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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.
Acute colitis in adult horses. A review with emphasis on aetiology and pathogenesis. This review article describes the different aetiological agents known or suspected to cause colitis in the adult horse, namely Salmonella spp., Clostridium spp., Ehrlichia risticii, Cyathostomes, fungi, various antibiotics, drugs, and toxins, with emphasis on their mechanism of action. For each of the infectious agents, diagnostic procedures are indicated. The effects of endotoxin can be important in all forms of equine colitis.
Survival of mycoplasmas inoculated in horse sera. Although it is known that commercialized bovine serum is sometimes contaminated with mycoplasmas, it is not clear whether mycoplasmas can survive in horse serum. In this study, as a preliminary examination of the survival of mycoplasmas inoculated in horse sera, the survivability of 8 strains of 7 mycoplasmas was tested. The results obtained reveal that two strains of M. bovis and M. gallisepticum were found to survive in non-heated and inactivated sera for 94 to 330 days at 30 or 37 degrees C. Three strains of M. bovirhinis, M. gateae and A. laidlawii lived for 7 to 330 days depending upon th...
Controlled dose confirmation study of a 2% moxidectin equine gel against equine internal parasites in The Netherlands. The efficacy of a 2% moxidectin equine gel at a dosage rate of 0.4 mg kg-1 was evaluated in a controlled trial at Utrecht University. Twelve yearling castrated male Shetland ponies grazed a pasture of 2 ha from May 1994 until housing in November. Six ponies were treated with moxidectin, whereas the others served as non-treated controls. Necropsy was carried out 35 days after treatment. Greater than 99% efficacy of moxidectin was observed on faecal egg output. No effect of moxidectin was observed on mucosal inhibited early cyathostome L3 (EL3) or on the total numbers of mucosal developing stage...
Prevalence of the virulence-associated gene of Rhodococcus equi in isolates from infected foals. The prevalence of the plasmid-encoded virulence-associated gene (vapA) of Rhodococcus equi, as determined by PCR, was found to be 98% in isolates from 154 foals with pneumonia, confirming the strong association of vapA with virulence. The vapA genes from 60 representative isolates were compared by digestion with the restriction endonuclease HinfI, and no evidence of sequence variation was detected.
Prevalence of equine piroplasmosis in Central Mongolia. Antigen for the indirect fluorescent antibody test (IFAT) was routinely prepared from infected erythrocytes from horses experimentally infected with Babesia equi and Babesia caballi. With the successful establishment of in vitro cultures of B. equi and B. caballi, it is now possible to employ culture-derived antigens in this test. In this study, in vitro-propagated B. equi- and B. caballi-infected erythrocytes were used as antigen in the IFAT. Various modifications to an established protocol had to be implemented to allow repeatable results. Cultures with 3-4% parasitized erythrocytes were fou...
Antibodies against some viruses of domestic animals in southern African wild animals. Twenty-four species of South African wild animals were tested for the presence of antibodies against the viruses of 16 common diseases of domestic animals. Positive results were obtained for African horsesickness, equine encephalosis, equid herpes virus-1, infectious bovine rhinotracheitis, Allerton disease (Herpes mammillitis), lumpy skin disease, parainfluenza, encephalomyocarditis, bluetongue, Wesselsbron disease, bovine ephemeral fever, and Akabane disease complex. No antibodies could be demonstrated against the viruses of equine influenza, equine infectious anaemia, equine viral arteritis...
Characterization and mutational studies of equine infectious anemia virus dUTPase. The macrophage tropic lentivirus, equine infectious anemia virus (EIAV), encodes a dUTPase in the pol gene that is required for efficient replication in macrophages. Two naturally occurring variants of the enzyme were expressed as recombinant proteins in Escherichia coli; metal chelate affinity chromatography was used to purify histidine-tagged recombinant enzymes to greater than 80% homogeneity in a single chromatographic step. Biochemical and enzymatic analyses of these preparations suggest that this method yields dUTPase that is suitable for detailed mutational analysis. Specific activities...
Detection of latency-associated transcripts of equid herpesvirus 1 in equine leukocytes but not in trigeminal ganglia. Results from Southern hybridization and PCR amplification experiments using a randomly synthesized reverse transcription-PCR product showed that peripheral blood leukocytes from horses showing no clinical signs of disease expressed a putative latency-associated transcript antisense to and overlapping the 3' end of the equid herpesvirus 1 (EHV-1) immediate-early gene (gene 64). A PCR product derived from this transcript has > or =96% identity with the published EHV-1 sequence. In situ hybridization studies of equine bronchial lymph nodes corroborated these findings and are consistent with re...
An outbreak of abortion in mares associated with Salmonella abortusequi infection. An abortion outbreak occurred in a herd of 38 horses, 26 of which were pregnant mares. Twenty-one mares aborted between 5-10 months of gestation. In no case were there indications of impending abortion. Pathoanatomical, histopathological, virological and bacteriological examinations were carried out on 4 aborted fetuses. Histopathology identified Gram-negative bacteria compatible with salmonella in all 4 placentae. By subsequent bacteriological examination Salmonella abortusequi was isolated as the single causative agent in each case. Nonmotile Salmonella abortusequi with antigenic formula 4,1...
Equine viral arteritis in newborn foals: clinical, pathological, serological, microbiological and immunohistochemical observations. Clinical, pathological, immunohistochemical, serological and microbiological findings are described for 2 geographically and temporally distinct equine arteritis virus (EAV) epidemics in newborn foals. Outbreak A occurred at a commercial Standardbred breeding facility; Outbreak B began in a group of research animals. Clinical signs were severe and primarily referable to the respiratory tract. Fever and leucopenia and/or thrombocytopenia were observed in foals surviving for more than 24 h. The most common gross pathological findings were limited to the respiratory tract. Common histopathologica...
Detection of African horse sickness virus in the blood of experimentally infected horses: comparison of virus isolation and a PCR assay. A reverse transcription-polymerase chain reaction (RT-PCR) assay followed by dot-blot hybridisation was used to detect African horse sickness virus (AHSV); the primers employed amplified the S7 gene that encodes the VP7 protein. The RT-PCR assay was compared with virus isolation for detecting AHSV in blood samples form horses experimentally infected with AHSV-4 and AHSV-9. The influence of sample storage and transportation and the effects of two anticoagulants (EDTA and heparin) were also studied. RT-PCR results were obtained within 48 hours as opposed to a minimum of 15 days for virus isolati...
Acute myelogenous leukaemia in a mare. A 5-year-old Thoroughbred mare presented with a 4 week history of weight loss, fever and leukopenia. Rectally, a large active foetus, thickened spleen and an abdominal mass were palpated. Leukopenia, mild anaemia, marked thrombocytopenia and hyperfibrinogenaemia were found. Cytology and cytochemical staining of a bone marrow aspirate supported a diagnosis of acute myelogenous leukaemia. The mare deteriorated despite medical therapy and was humanely euthanased.
Cardio-histopathological observations on aborted equine fetuses infected with equid herpesvirus 1 (EHV-1). Twenty-five aborted equine fetuses infected with equid herpesvirus 1 (EHV-1) were examined cardio-histopathologically. The main changes in the heart consisted of interstitial myocarditis and intramyocardial vascular lesions accompanied by degeneration and necrosis of the cardiac myocytes. Vascular pathology of intramyocardial small arteries and arterioles was characterized by endothelial cell necrosis and fibrinoid changes in the media. Eosinophilic intranuclear inclusion bodies characteristic of herpesvirus infection were detected in the myocardial cells and macrophages within and around the ...
Expression of the nonstructural protein NS1 of equine influenza A virus: detection of anti-NS1 antibody in post infection equine sera. The nucleotide sequence of the nonstructural protein NS1 of the influenza virus A/equine 2/Suffolk/89 was determined and found to be 97% identical to that of A/equine 2/Miami/63. A similar level of identity was shown for the deduced NS1 amino acid sequence. The NS1 gene was expressed, in its entirety and in part, as fusion proteins with glutathione S-transferase using the pGEX-3X expression vector. Antibodies to NS1 protein were detected in serum samples from ponies experimentally infected with influenza virus, but not in animals vaccinated with whole inactivated virus or in unprimed control a...
Purification and characterization of a hemolysin produced by Vibrio mimicus. Vibrio mimicus is a causative agent of human gastroenteritis. This pathogen secretes a pore-forming toxin, V. mimicus hemolysin (VMH), which causes hemolysis by three sequential steps: binding to an erythrocyte membrane, formation of a transmembrane pore, and disruption of the cell membrane. VMH with a molecular mass of 63 kDa was purified by ammonium sulfate precipitation and column chromatography with phenyl Sepharose HP and Superose 6 HR. The hemolytic reaction induced by VMH continued up to disruption of all erythrocytes in the assay system. Moreover, VMH that bound preliminarily to erythr...
The effects of ischemia and reperfusion on mucosal respiratory function, adenosine triphosphate, electrolyte, and water content in the ascending colon of ponies. The purpose of this study was to examine the effects of ischemia and reperfusion on the biochemical integrity of equine colonic mucosa to assess the relative roles of ischemic- and reperfusion-induced damage. Methods: Two hours of no-flow ischemia experimentally induced by 720 degrees counterclockwise ascending colon volvulus followed by 2 hours reperfusion after derotation. Methods: Ten ponies. Methods: Ascending colon biopsies were obtained every hour for measurement of mucosal adenosine triphosphate (ATP), water, sodium, and potassium content. Additional samples were homogenized for assay o...
Serodiagnosis of Babesia equi infection–a comparison of Dot-ELISA, complement fixation test and capillary tube agglutination test. The present study aimed to develop Dot-ELISA, complement fixation test (CFT) and capillary tube agglutination test (CAT) for serodiagnosis of Babesia equi infection and to compare their sensitivity with each other. For this study, sequential serum samples were collected from four donkeys experimentally infected with B. equi up to 90 days post infection (P.I.). B. equi antigen was prepared from the blood of a donkey showing more than 80% parasitaemia. Dot-ELISA, CF and CA tests were standardized as per the standard method. While performing CFT, it was observed that CFT standardized for the donk...
Equine herpesvirus 4 DNA in trigeminal ganglia of naturally infected horses detected by direct in situ PCR. Neuronal and lymphoid tissues of 15 randomly selected horses were analysed post mortem by liquid nested-PCR to study the tropism of equine herpesvirus 4 (EHV-4). In four animals the trigeminal ganglia and in one case the lung were positive. Using a direct in situ PCR the EHV-4 genome was localized in the nuclei of neurons and in the bronchiolar as well as alveolar epithelium of the lung. In none of these tissues could infectious virus or viral antigens be detected. Applying the more sensitive liquid RT-PCR, however, an acute infection was demonstrated in one of the trigeminal ganglia by amplif...
Detection and distribution of equine herpesvirus 2 DNA in the central and peripheral nervous systems of ponies. The distribution of equine herpesvirus 2 (EHV-2) DNA within neurological and lymphoid tissues from 12 EHV-2 seropositive Welsh mountain ponies was determined by PCR. The lymphoid sites sampled in this study were almost universally PCR positive, thus confirming the existing virus co-cultivation data which suggest that the lymph nodes draining the respiratory tract are the main reservoirs of EHV-2 DNA. In addition, EHV-2 DNA was also detected, albeit with lower frequency, within both the peripheral and central nervous systems (PNS and CNS) of these animals. Of the CNS sites sampled 11% were PCR-...
Herpesviral abortion in domestic animals. Abortion or neonatal disease may follow infection with several alpha, beta and gamma-herpesviruses. The alpha-herpesvirus, equid herpesvirus-1 (EHV-1), causes single or epizootic abortions or neonatal deaths in equids, and the closely related virus EHV-4 causes sporadic equine abortions. In cattle, the alpha-herpesviruses, bovine herpesvirus-1 (infectious bovine rhinotracheitis virus) and bovine herpesvirus-5 (bovine encephalitis virus), and a gamma-herpesvirus, bovine herpesvirus-4, have all been implicated as causes of abortion. In pigs, suid herpesvirus-1 (SHV-1: pseudorabies virus), an alp...
Melatonin protects mice infected with Venezuelan equine encephalomyelitis virus. We investigated whether the administration of melatonin (MLT) reduces the death rate and evolution of the disease in mice infected with Venezuelan equine encephalomyelitis (VEE) virus. Our results show that, MLT protects mice infected with the virus. The mortality rate was reduced from 100% to 16% merely by increasing the dose from 0 to 1000 micrograms/MLT per kg body weight MLT significantly postponed the onset of the disease and death by several days. In surviving mice very high titres of VEE virus IgM antibodies were found seven weeks after virus inoculation. MLT significantly reduced VEE v...
Cloning, expression, purification, and characterization of the major core protein (p26) from equine infectious anemia virus. The gene coding for the major core protein (p26) of the lentivirus equine infectious anemia virus (EIAV) was cloned from EIAV infected serum, expressed in E. coli, and the resultant protein purified to electrophoretic homogeneity. The protein was expressed in a soluble form and was purified by conventional protein separation methods. When analyzed by SDS-PAGE, under both reducing and non-reducing conditions, the purified protein migrated as a 26 kDa monomer. Recombinant p26 (rp26), therefore, does not contain any intermolecular disulfide bond. Gel filtration chromatography also indicated that ...
Epidemiologic aspects of Taylorella equigenitalis. Contagious equine metritis (CEM) is a sexually transmissible disease in mares. Although the disease is commonly diagnosed by culturing the causative bacterium Taylorella equigenitalis (T. equigenitalis) . false negative results do occur. A recently developed Polymerase Chain Reaction (PCR) assay, however, appeared to be much more sensitive, with initial results indicating an unexpected high incidence of the agent in selected horses. In this study, samples from 107 randomly selected mares with no clinical signs of CEM submitted for conventional culture were all negative for T. equigenitalis . b...
