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.
Slater JD, Lunn DP, Horohov DW, Antczak DF, Babiuk L, Breathnach C, Chang YW, Davis-Poynter N, Edington N, Ellis S, Foote C, Goehring L, Kohn CW....Amongst the infectious diseases that threaten equine health, herpesviral infections remain a world wide cause of serious morbidity and mortality. Equine herpesvirus-1 infection is the most important pathogen, causing an array of disorders including epidemic respiratory disease abortion, neonatal foal death, myeloencephalopathy and chorioretinopathy. Despite intense scientific investigation, extensive use of vaccination, and established codes of practice for control of disease outbreaks, infection and disease remain common. While equine herpesvirus-1 infection remains a daunting challenge for i...
Peregrine AS, McEwen B, Bienzle D, Koch TG, Weese JS.From 1991 to 2003, 24 cases of larval cyathostominosis were diagnosed at postmortem in equids, 15 (63%) from 2001 to 2003. Cases occurred from September to May, the majority from October to December. Median age was 12 mo. Diarrhea, colic, and weight loss were common clinical signs. Hypoalbuminemia and microcytosis were consistent findings. Cyathostominose larvaire chez des chevaux en Ontario: une maladie émergente? De 1991 à 2003, 24 cas de cyathostominose larvaire ont été diagnostiqués à l’examen post mortem chez des équidés dont 15 (63 %) entre 2001 et 2003. Les cas étaient rappor...
Daly JM, Whitwell KE, Miller J, Dowd G, Cardwell JM, Smith KC.Equine influenza is usually a transient and self-limiting disease. However, during an outbreak of equine influenza in the UK in 2003 there were reports of unusually severe clinical signs among unvaccinated animals. Two influenza-infected horses developed neurological signs, and one was subjected to euthanasia. Post-mortem examination of the brain revealed viral-type non-suppurative encephalitis, and influenza virus antigen was demonstrated by immunolabelling of sections of nasal mucosa. A syndrome known as influenza-associated encephalopathy has been described in man. Although not proved, the ...
Magdesian KG, Dujowich M, Madigan JE, Hansen LM, Hirsh DC, Jang SS.To determine molecular characteristics, antimicrobial susceptibility, and toxigenicity of Clostridium difficile isolates from horses in an intensive care unit and evaluate associations among severity of clinical disease with specific strains of C difficile. Methods: Prospective study. Methods: 130 horses. Methods: Feces were collected from horses admitted for acute gastrointestinal tract disease with loose feces and submitted for microbial culture and immunoassay for toxin production. Polymerase chain reaction assays were performed on isolates for toxins A and B genes and strain identification...
Gardner RB, Hart KA, Stokol T, Divers TJ, Flaminio MJ.A 5-week-old Fell Pony colt was examined for fever, lethargy, and anemia. The colt had been lethargic for 1 week before examination, had continued to nurse, had a temperature of 104°F (40°C), and was treated with ceftiofur (5 mg/kg IM q12h). Approximately 36 hours before examination, the colt developed watery diarrhea. Blood work performed by the referring veterinarian on the day of admission revealed a PCV of 10%.
Navarro JC, Medina G, Vasquez C, Coffey LL, Wang E, Suárez A, Biord H, Salas M, Weaver SC.Five years after the apparent end of the major 1995 Venezuelan equine encephalitis (VEE) epizootic/epidemic, focal outbreaks of equine encephalitis occurred in Carabobo and Barinas States of western Venezuela. Virus isolates from horses in each location were nearly identical in sequence to 1995 isolates, which suggests natural persistence of subtype IC VEE virus (VEEV) strains in a genetically stable mode. Serologic evidence indicated that additional outbreaks occurred in Barinas State in 2003. Field studies identified known Culex (Melanoconion) spp. vectors and reservoir hosts of enzootic VEE...
Newton JR, Daly JM, Spencer L, Mumford JA.Between March and May 2003, equine influenza virus infection was confirmed as the cause of clinical respiratory disease among both vaccinated and unvaccinated horses of different breeds and types in at least 12 locations in the UK. In the largest outbreak, 21 thoroughbred training yards in Newmarket, with more than 1300 racehorses, were affected, with the horses showing signs of coughing and nasal discharge during a period of nine weeks. Many of the infected horses had been vaccinated during the previous three months with a vaccine that contained representatives from both the European (A/eq/Ne...
Azlaf R, Dakkak A.The objectives of this epidemiological study on cystic echinococcosis (CE) in Morocco (2001-2004) were to update the prevalence of CE in different animal species living in the most important areas of the country and to collect protoscoleces and germinal layers for genetic research purposes. The post mortem inspection concerned 2948 sheep, 2337 goats, 618 cattle, 482 camels and 455 equines (325 horses, 60 mules and 70 donkeys) in five different regions: the Rif (Mediterranean coast and high mountains of the Rif), the Loukkos (Atlantic northwest plain), the center (Rabat and Casablanca regions),...
Scholz HC, Joseph M, Tomaso H, Al Dahouk S, Witte A, Kinne J, Hagen RM, Wernery R, Wernery U, Neubauer H.A polymerase chain reaction (PCR) assay targeting the flagellin P (fliP)-I S407A genomic region of Burkholderia mallei was developed for the specific detection of this organism in pure cultures and clinical samples from a recent outbreak of equine glanders. Primers deduced from the known fliP-IS407A sequence of B. mallei American Type Culture Collection (ATCC) 23344(T) allowed the specific amplification of a 989-bp fragment from each of the 20 B. mallei strains investigated, whereas other closely related organisms tested negative. The detection limit of the assay was 10 fg for purified DNA of ...
Kelly C, Bugg M, Robinson C, Mitchell Z, Davis-Poynter N, Newton JR, Jolley KA, Maiden MC, Waller AS.Improved understanding of the epidemiology of Streptococcus equi transmission requires sensitive and portable subtyping methods that can rationally discriminate between strains. S. equi is highly homogeneous and cannot be distinguished by multilocus enzyme electrophoretic or multilocus sequence-typing methods that utilize housekeeping genes. However, on sequence analysis of the N-terminal region of the SeM genes of 60 S. equi isolates from 27 strangles outbreaks, we identified 21 DNA codon changes. These resulted in the nonsynonymous substitution of 18 amino acids and allowed the assignment of...
Englund L, Pringle J.Dogs and horses are transported within the European Union for a number of reasons. The transport per se may cause physical problems, exemplified by hyperthermia in dogs and pleuropneumonia in horses, and the stress may reactivate latent infections such as canine herpesvirus-1 and equine herpesvirus-1. Preventive treatments are vital to protect dogs from ticks and mosquitoes transmitting their potentially lethal infectious agents, such as Leishmania donovani infantum, Babesia canis, Ehrlichia canis, and Dirofilaria immitis. However, records show that the travelling dogs are not fully protected ...
Grønbaek LM, Angen O, Vigre H, Olsen SN.Streptococcus equi is the cause of strangles in horses. To improve diagnostic sensitivity, development and evaluation of DNA-based methods are necessary. Objective: To evaluate diagnostic methods and observe the pattern of bacterial shedding during natural outbreaks. Methods: Two herds with natural outbreaks of strangles were visited over a period of 15 weeks and 323 samples originating from 35 horses investigated. The diagnostic use of a nested PCR test was evaluated using a collection of 165 isolates of Lancefield group C streptococci (species specificity) and swabs from nasal passages or fr...
Weese JS, Caldwell F, Willey BM, Kreiswirth BN, McGeer A, Rousseau J, Low DE.There are increasing reports of methicillin-resistant Staphylococcus aureus (MRSA) infection and colonization in horses and evidence that MRSA can be transmitted between horses and humans. The objective of this study was to investigate reports of skin infection in personnel working with a foal with community-associated MRSA colonization and subsequent infection. Clinical diagnostic specimens were collected from individuals reporting skin lesions following contact with the affected foal. Nasal and groin screening swabs were collected from other veterinary personnel that attended a voluntary scr...
Eaton BT, Broder CC, Wang LF.Within the past decade a number of new zoonotic paramyxoviruses emerged from flying foxes to cause serious disease outbreaks in man and livestock. Hendra virus was the cause of fatal infections of horses and man in Australia in 1994, 1999 and 2004. Nipah virus caused encephalitis in humans both in Malaysia in 1998/99, following silent spread of the virus in the pig population, and in Bangladesh from 2001 to 2004 probably as a result of direct bat to human transmission and spread within the human population. Hendra and Nipah viruses are highly pathogenic in humans with case fatality rates of 40...
Cohen ND, Carey VJ, Donahue JG, Seahorn JL, Brown SE, Riddle TW.To characterize the temporality of dates of breeding and abortion classified as mare reproductive loss syndrome (MRLS) among mares with abortions during early gestation. Methods: 2,314 mares confirmed pregnant at approximately 28 days after breeding from 36 farms in central Kentucky, including 515 mares that had early-term abortions. Methods: Farm veterinarians and managers were interviewed to obtain data for each mare that was known to be pregnant to determine pregnancy status, breeding date, last date known to be pregnant, and date of abortion. Results: Mares bred prior to April 1, 2001, app...
Rankin SC, Whichard JM, Joyce K, Stephens L, O'shea K, Aceto H, Munro DS, Benson CE.Salmonella enterica serovar Newport MDR-AmpC expressing TEM-1b and extended-spectrum beta-lactamase SHV-12 was isolated from affected animals during an outbreak of salmonellosis that led to a 3-month closure of one of the largest equine hospitals in the United States.
Egenvall A, Penell JC, Bonnett BN, Olson P, Pringle J.The aim of this study was to evaluate the potential usefulness of the database maintained by the Swedish insurance company Agria for providing disease statistics on Swedish horses. The demography of the horses insured for veterinary care during the period 1997 to 2000 was recorded and the incidence of morbidity, defined as horses that required veterinary care that cost more than the policy excess, was calculated. Yearly incidences were calculated for horses that required veterinary care at least once, first overall, and then for horses with complete insurance, by sex, age, breed group, breed, ...
Spiridonov SI, Gontarenko IA, Mukusheva MK, Fesenko SV, Semioshkina NA.The paper describes mathematical models for 137Cs behavior in the organism of horses and sheep pasturing on the bording area to the testing area "Ground Zero" of the Semipalatinsk Test Site. The models are parameterized on the base of the data from an experiment with the breeds of animals now commonly encountered within the Semipalatinsk Test Site. The predictive calculations with the models devised have shown that 137Cs concentrations in milk of horses and sheep pasturingon the testing area to "Ground Zero" can exceed the adopted standards during a long period of time.
Quinlivan M, Dempsey E, Ryan F, Arkins S, Cullinane A.Equine influenza is a cause of epizootic respiratory disease of the equine. The detection of equine influenza virus using real-time Light Cycler reverse transcription (RT)-PCR technology was evaluated over two influenza seasons with the analysis of 171 samples submitted for viral respiratory disease. Increased sensitivity was found in overall viral detection with this system compared to Directigen Flu A and virus isolation, which were 40% and 23%, respectively, that of the RT-PCR. The assay was also evaluated as a viable replacement for the more traditional methods of quantifying equine influe...
Ameni G.Epizootic lymphangitis (EL) was experimentally reproduced in four horses that had been purchased from an EL-free district. Two horses were injected with either 0.2 mL of the yeast form of Histoplasma capsulatum var. farciminosum (HCF) in pus (Horse 1), or 0.2 mL (ca. 20 mg) of a suspension in saline of the mycelial form (Horse 2), both into the pre-scapular and pre-femoral lymph nodes, with scarification of the skin of the left hind limb, conjunctiva of the right eye and the nasal membrane of the right nostril. The two other horses served as controls. Nodular lesions of EL appeared during the ...
Neubauer H, Sprague LD, Zacharia R, Tomaso H, Al Dahouk S, Wernery R, Wernery U, Scholz HC.Burkholderia mallei causes glanders or farcy in solipeds, a disease that must be reported to the OIE (Office International des Epizooties, Paris, France). The number of reported outbreaks has increased steadily during the last decade. Serodiagnosis is hampered by the considerable number of false-positives and -negatives of the internationally prescribed tests. The major problem leading to low sensitivity and specificity of complement fixation test (CFT) and enzyme-linked immunosorbent assay (ELISA) has been linked to the test antigens currently used, i.e. crude preparations of whole cells. Fut...
Ward MP.Since first being detected in New York in 1999, West Nile virus (WNV) has spread throughout the United States and more than 20,000 cases of equine WNV encephalomyelitis have been reported. A spatial model of disease occurrence was developed, using data from an outbreak of serologically confirmed disease in an unvaccinated population of horses at 108 locations in northern Indiana between 3 August and 17 October 2002. Daily maximum temperature data were recorded at meteorological stations surrounding the study area. The distribution of the total number of degree-days elapsing between July 4 and ...
Broquist HP, Mason PS, Hagler WM, Harris TM.When infested with the fungus Rhizoctonia leguminicola, certain forages, e.g., red clover hay, can cause a "slobber syndrome" of varying severity when consumed by ruminants. The causative agent has been presumed to be slaframine [(1S,6S,8aS)-1-acetoxy-6-aminooctahydroindolizine], which is produced by R. leguminicola. In one serious outbreak of the slobber syndrome in horses, the red clover forage involved was carefully examined and found to contain R. leguminicola and slaframine. An identical hay sample is shown here by ion-exchange chromatographic and gas chromatographic-mass spectrometric an...
Pascoe RR.The epidemiology of dermatomycocis due to Trichophyton equinum var autotrophicum was studied in a number of thoroughbred stables in south-east Queensland. The significant factors in the epidemiology were defined. The infection was readily transmitted, particularly by infected saddle-girths, on which the fungus could survive for 12 months. Mild abrasion from the saddle during work favoured the development of lesions and prolonged the recovery period. A pronounced age and seasonal incidence of the disease was demonstrated as young horses under the age of 3 years were most susceptible, and the ma...
Kuhar U, Malovrh T.The equine infectious anaemia virus (EIAV), which belongs to the Retroviridae family, infects equids almost worldwide. Every year, sporadic EIAV cases are detected in Slovenia. Objective: To characterise the Slovenian EIAV strains in the p15 gag gene region phylogenetically in order to compare the Slovenian EIAV strains with EIAV strains from abroad, especially with the recently published European strains. Methods: Cross-sectional study using material derived from post mortem examination. Methods: In total, 29 EIAV serologically positive horses from 18 different farms were examined in this stu...
Nemoto M, Niwa H, Kida H, Higuchi T, Orita Y, Sato S, Bannai H, Tsujimura K, Ohta M.A rare genotype G13P[18] group A rotavirus (RVA/Horse-tc/JPN/MK9/2019/G13P[18]) was isolated from a diarrhoeic foal for the first time in 28 years. The genotype constellation of the virus was assigned to G13-P[18]-I6-R9-C9-M6-A6-N9-T12-E14-H11 and was the same as that of the first isolated strain, RVA/Horse-tc/GBR/L338/1991/G13P[18]. Phylogenetic analysis suggests that the virus is related to RVA/Horse-tc/GBR/L338/1991/G13P[18] and is distant from typical equine rotaviruses of the G3P[12] and G14P[12] genotypes.
Bicout DJ, Carvalho R, Chalvet-Monfray K, Sabatier P.The paper examines the prevalence of equine infectious anemia (EIA) in horse populations in the northern part (comprising 89 cities) of Minas Gerais State, Brazil, from January 2002 to December 2004. Data on 8,981 agar gel immunodiffusion test results from the region were used as input for a statistical and autoregressive analysis model to construct a city-level map of the distribution of EIA prevalence. The following EIA prevalence (P) levels were found: 49 cities with 0 < P < or = 0.5%, 26 with 0.5% < P < or = 1.5%, 10 with 1.5% < P < or = 5%, and 4 with 5% < P < or = 25%.
Meade BJ, Timoney PJ, Donahue JM, Branscum AJ, Ford R, Rowe R.In 1998, a newly identified bacterium Taylorella asinigenitalis was isolated from the external genitalia and reproductive tracts of nurse mares, a stallion and donkey jacks in Kentucky. An extensive regulatory effort was implemented to contain the outbreak including the tracing and testing of 232 horses and donkeys on 58 premises. T. asinigenitalis was isolated from the reproductive tract of 10 adult equids, including two donkey jacks, one Paint Quarter-horse stallion and seven draft-type breeding mares. None of the infected horses had clinical signs of reproductive tract disease. The odds of ...
Elschner MC, Thomas P, Melzer F.Burkholderia mallei is a zoonotic agent causing glanders, a notifiable disease in equines. During the past decades glanders emerged, and the Kingdom of Bahrain reported outbreaks to the World Organization of Animal Health in 2010 and 2011. This paper presents the complete genome sequence of the Burkholderia mallei strain 11RR2811 Bahrain1.
Faverjon C, Leblond A, Lecollinet S, Bødker R, de Koeijer AA, Fischer EAJ.African horse sickness (AHS) and equine encephalosis (EE) are Culicoides-borne viral diseases that could have the potential to spread across Europe if introduced, thus being potential threats for the European equine industry. Both share similar epidemiology, transmission patterns and geographical distribution. Using stochastic spatiotemporal models of virus entry, we assessed and compared the probabilities of both viruses entering France via two pathways: importation of live-infected animals or importation of infected vectors. Analyses were performed for three consecutive years (2010-2012). Se...
Asenzo G, Wilkowsky S, Barrandeguy M, Mesplet M, Benitez D, Florin-Christensen M.An indirect ELISA (iELISA) for the detection of specific anti-Theileria equi antibodies in horse serum was developed. Its performance showed good concordance (K= 0.79) when compared with a competitive ELISA recommended by the World Organisation for Animal Health. Horse serum samples from two provinces located in the north and east of Argentina (Formosa and Entre Rios, respectively) were analyzed by this iELISA. A high percentage of positive horses were found in Formosa, consistent with the climatic conditions of the region that are apt for the development of tick vectors. Surprisingly, seropos...
Smyth GB, Dagley K.Anecdotally, some sections of the horse community were under the impression that there was a high mortality rate in horses in 2007 because of the EI epidemic. A survey of horse deaths in the Hunter Valley of New South Wales (NSW) in 2007 indicated that there were few infections and deaths attributable to equine influenza (EI) infections in foals, but other authors found a very high seroprevalence across all age classes. This study aimed to generate objective information on mortality and morbidity rates associated with EI in Australian horses during the 2007 epidemic.
Dargatz DA, Traub-Dargatz JL, Sangster NC.Antimicrobial and anthelmintic resistance are growing issues for the equine practitioner. The development of antimicrobial or anthelmintic resistance is a source of significant concern because of increased frequency of treatment failures and increased treatment costs. In addition, antimicrobial resistance may have important consequences for public health. Only through judicious use can the efficacy of antimicrobials and anthelmintics be prolonged. This article discusses the development of resistance and suggestions for control.
Walter J, Seeh C, Fey K, Bleul U, Osterrieder N.Equine herpesvirus myeloencephalopathy (EHM) is a severe manifestation of equine herpesvirus 1 (EHV-1) infection. Prevention and treatment of EHM during EHV-1 outbreaks is critical, but no reliable and tested specific medication is available. Due to the thromboischemic nature of EHM and due to the fact that EHV-1 entry in cells is blocked by heparin, it was hypothesized that this compound may be useful in reduction of EHM incidence and severity. Therefore, during an acute EHV-1 outbreak with the neuropathogenic G/D Pol variant, metaphylactic treatment with heparin to prevent EHM was initiated....
Schmitt B.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.
Dorrego A, Herranz C, Pérez-Sancho M, Camino E, Gómez-Arrones V, Carrasco JJ, De Gabriel-Pérez J, Serres C, Cruz-López F.Taylorella asinigenitalis is a non-pathogenic bacteria isolated from the genital tract of donkeys but also a cause of metritis and vaginal discharge in mares. It is closely related to Taylorella equigenitalis, the cause of Contagious Equine Metritis (CEM) in horses, and has been present in different countries in Europe since 1995. Up to date, there are no studies on the prevalence of T. asinigenitalis in the equine or asinine populations in Spain; this is the first report of the presence of T. asinigenitalis in donkeys (Equus asinus) from different breeds in three regions of Spain. A total of ...