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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.
Analysis of serotypes and electropherotypes of equine rotaviruses isolated in the United States. Equine group A rotaviruses isolated over a 10-year period in New York State, New Jersey, Kentucky, and Texas were compared serotypically and electropherotypically. All isolates were determined to be serotype 3 by reaction with hyperimmune antiserum to the serotype 3 H-2 strain of equine rotavirus. All displayed RNA electrophoretic migration patterns related to that of the H-2 strain but distinct from that of serotype 5 strain H-1. A serologic survey of 184 mares in Kentucky, which was done to determine the incidence of H-1 and H-2 infections, showed geometric mean serum neutralizing titers to ...
Amplification and differentiation of the DNA of an abortigenic (type 1) and a respiratory (type 4) strain of equine herpesvirus by the polymerase chain reaction. Unpurified DNA derived from cultures of equine fetal kidney cells infected with either equine herpesvirus type 1 or equine herpesvirus type 4 was amplified by the polymerase chain reaction using one pair of oligonucleotide primers. Restriction endonuclease digestion of the amplified segments with PvuII, followed by electrophoresis, revealed restriction fragment length polymorphisms which enabled the two virus types to be differentiated.
Aerobic bacterial isolates in horses in a university hospital, 1986-1988. Bacterial isolations were reviewed from equine trachea, guttural pouch, uterus, wounds, abscesses, blood, synovial fluid, and abdominal fluid submitted to the Clinical Bacteriology Laboratory of the School of Veterinary Medicine at the University of Montreal for aerobic bacterial culture from 1986 to 1988. Of the 733 samples submitted, 324 (44%) were positive for bacterial growth, and 233 antimicrobial sensitivity tests were performed. Seventy-six percent of all positive samples yielded one bacterial species and two were isolated from 22% of positive samples. Streptococcus zooepidemicus, Esche...
Serological and genomic characterization of L338, a novel equine group A rotavirus G serotype. A group A rotavirus designated L338 was isolated from the faeces of a diarrhoeic foal and was compared to 11 standard G serotype strains of group A rotaviruses by cross-neutralization. It was clearly distinct from serotypes G1 to G11 and thus representative of a novel rotavirus G serotype tentatively designated G13. The nucleic acid sequence of the virion protein 7 (VP7) coding region was determined and the deduced amino acid sequence compared to published sequences. Within VP7 regions A and B, L338 was clearly distinct from serotypes G1 to G12 (excluding G7 which has not been sequenced), but ...
The role of endothelial cell infection in the endometrium, placenta and foetus of equid herpesvirus 1 (EHV-1) abortions. One of three mares in the last trimester of pregnancy became paraplegic 7 days after experimental infection with EHV-1 and was killed 10 days after infection (d.p.i.). The other two mares aborted foetuses at 12 and 14 d.p.i. In the first mare, virus was detected by immunofluorescence (IIF) and immunoperoxidase (IP) staining in endothelial cells of the endometrium, placenta and umbilical vein, but not in any other foetal tissues. In the experimentally aborted foetuses, and in two other independent field cases of abortions, endothelial cell infection was also detected in the foetuses, both in ma...
Relations among synovial membrane histopathologic findings, synovial fluid cytologic findings, and bacterial culture results in horses with suspected infectious arthritis: 64 cases (1979-1987). A retrospective evaluation of 64 cases of suspected infectious arthritis in horses was undertaken to determine the relations among histopathologic findings in synovial membrane specimens, cytologic findings in synovial fluid samples, and bacterial culture results. Positive cultures were obtained from 55% of the joints, and 18 different bacterial organisms were cultured. Culturing of synovial fluid yielded bacterial growth more often than did culturing of synovial membrane. Histologic evaluation (H&E and Gram stain) of synovial membrane specimens provided little information to help distingu...
[The differentiation of viruses in the Venezuelan equine encephalomyelitis complex by using monoclonal antibodies and lanthanide immunofluorescence analysis]. Potentialities of differentiation between Venezuelan equine encephalomyelitis (VEE) complex viruses by time-resolved fluoroimmunoassay and enzyme immunoassay were studied. For this, 4 test systems were used based on different combinations of native and labeled polyclonal antibodies to VEE virus, strain Trinidad, and monoclonal (MCA) antibody MAK 14-7 to protein EL of this virus. The maximal sensitivity and specificity was achieved in the test system formed from native MCA MAK 14-7 for sensitization of the solid phase and labeled polyclonal immunoglobulins for demonstration of the test results....
Pleuropneumonia. The historical, clinical, diagnostic, and therapeutic aspects of pleuropneumonia are reviewed with emphasis placed on aggressive treatment and ultrasound diagnosis. The common sequelae are described, and appropriate treatment recommendations are included. A favorable prognosis may be expected for horses receiving long-term treatment.
Diagnosis and prevalence of leptospira infection in aborted and stillborn horses. A study was conducted to evaluate a recently available fluorescent antibody test (FAT) conjugate for the detection of leptospires in tissues of aborted and stillborn horses, to determine the leptospira antibody titers and compare serologic test results with FAT results, and to determine the prevalence of leptospira-induced abortions and stillbirths in the equine population of central Kentucky. From July 1, 1988 through June 30, 1989, 15 (2.5%) of 594 submissions (fetuses, stillborn foals, and/or placentas) were diagnosed as leptospirosis by the FAT (14 of 15 tested) and/or microscopic agglutin...
Verminous mastitis in a mare caused by a free-living nematode. Verminous mastitis was the reason for euthanasia of a 22-yr-old Paso Fino mare from Miami, Florida. The etiologic agent was a species of Cephalobus (Rhabditida: Cephalobidae), a genus of soil-inhabiting nematodes that were obviously multiplying in the mammary gland. Only females and larvae were detected in the tissues by histologic section or by teasing the tissue to liberate the worms. At least 12,900 individuals were present per gram of tissue. This is the first case of Cephalobus infecting horses and it indicates that not all histiotropic infections of horses by rhabditoid nematodes are by ...
Bacterial pneumonia. Bacterial pneumonia in the horse often occurs secondary to viral respiratory infection; however, primary infections can occur. A diagnosis of bacterial pneumonia is made on the basis of history, physical examination, and laboratory and radiographic findings. Treatment consists of appropriate antimicrobial therapy for at least 7 to 10 days; further therapy may be needed in more severe cases. Prevention of bacterial pneumonia includes attempting to prevent viral respiratory infections and appropriate management to prevent stress to the respiratory tract.
[Chlamydia as the cause of abortions in horses]. Between 1982 and 1989 59 equine fetuses were investigated for chlamydiae using animal experiments and embryonated eggs. Chlamydiae were isolated from 16 fetuses (27.1%) originating from 8 studs. The macroscopical lesions of the fetal organs were characterized by extensive haemorrhages. The histological picture shows severe lesions of the blood vessels of different organs. In 6 studs in which chlamydiae had been isolated, blood sera of clinically healthy and pregnant mares were investigated for antibodies during 1989 and 1990. Antibody titres between 1:10++ and 1:40 were detected by using compl...
Aetiologic study on an influenza-like epidemic in horses in China. About thirty thousands horses were affected and hundreds of them died in an epidemic caused by equine 2 influenza virus (H3N8) in China. The estimated morbidity and mortality accounted for 81% and 2%, respectively. The viral protein and RNA electrophoresis patterns revealed that the new isolates were antigenically different from the prototype strain influenza A/eq/Miami/1/63(H3N8). Therefore, the representative strain of the equine 2 subtype of influenza A virus recommended for producing reference reagents, vaccines, and for serological diagnosis must have been altered by antigenic drift.
Field evaluation of a commercial M-protein vaccine against Streptococcus equi infection in foals. A double-blind randomized clinical trial was undertaken to determine the value of parenterally administered Streptococcus equi M-protein vaccine in foals during an epizootic of strangles. Weaned mixed-breed foals (n = 664) housed on 2 adjacent feed-lots (A and B) arrived over a 5-day period, 2 weeks before primary vaccination. Foals in lot B (n = 114) were randomly administered vaccine (n = 59) or saline solution (placebo; n = 55) on 3 occasions at biweekly intervals. Foals in lot A (n = 450) were given 1 dose of vaccine (n = 225) or placebo. The following clinical observations were scored bli...
Corynebacterium pseudotuberculosis: in vitro susceptibility to 39 antimicrobial agents. The minimal inhibitory concentrations of 39 antimicrobial agents for 54 isolates of Corynebacterium pseudotuberculosis in vitro have been determined. The most active agents were penicillins, macrolides, tetracyclines, cephalosporins, lincomycin, chloramphenicol, and rifampicin. Most isolates were resistant to aminoglycosides, nitrofurans, polymyxins, nalidixic acid, and cycloheximide.
Equine infectious anemia virus and human immunodeficiency virus DNA synthesis in vitro: characterization of the endogenous reverse transcriptase reaction. The endogenous reverse transcriptase reaction of equine infectious anemia virus (EIAV) has been studied, and conditions allowing synthesis of full-length minus-strand DNA have been determined. In contrast to results reported for other retroviruses, synthesis of EIAV full-length minus-strand DNA was not impaired by high concentrations of Nonidet P-40, a nonionic detergent used to make the virion envelope permeable. All components of the reaction were titrated for maximum synthesis of complete minus strands, and a time course under the standardized conditions was determined. Minor subgenomic ban...
Antibodies in horses, mules and donkeys following monovalent vaccination against African horse sickness. A total of 256 sera collected from three species of domesticated equidae in four different Spanish provinces were examined 1-4 months after the administration of attenuated monovalent African horse sickness virus (AHSV) serotype 4 vaccine. Approximately 10% of the sera were negative by ELISA, virus neutralization, agar gel immuno-diffusion and complement fixation tests. Similar negative reactions were recorded with sera from two ponies after experimental primary vaccination. The rapid rise in antibodies in sera from these two ponies, after a second dose of vaccine, suggested they would probabl...
An assessment of the biological capacity of a Sacramento Valley population of Aedes melanimon to vector arboviruses. Daily survivorship, duration of the gonotrophic cycle, absolute abundance and season-long relative abundance were estimated for Aedes melanimon in the Sacramento Valley of California in 1987 and 1988 using mark-release-recapture (MRR) techniques and by monitoring changes in the abundance and parity rate of the native population. One objective of these studies was to determine the extent to which A. melanimon was biologically capable of serving as a horizontal arbovirus vector. Daily survivorship was estimated to be 0.90 and 0.84 in MRR studies conducted in September 1987 and August 1988, 0.89 ...
An outbreak of Equid herpesvirus abortion in New South Wales. Thirty-three of the 44 mares on a Thoroughbred stud in New South Wales aborted or lost foals within one day of birth. Gross pathological and histological changes were in keeping with Equid herpesvirus I (EHV-1) abortion. In the six foals that underwent virological examination, EHV was isolated and typed as EHV-1 by restriction endonuclease analysis. EHV-1 abortion had not occurred previously on this stud and the source of the infection was not identified.
Muscle disorders in the horse: a retrospective study. Case records of horses with muscle disorders presenting to the Veterinary Medical Teaching Hospital of the University of California, Davis, over a nine year period were evaluated. The objectives of the review were to identify the common myogenic muscle problems and their clinical features. Muscle disease of idiopathic aetiology following exercise was by far the most common condition noted. Other causes of myogenic muscle disorders included congenital, infectious, immune-mediated and nutritional factors.
Equine herpesvirus 1 sequence near the left terminus codes for two open reading frames. We have previously reported the sequence of the equine herpesvirus one genomic termini that are homologous to the genomic termini of other herpesviruses. In this paper, we present the nucleotide sequence adjacent to the left terminus sequence (map units 0.0087 to 0.0237). This sequence codes for two open reading frames (ORF) which are homologous to ORF2 and ORF3 of the varicella-zoster virus genome and are located at colinear positions. The L region sequence presented here also contains a segment that is involved in the generation of the genome of EHV-1 DI particles through recombination with ...
Aerobic and anaerobic bacterial isolates from horses with pneumonia or pleuropneumonia and antimicrobial susceptibility patterns of the aerobes. Frequency of aerobic and anaerobic isolates in 327 aspirates and in 123 pleural fluid samples from 327 horses with pneumonia or pleuropneumonia and antimicrobial susceptibility patterns of the aerobes were reported. Of the 327 horses, 75% survived, 20% were euthanatized, and 5% died. Tracheobronchial aspirates or pleural fluid specimens from 25 of the horses did not yield growth. Of the remaining 302 horses, 221 had only aerobic organisms isolated, whereas only anaerobes were isolated from 6 of the 302 horses. The remaining 75 horses had mixed aerobic and anaerobic bacterial infections. The su...
Identification of 15- to 17-kilodalton antigens associated with virulent Rhodococcus equi. Antigens of Rhodococcus equi were analyzed by immunoblotting with naturally infected foal sera. Immunoblots of whole-cell antigen preparations of clinical isolates of R. equi revealed that major protein bands with molecular masses of 15 to 17 kDa were present in all clinical isolates tested and all isolates virulent for mice. In contrast, the 15- to 17-kDa antigens were not identified by immunoblotting in ATCC 6939, a type strain of R. equi that was avirulent for mice. Whole-cell antigens of 102 environmental isolates were investigated by immunoblotting and the mouse pathogenicity test. Twenty...
Trypanosoma evansi infection in cattle, buffaloes and horses in Indonesia. Cattle, buffaloes and horses in several areas of Indonesia were examined for evidence of infection with Trypanosoma evansi by the microhaematocrit centrifugation technique (MHCT) and an enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to T. evansi. Evidence of infection was found in animals at each sampling site although differences were seen in prevalence rates between sites. Prevalence rates in buffalo were usually higher than in cattle in the same area while in horses they were much lower than in cattle or buffalo. An age-dependent prevalence rate was seen in buffalo an...
