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Topic:Infectious Disease
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.
Vancomycin kinetics in plasma and synovial fluid following intravenous administration in horses. Vancomycin hydrochloride was infused intravenously (i.v.) over a 30-min period in five horses at doses of 6.6, 11.0 and 15.4 mg/kg. Vancomycin concentration in plasma and synovial fluid samples was measured using a polarization immunoassay. A pharmacokinetic model was developed to accommodate the special features of the present study. The data were described by a two compartment open model with synovial fluid as an additional compartment in exchange with plasma. Minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) were measured for Staphylococcus aureus and Enteroco...
Antibody to a recombinant merozoite protein epitope identifies horses infected with Babesia equi. Horses infected with Babesia equi were previously identified by the presence of antibodies reactive with a merozoite surface protein epitope (D. P. Knowles, Jr., L. E. Perryman, L. S. Kappmeyer, and S. G. Hennager. J. Clin. Microbiol. 29:2056-2058, 1991). The antibodies were detected in a competitive inhibition enzyme-linked immunosorbent assay (CI ELISA) by using monoclonal antibody 36/133.97, which defines a protein epitope on the merozoite surface. The gene encoding this B. equi merozoite epitope was cloned and expressed in Escherichia coli. The recombinant merozoite protein, designated equ...
Equine ulcerative keratitis. Ulcerative keratitis is one of the most common vision-threatening diseases of the horse. Successful therapy, however, can be achieved in the majority of cases provided the diagnosis is made early and the treatment is specific for the disease. This article reviews the pathophysiology, clinical signs, and contemporary medical and surgical approaches to bacterial and fungal ulcerative keratitis in the horse.
Equine uveitis. Uveitis (inflammation of the iris, ciliary body, or choroid) is a potentially blinding condition with a significant economic impact on the horse industry. Variable symptoms are described, as well as a considerable range of structural and functional sequelae. Known causes of initial episodes include bacterial, viral, traumatic, and parasitic insults, with recurrence by immunologic mechanisms. Treatment strategies and management recommendations that may reduce the incidence or severity of episodes are discussed.
Molecular evidence for the origin of the widespread Venezuelan equine encephalitis epizootic of 1969 to 1972. Venezuelan equine encephalitis (VEE) virus is a mosquito-borne pathogen that has caused encephalitis in equine species and humans during sporadic outbreaks in the western hemisphere. The last, and most widespread, VEE outbreak occurred in South America, Central America, Mexico and the U.S.A. (Texas) during 1969 to 1972. We have cloned and sequenced the genome of a virulent VEE subtype I-AB virus, strain 71-180, isolated in Texas in 1971. Thirty-four nucleotide differences were detected between the genome of 71-180 virus and that of the subtype I-AB Trinidad donkey (TRD) virus isolated during t...
[Trichomonad infections of the oral cavity in horses in southern Germany]. 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...
Effect of treatment with oxytetracycline during the acute stages of experimentally induced equine ehrlichial colitis in ponies. Eighteen ponies were inoculated IV with Ehrlichia risticii-infected P388D1 mouse monocyte cells. Twenty-four hours after onset of fever (rectal temperature > 38.8 C), 9 ponies were treated with oxytetracycline (6.6 mg/kg of body weight, IV, q 24 h) for 5 days. The remaining 9 ponies served as infected nontreated controls. Mean scores of the following variables were not significantly different between groups on the day treatment was begun: rectal temperature, diarrhea, borborygmal sounds, feed intake, mental attitude, and evidence of a hyperresonant area in the abdomen. All ponies were obser...
Cryptococcal pneumonia and abortion in an equine fetus. Cryptococcus neoformans was the causative agent of pneumonia in a 9-month-old equine fetus aborted by a healthy American Paint mare. Endometritis was diagnosed on biopsy, and vaginal specimens obtained for culture were Cryptococcus-positive 1 month following abortion but not 5 months after abortion. Infection resolved without treatment between 1 and 5 months after abortion, and the mare was bred the following year and delivered a live premature foal without evidence of Cryptococcus infection.
Extended x-ray absorption fine structure studies of a retrovirus: equine infectious anemia virus cysteine arrays are coordinated to zinc. Zinc finger arrays have been established as a critical structural feature of proteins involved in DNA recognition. Retroviral nucleocapsid proteins, which are involved in the binding of viral RNA, contain conserved cysteine-rich arrays that have been suggested to coordinate zinc. We provide metalloprotein structural data from an intact virus preparation that validate this hypothesis. Extended x-ray absorption fine structure (EXAFS) spectroscopy of well-characterized and active preparations of equine infectious anemia virus, compared with a peptide with known coordination and in combination wit...
Renal dysfunction associated with infection of Leptospira interrogans in a horse. Renal failure associated with infection of Leptospira interrogans was detected in a horse. Fever, leukocytosis, pyuria, isosthenuria, and azotemia were suggestive of an inflammatory urinary tract disease. Despite persistent pyuria, no bacteria were found during routine microscopic examinations or bacteriologic culturing of urine. A fluorescent antibody examination of the urine was positive for L interrogans. Serologic testing during a 6-month period, supported an acute infection with L interrogans serovar pomona. Treatment with intravenously administered fluids and antimicrobials resulted in c...
Immunoblot analysis of the humoral immune response to Pythium insidiosum in horses with pythiosis. Reactions to Pythium insidiosum by sera from horses with active pythiosis were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Five strains of P. insidiosum were grown in nutrient broth and then sonicated. After centrifugation, supernatant antigens were separated by SDS-PAGE. An exoantigen of Conidiobolus coronatus was also tested. Bands with molecular weights between 97,000 and 14,000 were identified by Coomassie blue and silver staining. After being transferred to nitrocellulose, the antigens were reacted against sera from six horses w...
Structural proteins of equine arteritis virus. We have recently shown that the genome of equine arteritis virus (EAV) contains seven open reading frames (ORFs). We now present data on the structural proteins of EAV and the assignment of their respective genes. Virions are composed of a 14-kDa nucleocapsid protein (N) and three membrane proteins designated M, GS, and GL. M is an unglycosylated protein of 16 kDa, and GS and GL are N-glycosylated proteins of 25 and 30 to 42 kDa, respectively. The broad size distribution of GL results from heterogeneous N-acetyllactosamine addition since it is susceptible to digestion by endo-beta-galactosidas...
Equine herpesvirus 5: comparisons with EHV2 (equine cytomegalovirus), cloning, and mapping of a new equine herpesvirus with a novel genome structure. A new equine herpesvirus, provisionally designated equine herpesvirus 5 (EHV5; Browning and Studdert (1987) J. Gen. Virol. 68, 1441-1447), was examined for the degree of genomic difference from equine herpesvirus 2 (EHV2) by Southern hybridizations. EHV5 and EHV2 whole genomic DNA probes were highly specific for homologous DNA only, indicating that significant genomic difference exists between the two viruses. Restriction endonuclease analysis of EHV5 strain 2-141 (EHV5.2-141) revealed that the genome is 179 kb and exists as a single isomer. Clones representing 82% of the genome were obtained ...
Phylogenetic analysis of alphaviruses in the Venezuelan equine encephalitis complex and identification of the source of epizootic viruses. We studied the evolution of alphaviruses in the Venezuelan equine encephalitis (VEE) complex using phylogenetic analysis of RNA nucleotide sequences from limited portions of the nsP4, E1, and 3' untranslated genome regions of representative strains. The VEE complex constituted a monophyletic group of viruses (descended from a common ancestor); some serologic VEE varieties such as subtype III formed monophyletic groups while subtype I did not. Subtype II Everglades and variety ID enzootic viruses formed a monophyletic group which also included all epizootic variety IAB and IC VEE isolates. Ever...
Animal immunodeficiency viruses. Feline immunodeficiency virus (FIV) has morphological, physical and biochemical characteristics similar to human immunodeficiency virus (HIV), the cause of AIDS in man. However, it is antigenically and genetically distinct from HIV; an antigenic relatedness with equine infectious anaemia virus has been demonstrated. FIV has been molecularly cloned and sequenced. Diagnostic tests are commercially available and attempts at preparing inactivated, subunit and molecularly engineered vaccines are being made in different laboratories. During FIV infection a transient primary illness can be recognized...
Cross-reactivity of existing equine influenza vaccines with a new strain of equine influenza virus from China. A novel strain of equine influenza virus, influenza A/equine/Jilin (China)/1/89, has emerged which is genetically distinct from all earlier strains of equine influenza. It is therefore possible that the vaccines against equine influenza may be unable to protect horses against disease caused by this virus strain. In vitro serological assays established that there were low levels of immunological cross-reactivity between the new virus, the current vaccine strains and the strains of equine-2 influenza virus now in circulation.
Equine protozoal myelitis in Panamanian horses and isolation of Sarcocystis neurona. Schizonts of Sarcocystis neurona were identified microscopically in hematoxylin-eosin-stained spinal cord sections from 2 native Panamanian horses that exhibited clinical signs of equine protozoal myelitis (EPM). Spinal cord homogenate from a third Panamanian horse with EPM was inoculated onto monolayers of cultured bovine monocytes (M617). Intracytoplasmic schizonts containing merozoites arranged in rosette forms surrounding a central residual body first were observed 13 wk postinoculation. Parasites divided by endopolygeny and lacked rhoptries. Schizonts from each horse reacted with Sarcocys...
Measurement of the cytotoxic effects of different strains of Mycoplasma equigenitalium on the equine uterine tube using a calmodulin assay. The cytopathic effects induced by five strains of Mycoplasma equigenitalium for cells of equine uterine tube explants were tested by measuring changes in cellular and extracellular concentrations of calmodulin (CaM). Calmodulin concentrations in samples of total homogenate (TH) and total homogenate supernates (THS) of the infected equine uterine tube explants were significantly lower than respective measurements on noninfected controls. In tissue culture medium fractions (TCM) of some infected explants, CaM concentrations were significantly higher than noninfected controls (p > 0.95). The r...
Seroprevalence of antibodies to Borrelia burgdorferi in a population of horses in central Texas. Four hundred sixty-nine serum samples were obtained from horses admitted to the internal medicine service of the Texas Veterinary Medical Center between Jan 1 and Dec 31, 1990. Serum samples were tested by ELISA for antibody to Borrelia burgdorferi. Of these 469 samples, 1 (0.2%) was repeatedly seropositive for the organism by ELISA. Confirmatory testing by protein immunoblot was negative. The observed seroprevalence was 0%; the upper bound of the 95% confidence interval was 0.6%. These findings indicate the evidence of infection with B burgdorferi is presently uncommon in horses in central Te...
Serological responses of specific pathogen-free foals to equine herpesvirus-1: primary and secondary infection, and reactivation. Serum antibody (virus neutralisation, complement fixation, IgM and IgG) responses to equine herpesvirus-1 (EHV-1) infection were measured in six foals which were initially free from EHV-1 and EHV-4 infection and maternally-derived antibodies. Following primary infection, high titres of virus neutralisation and complement fixation antibodies were detectable against EHV-1, however, corresponding antibody levels against EHV-4 were low or inapparent, although the two viruses share a number of cross-reactive epitopes. In addition, following the primary infection with EHV-1, IgM levels increased bef...
Retrospective evaluation of factors associated with the risk of seropositivity to Ehrlichia risticii in horses in New York State. A retrospective study was designed to determine the distribution of equine monocytic ehrlichiosis among the equine population in New York state, and to identify factors associated with risk of disease. Serum samples submitted to the diagnostic laboratory of the university during the period from January 1985 through December 1986 were examined for antibodies to Ehrlichia risticii, using the indirect fluorescent antibody technique. Factors evaluated included geographic origin and date of submission of the sample, and age, breed, and sex of the horse. Logistic regression analysis was used to iden...
Serological evidence of equine herpesvirus type 1 (EHV-1) activity in polo horses in Nigeria. Serological evidence of Equine Herpes virus type 1 (EHV-1) activity in Polo horses in Nigeria is reported for the first time. Eighty-two percent of horses tested with known antigen had precipitating antibodies to EHV-1 while 43% of sera tested against antigen prepared from nasal discharges were positive suggesting that the virus was being excreted in the nasal discharges and probably acting as a source of infection for incontact animals as occurs in on-going acute infections. The result of this study indicates a high prevalence of EHV-1 activity among Polo horses in Nigeria and demonstrates th...
C3 fixed in vivo to cornea from horses inoculated with Leptospira interrogans. C3 was detected bound in vivo to the opaque cornea of horses inoculated with killed Leptospira interrogans. Employing epithelial corneal cells isolated from a monolayer in tissue culture, we proved that C3 is fixed in vitro to the intact cell surface after incubation with a fresh equine anti-Leptospira serum. These findings, in addition to the infiltration of cornea with neutrophils and lymphocytes, may explain the mechanisms of tissue damage in recurrent uveitis of horses with leptospirosis.
[Legionella antibodies in domestic animals]. Serological examination of 420 domestic animals for the presence of antilegionella antibodies indicates their high exposure to legionellae. On examination by the microagglutination reaction with a serum dilution of 1:64 or more the highest positive values were recorded in horses which reacted with antigens of L. pneumophila 1-14 in 36.2% and with antigens of another 19 types of legionellae in 47.8%. In pigs positive values recorded in 16.2% and in 21.1%; in cattle in 3.8% and 29.5%, in sheep in 7.5% and 11.3% and laboratory rabbits were quite negative. The importance of these findings with reg...
Acholeplasma multilocale sp. nov., isolated from a horse and a rabbit. Acholeplasma strains were isolated from the nasopharynx of a horse (strain PN525T [T = type strain]) and the feces of a rabbit (strain B1). One clone of strain PN525T and one clone of strain B1 were examined in detail. These clones were indistinguishable from each other and were serologically distinct from the previously described Acholeplasma and Mycoplasma spp. The strains had the following properties: guanine-plus-cytosine content of 31 mol%; sterol was not required for growth, which occurred under both aerobic and anaerobic conditions; glucose was metabolized; and arginine was hydrolyzed. ...
Sarcocystis neurona-associated ataxia in horses in Brazil. Sarcocystis neurona-like schizonts were found in sections of brain and spinal cord of two ataxic horses from Brazil. The diagnosis was supported by staining with anti-Sarcocystis serum in an immunohistochemical test. One of the affected horses was born in Argentina and raised in Brazil, and the other horse was born and raised in Brazil.
