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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.
Passive transfer, rate of decay, and protein specificity of antibodies against equine arteritis virus in horses from a Standardbred herd with high seroprevalence. To determine rate of decay of passively acquired antibodies in Standardbred foals on a farm with a high seroprevalence to equine arteritis virus (EAV) and to determine whether vertical or horizontal transmission of the virus was responsible for infection on the farm. Methods: Repeated-measures study. Methods: 46 Standardbred horses (15 brood mares and their foals, 5 stallions, and 11 young horses). Methods: Serum samples obtained from horses on the farm were evaluated by serum neutralization and western immunoblot analysis to detect EAV-specific antibodies. The half-life of passively acquired ...
Experimental infection of the human granulocytic ehrlichiosis agent in horses. Human blood collected from two patients from Westchester County, New York with human granulocytic ehrlichia (HGE) infection was inoculated into two ponies. Inoculated ponies developed clinical signs similar to a previous report (Madigan et al., 1995). Histopathological changes involved follicular hyperplasia of lymphoid tissues. HGE DNA was detected by PCR in muscle, fascia, peritoneum, and adrenal gland after the ponies produced a high level of antibodies to HGE. We suggest that HGE may reside in poorly vascularized connective tissues, where the antibodies may have some difficulties to penetr...
The S2 gene of equine infectious anemia virus is dispensable for viral replication in vitro. Equine infectious anemia virus (EIAV) contains the simplest genome among lentiviruses in that it encodes only three putative regulatory genes (S1, S2, S3) in addition to the canonical gag, pol, and env genes, presumably reflecting its limited tropism to cells of monocyte/macrophage lineage. Tat and Rev functions have been assigned to S1 and S3, respectively, but the specific function for the S2 gene has yet to be determined. Thus, the function of S2 in virus replication in vitro was investigated by using an infectious molecular viral clone, EIAVUK. Various EIAVUK mutants lacking S2 were constr...
Herpesvirus myeloencephalopathy in horses: 11 cases (1982-1996). To determine results of CSF analysis in horses with equid herpesvirus myeloencephalopathy (EHM) and to determine whether results of CSF analysis were associated with outcome. Methods: Retrospective study. Methods: 11 horses. Methods: Medical records of all horses admitted to the veterinary teaching hospital between February 1982 and March 1996 in which EHM was diagnosed were reviewed. Results: 7 horses were < or = 4 years old; 8 were admitted during January, February, or March. Six horses were febrile prior to admission, but none was febrile on the day of admission. Five horses had been sta...
Rabies prophylaxis following the feeding of a rabid pony. A survey was performed to identify people who were exposed to a rabid pony and determine whether or not they received rabies postexposure prophylaxis (PEP). Sixty-one visitors who came in contact with the rabid pony were identified. These visitors heard about the rabid pony via the news media. Forty-five visitors were exposed during the 2 weeks before the pony died. Thirty-two of these 45 visitors received PEP. Thirty-one visitors had or may have had saliva contact to an open wound or mucosa and all 31 received PEP. Fourteen visitors had no saliva contact to a wound or mucosa and one received ...
Virological and molecular biological investigations into equine herpes virus type 2 (EHV-2) experimental infections. Two 18-month-old naturally reared ponies were used to investigate the pathogenicity of EHV-2. After dexamethasone treatment, pony 1 was inoculated intranasally with EHV-2 strain T16, which has been isolated from a foal with keratoconjunctivitis superficialis and pony 2 was similarly inoculated with strain LK4 which was originally isolated from a horse with upper respiratory tract disease. Following virus inoculation, pyrexia was not detected in either pony but both developed conjunctivitis, lymphadenopathy, and coughing. EHV-2 was detected in nasal mucus samples up to day 12 post infection (p....
Babesia equi field isolates cultured from horse blood using a microcentrifuge method. Babesia equi, a causative agent of equine piroplasmosis, was isolated from horses in the Chaco Province of Argentina, a known piroplasmosis endemic region. Fifteen B. equi field isolates were acquired by culture from 23 actively working horses from 2 ranches. The horses appeared healthy with no clinical signs or histories indicative of equine piroplasmosis. All 23 horses had B. equi-specific antibody activity by the indirect fluorescent antibody test and 18 were also complement fixation test positive for B. equi. Equine erythrocytes were prepared for parasite culture using a microcentrifuge tu...
[Fundamentals of hygiene to be used for stallions in an instrumental artificial insemination]. Equine artificial insemination (AI) meanwhile has been widely established in the warm blood horse industry. Because of its importance consistent hygienic aspects and their significance for the use of stallions as semen donors in AI-programs are presented and clarified. Incidence as well as importance of equine venereal infectious diseases are considered. Data of physiological bacterial genital flora and treatment principles of therapeutic control of venereal infectious bacterial agents as well as a model of control of Equine Viral Arteritis are given. A prophylactic hygiene program for donor s...
A questionnaire survey on nematode control practices on horse farms in Denmark and the existence of risk factors for the development of anthelmintic resistance. A questionnaire survey to obtain information on endoparasite control practices and management on 68 Danish horse farms was undertaken in 1995. The study revealed that foals, young horses and adults were on average, annually treated 4.3, 4.0 and 3.7 times, respectively. The most commonly used drug from 1993-1995 was ivermectin. On average 2.4 different drugs were used annually. The most used method of weight estimation was eye measure: for foals by 78%, for youngsters by 81% and adults by 82% of the herd owners. The most commonly used weight in the dosing of anthelmintics was individual weights...
Survey of anthelmintic resistance on Danish horse farms, using 5 different methods of calculating faecal egg count reduction. This study reports on the prevalence of anthelmintic resistance in strongyles of horses in Denmark. Of 5 methods used for the calculation of faecal egg count reduction (FECR) the method recommended by the World Association for the Advancement of Veterinary Parasitology, for the detection of resistance in sheep was the most sensitive procedure for detecting resistance. Using this method benzimidazole resistance was detected on 33 of 42 farms (79%) examined. Pyrantel was tested on 15 farms and FECR tests indicate resistance on 3 (30%) farms. On 2 farms on which resistance to pyrantel was detecte...
Monitoring and detection of acute viral respiratory tract disease in horses. To develop a system to monitor and detect acute infections of the upper respiratory tract (i.e., nares, nasopharynx, and pharynx) in horses and to assess the association among specific viral infections, risk factors, and clinical signs of disease. Methods: Prospective study. Methods: 151 horses with clinical signs of acute infectious upper respiratory tract disease (IURD) from 56 premises in Colorado. Methods: Health management data, blood samples, and nasal or nasopharyngeal swab samples were obtained for 151 horses with clinical signs of acute IURD. Of these horses, 112 had an additional blo...
Diversity of genomic electropherotypes of naturally occurring equine herpesvirus 1 isolates in Argentina. The genomes of 10 equine herpesvirus 1 (EHV-1) strains isolated in Argentina from 1979 to 1991, and a Japanese HH1 reference strain were compared by restriction endonuclease analysis. Two restriction enzymes, BamHI and BglII, were used and analysis of the electropherotypes did not show significant differences among isolates obtained from horses with different clinical signs. This suggests that the EHV-1 isolates studied, which circulated in Argentina for more than 10 years, belong to a single genotype.
Comparative molecular characterization of Corynebacterium pseudotuberculosis of different origin. Ribotyping and susceptibility to 17 antimicrobial agents were used to compare 37 isolates of Corynebacterium pseudotuberculosis (28 from horses, 1 from cattle, 3 from sheep and 5 from goats) derived from various types of lesions, and different geographic locations. According to the presence of nitrate reductase, all but one isolate from horses reduced nitrate (nitrate-positive), whereas all isolates from sheep and goats were unable to reduce nitrate (nitrate-negative). The ribotype of the nitrate-negative isolate from a horse with ulcerative lymphangitis was identical to all the other isolates...
Equine infectious anemia virus is found in tissue macrophages during subclinical infection. The equine infectious anemia virus (EIAV) often results in lifelong subclinical infection following early episodes of clinical disease. To identify the cellular reservoirs of EIAV during subclinical infection, horses were infected with EIAV and allowed to develop subclinical infections. Horses with acute disease served as a basis for comparison. The tissue distribution, replication status, location of infected cells, and viral load were characterized by PCR for proviral DNA and reverse transcriptase PCR for viral RNA, in situ hybridization, and in situ PCR. Proviral DNA was widespread in tissu...
Risk factors associated with Corynebacterium pseudotuberculosis infection in California horses. A case-control study was designed using equine medical records from the UC Davis Veterinary Medical Teaching Hospital (VMTH) and data derived through a mailed survey. The objective was to evaluate the associations between horse demographics, horse-management factors, and equine Corynebacterium pseudotuberculosis infection in California. Horses admitted to the VMTH between July 1 1992 and June 30 1994 served as the study base for case identification and simple random sampling of 800 controls. A questionnaire was mailed to the owners of all horses enrolled in the study to collect data on demogra...
Application and evaluation of a mailed questionnaire for an epidemiologic study of Corynebacterium pseudotuberculosis infection in horses. The objective of this study is to describe the design, application and validity of a self-administered (mailed) questionnaire to collect data on potential risk factors for Corynebacterium pseudotuberculosis infection in California horses. Horses admitted to the UC Davis Veterinary Medical Teaching Hospital (VMTH) between 1 July 1992 and 30 June 1994 served as the study base for case identification and simple random sampling of 800 control horses. A questionnaire was mailed to owners of the study horses, followed by a reminder postcard and a second copy of a questionnaire. Data were collected o...
An immunohistochemical investigation of the adult stage of the equine parasite Strongylus vulgaris. Adult Strongylus vulgaris, collected from the caecum of infected horses and embedded in paraplast using standard methods, were sectioned for immunohistochemistry (IHC) studies. Antibodies were raised in rabbit against the excretory-secretory product (ESP) and against two constituent protein bands (28-30 kDa). The use of sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), enzyme-linked immunosorbent assay (ELISA) and immunoblotting indicated the immunogenicity of ESP and of the subunits (28-30 kDa). In ELISA, both rabbit hyperimmune sera recognized the ESP and (28-30 kDa) ban...
Serologic response of horses to the structural proteins of equine arteritis virus. Equine arteritis virus (EAV) is the causative agent of equine viral arteritis, an apparently emerging disease of equids. In this study, the antibody response of horses to the structural proteins of EAV was evaluated using gradient-purified EAV virions and baculovirus-expressed recombinant EAV structural proteins (G(L), G(S), M, N) as antigens in a Western immunoblotting assay. Thirty-three sera from horses that previously had been naturally or experimentally infected with EAV were evaluated, including samples from mares, geldings, and both persistently and nonpersistently infected stallions. S...
Serologic response of horses to the structural proteins of equine arteritis virus. Equine arteritis virus (EAV) is the causative agent of equine viral arteritis, an apparently emerging disease of equids. In this study, the antibody response of horses to the structural proteins of EAV was evaluated using gradient-purified EAV virions and baculovirus-expressed recombinant EAV structural proteins (G(L), G(S), M, N) as antigens in a Western immunoblotting assay. Thirty-three sera from horses that previously had been naturally or experimentally infected with EAV were evaluated, including samples from mares, geldings, and both persistently and nonpersistently infected stallions. S...
Local and systemic isotype-specific antibody responses to equine influenza virus infection versus conventional vaccination. Inactivated alum-adjuvanted conventional equine influenza virus vaccines are of poor efficacy and offer limited short-term protection against infection. In sharp contrast, natural infection with equine influenza virus confers long-term protective immunity. In order to identify the protective immune responses to equine influenza virus, the influenza virus-specific IgA, IgGa, IgGb, IgGc and IgG(T) antibody responses in nasal secretions and serum induced by natural infection and a commercial vaccine were studied by ELISA. Two groups of four influenza-naive ponies were established. In the natural ...
Zoonotic disease in Australia caused by a novel member of the paramyxoviridae.
Clinical infectious diseases : an official publication of the Infectious Diseases Society of America
Twenty-three horses and three humans in Queensland, Australia, were infected with a novel member of the Paramyxoviridae family of viruses in two geographically distinct outbreaks. Two of the humans died-one died of rapid-onset respiratory illness, and the other died of encephalitis. The third infected human developed an influenza-like illness and made a complete recovery. All infected humans had close contact with sick horses. Since the two outbreaks occurred at sites 1,000 km apart and no known contact between the two groups of humans and horses occurred, extensive testing of animals and bird... [Animal bites at the casualty department of the Oslo City Council]. During a 2-year period all Casualty Department data charts with the diagnosis "animal bite" were reviewed as part of internal quality control. Of 1,051 recorded episodes, 503 (48%) were women and 147 (14%) children under 16 years of age. 951 (90%) wounds were treated without closure. Half of the patients were not given antibiotics on the first visit, whereas one third were given penicillin. Tetanus status had been evaluated on 1,015 (97%) charts. Most bites were caused by dogs (76%), cats (17%), and horses (2%). Children were the victims of 118 (15%) dog bites, eight (4%) cat bites, and ten (5...
Molecular basis for antigenic variation of a protective strain-specific antigen of Ehrlichia risticii. Ehrlichia risticii, the causative agent of Potomac horse fever, has recently been isolated from many vaccinated horses with typical clinical signs of the disease. The heterogeneity of the E. risticii isolates obtained from the vaccinated horses necessitates the identification of the molecular basis of strain variations to elucidate the vaccine failure and to aid in the development of an efficient vaccine against this disease. As an attempt, two major cross-reacting surface antigen genes of 50- and 85-kDa antigens, present separately in strains 25-D (isolated in 1984) and 90-12 (isolated in 199...
Diversity among isolates of Actinobacillus equuli and related organisms as revealed by ribotyping. The objective of this work was to examine the diversity within Australian isolates of Actinobacillus equuli and related organisms by the genotypic method of ribotyping. Methods: Ribotyping, performed using the enzyme HaeIII, was used to examine the diversity in 12 field isolates of A equuli (five being capable of fermenting L-arabinose), one field isolate of Pasteurella caballi and two unclassifiable field isolates. Isolates were obtained from Australian horses, except for three isolates of A equuli (one L-arabinose positive and two L-arabinose negative) which were obtained from horses and a p...
Suspected bacterial meningoencephalitis in two adult horses. Bacterial infections (such as meningitis or meningoencephalitis) of the central nervous system are rare in horses. They are most prevalent in neonates as a result of septicaemia. A few cases have been reported in the adult and most have been fatal. Streptococcal species appear to be the organism most commonly identified in these cases. Thus, this disease may be a secondary complication of upper respiratory tract infections. Clinical signs are extremely variable making diagnosis difficult. In most cases, postmortem has been the definite diagnostic procedure. This paper describes the clinical co...
Redescription of Babesia equi Laveran, 1901 as Theileria equi Mehlhorn, Schein 1998. The horse-parasitizing species Babesia equi Laveran, 1901 was redescribed as Theileria equi Mehlhorn, Schein 1998 and, thus, transferred from one valid genus to another. This transfer was needed since it turned out that this horse parasite showed the relevant characteristics of theilerians with regard to biological data, morphological features, biochemical properties, and molecular biological relationships.
Clinical appearances, healing patterns, risk factors, and outcomes of horses with fungal keratitis: 53 cases (1978-1996). To compare initial clinical appearances, healing mechanisms, risk factors, and outcomes of horses with fungal keratitis. Methods: Retrospective analysis. Methods: 52 horses (53 eyes) with fungal keratitis. Methods: Medical records and clinical photographs of eyes were reviewed. Keratomycoses were categorized on the basis of clinical appearance at initial examination and pattern of healing. Results: Five distinct forms of mycotic keratitis were recognized. Of 53 affected eyes, 34 (64%) retained sight and had varying degrees of corneal scarring after treatment, 6 (11%) had a cosmetic appearance ...
