Infections in horses encompass a range of diseases caused by various pathogens, including bacteria, viruses, fungi, and parasites. These infections can affect different systems within the horse, such as the respiratory, gastrointestinal, and integumentary systems, leading to a variety of clinical signs depending on the pathogen and the severity of the infection. Common infectious diseases in horses include equine influenza, strangles, and equine herpesvirus. Diagnosis often involves clinical examination, laboratory testing, and sometimes imaging, to identify the causative agent and assess the extent of the disease. Treatment strategies may include antimicrobial therapy, supportive care, and preventive measures such as vaccination and biosecurity practices. This page aggregates peer-reviewed research studies and scholarly articles that explore the pathogenesis, diagnosis, treatment, and prevention of infectious diseases in equine populations.
TOMCSIK J, SCHWARZWEISS H.1. From beef stroma pretreated at room temperature with acetone and alcohol, a fraction was isolated with boiling 100% alcohol which, in a dilution of 1:500,000, combines with the sheep blood agglutinin of human serum produced during serum sickness. Using the terminology of Schiff, this fraction corresponds to the heterogenetic serum sickness antigen; it could be separated to a large extent from the heterogenetic mononucleosis antigen which also occurs in beef stroma.
2. The so-called serum sickness antigen also occurs heterogenetically in guinea pig kidney and it could also be isolated from ...
Martins ALM, Estevam LGTM, Freire MA, Lima ACVMDR, de Oliveira FCB, Dutra-Rêgo F, Carvalho GML, Ribeiro VM, Paz GF.Equine leishmaniasis is a widespread disease in Brazil, mainly caused by Leishmania (Viannia) braziliensis, with occasional cases involving Leishmania (Leishmania) infantum. This study reports a mixed infection in a 6-year-old mare from rural Itabirito, Minas Gerais, Brazil. The mare exhibited nodular cutaneous lesions on all limbs but had no other health issues. Skin and bone marrow samples were collected and analyzed using parasitological and molecular methods targeting the hsp70 gene and ITS1 region. Both L. (V.) braziliensis and L. (L.) infantum were identified, confirming a mixed infectio...
Graham AE, Colgate VA, Floyd EF.Geographical specific data is required to guide empirical antimicrobial selection in equine neonates. Objective: Evaluate antibiograms and survival in foals from a United Kingdom (UK)-based hospital to guide antimicrobial selection. Methods: Blood and synovial fluid samples from 208 foals ≤ 30 days old admitted to Rossdales Equine Hospital from 2018 to 2023. Methods: Retrospective cohort study. Antimicrobial susceptibility was assessed by disc diffusion method. Bacterial culture and susceptibility and foal survival were recorded. The effects of the presence of positive culture or multi...
Badr C, Arbi M, Souiai O, Larbi I, Nsiri J, Elbehi I, Bouslama Z, Bennour MA, Essaied MS, Ines Khosrof , Chabchoub A, Ben Aoun B, Ghram A, Lachheb J.Equine influenza (EI) is a highly contagious viral respiratory disease affecting equids, with the potential of causing widespread outbreaks across Europe, the Americas, Asia, and other regions of the world. In Tunisia, in the spring of 2021, an EI virus outbreak occurred in a farm housing purebred Arabian horses that exhibited respiratory signs. This outbreak led to a national lockdown on horse movements and the cancellation of equestrian events. A total of 432 serum samples, collected from 2018 to 2021, were tested using ELISA competition assay. In addition, 100 Nasal swabs were collected dur...
Bannai H, Kambayashi Y, Kume K, Takebe N, Endo Y, Kawanishi N, Nemoto M, Tsujimura K.The endemic situation of respiratory disease caused by equine herpesvirus type-1 (EHV-1) and type-4 (EHV-4) was investigated in a training facility for Thoroughbred yearlings in Japan. Vaccination typically starts in mid-September or early October-only after all yearlings have arrived-leaving those introduced earlier unprotected. To bridge this immunity gap, a revised vaccination program that started earlier was implemented. In 2021-2022 and 2022-2023, yearlings were allocated to three groups according to their introduction dates. Each group received a live EHV-1 vaccine (Equi N Tect ERP, Niss...
Kyari F, Pogu CJ, Mairiga IA, Adamu L.Nematode infections are a significant health concern in horses, causing a range of clinical signs and economic losses. Early detection and diagnosis are crucial for effective treatment and management. Unassigned: Examining the application of the systemic immune Inflammatory index (SII) as a predictor for nematode infections in horses, using platelets count, leucocytes count, and neutrophils count. Unassigned: A cross-sectional study was conducted on 164 horses, consisting of 66 horses with nematode infections and 98 horses without infections. The SII was computed using the platelets count, leu...
Khan A, Jose-Cunilleras E, Hyde E, Olajide E, Polo MC, Goehring LS.Equid alphaherpesvirus 1 (EHV-1) remains a major concern for the equine industry, with recent outbreaks at international equestrian events highlighting the need for improved surveillance during competitions. Objective: To investigate EHV-1 and -4 presence in shared airspaces and environmental surfaces in direct contact with horses at international equestrian events; and to evaluate air sampling as a surveillance alternative to individual horse testing. Methods: Cross-sectional field study. Methods: Air (37) and surface samples (205) were collected from temporary stabling facilities across six ...
Neira-Egea P, Alamar Malvoisin C, de la Cuesta-Torrado M, Bautista-Erler C, Vitale V, Jolly S, Cesarini C. spp. are ubiquitous yeasts that are part of most mammals' microbiota and can become opportunistic pathogens under predisposing conditions. Interestingly, recent studies in human medicine report an increased abundance of spp. in association with inflammatory bowel disease (IBD). Gastrointestinal candidiasis has been primarily reported in neonatal foals, but not in adult horses. The aim of this study is to describe the morphological, histopathological, and microbiological features of gastric lesions associated with infiltration in five horses referred to two tertiary hospitals for different r...
Gandini M, Bertone C, Giusto G.Castration remains a common surgical procedure in equids, yet postoperative complications such as hemorrhage, infection, and eventration persist, influencing surgical outcomes. This retrospective study introduced a novel modified semi-closed castration technique aimed at minimizing these complications. Eighty-five sexually intact mature male equids (including horses, ponies, and donkeys) underwent the described inguinal castration procedure under general anesthesia. The technique involved a carefully managed opening and subsequent secure closure of the parietal vaginal tunic, enabling direct i...
Ceriotti S, Clark-Price S, Cole R, Kramer A, Sandey M, Mora M.This case describes a 15-year-old Thoroughbred mare with fistulous withers that progressed to vertebral osteomyelitis and spinal epidural abscess (SEA), a severe complication that has yet to be reported. Initially treated with antibiotics and anti-inflammatory medication, the mare developed acute hindlimb ataxia and spastic paresis, suggesting spinal cord compression at T3-L3. Diagnostic imaging revealed vertebral fractures and abscessation, but vertebral canal involvement could not be confirmed. Despite aggressive medical therapy, including antimicrobials, corticosteroids, and neuroprotective...
Chinyere CN, Ajaebili AC, Peter-Ajuzie IK, Galadima HB, Daodu OB, Fatola OI, Okolo CC, Alaba BA, Akinniyi OO, Omoniwa DO, Edeh ER, Olorunfemi AB....African horse sickness (AHS) is a severe, infectious arthropod-borne disease of equids caused by the AHS virus (AHSV). It is endemic in Sub-Saharan Africa, and several sporadic outbreaks of the disease have been reported in Nigeria in the past 5 decades. Following a recent outbreak of the disease in Lagos State, this study was conducted to investigate the prevalence of (AHSV) antibodies in apparently healthy horses and some selected wildlife sampled in four geographical regions of Nigeria. Using a competitive enzyme-linked immunosorbent assay, 575 serum samples collected from horses in five ...
Mukhanbetkaliyev Y, Yessembekova G, Mukhanbetkaliyeva A, Akmambayeva B, Kadyrov A, Uskenov R, Bostanova S, Ashirbek A, Korennoy F, Abdrakhmanov S.Equine herpesvirus 1 (EHV-1) is one of the most dangerous viral diseases affecting ungulates, and is characterized by a wide range of clinical manifestations in horses, including rhinopneumonia, abortion, neonatal death, and myeloencephalopathy. It is well known for causing mass abortions in mares and respiratory diseases in young animals. Once introduced into a horse breeding farm of any type, EHV-1 tends to establish as a persistent infection. The disease is reported on nearly all continents and causes substantial annual economic losses to horse breeding operations. In Kazakhstan, 34 EHV-1 o...
Parashar R, Singla LD, Kaur P, Sharma SK.Relative association of haemato-biochemical findings with oxidative stress markers was evaluated between natural patent and latent infection of in horses to divulge the role of these parameters in the pathogenesis of illness due to non-availablity in literature. Blood samples were collected from 429 equines of 16 districts of the Punjab and samples positive by conventional microscopy (patent Group I; oll = 13), by polymerase chain reaction (PCR) (latent group II; = 38) and healthy control (group III, = 64) were compared for haematological-biochemical index and stress parameters....
Nemoto M, Kawanishi N, Kamei R, Furusho K, Kawauchi K, Yabuuchi Y, Oue Y, Uchida Y, Nishiura H, Reedy SE, Chambers TM, Li F, Bannai H, Yamanaka T....In April and May 2025, outbreaks of equine influenza occurred for the first time in 17 years in Japan. Equine influenza virus (EIV) of the H3N8 subtype was mainly detected in heavy draft horse populations in Kumamoto Prefecture and the Tokachi area of Hokkaido. In total, 10 EIVs were isolated from infected horses and then were used for genetic and serological analyses. Phylogenetic analysis of all eight genes revealed that all Japanese isolates were clustered with the Florida sublineage clade 1 (Fc1) viruses and were closely related to North American Fc1 viruses detected in 2024-2025. The resu...
Hardefeldt L, Thomas K, Page S, Norris J, Browning G, El Hage C, Stewart A, Gilkerson J, Muscatello G, Verwilghen D, van Galen G, Bauquier J....The growing problem of antimicrobial resistance also affects equine veterinarians with increasing frequency. Antimicrobial stewardship and responsible prescribing are essential for a future in which effective antimicrobials are available, as it is unlikely that new antimicrobials will become available for use in horses. While antimicrobials are commonly used to treat equine infections, complications with therapy are also relatively common. Antimicrobial-associated diarrhoea, immune-mediated diseases, and nephrotoxicity have been reported as sequelae of antimicrobial therapy in equine practice....
Poci Palumbo MI, Maciel Cavalcante R, Martins Amorim R, De Vasconcelos Machado VM, Sousa Rocha N, Garcia Ribeiro M, Cagnini DQ, Secorun Borges A.Bacterial infection of the equine central nervous system is rare. This report describes the clinical features, computed tomography (CT) findings, and postmortem results of a 3-month-old female Quarter Horse with an intracranial abscess. Clinical signs included seizures, depression, and bilateral blindness. CT imaging demonstrated a large space-occupying lesion in the left cerebral hemisphere, associated with a frontal bone fracture. Necropsy and histopathology confirmed the presence of an abscess secondary to head trauma. Bacterial culture identified Streptococcus equi subsp. zooepidemicus as...
Samuels AN, Collins NM, Hanlon K, Bartish C, Kelly P, Kamr AM, Toribio RE.Early and accurate identification of septicemia in neonatal foals improves survival. In human medicine, the neutrophil-to-lymphocyte ratio (NLR), neutrophil-to-monocyte ratio (NMR), monocyte-to-lymphocyte ratio (MLR), and plasma cell-free DNA (cfDNA) aid in early bacteremia detection. This study evaluated the diagnostic utility of these markers in conjunction with other clinical and hematological parameters in hospitalized foals < 5 days old to predict positive blood culture at admission and to distinguish between Gram-positive, Gram-negative, or polymicrobial bacteremia. A total of 391 foal...
Whitlock F, Newton R, King S, Ionescu AM, Higgins S.With the geographical distribution of West Nile virus expanding, there is growing concern about the potential for an incursion to the UK. Here, Fleur Whitlock, Richard Newton, Simon King, Andra-Maria Ionescu and Sara Higgins provide a timely reminder of key aspects of the virus' biology.
Uprety T, Durazo J, Paul L, Metiner K, Ruby R, Loynachan A, Janes J, Kenndy L, Cassone L, Molly E, Quick M, Morgan J, Beyhan S, Erol E.Neorickettsia risticii (N. risticii) is an obligatory intracellular bacterium that causes Potomac horse fever (PHF), a disease clinically characterized by diarrhea, pyrexia, and laminitis in horses. Although sporadic reports of N. risticii infection have been linked to abortion in mares, a detailed retrospective study, including genomic analysis of the pathogen from an aborted fetus, has not been published. This study examined 546 fecal samples from clinically ill horses (January 1, 2017-December 31, 2024) and 833 colon samples from aborted equine fetuses (September 20, 2018-December 31, 2024)...
Berghaus LJ, Venner M, Helbig H, Hildebrandt D, Hart K.Rhodococcus equi causes pneumonia in young foals, but disease susceptibility and severity vary. Cortisol and vitamin D modulate immune responses and cytokine production during bacterial infection, and altered concentrations are associated with sepsis in neonatal foals. We hypothesised an age and disease effect on circulating steroid hormone concentrations in foals, and that differences in cytokines and steroid hormone concentrations would predict disease severity in pneumonic foals. Objective: To investigate circulating concentrations of various cytokines, cortisol and vitamin D as predictors ...
Şahinkesen İ, Bilge-Dağalp S.Equine herpesvirus 1 (EHV-1) and Equine herpesvirus 4 (EHV-4) are major viral pathogens of horses that contribute to respiratory disease, abortion, and neurological disorders, leading to economic losses in the equine industry. Accurate serological diagnosis is critical for disease surveillance and control. This study aimed to develop and validate an in-house enzyme-linked immunosorbent assay (ELISA) for detecting antibodies against EHV-1 and EHV-4 in horse sera. Serum samples previously confirmed by virus neutralization test (VNT) and a commercial ELISA were used to optimize the assay. Cut-off...
Kuzmina TA, Königová A, Burcáková L, Syrota Y, Babják M, Várady M.Strongylids and parascarids are the most widespread equine parasites worldwide; however, up-to-date data from Slovakia remain limited. This work bridges that gap by examining the prevalence and level of gastrointestinal helminth infections in Slovak horses. In the study, 392 fecal samples from horses on 24 farms were analyzed using the McMaster method with a sensitivity of 50 eggs per gram (EPG) for detecting nematode eggs and a double-centrifugation/combined sedimentation-flotation protocol for detecting Anoplocephala spp. eggs. Information on the age and breed of horses, management condition...
Wickenden H, Lightbody KL, Peczak N, Stevens KB, Pollard D, Blake DP, Austin CJ, Matthews JB, Fox MT.Anoplocephala perfoliata is the most common equine tapeworm infection. This parasite is found at the small/large intestinal junction and has been associated with colic. The cestode has an indirect lifecycle involving oribatid mite intermediate hosts, though little is known of its epidemiology. This study aimed to monitor seasonal fluctuations in pasture oribatid mite numbers and the presence of Anoplocephala spp. DNA in mite samples collected from three equine premises in the UK. Exposure to infection in resident horses was assessed by measuring tapeworm-specific salivary antibodies. The data ...
Countrymann K, Ruby R, Miller AD.Equine meningoencephalomyelitis is an important cause of morbidity and mortality and is associated with a wide variety of infectious etiologies. Because of the lack of large retrospective studies, the prevalence and incidence of these diseases are unknown. Here we describe 171 cases of meningoencephalomyelitis in horses submitted to the Section of Anatomic Pathology at the New York State Animal Health Diagnostic Center (Cornell University, Ithaca, NY, USA) from 1996-2023. Neuroinflammatory disease was identified in 5.4% of submitted horses with a wide breed, age, and sex distribution. A parasi...
Studzińska M, Klockiewicz M, Szczepaniak K, Demkowska-Kutrzepa M, Roczeń-Karczmarz M, Tomczuk K.The resistance of strongyles to pyrantel pamoate has been reported in publications worldwide. There is no data on its efficacy in horses in Poland. Therefore, the aim of this study was to evaluate the effectiveness of pyrantel pamoate to control strongyle invasions in young horses. The study involved horses of both sexes, aged 1 to 2 years, and was conducted in two seasons (spring and the end of summer). Feces were collected 24 hours before and 14 days after deworming, and they were then examined using McMaster's and combined sedimentation-flotation methods. Results revealed that in spring, th...
Merle R, Feuer L, Frenzer K, Plenio JL, Bethe A, Sarnino N, Lübke-Becker A, Bäumer W.: A mandatory monitoring of the use of antibiotics in horses in the European Union will come into force from 2027 on. The aim of the study was to explore the potential implementation of a monitoring system and to provide an overview of antibiotic use in horses in Germany. : Data on all consultations from 57 German practices between 2018 and 2023 were obtained. The dataset included basic data about the horse, free-text diagnoses (allocated to one of 20 categories), and treatments. Information on the administered or dispensed pharmaceutical product was recorded for antibiotic treatment consultat...
Vitale V, Bindi F, Bertelloni F, Sala G, Cingottini D, Bonelli F, Sgorbini M.Bacterial contamination of intravenous catheters in hospitalized horses may pose risks for both patient care and public health due to potential antimicrobial resistance and zoonotic transmission. This prospective clinical study aimed to evaluate the incidence of catheter contamination in equine patients admitted to a Veterinary Teaching Hospital between 2020 and 2021. All horses requiring intravenous catheterization were included, and data were collected on patient signalment, clinical status, duration of catheterization, treatments, and outcomes. Two catheter types were used: 5 cm polytetrafl...
Hacilarlioglu S, Bilgic HB, Karagenc T, Aydin HB, Toker H, Kanlioglu H, Pekagirbas M, Bakirci S.Equine piroplasmosis (EP), caused by and , is a tick-borne disease posing significant threats to equine health and the horse industry worldwide. Other vector-borne blood parasites, including , spp., and spp., can also infect horses; however, their prevalence remains poorly characterized in Türkiye. This study aimed to determine the molecular prevalence of , , , spp., and spp. in equids from the Western Aegean Region of Türkiye. Blood samples were collected from 388 clinically healthy equines across İzmir, Aydın, Denizli, and Muğla provinces. Species-specific PCR assays were performed...
Jelocnik M, Hall C, Dennis S, Mitchell K, Blishen A, Mashkour N, Anstey SI, Jenkins C, Jeffers K, El-Hage C, McMillan D, Gilkerson J.Infectious diseases significantly impact equine health and welfare, causing illness and death, and loss of productivity globally. One such disease is 'strangles', a highly contagious upper respiratory condition in horses caused by Streptococcus equi subspecies equi (SEE). Diagnostic methods for this pathogen include sensitive molecular assays and less reliable bacterial isolation and biochemical testing. However, the presence of closely related streptococci, such as Streptococcus equi subspecies zooepidemicus (SZOO), may confound diagnosis. Rapid assays for SEE are crucial for outbreak control...
McLinden LA, Kemp-Symonds JG, Daly JM, Blanchard AM, Waller AS, Freeman SL.Infection with Streptococcus equi subspecies equi (S. equi) is characterised by acute disease, with about 10% of infected animals remaining persistently infected. Clinically, infection with S. equi cannot readily be distinguished from infection caused by other respiratory pathogens, including Streptococcus equi subspecies zooepidemicus (S. zooepidemicus), equine influenza virus, and equine herpes virus. Screening protocols, with appropriate quarantining facilities, are important to detect horses infected with S. equi and avoid strangles outbreaks. Virulent strains of S. zooepidemicus can also ...
Seeger MG, de Vargas APC, Vogel FSF, Cargnelutti JF.Streptococcus equi subsp. equi (S. equi) is the etiological agent of strangles, a contagious equine disease characterized by lymph node abscess and respiratory complications. To clarify the epidemiology and virulence factors of isolates, this study demonstrated phenotypic and genotypic differences between S. equi obtained from nasal secretions and lymph node aspirates of clinical strangles cases. Additionally, circulating alleles were differentiated through sequencing of the 5' end of the seM gene. A total of 23 clinical isolates collected from horses with strangles over the past decade were a...
