Disease outbreaks in horses refer to the occurrence and spread of infectious diseases within equine populations. These outbreaks can be caused by various pathogens, including bacteria, viruses, and parasites, and can lead to significant health issues in affected horses. Common diseases that may result in outbreaks include equine influenza, equine herpesvirus, strangles, and equine infectious anemia. The transmission of these diseases can occur through direct contact, environmental exposure, or vectors such as insects. Disease outbreaks can have substantial impacts on horse health, welfare, and the equine industry as a whole. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, transmission dynamics, and management strategies associated with disease outbreaks in equine populations.
Walton TE, Jochim MM, Barber TL, Thompson LH.Eighteen equids were inoculated with eastern equine encephalomyelitis (EEE) and 18 equids with western equine encephalomyelitis (WEE) viruses to produce EEE virus- and WEE virus-immunized equids. Twelve surviving EEE virus-seropositive equids, 15 surviving WEE virus-seropositive equids, and 10 nonimmunized, seronegative equids (controls) were subsequently inoculated with an equine pathogenic (epizootic) strain of Venezuelan equine encephalomyelitis (VEE) virus to determine cross-protective immunity. Challenge infection produced 90% mortality in control (nonimmunized) equids, and 40% mortality ...
van den Ingh TS, Hartman EG, Bercovich Z.A Leptospira interrogans serogroup australis serovar lora infection in a stud farm is reported. During three successive years (1984-1986) clinical leptospirosis with a severe often rapid, fatal course was seen in 12 foals. Clinical examination revealed severe respiratory distress, depression and pyrexia. Other symptoms were diarrhea (2), jaundice (1), and an unsteady gait (1). Morphological characteristics of the disease were massive pulmonary haemorrhage and haemorrhagic-thrombotic or extracapillary glomerulonephritis with tubulonephrosis and interstitial oedema. In most foals high or increas...
Lamarque D, Haessler C, Champion R, Granga D, Bendina , Steinmetz P, Guelina A, Maurice Y.An epidemic of human and animal anthrax raged in Chad mainly in the Department of Chari Baguirmi from September to December 1988, infesting more than 50% of donkeys and horses. 716 human cases have been reported, with 88 deaths. Thanks to a geographical distribution of animal and human prevalence, one sees immediately the interdependency between sanitary state of live-stock and public health. An unusual means of transmission from donkey to donkey by insects as the vector is suggested to explain the intensity of animal epidemics. Two strains of B. anthracis were isolated and described. Systemat...
Mason DK, Watkins KL, Luk CM.An outbreak of respiratory disease among thoroughbred horses in training in Hong Kong was caused by equine herpesvirus 1 (EHV-1) subtype 1 (abortion strain). Two of the horses affected by EHV-1 were serially blood sampled over a period of several weeks and their haematological values measured. There was an increase in monocyte count in the first few days which steadily decreased in one horse, but the other had a second monocyte peak after a period of exercise, thus demonstrating the importance of not working animals in the early stages of the disease.
Sweeney CR, Benson CE, Whitlock RH, Meirs DA, Barningham SO, Whitehead SC, Cohen D.The age-specific attack rates of Streptococcus equi infections of the upper respiratory tract and lymph nodes (strangles) in horses for the different age groups were 17.6% for broodmares, 47.5% for 1-year-old horses, and 37.5% for foals. Streptococcus equi was isolated from nasal, pharyngeal, or lymph node specimens in 31 (60.8%) of 51 sick horses. A male 1-year-old horse, shipped from Kentucky to farm A, was considered to be the index case. Six (19.4%) of 31 horses with strangles remained as shedders of S equi after clinical signs of the disease had ended. Shedders of S equi were not identifi...
ter Laak EA, Fennema G, Jaartsveld FH.Contagious Equine Metritis (CEM) was detected in the Netherlands for the first time in 1987. A total number of five mares (Dutch saddle-horse) were infected in three separate outbreaks. The origin of the infection could not be determined in any of the cases. As the isolates of the causal organism, Taylorella equigenitalis, showed auto-agglutination, diagnosis was difficult. Therefore, an indirect immune fluorescence test as used to diagnose the second isolate. Five strains were isolated, which all were resistant to streptomycin. The prevalence of CEM since 1981 is summarised. The importance of...
Ray AC, Kyle AL, Murphy MJ, Reagor JC.In addition to the 3-striped blister beetles (Epicauta temexa and E occidentalis), other sources of equine cantharidin toxicosis were identified at the Texas Veterinary Medical Diagnostic Laboratory and included E albida and E attrivittata and the previously incriminated E pardalis and E pennsylvanica. Improved methods for diagnosing cantharidin or blister beetle toxicosis involve partial purification of urine and gastric content extracts, using silica cartridges, followed by analysis, using capillary gas chromatography/mass spectrometry. During a 26-month period, 53 episodes of cantharidin to...
Cook BR.Twenty-five years ago Williams and Sweatman suggested that in Great Britain there are two subspecies of Echinococcus granulosus--E. granulosus granulosus and E. granulosus equinus. Echinococcus granulosus granulosus does not mature either in foxes or in horses: E. granulosus equinus will mature in either. The prepatent period of E. granulosus granulosus in the definitive host is about 42 days while that of E. granulosus equinus is about 70 days. Each subspecies has a characteristic morphology. More recently, in the course of seven experiments, dogs, red foxes (Vulpes vulpes crucigera), arctic ...
Crucière C, Guillemin MC, Roseto A, Wirbel A, Plateau E.Monoclonal antibodies (Mo Abs) were prepared against influenza/A/equine/Prague/1/56 (H7N7) and influenza/A/equine/Miami/1/63 (H3N8) reference strains of equine influenza virus. These monoclonals were tested against the 2 reference strains, 8 field strains of equine influenza virus, 3 human influenza viruses possessing the H3 hemagglutinin, and one virus of human origin possessing the H1 hemagglutinin. Two antibodies were obtained in one fusion against the Prague/1/56 strain and reacted only with this strain. Four anti/A/equine/Miami/1/63 Mo Abs were obtained in one fusion. They differentiated ...
Antal V, Antal T, Szabó I, Vajda G, Polner A, Szollár I, Totth B, Laber G, Stipkovits L.The authors examined 585 samples from 92 mares of 2 studs and 346 nasal swabs taken from their foals for the presence of mycoplasmas. The positive rates of mares and foals were 81.5% and 71.7%, respectively, with positivity of samples being variable. Clinical symptoms developed in 2-4 waves and lasted 3-7 days, with intervals of 7-12 days. The disease started in April among foals born in February, at an average age of 88 days. Later on, the average age of the affected foals decreased. There was a correlation between presence of mycoplasmas in nasal cavity and disease of foals.
Andersson-Eklund L, Andersson L, Sandberg K.A study was carried out to attempt to explain the basis of the association between the Es locus and starting proportion in Swedish Trotters which had been observed previously. The effect of Es genotype on starting proportion has diminished among horses born in the late 1970s. There are indications that the incidence of leg lesions varies between Es genotypes. If this is true, it is possible that the decreasing effect of the Es locus on starting proportion is due to the environmental changes which have been made at race tracks in the early 1980s to reduce the strain on the legs of the trotters....
Kawaoka Y, Webster RG.A severe influenza outbreak occurred in horses in South Africa in 1986. The causative agent was identified as an influenza virus [A/Equine/Johannesburg/86 (H3N8)]. Antigenic analyses of the hemagglutinin (HA) with ferret antisera and monoclonal antibodies showed that the Eq/Johannesburg/86 virus is similar to recent equine H3 viruses. The nucleotide sequence analysis on the HA genes of Eq/Johannesburg/86 and other equine H3 influenza viruses, together with the epidemiological data, clearly demonstrated that the Eq/Johannesburg/86 virus was derived from a virus that had been circulating in hors...
Onder Z, Duzlu O, Yildirim A, Ciloglu A, Okur M, Inci A.This study reports intense horn fly infestations of horses raised in an important wetland ecosystem, Sultan Marshes in Central Anatolia, Turkey. In total, seven horses raised together were found to be harbored over 500 flies per site of each animal. Totally, 376 fly specimens were collected from the horses by using the nets and were subjected to the laboratory for species identification. All flies were morphologically identified as the adults of Haematobia irritans. Partial fragments of mitochondrial cytochrome oxidase I (mt-COI) gene from totally 50 isolates were amplified for sequence and ph...
Gülegen E, Girisgin O, Girisgin AO, Cirak VY.The aim of the present study was to examine sport horses in Northwest Turkey for Eimeria (E.) leuckarti infections. Between 2004 and 2008 fecal samples from 549 horses of different age, breed and sex of 21 farms were examined for E. leuckarti oocysts using a qualitative method which involved centrifugation/flotation and saturated sugar solution as medium. The prevalence of infection was evaluated relative to host age, sex, breed and pasture availability. 16 (2.9%) horses were found to be infected with E. leuckarti, whilst infected horses were located in nine (42.8%) farms. Younger horses (<...
Smith BP, Timm K, Jahn S, Reina-Guerra M.Three of 33 ponies died after the herd had been moved to a new environment 3 months earlier. One mare died without premonitory signs of illness. Shortly thereafter, a 5-day-old foal and a 2-year-old gelding died after brief illness. Although cultures were not performed on the mare, Salmonella typhimurium was isolated from the feces and tissues of the foal and gelding. Lesions in the foal were confined to ecchymotic hemorrhages on the mucosal surface of the colon and petechial hemorrhages in the splenic capsule, with adhesions to the parietal peritoneum. The gelding had evidence of severe typhl...
Czernomysy-Furowicz D.In the springtime of 1995, 10 per cent of foals at a stud-farm died due to suppurative lesions. Three dead foals were examined. The manifestations of watery diarrhoea and pneumonia were observed. A profuse growth of an enterotoxigenic strain of Yersinia pseudotuberculosis was obtained from the internal organs of the foals. The foals with clinical symptoms of pneumonia and watery diarrhoea were immunized with Propionibacterium acnes t. II. All mares and their offspring from the stud were treated with an immunomodulator (Propionibacterium acnes t. II) and then vaccinated with a formalin-inactiva...
Fletcher MA, Caldwell KE, Saez L, Latif Z.A sialoglycoprotein from horse erythrocytes was isolated in essentially homogeneous form and found to contain the neuraminidase-sensitive determinant of the horse erythrocyte for Paul-Bunnell heterophile antibodies of infectious mononucleosis. This reactivity was retained after covalent coupling of the antigen to latex particles. The latex reagent has greater stability (greater than 3 years) than either fresh or preserved horse erythrocytes. It can be used in a direct slide test; no absorption of the serum is necessary. The new test compared favorably with some standard tests for infectious mo...
Gräfner G, Zimmermann H, Karge E, Münch J, Ribbeck R, Hiepe T.Systematic faunal studies in the district Schwerin showed at the present time there are 3 more or less damage-biotopes existing in the districts of Perleberg, Ludwigslust and Parchim; 5 river sources can be considered as potential sources, 5 are temporary and 2 are ephemeral whilst in 3 further areas environmental influences such as effluent impairs the flow of the river and the developmental stages of Simuliidae were not observed.--The following species were found: Boophthora erythrocephala, Wilhelmia salopiensis, Wilhelmia equina, Odagmia ornata, Eusimulium aureum and Eusimulium lundstroemi....
Salciccia A, Sandersen C, Grulke S, de la Rebière de Pouyade G, Caudron I, Serteyn D, Detilleux J.The objectives of this study were to describe and relate perioperative changes in blood leukocyte counts to the outcome of surgical colic horses, determine a cut-off value in the early postoperative period to obtain an indicator of the outcome, and compare the obtained value to a validation population of horses. Fifty-three horses undergoing colic surgery were included in the descriptive part of the study. Total leukocyte counts were performed before, during and serially after surgery. A receiver operating characteristic analysis was performed on the leukocyte counts of 45 of these horses to d...
Berman N, Tirosh-Levy S, Steinman A, Minderigiu A, Blinder E, Leszkowicz Mazuz M. is a tissue cyst forming coccidia, which affects multiple host species worldwide. Equine besnoitiosis is characterized mainly by generalized skin lesions and cysts in the scleral conjunctiva. Recent reports revealed exposure to in equines in Europe and the United States. However, the exposure to spp. in the Israeli equine population was never investigated. The aim of this study was to evaluate the seroprevalence and associated risk factors for besnoitiosis in equids in Israel. A cross-sectional serosurvey was performed using serum samples of apparently healthy horses ( = 347), donkeys ( = 9...
Ahearne MM, Pentzke-Lemus LL, Romano AM, Larsen ED, Watson AM, O'Fallon EA, Landolt GA.Equine influenza virus is a common cause of respiratory disease in equids. Few reports describe clinical presentation and disease progression in donkeys. Objective: Describe the clinical and diagnostic findings, outcome, and pathologic lesions associated with influenza pneumonia in donkeys. Methods: Thirteen unvaccinated donkeys ranging from 1 week to 12 years of age and sharing clinical signs and exposure history. Methods: Retrospective case series. Medical records from June to July 2020 at the Colorado State Veterinary Teaching Hospital and collaborating referring veterinary practices wer...
Vignjević G, Vrućina I, Sestak I, Turić N, Bogojević MS, Merdić E.The West Nile Virus (WNV) is a zoonotic arbovirus that has recently been causing outbreaks in many countries in southern and Central Europe. In 2012, for the first time, it caused an outbreak in eastern Croatia with total of 7 human clinical cases. With an aim of assisting public health personnel in order to improve survey protocols and vector control, the high risk areas of the WNV transmission were estimated and mapped. The study area included cities of Osijek and Slavonski Brod and 8 municipalities in Vukovarsko-Srijemska County. Risk estimation was based on seroprevalence of WNV infections...
Cazeau G, Leblond A, Sala C, Froustey M, Beck C, Lecollinet S, Tapprest J.Few studies about the use of quantitative equine mortality data for monitoring purposes are available. Our study evaluated the utility of monitoring emerging equine diseases using mortality data collected by rendering plants. We used approaches involving modelling of historical mortality fluctuations and detection algorithm methods to analyse changes in equine mortality in connection with the West Nile Virus (WNV) outbreak that occurred between July and September 2015 along the Mediterranean coast of France. Two weeks after the first equine WNV case was detected by clinical surveillance, detec...
Kim I, Cohen ND, Carroll RJ.The authors describe a method for assessing and characterizing effect heterogeneity related to a matching covariate in case-control studies, using an example from veterinary medicine. Data are from a case-control study conducted in Texas during 1997-1998 of 498 pairs of horses with colic and their controls. Horses were matched by veterinarian and by month of examination. The number of matched pairs of cases and controls varied by veterinarian. The authors demonstrate that there is effect heterogeneity related to this characteristic (i.e., cluster size of veterinarians) for the association of c...
Stros K, Krivanec K, Komárek J, Malinský B.There is a description of equine dermatophytosis enzootic, caused by the microscopic fungus Trichophyton equinum. The disease affected 32 horses, mostly young, all in the same herd (74.4%). The diseased horses were successfully treated with the preparation Fenoform forte, applied superficially at the concentration of 0.5% of the active substance. The authors made an attempt to determine the criteria for clinical differentiation of fully developed trichophytosis and microsporosis of horses. Trichophytosis (T. equinum) is characterized as typical numerous small and round patches, covered by smal...
Honnas CM, Schumacher J, McClure SR, Crabill MR, Carter GK, Schmitz DG, Hoffman AG.Medical records of 10 horses with olecranon bursitis were reviewed to examine treatments, evaluate a technique for en bloc resection of the bursa in standing horses, and determine outcome of the horses after treatment. Before admission, 6 horses had been treated by needle aspiration of fluid from the mass, followed by injection of corticosteroids. Subsequent treatment for 2 of these 6 horses included open drainage and packing of the cavity with gauze soaked in 7% iodine solution. None resolved after these treatments. After admission to the hospital, 5 horses were treated medically and 5 were t...
Doherr MG, Carpenter TE, Wilson WD, Gardner IA.To determine whether horses with Corynebacterium pseudotuberculosis infections that were examined at a veterinary medical teaching hospital between July 1, 1992, and June 30, 1994 had patterns of temporal or spatial clustering. Methods: 134 case and 800 control horses randomly selected from all non-case horses admitted during the study period. Methods: Admission date and geographic location were determined. Scan, Cuzick & Edwards', and Knox tests were applied to determine whether case horses had patterns of temporal or spatial clustering. Results: For all windows > or = 3 days (134 case...
Kirkland PD.During the 2007 equine influenza (EI) outbreak in Australia, diagnostic laboratories and the use of appropriate tests played a pivotal role in the response to the crisis. This role began with the detection of EI virus in New South Wales (NSW) on the evening of 24 August 2007 and culminated in providing the final 'proof of freedom' from EI in March 2008. The tests that were used during the EI response were able to provide results quickly, and with high sensitivity and specificity. This section of the supplement describes the roles and functions of the Australian laboratories; tests used and the...
Kaiser A, Meier HP, Doherr MG, Perler L, Zanoni R, Gerber V.Since 1991, no cases of Equine Infectious Anemia (EIA) have been reported in Switzerland. Risk factors for introduction of the virus into Switzerland are still present or have even increased as frequent inapparent infections, large numbers of imported horses, (since 2003) absence of compulsory testing prior to importation, EIA cases in surrounding Europe, possible illegal importation of horses, frequent short-term stays, poor knowledge of the disease among horse owners and even veterinarians. The aim of this study was to provide evidence of freedom from EIA in imported and domestic horses in S...
Powell DG.Examples of equine disease surveillance at the local, regional, national and international level are discussed in this article. Reporting systems at each level are also considered, and the increasing importance of laboratory confirmed diagnoses is emphasized. The need to develop national disease reporting systems is addressed, particularly with respect to conforming to international trading standards.
Drummer HE, Reynolds A, Studdert MJ, MacPherson CM, Crabb BS.Sera from 33 Australian thoroughbred mares were tested during an outbreak of equine herpesvirus 1 (EHV1) abortion with an enzyme-linked immunosorbant assay (ELISA) for the presence of EHV1-specific antibodies. The ELISA used a recombinant EHV1 antigen derived from glycoprotein G (gG) and distinguished antibodies to EHV1 from those of the antigenically related and widespread herpesvirus EHV4. Sera were obtained from most of the mares on three occasions, three, 13 and 67 days after the first abortion. Mares which were negative in the ELISA were kept separate from mares which were positive. A sec...
Edwards WC, Edwards RM, Ogden L, Whaley M.Cantharidin content of male and female Epicauta occidentalis and E conferta was determined. Aspects of the life cycle of blister beetles, taxonomy, pheromonal and adaptive functions of cantharidin relative to the medico-legal aspects of cantharidin poisoning, prevention and control in horses are discussed.
Losinno SJ, Aguilar J, Carbonetti L, Ferniot E, San Esteban F, Flores Suares CM.Strategies for parasite control have undergone major changes in recent years, especially in Europe and the United States, replacing traditional approaches by schemes based on surveillance and selective therapy. A first step in helminth control planning is to understand and demonstrate how horse owners or trainers currently control nematodes. The aim of this study was to collect information, through a survey, about important aspects of routine anthelmintic strategies in sport horses in Argentina and other regional countries. A total of 100 surveys were sent. Sixty nine were responded, 53% of th...
Rubes J, Borkovec L, Horínová Z, Urbanová J, Proroková I, Kulíková L.Cytogenetic examinations were carried out in 13 cattle farms, two herds of horses, one stag farm and 13 pig farms in areas with different levels of environmental contamination. The frequency of aberrant cells per 100 mitoses was 3.67 +/- 1.89 in pigs (n = 260) and 4.16 +/- 2.4 in herbivores (n = 497). This is a significant difference (p < 0.01). Ten times higher frequencies of chromatid exchanges were found in pigs. The examined herds were classified into three groups by the level of environmental contamination (satisfactory, impaired and severely impaired environment). Significant differen...
Dhand NK, Sergeant ES.The aim of this preliminary study was to estimate the proportions of seropositive horses on infected premises (IPs) in order to assess the attack risk of the disease. Logistic regression analyses were conducted to evaluate the differences in attack risks between enterprise sizes and predefined spatial clusters/regions. The average attack risk experienced during the outbreak was 96.88% (median 100%), but it differed according to the size of the enterprise and other geographic and demographic conditions. The highest attack risks were observed in the Dubbo cluster/region and the lowest in the Nar...
Dwyer RM.Disinfection of equine premises provides a challenge to farm managers, in view of the variety of surfaces which may be contaminated and the wide variety of horse pathogens. Of the commonly occurring infectious diseases for which disinfection and disease control are especially important, rotavirus diarrhoea, salmonellosis and strangles are the most difficult to control. Phenolic disinfectants have been scientifically demonstrated to be effective in the presence of organic matter and are also virucidal. When used after thorough cleaning and rinsing of stall surfaces, phenolics have proved effect...
Bannai H, Tominari M, Kambayashi Y, Nemoto M, Tsujimura K, Ohta M.Antibody response in horses after accelerated-schedule Getah virus vaccination was evaluated for its potential adoption during outbreaks. One-year-old Thoroughbred horses received two doses of priming vaccinations following an accelerated schedule (accelerated group: 14-day interval, n = 30) or the conventional schedule (control group: 28-day interval, n = 30). At Day 14, both groups showed similar seropositive rates (66.7% in control group and 73.3% in accelerated group) and geometric mean (GM) virus-neutralizing titers (5.2 [95% confidence interval (CI), 3.0-8.8] in control group and 5.3...
de la Rúa-Domènech R, Mohammed HO, Atwill ER, Cummings JF, Divers TJ, Summers BA, deLahunta A, Jackson C.To examine the regional variations in the distribution of equine motor neuron disease (EMND) in the United States and the factors that might explain those variations. Methods: Cluster investigation and case-control study. Methods: The study population consisted of 97 horses with histopathologically confirmed EMND and 698 controls with diagnosis of other spinal cord disorders at 21 US veterinary teaching hospitals participating in the Veterinary Medical Data Base. Methods: The total horse population of the United States was divided into 21 regions, and the regional incidence rates of EMND from ...
Hryhorczuk DO, Withrow WA, Hesse CS, Beasley VR.The authors investigated an outbreaks of unusual illnesses in humans and horses residing within 1.3 km of a wire reclamation incinerator. The study included site visits; medical and veterinary examinations; analyses of furnace ash, fly ash, soil, and biologic samples for air residues. Tetrachlorodibenzo-p-dioxins (TCDDs) and tetrachlorodibenzofurans (TCDFs) were discovered in furnace ash, fly ash, soil, horse fat, and horse liver samples.
Agnihotri K, Pease B, Oakey J, Campbell G.In 2011, a 2-year-old horse in northern Queensland, Australia, was reported to have developed mild neurologic signs, and a blood sample was submitted for laboratory investigation. Virus isolation was performed using the blood sample, and an orbivirus was isolated. This was confirmed to be a strain of Elsey virus (ELSV) after transmission electron microscopy and nucleotide sequencing. The nucleotide sequence was compared with those in GenBank, and had 100% identity with ELSV previously reported from the Northern Territory, Australia. ELSV is taxonomically closely related to Peruvian horse sickn...
Olufemi OT, Edeh ER, Isyaku MS, Haliru M, Samaila S, Mshelia PW, Owolodun OA, Newton JR, Daly JM.Equine influenza (EI) is a fast-spreading respiratory disease of equids caused by equine influenza A virus (EIV), often resulting in high morbidity and a huge economic impact on the equine industry globally. In this cross-sectional study to determine the seroprevalence of EI and its associated risk factors, sera from 830 horses bled on a single occasion in Northwest Nigeria between October 2019 and January 2020 were screened for antibodies to A/equine/Richmond/1/2007 (H3N8) using the single radial haemolysis (SRH) assay. Antibodies were detected in 71.3% (592/830, 95% CI: 68−74%) of horses (...
Mohan K, Muvavarirwa P, Pawandiwa A.Among the Actinobacillus spp. only A. lignieresii represents a homogenous and well studied taxon. However, haemolytic and non-haemolytic strains of A. equuli and A. suis are also isolated from a wide range of diseases in a variety of hosts. These isolates often pose problems in definitive identification. Consequently, several studies have been published, emphasizing the need for detailed studies to reclassify various members of this genus and also to assess their disease significance. We isolated 48 strains of Actinobacillus from clinical cases in horses, cattle, sheep, cat, pigs and ostrich. ...
