames EG, Mickelson JR, Nout-Lomas YS, Landolt G, Sanz M, Gardner K.Equine myotonic dystrophy (eMD) is a rare neuromuscular disorder of undetermined origin marked by muscle hypertrophy and stiffness, dystrophic muscle histopathology, and myotonic discharges. In humans, myotonic dystrophy (DM) arises from trinucleotide repeat expansions in dystrophia myotonica protein kinase (DMPK) (DM1) or tetranucleotide expansions in cellular nucleic acid-binding protein (CNBP) (DM2), which disrupt mRNA processing and induce embryonic splicing patterns across multiple genes. In 6 eMD Quarter Horse types, (2-36 months-of-age) and 8 control Quarter Horses we determined: (1) fi...
Garzaro D, Rodríguez N, Medina G, Alcazar W, Gualdron M, Siem JA, Sulbaran Y, Barrios M, Liprandi F, Jaspe RC, Pujol FH.Madariaga virus (MADV), formerly known as the South American variant of Eastern Equine Encephalitis virus (EEEV), is an alphavirus that belongs to the family and has been periodically infecting equids in Venezuela since its first identification in 1975. This study reports the isolation and molecular characterization of MADV isolated from a horse in December 2024 in the context of MADV cases reported in Venezuela. Methods: Antibodies to the rabies virus were detected by indirect immunofluorescence, and to the Equine Infectious Anemia virus (EIAV) by passive immunodiffusion. MADV RNA was detect...
Qin S, Kulabieke T, Mizhamuhan D, Zhang M, Jin M, Abula G, Pi M, Wang H, Zhang Y, Guo Q.Equine theileriosis, caused by the protozoan parasite , represents a significant economic threat to the equine industry. In Xinjiang, China, an endemic area for this disease, systematic research on the genetic diversity of has been notably lacking. The aim of this study was to obtain molecular epidemiological data pertaining to the parasite in selected regions of Xinjiang, China, and analyze the genetic characteristics (including rRNA, , and genes) and genotype distribution patterns of isolates from these regions, providing a scientific basis for developing targeted prevention and control s...
Dorrego A, Olvera-Maneu S, Jose-Cunilleras E, Gago P, Raez A, Rivera B, Oporto A, Gonzalez S, Cruz-Lopez F.The forest fly ) is an obligate haematophagous dipteran insect (order Diptera) that primarily infests horses and may contribute to the circulation of vector-borne pathogens. This study aimed to investigate the presence of , s.l., , and , important vector-borne pathogens of equids, in forest flies collected from horses in endemic areas of Spain. A total of 170 forest flies were collected from 39 equids across four geographical regions in Spain (Segovia, Madrid, Toledo, and Menorca) and blood samples were collected from 27 of these horses. All flies were morphologically and molecularly identifi...
Toda J, Miyasaka J, Osako H, Murata K, Yunus M, Amalia R, Soe BK, Sato H.Food poisoning caused by consuming raw horsemeat contaminated with Sarcocystis is a significant public health concern. Two morphotypes of sarcocysts in horsemeat, characterized by upright and folded villar protrusions, are typically identified as Sarcocystis fayeri and S. bertrami, respectively. However, recent molecular studies focusing on the ribosomal RNA gene (rDNA) and mitochondrial cytochrome c oxidase subunit I gene (cox1) have indicated a conspecific relationship between these two morphotypes using a limited number of specimens. To explore further genetic diversity in equid sarcocysts,...
Tramboo SR, Shahardar RA, Allaie IM, Bulbul KH.Benzimidazole (BZ) anthelmintics have been used indiscriminately in equids to control nematode infections throughout the world including India and has led to the development of BZ resistance. In order to determine the current status of BZ resistance in equids of Kashmir against intestinal strongyles (IS), the present study was conducted using faecal egg count reduction test (FECRT) and Allele specific PCR (AS-PCR). The study was conducted on ponies from three major tourist destinations of Kashmir viz; Gulmarg, Pahalgam and Sonamarg in accordance with the WAAVP guidelines. The animals which wer...
Bertuglia A, Cantatore F, Pallante M, Manassero L, Bergamini L, Riccio B, Pagliara E.To report the incidence, and clinical and pathological findings of developmental lateral patellar luxation in Standardbred yearlings diagnosed with femoropatellar dysplasia (FPD) and demonstrate that osteochondral lesions in the lateral trochlear ridge (LTR) of the femur observed in the affected horses are osteochondral lesions related to patellar maltracking.Retrospective case series. Medical records were retrospectively reviewed for Standardbreds <12 months of age diagnosed with FPD between 2017 and 2023.A total of 10 Standardbred yearlings developed FPD (incidence 6.4 cases per 1,000 foals)...
Nowicka B, Łopuszyński W, Krajewska-Wędzina M, Biazik A, Sobuś M, Polkowska I, Szacawa E.Gastrointestinal mycobacteriosis in horses is difficult to diagnose because of the pathogen's intracellular nature and the non-specific clinical symptoms. Effective accurate diagnosis facilitates prognosis and treatment. Current diagnostic procedures and methods of collecting material do not permit definitive antemortem diagnosis. However, culturing, acid-fast bacilli staining, histopathology, PCR and immunological marker evaluation may prove useful. Unassigned: Three horses were admitted to a clinic for intensive care and a final diagnosis. Physical examination and additional tests were perfo...
Petry S, Tapprest J, Maillard K, Barbut F, Duquesne F, Kozak S, Foucher N, Bernez-Romand M, Bridoux L, Poquet I. an anaerobic, spore-forming enteropathogen, is less studied in animals than in humans despite its importance in One Health. We evaluated occurrence, diversity, circulation, and virulence in French Equidae ( = 100) after their necropsy in northwestern France, from 2019 to 2021. We systematically recovered all cecal contents and any watery intestinal contents. We isolated strains, determined their toxin gene profile by PCR, and established their PCR-ribotype according to the WEBRIBO database. We also performed free toxin detection. Twenty-seven Equidae were positive for and 20 had a toxigeni...
