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.
Barrett MW, Chalmers GA.To determine the exposure of free-ranging pronghorns (Antilocapra americana Ord) to selected pathogens, serum samples were obtained from 33 live-trapped animals from southwestern Saskatchewan in 1970, and from 26 and 51 animals from southeastern Alberta, in 1971 and 1972, respectively. Antibodies were found to the agents of parainfluenza 3, bovine virus diarrhea, eastern and western encephalomyelitis, infectious bovine rhinotracheitis and the chlamydial group. No serologic reactors were found to the agents of bluetongue, epizootic hemorrhagic disease, brucellosis, or leptospirosis (4 serotypes...
Dutta SK, Shipley WD.Foals (farms 1 and 2) and mares (farms 1 and 3) vaccinated with a commercially available rhinopneumonitis vaccine were tested for the level of antibodies and for protection against the natural infection. The serum-neutralization (SN) antibody titers against equine herpesvirus type 1 were 1:8 or less in the majority of foals and 1:16 or higher in about 10%. The level of the nasal secretory antibody in the foals (farm 2) was less than 1:4. The vaccinated foals did not show any apparent respiratory tract infection for about 6 months and then an epizootic of respiratory tract disease appeared on f...
Lutz JE, Boersema JH, Németh F.Biopsies of the skin of the umbilical area were taken from ninety-nine horses and one donkey, all reared in the Netherlands. The biopsy specimens were examined for the presence of microfilariae by a recovery procedure. Microfilariae were identified in eight horses. These were microfilariae of the species Onchocerca cervicalis in each case.
Villasmil DP, De Siger J, Barrientos MP, Mussgay M, Mackenzie RB.
Summary
Seven donkeys were immunized with a Venezuelan equine encephalitis virus vaccine which had been prepared by inactivation of the virus with formalin and Tween-80-Tri(n-butyl)phosphate and addition of saponin. Fourteen days later they, and four non-vaccinated controls, each received 50,000 suckling mouse intraperitoneal LD50 units of challenge virus. None of the seven immunized donkeys demonstrated signs of clinical illness or viremia. Of the four non-vaccinated controls, all became ill and one died. These results suggest that more extensive experiments might well be carried out on ...
Dutta SK.An adenovirus was isolated from a foal with respiratory tract disease. The virus produced cytopathic effects (CPE) in equine embryo kidney (EEK) cell culture, contained deoxyribonucleic acid (DNA), was resistant to chloroform and pH 3, and was moderately resistant to heat. The virus caused hemagglutination of human (type O) erythrocytes. Viral density was 1.34 g/cm,3 and diameter was 75 nm. An adenovirus-associated virus (AAV) isolated from the infected cell culture was 22 nm in diameter. These viruses are classified as equine adenovirus and equine AAV.
Azzie MA.Contrary to common belief, Gastrodiscus aegyptiacus can be pathogenic to horses. History of cases of a particular stud, necropsy findings, diagnosis, and successful treatment with hexachlorophene and with dichlorvos are recorded. The presence of eggs can be established by a special flotation technique.
Pedersen CE, Eddy GA.Polyacrylamide gel electrophoretic examination of viruses selected from the Venezuelan equine encephalomyelitis (VEE) complex revealed distinct strain to strain differences in profiles of the two virion envelope proteins. The core protein was identical in all viruses tested. We detected five electrophoretic patterns into which the virus strains could be classified and these were designated alpha (alpha), beta (beta), gamma (gamma), delta (delta), and episolon (episolon). Isolates representing variant E of subtype I exhibited a profile characterized by only one apparent envelope band. The epizo...
Mansmann RA.Little has been written about the use of antibiotics in the horse. This article is based on personal experiences related to equine clinical medicine and literature review and certainly does not represent all the possible therapeutic regimens that can he employed in the horse. There are two concepts that this article will emphasize. First and most importantly, when an infective process is suspected in a patient, cul-tures and sensitivities are the most important determinations to be made prior to antibiotic therapy. Whether in the treatment of a single case or in the treatment of a herd problem...
Moch RW, Ebner EE, Barsoum LS, Botros BA.Seven hundred and fifty-eight serum samples from domestic and wild animals in Ethiopia were tested for leptospiral antibodies by the microscopic agglutination test. The following percentages of seropositivity were obtained: horse (91.3 per cent), cow (70.7 per cent), pig (57.1 per cent), goat (47.3 per cent), sheep (43.4 per cent), camel (15.4 per cent), and dog (8.3 per cent). All 54 samples from birds and wild animals were seronegative. Most of the positive sera exhibited reaction to more than one serotype and antibodies to serotype butembo were predominant in sera of the majority of the exa...
Erickson GA, Maré CJ.Goat Venezuelan equine encephalomyelitis (VEE) antiserum and normal serum were conjugated and evaluated for staining sensitivity and specificity. Cross-staining with either eastern or western equine encephalomyelitis virus-infected cells did not occur. The baby hamster kidney (BHK-21) cell line when combined with highly specific VEE conjugate detected 100 medium suckling mouse intracerebral lethal doses (suckling mouse LD-50/IC) of the 1B subtype of VEE virus per milliliter of equine tissue suspension. Conjugated goat antiserum was assayed for sensitivity for detection of VEE virus-infected eq...
Harrington DD.Spontaneous Tyzzer's disease is described in quarter horse foals which died suddenly with no clinical history of apparent illness. Significant gross findings included icterus, focal paletan areas in the liver and catarrhal entercolitis. Focal dark red lesions were present in the small intestine of one foal, and the mesenteric lymph nodes of another were enlarged and hyperemic. Histopathologically, the liver showed multiple discrete and confluent foci of necrosis, fatty change, sinusoid congestion and haemorrhage. Bundles of intracytoplasmic bacilli were demonstrated in hepatocytes at the margi...
Lewis GE, Huxsoll DL, Ristic M, Johnson AJ.Dogs (German Shepherd Dogs and Beagles), cates, rhesus macaques (Macaca mulatta), and baboons (Papio anubis) were inoculated with Whrlichia equi, the etiologic agent of equine ehrlichiosis. Within 3 to 7 days after inoculation, morulae were observed in the eosinophils of cats, neurtrophils of macaques and baboons, and in both neutrophils and eosinophils of dogs. The severe disease produced in horses by this agent was not a feature of E equi infection in dogs, cats, macaques, and baboons. However, a susceptible horse, inoculated with the pooled blood of 2 infected macaques, developed severe cli...
Powell DG.During the past 20 years the equine population of Great Britain and Ireland has increased with the result that the practising veterinary surgeon is more frequently called upon to advise on equine problems. A significant portion of this advice is concerned with the examination of horses showing signs of this advice is concerned with the examination of horses showing signs of respiratory disease. Numerous pathogens, which include viruses, bacteria, parasites and moulds invade the respiratory tract causing similar signs of illness. It is therefore difficult to provide an aetiological diagnosis ba...
Levitt NH, Miller HV, Pedersen CE, Eddy GA.The development of a new diagnostic procedure for the identification of Venezvelan, eastern and western equine encephalomyelitis (VEE, EEE, WEE) viruses is described. The procedure utilizes virus precipitation with reference fluorescein-conjugated gamma globulin, followed by cellulose acetate electrophoresis. Clinical specimens containing varying concentrations of virus yielded, in primary duck embryo cell culture, sufficient virus for detection within 22 to 44 hours. Identification of VEE, EEE and WEE virus in specimens was accomplished by microprecipitation within this time. In contrast to c...
Fontaine M, Aymard-Henry M.From the Revised Nomenclature of WHO, the fowl influenza virus A/Duck/Ukraine/63 (Hav7 Neq2) has the same neuraminidase as the equine virus A/equi 2/Miami/63 (Heq2 Neq2); the A/Chicken Germany "N"/49 virus has the same neuraminidase as the equine virus A/equi 1/Prague/56. A comparative study of the antigenic specificities confirms that the Neq2 neuraminidases are closely connected, whatever their animal origin, and that the fowl strain Hav7 Neq2 can be used for the titration of anti Neq2 antibodies in the serums of animals immunized with the equine virus Heq2 Neq2. The Neqi neuraminidases of v...
Scherer WF, Madalengoitia J, Flores W, Acosta M.Two strains of eastern encephalitis (EE) virus were isolated in the Amazon region of Peru near Pucallpa, Loreto Department, using sentinel hamsters. EE virus antibodies were found in healthy horses at both Pucallpa and Iquitos in the same Department. Fourteen group C and four Guama group arboviruses were recovered from sentenel hamsters and mosquitoes near Iquitos. The group C agents were Caraparu-Ossa, Marituba, and Oriboca-Itaqui viruses, and the Guama group agents were Bimiti virus. Besides providing a detailed account of these investigations, this article includes a current list of known a...
Correa WM.Smears and imprints were made from the liver of 27 equine fetuses, believed to have aborted as a result of Equine Virus Abortion (EVA) infection. Several different fixatives and staining techniques were employed for the demonstration of typical intra-nuclear inclusion bodies in these preparations, and the following conclusions were reached. Methanol proved to be the best fixative and Pappenheim's panoptic method was the best staining technique, giving good contrast and definition of the inclusion bodies. Cytological methods provided a simple and rapid means of diagnosis, but histological secti...
Timoney PJ.The usefulness of the double immunodiffusion test for the diagnosis of louping ill infection was investigated. Whereas louping ill viral antigen was not detected in brain material from field cases of the infection, its presence was readily confirmed in suckling mouse brain isolates of the virus. The double immunodiffusion test was found to be unreliable as a serological test for the retrospective diagnosis of louping ill infection in the horse.
Whipp SC, Donta ST.Antibody titers to Escherichia coli heat-labile enterotoxin (LT) were measured in serum samples collected from mature cows, butcher pigs, mature sows and adult sheep, horses, dogs, cats, turkeys, and chickens. The frequency of LT antitoxin titers was greatest in sows (94%) and less in cows (38%). Titers were higher in swine than in cattle. There were no LT antitoxin titers in serums from sheep, horses, dogs, cats, turkeys, and chickens. It was concluded that LT-producing Escherichia coli are prevalent in the swine population, but much less so in cattle and the other species examined.
Gaschen L, LeRoux A, Trichel J, Riggs L, Bragulla HH, Rademacher N, Rodriguez D.The magnetic resonance (MR) imaging findings of foals with infectious and noninfectious arthritis are described. Six foals with infectious arthritis and three foals with noninfectious arthritis were grouped based on synovial fluid analysis results and examined with radiography and MR imaging. Four out of six foals with infectious arthritis had osseous lesions in MR images indicative of osteomyelitis and only 4/19 lesions were detected on digital radiographs. The three foals with noninfectious arthritis had no osseous lesions in MR images or radiographically. Of the six joints that had osseous ...
Webster WR.This section outlines the most important issues addressed in the management of the response in the two infected states, New South Wales and Queensland. There were differences in the management of the response between the states for logistic, geographic and organisation structural reasons. Issues included the use of control centres, information centres, the problems associated with the lack of trained staff to undertake all the roles, legislative issues, controls of horse movements, the availability of resources for adequate surveillance, the challenges of communication between disparate groups...
Etcheverrigaray ME, Oliva GA, Zabala Suárez JE.Twenty seven per cent of 238 serum samples obtained from horses with clinical diagnosis were positive for the immunodifusion test, while 17% of the 452 sera obtained from asintomatic horses were positive. Twenty one per cent of the 870 sera studied were positive.
Voermans M, Skidell J, Winberg F.Prestenotic oesophageal dilatation and stricture were diagnosed in a horse with a history of trauma in the cervical area and recurrent oesophageal obstruction. The diagnosis was established on the basis of the clinical examination, endoscopy, and positive contrast oesophagography. Conservative treatment was unsuccessful and surgical intervention was necessary. Oesophageal myectomy combined with myoplasty was performed, simultaneously relieving the dilatation and the stricture. No abnormalities were detected 8 weeks after surgery. The horse was on a normal diet and oesophageal obstruction did r...
Mansell SE, Behnke MC.The nematode Onchocerca cervicalis is the most common causative agent of equine onchocerciasis; this condition is characterised by pruritus and dermatitis and is a differential diagnosis for insect bite hypersensitivity. Onchocerciasis is currently presumed of minor importance within the UK, however prevalence may increase if macrocyclic lactone use declines amid concerns about anthelmintic resistance in gastrointestinal nematodes. This survey aimed to establish O. cervicalis awareness and knowledge levels amongst UK equine veterinarians and to determine approximate numbers of UK horses affect...
Schöl H, Beelitz P, Gothe R.Trichomonads of the oral cavity were found in 9 of 60 investigated horses. Apart from dental tartar, the oral cavity showed no clinical signs in all positive horses. The clinical investigation of these horses additionally revealed colic in 4 and coughing in 4 horses as well as lumbago in 1 animal. By means of scanning electron microscopy the trichomonads were shown to be round or piriform with an average length of 7.6 microns and greatest width of 6.3 microns. They had 4 anterior flagella with an average length of 8.3 microns, an undulating membrane measuring 8.7 microns with no trailing flage...