The study of viral infections that affect equine species assesses the relationship between viruses and horses. Infections can lead to a range of clinical symptoms and may impact the health and performance of horses. Common equine viruses include Equine Influenza Virus, Equine Herpesvirus, and West Nile Virus, among others. Understanding the mechanisms of viral transmission, pathogenesis, and host immune responses is essential for developing effective prevention and treatment strategies. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, molecular biology, and clinical management of viral infections in horses.
King LS.The behavior of a fixed strain of Eastern equine encephalomyelitis virus was studied in guinea pigs after intraocular inoculation. Such inoculation concerns the central and not the peripheral nervous system. The susceptibility to intraocular injection lies midway between the highly virulent intracerebral and the quite avirulent peripheral routes. The virus must act for 10 to 13 hours in order to induce a fatal infection. Removal of the inoculated eyeball before this interval almost always prevents fatality although it may allow immunity to develop. The virus, at suitable intervals after inject...
Olitsky PK, Harford CG.Young (12 to 15 day old) mice are approximately as susceptible to the virus of equine encephalomyelitis, Eastern or Western strain, when it is given intraperitoneally as are adult mice when the virus is injected intracerebrally. With this susceptibility by the intraperitoneal route as a basis, the injection of immune serum-virus mixtures intraperitoneally was found to result in protection in dilutions which give rise to infection after intracerebral inoculation. The difference of protective power by the two indicated routes was shown not to depend on the amount of inoculum nor on the age of th...
Findlay GM, Maccallum FO.(1) Among 3,100 persons immunized against yellow fever with virus and immune serum over a period of five years, 89 cases of jaundice have been traced.(2) The symptoms are those of a hepatitis and closely resemble those produced by common infective hepatic jaundice, cases of which have frequently been noted as occurring in the same areas.(3) The average period between the time of inoculation and the development of hepatitis is between two and three months.(4) Attention is directed to the occurrence of hepatitis in horses, usually two to three months after immunization against the viruses of hor...
Hurst EW.The virus of equine encephalomyelitis (eastern strain) evokes in the horse, calf, sheep and dog an unusually intense encephalomyelitis characterized by acute primary degeneration of nerve cells, the appearance in neurons of the brain stem and elsewhere of nuclear inclusions resembling those in Borna disease and poliomyelitis, polymorphonuclear infiltration in the nervous tissues with early microglial proliferation, and perivascular cuffing with mononuclears and polymorphonuclears in varying proportions. The grey matter is affected more than the white. Lesions may be less marked in the striatum...
Olitsky PK, Cox HR, Syverton JT.We have studied certain properties, additional to those previously described (3), of the virus of vesicular stomatitis of horses, and of the characteristic biological reactions of the virus of equine encephalomyelitis. It has been found that the virus of stomatitis, ordinarily dermotropic, can acquire neurotropism and the neurotropic encephalomyelitis virus can, in turn, be rendered dermotropic in its action. The neurotropism in both instances is associated with definite, although not pronounced, viscerotropism. Both viruses can bring about a similar infection in the white mouse, rat, guinea p...
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...
Vesicular stomatitis is an infrequent yet important vesicular disease of cattle, horses, and swine. Periodic outbreaks of this disease in the United States have caused economic losses in cattle herds because of decreased production, movement restrictions, and trade embargoes. Vesicular stomatitis causes clinical signs indistinguishable from those of foot-and-mouth disease. It is of utmost importance that appropriate samples are collected from clinical cases of vesicular disease in cattle and swine so a rapid laboratory diagnosis can be made.
The goal of this work was the development of suitable (real-time) RT-PCR techniques for fast and sensitive diagnosis of EAV and for molecular-epidemiological characterisation of viral strains, as an alternative to virus isolation. To this purpose two conventional RT-PCR methods and one real-time RT-PCR were adapted to detect the broadest possible spectrum of viral strains. Several dilutions with Bucyrus strain showed a 100-fold higher sensitivity of real-time RT-PCR and heminested RT-PCR compared to simple RT-PCR. Making use of 11 cell culture supernatants of different EAV isolates and 7 semen...
Equine arteritis virus (EAV) is the causative agent of equine viral arteritis (EVA), a respiratory and reproductive disease of equids. There has been significant recent progress in understanding the molecular biology of EAV and the pathogenesis of its infection in horses. In particular, the use of contemporary genomic techniques, along with the development and reverse genetic manipulation of infectious cDNA clones of several strains of EAV, has generated significant novel information regarding the basic molecular biology of the virus. Therefore, the objective of this review is to summarize cur...
Pusterla N, Dorman DC, Burgess BA, Goehring L, Gross M, Osterrieder K, Soboll Hussey G, Lunn DP.Equine herpesvirus type 1 (EHV-1) infection is associated with upper respiratory disease, EHM, abortions, and neonatal death. Objective: Are nasal secretions a more sensitive biological sample compared to blood for the detection of EHV-1 infection? How long is EHV-1 detectable after primary infection by PCR? Methods: MedLine and Web of Science searches identified original peer-reviewed reports evaluating nasal shedding and viremia using virus isolation methods or PCR published in English before October 9, 2023. Results: Sixty experimental and 20 observational studies met inclusion criteria. EH...
Soboll-Hussey G, Dorman DC, Burgess BA, Goehring L, Gross P, Neinast C, Osterrieder K, Pusterla N, Lunn DP.Equine herpes virus type 1 (EHV-1) infection in horses is associated with upper respiratory disease, neurological disease, abortions, and neonatal death. Objective: To determine if there is an association between the level and duration of EHV-1 viremia and either abortion or equine herpesvirus myeloencephalopathy (EHM) in domesticated horses? Methods: A systematic review was performed searching numerous databases to identify peer reviewed reports that evaluated viremia and EHM, or viremia and abortion published before January 19, 2021. Randomized controlled trials and observational studies wer...
Schneider C, James K, Craig BW, Chappell DE, Vaala W, van Harreveld PD, Wright CA, Barnum S, Pusterla N.Equine rhinitis B virus is a lesser-known equine respiratory pathogen that is being detected with increasing frequency via a voluntary upper respiratory biosurveillance program in the United States. This program received 8684 nasal swab submissions during the years 2012-2023. The nasal swabs were submitted for qPCR testing for six common upper respiratory pathogens: Streptococcus equi subspecies equi (S. equi), equine influenza virus (EIV), equine herpesvirus type 1 (EHV-1), equine herpesvirus type 4 (EHV-4), equine rhinitis A virus (ERAV), and equine rhinitis B virus (ERBV). The overall ERBV ...
Salgado CRS, Silva ADNE, Arruda IF, Millar PR, Amendoeira MRR, Leon LAA, Teixeira RBC, de Lima JTB, Chalhoub FLL, Bispo de Filippis AM, Fonseca ABM....Hepatitis E virus (HEV) infection has been demonstrated in various animal species; those recognized as potential zoonotic reservoirs pose a considerable risk to public health. In Brazil, HEV-3 is the only genotype identified in humans and swine nationwide, in a colony-breeding cynomolgus monkey and, recently, in bovines and capybara. There is no information regarding HEV exposure in the equine population in Brazil. This study aimed to investigate anti-HEV antibodies and viral RNA in serum samples from horses slaughtered for meat export and those bred for sport/reproduction purposes. We used a ...
Caballero-Gómez J, Rivero-Juárez A, Cano-Terriza D, Fajardo T, Buono F, Jose-Cunilleras E, García J, Alguacil E, Rivero A, García-Bocanegra I. (HEV) is an important emerging zoonotic virus in Europe. Although domestic pigs and wild boar are the main reservoirs of this pathogen, susceptibility to this virus has been confirmed in a growing number of animal species, including equines. However, their role in the epidemiology of this virus remains poorly understood. Our aim was to assess HEV circulation and identify potential risk factors associated with exposure in equid species in different European countries. A total of 596 equines, including 496 horses, 63 donkeys and 37 mules/hinnies bred in four European countries (Spain, Italy, Un...
Magallanes S, Llorente F, Ruiz-López MJ, Martínez-de la Puente J, Soriguer R, Calderon J, Jímenez-Clavero MÁ, Aguilera-Sepúlveda P, Figuerola J.West Nile virus (WNV) is a re-emerging zoonotic pathogen with increasing incidence in Europe, producing a recent outbreak in 2020 in Spain with 77 human cases and eight fatalities. However, the factors explaining the observed changes in the incidence of WNV in Europe are not completely understood. Longitudinal monitoring of WNV in wild animals across Europe is a useful approach to understand the eco-epidemiology of WNV in the wild and the risk of spillover into humans. However, such studies are very scarce up to now. Here, we analysed the occurrence of WNV and Usutu virus (USUV) antibodies in ...
Emelogu U, Lewin AC, Balasuriya UBR, Liu CC, Wilkes RP, Zhang J, Mills EP, Carter RT.Equid alphaherpesvirus 1 (EHV-1) is a global viral pathogen of domestic equids which causes reproductive, respiratory and neurological disease. Few isolates acquired from naturally infected USA-based hosts have been fully sequenced and analyzed to date. An ORF 30 (DNA polymerase) variant (A2254G) has previously been associated with neurological disease in host animals. The purpose of this study was to perform phylogenomic analysis of EHV-1 isolates acquired from USA-based hosts and compare these isolates to previously sequenced global isolates. EHV-1 was isolated from 23 naturally infected USA...
Virtanen J, Hautala K, Utriainen M, Dutra L, Eskola K, Airas N, Uusitalo R, Ahvenainen E, Smura T, Sironen T, Vapalahti O, Kant R, Virtala AK....Parapoxviruses (PPV) cause skin and mucous membrane lesions in several animal species, and of the five recognized PPVs, at least three are zoonotic. Equine PPV (EqPPV) is the sixth one initially described in humans in the United States and later in a severely sick horse in Finland in 2013-2015. In 2021-2022, a large-scale pustulo-vesicular pastern dermatitis outbreak occurred in horses all over Finland. This study aimed at analysing the outbreak, identifying and describing the causative agent, describing clinical signs, and searching for risk factors. EqPPV was identified as a probable causati...
Kreutzfeldt N, Chambers TM, Reedy S, Spann KM, Pusterla N.Dexamethasone is routinely administered to horses but its effect on the antibody response to a commercial EIV/EHV vaccine is unclear. Objective: Horses receiving dexamethasone will have lower postvaccination antibody levels against EIV and EHV-1 than vaccinated controls. Methods: Fifty-five healthy adult research horses. Methods: Randomized cohort study. Control (no vaccine, group 1), vaccination only (EIV/EHV-1/EHV-4, Prestige 2, Merck Animal Health, group 2), vaccination and concurrent single intravenous dose of dexamethasone (approximately .05 mg/kg, group 3), vaccination and 3 intravenou...
Stasiak K, Socha W, Rola J.Loss of pregnancy in mares is a major cause of economic and emotional impact for horse breeders. It can have many different infectious and noninfectious causes. The aim of this study was identification of the main viral causes of abortion in mares in Poland based on tissue samples from 180 aborted foetuses submitted for testing between 1999 and 2022. Unassigned: Tissues of aborted foetuses collected from different horse studs throughout Poland were tested for the presence of equine herpesvirus types 1 and 4 (EHV-1/-4) and if negative, for equine arteritis virus (EAV). The examination was perfo...
Kaps M, Wenderoth J, Aurich J, Aurich C.Equine viral arteritis (EVA) can induce a persistent carrier state in stallions which then shed the virus via semen. About 30 years ago, obligatory EVA testing of stallions used for artificial insemination (AI) was implemented in the European Union. Information on the efficacy of these regulations on the prevalence of EVA in stallions are not yet available. Therefore, we retrospectively analyzed results of serological and virus antigen testing for EVA in sires of different age and breed referred to Vetmeduni Vienna for semen preservation or veterinary diagnostic procedures between 2001 and 202...
İncili CA, Eröksüz Y, Otlu B, Kara E, Tanrıverdi ES, Timurkan MÖ, Kalender H, Eröksüz H.Moellerella wisconsensis is a Gram-negative, facultative anaerobic bacillus of Entero-bacteriaceae family, and it is an uncommon pathogen in domestic animals. To date, five cases were reported including two dogs, two cattle, and a goat. Streptococcus equisimilis is the second common bacterial agent after the S. equi subsp. zooepidemicus in equine pneumonia cases. The present report describes the isolation of M. wisconses from lungs and spleen of a 10-year-old Arabian horse (May 08, 2022) at post-mortem examination being co-infected with S. equisimilis. Clinical and pathological findings includ...
Zhang Z, Guo K, Chu X, Liu M, Du C, Hu Z, Wang X.Equine infectious anemia (EIA) is a contagious disease of horses caused by the equine infectious anemia virus (EIAV). The clinical signs at the acute phase include intermittent high fever, thrombocytopenia, hemorrhage, edema, and anemia. The clinical signs at chronic and relapsing subclinical levels include emaciation and progressive weakness. Surviving horses become lifelong carriers because of the integration of the viral genome into that of the host, and these horses can produce and transmit the virus to other animals. This increases the difficulty of imposing practical control measures to ...
El-Zayat M, Shemies OA, Mosad SM, El Rahman SA.Equine herpes viruses (EHVs) are considered one of the most important respiratory pathogens in equids, resulting in serious outcomes for equine health worldwide. The objectives of the current research were the detection, molecular characterization, and isolation of EHV-1 and EHV-4 circulating within different equine populations in Egypt, either clinically or in apparently healthy horses. Unassigned: A total of 120 field samples were collected, and DNA was extracted. Screening and typing of extracted DNA were done by consensus and conventional PCR assays for detection of EHV-1 and EHV-4, follow...
Tirosh-Levy S, Shaiman Barom L, Novak S, Eyngor M, Schvartz G, Yakobson B, Steinman A.Rabies is a fatal zoonotic disease affecting all mammalian species. It is caused by the rabies virus and is prevalent worldwide. Horses are not commonly infected with rabies but their vaccination is recommended due to the potential zoonotic risk. This study aimed to evaluate the duration of immunity following rabies vaccination in horses. A total of 126 serum samples were collected from 93 horses, vaccinated 6 to 91 months before sampling. Rabies-virus-neutralizing antibody (RVNA) levels were evaluated using the Rabies Fluorescent Focus Inhibition Test (RFFIT). A protective RVNA titer of above...
Wilkin T, Hamilton NA, Cawley AT, Bhat S, Baoutina A.The term 'gene doping' is used to describe the use of any unauthorized gene therapy techniques. We developed a test for five likely candidate genes for equine gene doping: , , , and . The test is based on real-time polymerase chain reaction (PCR) and includes separate screening and confirmation assays that detect different unique targets in each transgene. For doping material, we used nonviral (plasmid) and viral (recombinant adeno-associated virus) vectors carrying complementary DNA for the targeted genes; the vectors were accurately quantified by digital PCR. To reduce non-specific amplific...
Tanaka Y, Watanabe K, Takeyama A, Tagami M, Hamano H, Fukumoto N, Nambo Y, Kobayashi Y.Equine testicular arteritis commonly occurs as a consequence of the migration of nematode larvae or equine arteritis virus (EAV) infection. However, testicular arteritis without evidence of these infections has been reported, and the underlying pathogenesis remains unclear. We encountered testicular arteritis without evidence of nematode or EAV infection in a 3-year-old male heavy draft horse with scrotal enlargement. Grossly, the volume of the pampiniform plexus was markedly increased due to edema. Histologically, non-suppurative and necrotizing testicular arteritis, characterized by lymphocy...
Shakeel M, Choi Y, Yoon M.Cryptorchidism affects spermatogenesis and testis development, often resulting in stallion subfertility/infertility. This study aims to identify the specific germ cells impacted by cryptorchism in stallions. In a previous study, we found that PGP9.5 and VASA are molecular markers expressed in different germ cells within stallions. Herein, we assessed the heat stress-induced response of spermatogonial stem cells (SSCs) in the seminiferous tubules (ST) of cryptorchid stallion testes (CST) and normal stallion testes (NST). This goal was accomplished by comparing PGP9.5 and VASA expression pattern...
Goodrich LR, McIlwraith CW, Grieger J, Kraus VB, Stabler T, Werpy N, Phillips J, Samulski RJ, Frisbie D.To evaluate the effects of a gene transfer approach to IL-1β inhibition in an equine osteochondral chip fragment model of joint injury using a self-complementary adeno-associated virus with interleukin receptor antagonist transgene cassette (scAAVIL-1ra), as posttraumatic osteoarthritis in horses, similar to people, is a significant clinical problem. Methods: 16 horses were utilized for the study. Methods: All horses had an osteochondral chip fragment induced arthroscopically in one middle carpal joint while the contralateral joint was sham operated. Eight horses received either scAAVIL-1ra o...
Taesuji M, Rattanamas K, Yim PB, Ruenphet S.The Flinders Technology Associates (FTA) card, a cotton-based cellulose membrane impregnated with a chaotropic agent, effectively inactivates infectious microorganisms, lyses cellular material, and fixes nucleic acid. The aim of this study is to assess the stability and detection limit of various RNA viruses, especially the avian influenza virus (AIV), Newcastle disease virus (NDV), and African horse sickness virus (AHSV), on the FTA card, which could significantly impact virus storage and transport practices. To achieve this, each virus dilution was inoculated onto an FTA card and stored at r...
Nardini R, Pacchiarotti G, Svicher V, Salpini R, Bellocchi MC, Conti R, Sala MG, La Rocca D, Carioti L, Cersini A, Manna G....Equine hepacivirus (EqHV, Flaviviridae, hepacivirus) is a small, enveloped RNA virus generally causing sub-clinical hepatitis with occasional fatalities. EqHV is reported in equids worldwide, but for Italy data are limited. To address this, a survey study was set up to estimate prevalence at a national level and among different production categories (equestrian; competition; work and meat; reproduction) and national macro-regions (North, Central, South, and Islands). Data obtained testing 1801 horse serum samples by Real-Time RT PCR were compared within the categories and regions. The NS3 frag...
