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Topic:Infection
Infections in horses encompass a range of diseases caused by various pathogens, including bacteria, viruses, fungi, and parasites. These infections can affect different systems within the horse, such as the respiratory, gastrointestinal, and integumentary systems, leading to a variety of clinical signs depending on the pathogen and the severity of the infection. Common infectious diseases in horses include equine influenza, strangles, and equine herpesvirus. Diagnosis often involves clinical examination, laboratory testing, and sometimes imaging, to identify the causative agent and assess the extent of the disease. Treatment strategies may include antimicrobial therapy, supportive care, and preventive measures such as vaccination and biosecurity practices. This page aggregates peer-reviewed research studies and scholarly articles that explore the pathogenesis, diagnosis, treatment, and prevention of infectious diseases in equine populations.
Histopathological and immunofluorescent studies on transplacental infection in experimentally induced abortion by equine arteritis virus. Five pregnant mares, at between 6 and 8 months gestation, were experimentally infected with the Bucyrus strain of equine arteritis virus (EAV). Of the five mares, four aborted and one died. The pathogenesis of the abortions was studied, using histopathologic techniques, tissue immunofluorescence and virus isolation. Common microscopic lesions in the maternal reproductive organs indicated myometritis with a degeneration of the myocytes and an infiltration of the mononuclear cells. Epithelial cells of the endometrial gland showed sporadic degeneration. Lesions in the fetal tissue included an atr...
Immunohistochemical diagnosis of eastern equine encephalomyelitis. An immunohistochemical (IHC) assay was developed for the detection of eastern equine encephalomyelitis (EEE) virus antigen in formalin-fixed, paraffin-embedded tissues. All cases of EEE diagnosed at the Michigan State University Animal Health Diagnostic Laboratory from 1991 through 1994 were evaluated. The diagnosis was based on histopathologic examination of the brain and confirmatory virus, isolation. Sections of cerebrum from 26 equids and 5 birds were assessed by IHC. Histologically normal brain tissues from 2 horses and 1 pheasant and brain tissues from 2 cases of equine neurologic diseas...
Detection of eastern equine encephalomyelitis virus RNA in formalin-fixed, paraffin-embedded tissues using DNA in situ hybridization. Eastern equine encephalomyelitis (F.EE) virus was detected in infected formalin-fixed horse and emu tissues and in infected chicken embryo fibroblasts. Results of in situ hybridization using a digoxigenin-labeled 40-base DNA probe complementary to a conserved region of the EEE virus RNA compared favorably with results of both virus isolation and serum neutralization tests. This technique may be useful for diagnosis of EEE virus infection in various animal species, especially when fresh tissues are not available for analysis, and also will provide a means for studying the involvement of alphavi...
Equine neonatal septicaemia: 24 cases. Equine neonatal septicaemia was confirmed in 24 foals hospitalised at the Rural Veterinary Centre between 1989 and 1992 with suspected septicaemia. Septicaemia was confirmed by culture of bacteria from blood of live foals and tissues obtained at necropsy of foals that died or were euthanased. Pathogenic bacteria isolated were predominantly Enterobacteriaceae (including Escherichia coli and Salmonella serovars) and Actinobacillus equuli. Clinical manifestations of septicaemia included signs of depression, dehydration, abnormalities in body temperature and manifestations of localised infection i...
Comparison of the reappearance of strongyle eggs on foals, yearlings and adult horses after treatment with ivermectin or pyrantel. The reappearance of strongyle eggs in faeces after treatment with ivermectin or pyrantel embonate was investigated in 22 foals, 36 yearlings, and 45 adult horses on five Dutch horse farms. The results confirmed earlier studies which showed an egg reappearance period of 9 and 6 weeks after ivermectin and pyrantel treatment, respectively. There were no differences between the egg reappearance periods of foals, yearlings, and adult horses. The mean egg counts of the yearlings were, however, consistently higher than the mean egg counts of the adult horses and foals in both ivermectin- and pyrantel...
Anomalous inheritance of a paternally derived trophoblast antigen. Recurrent spontaneous abortion occurs in 1 in 500 random matings and usually results in abortion of all pregnancies. If absence of antibody to a paternally derived antigen caused abortion, the woman would be expected to make antibody to the other paternal antigen and abort only half her pregnancies. Methods: Microvesicles were prepared from equine placentae. Acid-eluted IgG antibody was eluted from the polymorphic R80K antigen and used to type the residual R80K antigen on vesicles or on peripheral blood leucocytes. Results: In several equine sibships all the half-sibs had the same paternal R80...
Cross-sectional evaluation of environmental, host, and management factors associated with risk of seropositivity to Ehrlichia risticii in horses of New York state. To locate counties within New York state with a high seroprevalence among the equine population, to determine host, management, and environmental factors that were associated with seropositivity to Ehrlichia risticii, and to determine evidence for arthropod- or helminth-mediated transmission of E risticii to horses. Methods: Cross-sectional study. Methods: A random sample of 3,000 of the 39,000 equine operations in New York state was selected, and 2,587 horses from 511 operations were tested. Methods: Blood samples were collected from horses and tested for seropositivity, using the indirect fl...
A morphometric study of bone marrow megakaryocytes in foals infected with equine infectious anemia virus. Morphometric evaluation of bone marrow core biopsies was used to determine megakaryocyte (MK) numbers and MK size in nine foals with equine infectious anemia virus (EIAV)-induced thrombocytopenia. Both immunocompetent normal foals and foals with severe combined immunodeficiency (SCID) were used. Platelet counts were made three times weekly following viral infection. Bone marrow core biopsies were taken from the ilium of each foal prior to experimental infection, immediately after the onset of thrombocytopenia, and at necropsy. All foals developed thrombocytopenia by 23 days postinfection. The ...
Alterations in the equine herpesvirus type-1 (EHV-1) strain RacH during attenuation. The equine herpesvirus type-1 modified live-vaccine strain RacH (256th passage on porcine embryonic kidney cells) was investigated by restriction-enzyme analysis and compared to representative plaque isolates of the 12th passage (RacL11, RacL22) and 185th passage (RacM24, RacM36). The restriction patterns of all Rac plaque isolates differed compared with reference strain Ab4. The left UL terminus was shortened by 0.1 kbp and a missing BamHI site led to the fusion of the f and t fragments. In some Rac derivatives, losses of restriction sites without deletions were observed: 1. One BamHI site lo...
Fine specificity of equine infectious anaemia virus gp90-specific antibodies associated with protective and enhancing immune responses in experimentally infected and immunized ponies. Equine infectious anaemia virus (EIAV) provides a model for examining the natural immunological control of a persistent lentivirus infection and for evaluating the efficacy of various vaccine strategies. As an initial characterization of antibody responses associated with protective or enhancing immune responses elicited by experimental infections or vaccinations, we have utilized synthetic peptide ELISA to characterize the fine specificity of antibodies to linear determinants of the EIAV surface glycoprotein, gp90. The data indicated that serum antibodies associated with protective or enhanci...
Platelet-activating factor and not thromboxane A2 is an important mediator of endotoxin-induced platelet aggregation in equine heparinised whole blood in vitro. Endotoxin has previously been shown to induce platelet aggregation in equine heparinised whole blood. This study aimed to determine whether platelet-activating factor or products of cyclo-oxygenase metabolism (thromboxane A2 or prostaglandins) were important in mediating the response of platelets to endotoxin. The effects of the following drugs on endotoxin-induced aggregation were investigated: aspirin, flunixin meglumine and carprofen (non-steroidal anti-inflammatory drugs); CV-3988 and WEB2086 (platelet-activating factor receptor antagonists); quinacrine (phospholipase A2 inhibitor). The ef...
Surgical treatment for colic in the foal (67 cases): 1980-1992. Sixty-seven foals age < 150 days underwent a ventral celiotomy for colic. Of the 67 foals, 51 foals (82%) recovered from anaesthesia and 42 (63%) were subsequently released from the hospital. Three (6%) of the 51 foals were subjected to a repeat celiotomy. Long term follow-up was available on 36 foals. Twenty-nine (57%) of the 51 foals recovered from anaesthesia, were alive at least 2 years following surgery. Adhesions were identified in 8 (17%) of the foals which recovered from general anaesthesia but were subsequently subjected to euthanasia due to recurrent colic. Strangulating lesions were...
Prevalence of sarcocysts in livestock of northwest Ethiopia. A survey of Sarcocystis was conducted in cattle, sheep, goats, donkeys and chickens. A total of 671 haematoxylin-eosin (H-E) stained muscle tissue samples, including diaphragm, masseter, cardiac and oesophageal musculatures were examined. Additionally, cardiac muscle samples from 40 fetuses were included. An infestation rate of 93% in sheep, 82% in cattle, 81% in goats, 16.6% in donkeys and 6.6% in chickens was noted. The infestation rate of diaphragm, masseter, cardiac and oesophageal musculatures seems to be similar. None of the 40 fetal heart muscle samples from bovine, ovine, caprine and d...
The role of the gene 71 product in the life cycle of equine herpesvirus 1. Equine herpesvirus type 1 (EHV-1) gene 71 encodes a heavily O-glycosylated 192 kDa protein with no identified herpesvirus homologue. Isolation of a deletion mutant in gene 71 (ED71) demonstrated that its protein product is not essential in vitro. To investigate the role of the gene 71 protein in the virus life cycle, ED71 has been characterized in vitro in terms of cellular adsorption, penetration, egress and transmission compared to wild-type and revertant virus. ED71 virions adsorbed to cells less efficiently than wild-type and revertant virus with a consequential effect on virus penetration...
Lymphocyte subsets in the endometrium of genitally normal mares and mares susceptible to endometritis. The density and distribution of MHC Class II positive cells and subpopulations of lymphocytes were studied in the endometrium of genitally normal mares and mares susceptible to endometritis. In genitally normal mares, more MHC Class II positive cells were present in the epithelium and stratum compactum during oestrus than dioestrus. Significantly more CD4+ and CD8+ lymphocytes were present in the stratum compactum than in the stratum spongiosum. CD4+ lymphocytes were present in greater numbers than CD8+ lymphocytes in the stratum compactum but approximately equal numbers were present in the st...
Subcellular localization of the nonstructural protein NS3 of African horsesickness virus. The subcellular localization of the minor nonstructural protein NS3 of African horsesickness virus (AHSV) has been investigated by means of immunogold electron-microscopical analysis. NS3 was observed in perturbed regions of the plasma membrane of AHSV-infected VERO cells, and its presence appears to be associated with events of viral release. These events are budding, whereby released viruses acquire fragments from the host-cell membrane, as well as by the extrusion of nonenveloped particles through the cell membrane. The membrane association of NS3 was confirmed by its detection in the disru...
Intestinal ciliates found in the feces of Japanese native Tokara pony, with the description of a new genus and a new species. The composition of intestinal ciliates excreted in the feces of 20 Tokara native ponies kept in Iriki farm of Kagoshima University was surveyed. Eleven genera consisting of 18 species were identified based on the description of Strelkow. One new genus including a new species, Wolskana tokarensis n. gen., n. sp., of the family Buetschliidae was recognized and described. The average ciliate density of all horses was 13.8 x 10(3)/ml. Those of stallions (n = 5), mares (n = 11) and foals (n = 4) were 3.9, 16.1 and 43.3 x 10(3)/ml respectively. The value of stallions was significantly lower and that...
Lack of virulence of the murine fibroblast adapted strain, Kentucky A (KyA), of equine herpesvirus type 1 (EHV-1) in young horses. The virulence of the cell culture adapted KyA strain of equine herpesvirus type 1 (EHV-1), which lacks at least six genes by deletions in its genome, was assessed by intranasal inoculation of six young horses that were serologically negative for EHV-1. No horses showed clinical signs, and a neutralizing antibody response against EHV-1 was detected in two horses which had antibodies against EHV-4 prior to the inoculation. A challenge experiment using a highly virulent strain of EHV-1 conducted 4 weeks later against 4 of the 6 horses inoculated intranasally with the KyA strain and 2 control hors...
[Spectrum of species and incidence of endoparasites in foals and their mother mares from breeding farms with and without anthelmintic prophylaxis in upper Bavaria]. In this epidemiological study 37 foals and mares were included, which have been coproscopically examined in regular intervals over a period lasting up to 13 months. The animals derived from nine breeding farms. In three of these farms no anthelmintics were used before this investigation, whereas in six farms at least three years before regular prophylactic treatments with anthelmintics have been carried out. This investigation revealed no differences in the species spectrum of endoparasites as well as in the incidence of infections as regards to the breeding farms with and without anthelmintic...
The Centre for Tropical Veterinary Medicine (CTVM) pulling its weight in the field of draught animal research. Draught animal research carried out by scientists at the Centre for Topical Veterinary Medicine (CTVM) in Edinburgh and overseas is reviewed and the major findings are reported. The remit for the work has been to provide basic information on draught animals which can be applied by researchers and extension workers to their own geographic situations. Instrumentation is described which has been designed and manufactured to assist in the measurement of draught animal performance, particularly work output and energy consumption. Energy requirements of cattle, buffaloes and equids for work and ways...
[Congenital bile duct cysts and liver fibrosis in a foal]. A three-week-old foal was submitted to the clinic because of a minor traumatic injury at the lower jaw. At admission the foal exhibited diarrhea, a distended abdomen and reduced general condition. These findings could not be associated with the injury. On abdominal radiography decreased abdominal detail and a dorsocaudal displacement of the intestine was present. Ultrasonographically multiple fluid-filled cystic structures of several centimeters in diameter were identified. These cystic structures appeared to be associated with the liver. At laparotomy and at necropsy the liver was markedly en...
Characterization of Escherichia coli isolated from foals. Serotype, biotype, antibiogram, hemolysin production, fimbrial hemagglutinins, select toxin genes (STb, STaP, LT, slt1 and slt2) and the attaching effacing (eae) gene were determined for 99 foal strains of E. coli. E. coli from diarrheic and normal foals could not be distinguished by serotype, biotype, or antibiogram. Differences (P < or = 0.05) were observed in hemolysin production (11.5% vs 0%) and the expression of mannose-resistant hemagglutinins (23% vs 13%) among E. coli from diarrheic and healthy foals, respectively. Three of the E. coli strains from diarrheic foals were positive wit...
Lymph pathways associated with three types of follicle structure found in gut-associated lymphoid tissue of horse ileum. In the horse ileum, lacteals in the villi are continuous with prelymphatic intercellular channels and a plexus of lymphatic sinuses in the lamina propria that encircle the domes of the follicle/dome structures and proprial follicles. These sinuses may act as the major entry site for many of the lymphocytes migrating from gut-associated lymphoid tissue via the lymphatic system. Vessels from this plexus penetrate the muscularis mucosae and lymph flows into lymphatic vessels within the interfollicular tissue between the follicles of both follicle/dome structures and lymphoglandular complexes (LGC...
Actinobacillus suis septicaemia in two foals. A 24-hour-old Hackney ony filly developed signs of weakness, depression and a poor suck reflex, with harsh lung sounds over both fields, and a 48-hour-old Arabian colt from a normal birth which had sucked vigorously developed loose stools and became depressed, weak and anorectic. Both foals had serum IgG concentrations greater than 800 mg/dl, but each had a severe neutropenia with a left shift, and blood cultures from both of them yielded Actinobacillus suis. The A suis isolates had different antimicrobial susceptibility patterns and, in the case of the Arabian, the isolate was resistant to co...
Attempts to find phenotypic markers of the virulence plasmid of Rhodococcus equi. Four isolates of Rhodococcus equi, from pneumonic foals, and containing the 85 kb virulence plasmid, a porcine isolate containing an 80 kb plasmid, and their plasmid cured derivatives, were examined for 239 phenotypic properties in an attempt to find characters other than the virulence-associated protein (VapA) which might be encoded by the virulence plasmid in organisms grown at 37 degrees C. Tests chosen included those which have previously given variable results for R. equi isolates, since such variability might be attributed to plasmid curing, and characteristics which have been described ...
