Infectious diseases in horses encompass a range of illnesses caused by bacteria, viruses, fungi, or parasites. These diseases can affect various systems within the equine body, leading to symptoms that range from mild discomfort to severe systemic illness. Common infectious diseases in horses include equine influenza, strangles, equine herpesvirus, and West Nile virus. These diseases can be transmitted through direct contact with infected animals, contaminated surfaces, or vectors such as insects. Understanding the mechanisms of transmission, pathogenesis, and immune response is essential for effective prevention and control. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, diagnosis, treatment, and management of infectious diseases in horses.
Floyd K, Suter PF, Lutz H.Direct staining of the granules of blood eosinophils by anti-immunoglobulin fluorescein isothiocyanate (FITC) conjugates was observed when feline blood smears were tested for presence of feline leukemia virus (FeLV) antigen by immunofluorescent antibody. When blood smears of other species including swine, horses, cattle, dogs, sheep, birds, and human beings were examined, direct staining of eosinophils by FITC conjugates was also detected. This FITC staining was restricted to eosinophils and was not observed in neutrophils, lymphocytes, and platelets. Direct FITC staining of eosinophils does n...
Ellis WA, Bryson DG, O'Brien JJ, Neill SD.During an investigation of equine abortion, leptospiral infection was demonstrated in nine out of 22 foetuses examined by immunofluorescence and culture. Strains belonging to four serogroups (Australis, Pomona, Hebdomadis and Icterohaemorrhagiae) were isolated. The age of leptospira infected foetuses ranged from six months to term.
Stalheim OH, Cottew GS, Freundt EA, Koski TA, Leach RH, Perreau P, Stone SS.Antisera to 10 mycoplasma species of bovine origin were produced in 10 ponies and were distributed for evaluation in growth-inhibition tests at 6 laboratories in Australia, England, Denmark, France, and the United States. Except for a few failures with some antigens produced at the 6 laboratories, the antisera induced large zones of growth inhibition in homologous, but not heterologous, systems. These antisera may be useful as standard reagents for the identification of the bovine mycoplasmas.
Coloe PJ, Ireland L, Vaudrey JC.We record a fatal case of gas-oedema disease (malignant oedema) in a 5-year-old horse. The nature of the lesion is consistent with a gas-oedema type infection due to a Clostridium spp. The causative organism was isolated and identified by conventional biochemical tests and by gas-liquid chromatographic analysis of its metabolic products as Clostridium fallax, but significant variations in the reported biochemical characteristics of Cl. fallax were detected. We believe that this is the first reported case of Cl. fallax infection in a horse.
Bertram TA, Coignoul FL, Jensen AE.Equine neutrophils were combined with contagious equine metritis organism (CEMO) or Escherichia coli in vitro in the presence of seminal plasma, uterine flushings, or Hank's balanced salt solution (HBSS). Phagocytosis and intracellular killing were estimated by bacterial culture and light and electron microscopy. With lysed neutrophils, the numbers of colony-forming units of CEMO and E coli increased in seminal plasma and uterine flushings. Numbers of CEMO decreased in HBSS. The numbers of CEMO increased more in the presence of seminal plasma than the other media. When neutrophils were in the ...
Ellis WA, O'Brien JJ, Cassells JA, Montgomery J.Thirteen strains of pathogenic leptospires were isolated from 12 of 91 horses; seven strains belonged to the Australis serogroup (serotype bratislava) with three, two and one strains belonging to the Icterohaemorrhagiae, Hebdomadis (serotype hardjo) and Autumnalis serogroups respectively. Using leptospires isolated from horses and others representing the known parasitic Leptospira serogroups, a sample of 650 mares' sera was tested for agglutinating antibodies. Antibodies were found in 89.1 per cent of sera. The predominant reaction was to serotype bratislava, strain S/1334/79, isolated in this...
Sabine M, Feilen C, Herbert L, Jones RF, Lomas SW, Love DN, Wild J.Until 1977 no case of abortion caused by equine herpesvirus 1 (EHV1) had been recorded in Australia although the virus, called equine rhinopneumonitis virus, had been known to have been present at least since 1962. Outbreaks of EHV1 abortion occurred in New South Wales in 1977 and in 1981. Sporadic cases of EHV1 abortion had been confirmed in some parts of Australia each year since 1975. It was concluded that an abortigenic subtype of EHV1 had been introduced to Australia in 1977 and that the previously endemic respiratory subtype occasionally caused abortion. Virus isolation in a variety of c...
De Vroey C, Wuytack-Raes C, Fossoul F.Several M. praecox isolates of saprophytic origin were obtained in Belgium from horses and their surroundings. Visualization of macroconidia in dust collected in stables proved its saprophytic origin. A few strains were obtained from human cases of tinea corporis.
Collins P.In vitro sensitivity data suggest that acyclovir should be effective against clinical manifestations of herpes simplex virus types 1 and 2, varicella-zoster virus and possibly Epstein-Barr virus. The clinical potential against herpes simplex virus types 1 and 2 is further supported by results in animal models. Human cytomegalovirus and the veterinary herpes viruses, with the possible exception of equine herpes virus type 1, may be insufficiently sensitive to be amenable to treatment.
Emmons RW, Woodie JD, Laub RL, Oshiro LS.Main Drain virus, which is thought to be transmitted normally among rabbits and various rodents by its natural vector, Culicoides variipennis, was isolated repeatedly from brain tissue of a sick horse from Sacramento County, California, and was implicated as the causative agent. Signs of illness were incoordination and ataxia, stiff neck, head pressing, inability to swallow, fever, and tachycardia.
Calisher CH, Emerson JK, Muth DJ, Lazuick JS, Monath TP.Sera from horses and human beings with clinically diagnosed western equine encephalitis (WEE) virus infections were tested for hemagglutination-inhibition (HI), complement-fixation (CF), and neutralizing (N) antibody to WEE virus. These tests confirmed infection in 43.8% (HI), 56.3% (CF), and 80.4% (N) of horses and 54.5% (HI), 59.1% (CF), and 77.3% (N) of human beings. Use of the N test as an adjunct to the HI and CF tests increased the likelihood of serologic confirmation to 91.7%. In both horses and human beings, N antibody increased steeply at the end of the 1st week after onset. The resul...
Toro M, León E, López R, Pallota F, Garcia JA, Ruíz A.Assays dealing with the therapeutic and prophylactic activity of isometamidium on experimental infections by Trypanosoma vivax and T. evansi were carried out. The drug was found to be highly effective against T. vivax infection in sheep and cattle in which periods of protection ranging from 118 to 195 days were achieved. No complete effects against infection by T. evansi were observed. The drug was well tolerated in sheep and cattle while side-effects were noted in treated mares. It was concluded that isometamidium could be used to prevent damage and economical losses caused by T. vivax in Ven...
Morris DD, Whitlock RH, Palmer JE.Fecal samples from 74 horses with diarrhea were examined microscopically for leukocytes and epithelial cells. The diarrhea was categorized as either acute (less than two weeks) or chronic, Salmonella positive or negative, and mild or severe (based on the fecal consistency). A large number of fecal leukocytes was strongly suggestive of salmonellosis; however, approximately 1/3 of the horses with Salmonella-negative diarrhea also shed fecal leukocytes. Fecal leukocytes were more common in horses with acute and/or severe diarrhea regardless of cause. Numbers of fecal colonic mucosal epithelial ce...
Conner ME, Gillespie JH, Schiff EI, Frey MS.A total of 142 equine fecal samples (93 field fecal and 49 experimental fecal specimens) were examined for rotavirus using direct electron microscopy (EM) and the Rotazyme test. Eighty-six stool specimens were diarrhea samples. The Rotazyme test sensitivity and accuracy as compared to EM was determined by the visual (color reaction) and spectrophotometric methods. The overall agreement was 94.8% and 92.3% between EM and Rotazyme visual and spectrophotometric methods, respectively when suspect reactions (1 + color reaction or net absorbance between 0.05 and 0.1) were not included. The Rotazyme ...
Lynch JA.A Staphylococcus aureus infection in a mature horse, resulting from trauma, is described, which proved refractory to antibiotic therapy directed by the results of antibiotic sensitivity testing. After a prolonged course, rapid resolution of the infection was achieved with the administration of an autogenous formalized bacterin.
Silver IA, Brown PN, Goodship AE, Lanyon LE, McCullagh KG, Perry GC, Williams IF.This project was carried out over a five year period (1977 to 1981 inclusive) at the University of Bristol following discussion between the British Veterinary Association and the Royal College of Veterinary Surgeons about the efficacy of, and ethical justification for, the practice of 'firing' (cautery). These discussions had been promoted by parliamentary questions but led to no firm conclusions because previously reported clinical investigations on specific treatments lacked adequate comparisons and controls and thus did not provide scientifically acceptable, statistically valid data. The pr...
Hoff GL, Bigler WJ, Buff EE, Beck E.Research and surveillance programs relating to the occurrence and distribution of western equine encephalomyelitis virus in Florida, conducted between 1955 and 1976, suggest that the virus is (1) an endemic arbordae, (2) transmitted in a continuous cycle throughout the year by Culiseta melanura mosquitoes, and (3) restricted to fresh water swamps and waterways in central, north, and northwest Florida.
Boyle AG, O'Shea K, Stefanovski D, Rankin SC.There is debate around the clinical significance of Streptococcus equi subsp. equi detection in low numbers using quantitative real-time PCR (qPCR). Propidium monoazide (PMA) qPCR has been used to differentiate DNA from viable and nonviable bacterial cells. The aim of this study was to evaluate the ability of PMA eqbE SEQ2190 triplex qPCR to differentiate DNA from viable and nonviable S. equi in positive and suspect positive clinical specimens. Fifty-seven stored (frozen and refrigerated) positive (36) or suspect positive (21) clinical specimens (determined via SeeI qPCR as the gold standard) ...
Shen DT, Gorham JR, Jones RH, Crawford TB.Laboratory-colonized mosquitoes, Culex tarsalis, aedes aegypti, Culiseta inornata, and Anopheles free-borni, and the biting gnat, Culicoides variipennis, were exposed to equine infectious anemia virus. Exposure to the virus was by intrathoracic inoculation for mosquitoes and by oral ingestion of an infective blood meal through a membrane for C variipennis. After various intervals, groups of 15 to 20 insects were homogenized and inoculated into susceptible ponies. Positive immunodiffusion test results were used as criterion for equine infectious anemia infection in ponies. Virus was not detecte...
Ordonez JV, Scherer WF, Dickerman RW.During the wet seasons of 1972 and possibly 1971, sentinel horses became infected by Venezuelan encephalitis (VE) virus in a temporally and geographically progressive manner inland from an enzootic marsh focus of virus on the Pacific couast of southeastern Guatemala. During the wet seasons of 1972 and 1973, VE virus was detected by sentinel horses (and a sentinel hamster in 1972) in a small woods 10 km north of the marsh, but virus was undetectable there during the dry seasons of 1973 and 1974 and the wet season of 1974. Culex (Melanoconion) mosquitoes were found in this woods and at the marsh...
McCool CJ, Gilfedder J.This study explores a rare case where an equine disease was found to be caused by Salmonella anatum, an organism typically associated with cattle, in a week-old foal and its […]
Heinrich B.This research article corrects a common misconception about the energy metabolism in horses during short sprinting and long-distance running events, emphasizing that short sprints are primarily powered by anaerobic activity, […]
Coggins L, Auchnie JA.Equine infectious anemia (EIA) has been enzootic in Hong Kong since the end of World War II. In 1972, a serologic survey of the horses at the Hong Kong Jockey Club indicated 23% prevalence of EIA. Disease control measures were instituted, and the spread of infection was reduced. In 1976, the prevalence of EIA was believed to be sufficiently low to implement procedures for eradication of EIA from all horses in Hong Kong. A correlation between EIA and poor performance of racehorses was demonstrated.