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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.
Multicentric cutaneous pythiosis in a foal. A 5-month-old male Quarter Horse was examined because of multicentric, granulomatous, cutaneous lesions of the dorsum and prepuce. The cutaneous lesions were excised, and sodium iodide was administered orally for 2 weeks. Multicentric cutaneous pythiosis was diagnosed by histologic examination and immunoperoxidase staining of excised tissues. By 3 months after surgery, all lesions had healed.
Prevalence and serovars of leptospira involved in equine abortions in central Kentucky during the 1990 foaling season. A study to determine the prevalence of leptospira-induced abortions in the central Kentucky equine population during the 1990 foaling season and to determine the leptospira serovars responsible was conducted. From July 1, 1989 through June 30, 1990, 32 (4.4%) of 726 submissions (fetuses, stillborn foals, and/or placentas) were diagnosed as leptospirosis by the fluorescent antibody test and/or microscopic agglutination test. Attempts were made to isolate leptospires from the fetal tissues and/or the dam's urine in 31 of these cases. Leptospira interrogans serovar kennewicki was isolated from 11...
Haematology of experimental babesiosis and ehrlichiosis in steroid immunosuppressed horses. An investigation was carried out to study the haematology of steroid immunosuppressed horses experimentally infected with Babesia equi and Ehrlichia equi, separately or simultaneously. Horses infected with both pathogens showed less marked changes in their haematology than those inoculated with either pathogen separately. This appeared to result from early elimination of the more pathogenic Babesia as Ehrlichia spread through the granulocytes. The apparent suppression of Babesia by Ehrlichia is of field clinical importance and merits further investigation for its apparent useful potentials in ...
Precipitin response of the mitogen produced by Strongylus vulgaris arterial larvae. The precipitin response of the mitogen produced by Strongylus vulgaris arterial larvae was investigated. IgG (T) from the sera of horses naturally infected with S. vulgaris adults and arterial larvae recognised the presence of two antigenic components of the mitogenic fractions. The results obtained seem to confirm that these antigens are immunogenic in stimulating the production of increased levels of IgG(T) in infected animals, and showed that the procedures could be used as immunological tools in the diagnosis of S. vulgaris infection.
The pathogenicity of Ab4p, the sequenced strain of equine herpesvirus-1, in specific pathogen-free foals. The sequencing of the genome of equine herpesvirus-1 (EHV-1) is reported in Elizabeth A. R. Telford, Moira S. Watson, Kathryn McBride, and Andrew J. Davison, 1992, Virology, 189, 304-316. The sequence was derived using a plaque-purified clone of EHV-1 strain Ab4 (designated Ab4p). To ensure that Ab4p shares the pathogenic characteristics of parental Ab4 (hereafter Ab4), both were inoculated intranasally into foals, specifically free from EHV-1 and EHV-4. Clinical signs, including rectal temperature, were similar for both viruses. In addition, nasal shedding of virus was observed over a 1- to 2...
Effects of equine infectious anemia virus on hematopoietic progenitors in vitro. Direct effects of equine infectious anemia virus (EIAV) on hematopoiesis in vitro were studied. Bone marrow mononuclear cells from clinically normal horses were incubated with 100 TCID50 of EIAV/10(7) cells. These cells were cultured to assay for colonies derived from erythroid progenitors, granulocyte/monocyte progenitors, and fibroblastic progenitors. The EIAV had a selective suppressive effect on the erythroid progenitors. Colony-forming units-erythroid were suppressed to 80% of that for medium controls (P = 0.011). Burst-forming units-erythroid were suppressed to 70% of that for medium con...
Gardnerella vaginalis: characteristics, clinical considerations, and controversies. The clinical significance, Gram stain reaction, and genus affiliation of Gardnerella vaginalis have been controversial since Gardner and Dukes described the organism as the cause of "nonspecific vaginitis," a common disease of women which is now called bacterial vaginosis. The organism was named G. vaginalis when taxonomic studies showed that it was unrelated to bacteria in various genera including Haemophilus and Corynebacterium. Electron microscopy and chemical analyses have elucidated the organism's gram-variable reaction. Controversy over the etiology of bacterial vaginosis was largely res...
Lyme borreliosis in cattle and horses: a review of the literature. A complete search of the literature concerning Lyme borreliosis as it relates to horses and cattle was done. The epidemiology, pathogenesis, immunological response to the disease, diagnosis and treatment are discussed. A review of clinical cases in horses and cattle is presented. Clinical signs of Lyme borreliosis in horses include: chronic weight loss, sporadic lameness, laminitis, low grade fever, swollen joints, muscle tenderness, and anterior uveitis. In addition to those clinical signs, neurological signs such as depression, behavioral changes, dysphagia, head tilt and encephalitis can be...
Venezuelan equine encephalomyelitis and African horse sickness. Current status and review. The arthropod-borne virus (arbovirus) diseases of livestock have worldwide impact. The prevention of an introduction of an exotic disease and the control of one subsequent to an introduction will require the attention, cooperation, and support of the livestock industry, regulatory agencies, and researchers. The most effective protection of our livestock industries is to prevent the introduction of an exotic disease agent. This implies complete restriction of animal imports and exports. However, "zero risk" is an unacceptable option in today's world of internationally integrated and interdepend...
Restriction enzyme maps for equine adenovirus 1 genome. Physical maps were constructed for the genome of equine adenovirus 1 (EAV1) using the restriction enzymes; DraI, EcoRV, NotI and SfiI. The total size of the EAV1 genome was 34.4 kb estimated by comparison with known DNA standards and the polarity of the fragment order, with respect to the left and right molecular ends, was determined by hybridization with known regions of the human adenovirus 2 (HAV2) genome.
Efficacy of inactivated whole-virus and subunit vaccines in preventing infection and disease caused by equine infectious anemia virus. We report here on a series of vaccine trials to evaluate the effectiveness of an inactivated equine infectious anemia virus (EIAV) whole-virus vaccine and of a subunit vaccine enriched in EIAV envelope glycoproteins. The inactivated vaccine protected 14 of 15 immunized ponies from infection after challenge with at least 10(5) 50% tissue culture-infective doses of the homologous prototype strain of EIAV. In contrast, it failed to prevent infection in any of 15 immunized ponies that were challenged with the heterologous PV strain. Levels of PV virus replication and the development of disease, ho...
The production of equine monoclonal immunoglobulins by horse-mouse heterohybridomas. Studies were carried out to determine the optimum conditions for the production of equine monoclonal antibodies (MAbs). Lymphocytes from ponies immunised with influenza A equine 2 virus, isolate A/Equine/Newmarket/79 (H3N8) were fused with mouse myeloma (NSO) cells and with horse-mouse heterohybridomas made aminopterin-sensitive by selective growth in 8-azaguanine. Although all fusions initially resulted in heterohybridoma colonies that secreted equine immunoglobulin, many of these were unable to maintain secretion for longer than a few weeks. Increasing the time between immunisation and the b...
Diversity of the antibody responses produced in ponies and mice against the equine influenza A virus H7 haemagglutinin. A large panel of mouse monoclonal antibodies was produced and tested against field isolates of the equine H7N7 influenza A virus subtype. Only a limited degree of H7 haemagglutinin variation was detected. At least four antigenic sites were identified by selecting variant viruses in eggs. The limited variation in the field did not correlate with the frequency of variant viruses detected in eggs; this frequency was similar to those reported for other influenza viruses. We sought to determine whether the limited amount of variation could be correlated with an epitope-restricted antibody response ...
Cryptococcosis in seven horses. The clinical, radiographic and post-mortem findings in 6 horses with cryptococcal pneumonia and one horse with an abdominal cryptococcal granuloma are described. In pulmonary cryptococcosis, the lesions were either diffuse and multiple, with bilateral lung involvement, or localised mainly to the dorsocaudal region of one lung. The cases of diffuse multiple cryptococcosis were thought to be associated with haematogenous spread of the fungus after gastrointestinal infection and dissemination from regional lymph nodes. The localised form of the disease was thought to have been associated with inh...
Genomic variation and segregation of equine infectious anemia virus during acute infection. Equine infectious anemia virus (EIAV) is a lentivirus that infects and persists in the monocyte/macrophage populations of blood and tissues. We employed polymerase chain reaction to investigate the distribution and the level of genome variability of EIAV DNA in different tissues of a horse infected with a highly virulent variant of the Wyoming strain of the virus. Long terminal repeat, gag, and pol primer pairs were used to direct the amplification of EIAV DNA from the peripheral blood mononuclear cells and from cells, presumably the macrophage subtypes, of the kidney, spleen, liver, lymph nod...
[Three cases of virus isolation from horse fetuses diagnosed with equine arteritis virus (EAV) abortion from stud farms with different breeds]. Three cases of abortions were diagnosed as caused by Equine Arteritis Virus (EAV) by isolation and typing of this virus from the respective fetuses. All 3 abortions were single cases, one occurring on a stud with Iceland Ponies, one with Warmbloods, one with Lipizzaner horses. On each stud horses of the respective breed were kept exclusively, therefore there existed no epidemiologic link. By means of seroneutralization tests performed on in contact horses it could be shown, that EAV had only been introduced recently into the stud with the Iceland Ponies. An extraneous mare stabled temporarily ...
Biochemical analysis by SDS-PAGE and western blotting of the antigenic relationship between Leptospira and equine ocular tissues. The antigenic relationship between Leptospira interrogans, equine cornea and lens was previously noted in our studies. Serum antibodies from horses inoculated with serovars wolffi, pomona, icterohaemorrhagiae, and tarassovi, were able to bind to five antigenic fractions from both cornea and lens, as demonstrated by immunoblotting. These antigens seem to be made up of protein and carbohydrates. After treatment with periodate for cleavage of glycoside ring structures, those fractions kept their condition of target for anti-Leptospira antibodies. Nevertheless, all fractions lost that condition af...
Isolation and characterization of alpha 1-acid glycoprotein from horses, and its evaluation as an acute-phase reactive protein in horses. Equine alpha 1-acid glycoprotein (alpha 1AG) was isolated from equine serum by successive ammonium precipitation, anion- and cation-exchange chromatographies, and gel filtration. Purified equine alpha 1AG had a molecular weight of 46,000 +/- 1,000, and contained 31.4% carbohydrate. Gel isoelectric focusing revealed an isoelectric point range of 2.8 to 3.7. With immunoelectrophoresis, it was found that alpha 1AG migrated to the alpha 1-globulin region. Single radial immunodiffusion was used for quantitative measurement of alpha 1AG in equine serum. In clinically normal foals, serum alpha 1AG wa...
A soluble recombinant fusion protein of the transmembrane envelope protein of equine infectious anaemia virus for ELISA. The use of the bacterial expression vector, pGex, to produce an abundant, soluble fusion protein of gp45 from equine infectious anaemia virus is described. Purification of the recombinant protein was achieved by one step affinity chromatography on immobilized glutathione using competitive elution so no harsh conditions were required. This provides a readily available antigen that is defined, plentiful and cheap. Yields of 3.5 mg of purified soluble protein/litre of bacterial culture were obtained. This antigen was found to be suitable for ELISA. Background reactivity to either the glutathione-...
Necropsies of eight horses infected with Strongylus equinus and Strongylus edentatus. Ponies (n = 8) approximately 18 months old, were infected with 20,000 to 30,000 infective larvae of Strongylus equinus with less than 10% contamination with Strongylus edentatus larvae and necropsied 7 months post-infection. Lesions were present in the omentum, liver, pancreas, ventral colon, caecum and occasionally in the lungs. There were numerous intraabdominal adhesions and severe multiple granulomatous omentitis. Pancreatic damage, which characterises S. equinus, was exceptionally mild and was manifested mainly by slight periductular infiltration of eosinophils. Granulomas associated with...
Metastatic granulosa cell tumor in a mare. A 5-year-old Quarter Horse mare was referred for evaluation of an acute non-weightbearing lameness of the left hind limb in which musculoskeletal abnormalities had not been detected. After admission, the mare had signs of colic. Exploratory laparotomy revealed the left ovary to be large, masses in the left sublumbar space, and diffuse infiltration of the mesentery, omentum, liver, and spleen with variably-sized masses. The mare was euthanatized, and granulosa cell tumor was identified on histologic examination of the left ovary, left sublumbar and cranial thoracic lymph nodes, omentum, mesente...
Chlamydia psittaci infection in horses: results of a prevalence survey and experimental challenge. Nasal and conjunctival swabs were obtained from 300 horses and Chlamydia psittaci was isolated from 15 of them (5 per cent). Eleven nasal swabs and six conjunctival swabs were positive on culture, but there was no association between the isolation of the organism and the presence of clinical ocular or respiratory disease. Six ponies were challenged with an equine isolate of C psittaci into the eye, nasal cavity or bronchial tree. The organism could be isolated from nasal and conjunctival swabs taken from the ponies for up to 17 days after challenge, but there was no clinical evidence of diseas...
Equine arteritis virus: an overview. The causative agent of the respiratory disease equine viral arteritis is a small, single-stranded RNA virus with a genome organization and replication strategy related to that of coronaviruses and toroviruses. Clinical signs of infection in horses vary widely and severe infection can lead to pregnant mares aborting. Infected horses generally make good recoveries but stallions may become semen shedders of equine arteritis virus (EAV). These carrier stallions play an important role in the dissemination and perpetuation of EAV. Laboratory tests exist to detect virus and the equine immune response...
