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Topic:Disease Etiology
Disease etiology in horses refers to the study of the causes and development of diseases within equine populations. It encompasses various factors, including genetic predisposition, environmental influences, infectious agents, and nutritional imbalances, that contribute to the onset and progression of diseases in horses. Understanding disease etiology is essential for identifying risk factors and implementing preventative measures in equine health management. This topic includes research on pathogen-host interactions, the impact of management practices on disease incidence, and the role of genetic and environmental factors in disease susceptibility. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, contributing factors, and implications of disease etiology in horses.
Transient alteration in intestinal permeability to technetium Tc99m diethylenetriaminopentaacetate during the prodromal stages of alimentary laminitis in ponies. To determine whether mucosal permeability is altered during the prodromal stages of alimentary laminitis. Methods: 15 healthy adult ponies. Methods: intestinal permeability was evaluated for control ponies (n = 5) and for ponies 4 to 12 (n = 5) and 20 to 28 (n = 5) hours after administration of carbohydrate overload. Mucosal permeability was determined by measuring the percentage of orally administered technetium Tc99m diethylenetriaminopentaacetate (99mTc-DTPA) excreted in urine during an 8-hour period, then measuring blood radioactivity at hourly intervals. Plasma endotoxin-like activity was...
Localisation of gelatinase activity in epidermal hoof lamellae by in situ zymography. In situ gelatin zymography is a technique, which utilises a gelatin-based emulsion overlay to detect and, more importantly, localise the gelatinase activity in underlying tissue. Gelatinase A [matrix metalloproteinase-2 (MMP-2)] and gelatinase B [matrix metalloproteinase-9 (MMP-9)] are present in equine hoof homogenates and supernatants from cultured hoof explants by SDS-PAGE gelatin zymography, and it has been assumed that the enzymes are derived solely from matrix and epithelia and not from other sources such as leucocytes. Using in situ zymography, gelatinases are shown to be localised with...
Immunohistochemical studies in equine recurrent uveitis (ERU). Despite extensive clinical research, the etiology of equine recurrent uveitis (ERU) is still unknown. After an immunologic pathogenesis was established in recurrent uveitis in humans, a similar pathogenic mechanism was assumed to exist in ERU. To investigate whether immunopathologic mechanisms are involved in ERU, 20 eyes of 15 horses with ERU were examined immunohistochemically with a T cell marker, B cell marker, and anti-major histocompatibility complex (MHC) class II antibodies. Twenty-six eyes of 20 horses were used for investigation of MHC class II antigen expression in normal equine eye...
Diagnosis and sero-epizootiology of equine herpesvirus type 1 and type 4 infections in Japan using a type-specific ELISA. Recently, a type-specific ELISA using equine herpesvirus type 1 (EHV-1) and type 4 (EHV-4) glycoprotein Gs (gGs) was developed by Crabb and Studdert [1993]. To investigate the dissemination of EHV-1 and -4 among horses in Japan, we applied their ELISA as suitable for discriminating between EHV-1 and -4 infections serologically. Type-specificity of the ELISA was confirmed by using paired sera of infected horses with either EHV-1 or -4. Application of the ELISA to sera collected before and after the winter season of 1995-1996 from 80 racehorses revealed that 30 horses showed significant antibody...
Pathogenesis of Babesia caballi infection in experimental horses. The present study was designed to investigate the role of cytokines in the pathogenesis of Babesia caballi in experimentally infected horses. The expression of cytokine mRNA was determined by using reverse transcription-polymerase chain reaction in two B. caballi-infected horses for 2 weeks after the infection. In one horse, there was up-regulation of interferon-gamma, tumor necrosis factor-alpha (TNF-alpha) and interleukin-2 mRNAs, while in the second horse, expression of only TNF-alpha mRNA was up-regulated. No change was observed in interleukin-4 mRNA in both of the horses. To know the rela...
Equine infectious anemia virus Gag polyprotein late domain specifically recruits cellular AP-2 adapter protein complexes during virion assembly. We have identified an interaction between the equine infectious anemia virus (EIAV) late assembly domain and the cellular AP-2 clathrin-associated adapter protein complex. A YXXL motif within the EIAV Gag late assembly domain was previously characterized as a sequence critical for release of assembling virions. We now show that this YXXL sequence interacts in vitro with the AP-50 subunit of the AP-2 complex, while the functionally interchangeable late assembly domains carried by the Rous sarcoma virus p2b protein and human immunodeficiency virus type 1 p6 protein, which utilize PPPY and PTAPP ...
Public veterinary medicine: public health. Serologic evaluation of vesicular stomatitis virus exposure in horses and cattle in 1996. To determine potential risk factors for vesicular stomatitis (VS) in Colorado livestock in 1995 and evaluate VS virus (VSV) exposure of Colorado livestock in 1996. Methods: Retrospective case-control study of VS risk factors and seroprevalence evaluation. Methods: Premises included 52 that had VS-positive animals and 33 that did not have VS-positive animals during the 1995 epidemic, and 8 in the vicinity of premises that had VS-positive animals during the 1995 epidemic. Methods: Layout and management data for premises were collected during site visits in 1996. Signalment and management data we...
Equine SCID: mechanistic analysis and comparison with murine SCID. V(D)J rearrangement is the molecular mechanism by which an almost limitless number of unique immune receptors is generated. V(D)J rearrangement involves two DNA breaks and religations resulting in two DNA joints; coding and signal joints. If V(D)J recombination is impaired (as in murine SCID (C.B-17 mouse] or RAG [Recombinase Activating Genes) deficient mice), B lymphocyte and T lymphocyte development is blocked and severe immunodeficiency results. The first animal model of SCID was reported in Arabian foals in 1973. Recently we demonstrated that the mechanistic defect in SCID foals is V(D)J r...
Interaction of transforming growth factor-beta-1 with alpha-2-macroglobulin from normal and inflamed equine joints. Binding between equine plasma alpha-2-macroglobulin (alpha 2M) and several cytokines known to participate in inflammatory reactions in other species was initially examined. Plasma was obtained from 5 horses with various abnormalities. Samples, both untreated and after reaction with methylamine, were incubated with exogenous, radiolabeled, porcine-derived transforming growth factor-beta-1 (125I-TGF-beta 1), recombinant human interleukin-1-beta (125I-IL-1 beta), and recombinant human tumor necrosis factor-alpha (125I-rhTNF-alpha). They were then subjected to nondenaturing polyacrylamide gel elec...
Prevalence and risk factors of bone spavin in Icelandic horses in Sweden: a radiographic field study. The present field study was performed to estimate the prevalence of radiographic signs of bone spavin (RSBS) and to evaluate some possible risk factors for RSBS in the Icelandic horse in Sweden. The survey included horses from 11 farms involving 379 horses, comprising 238 geldings, 125 mares and 16 stallions. Age ranged from 0 to 19 years with a mean age of 8.1 years. Horses were radiographed with a dorsolateral-plantaromedial-oblique projection of both tarsi. Information about age, gender, origin, working intensity, number of gaits and age when saddle broken were obtained by interviewing the ...
Influence of fecal shedding of Salmonella organisms on mortality in hospitalized horses. To predict mortality of horses by use of clinical data from the first day of hospitalization, to determine whether fecal shedding of Salmonella organisms is related to severity of clinical disease, and to determine the impact of fecal shedding of Salmonella organisms on mortality. Methods: Prospective study. Methods: 1,446 hospitalized horses. Methods: Medical information was obtained from horses hospitalized in an intensive care unit or isolation facility during a 4.5-year period. A model was created to predict mortality, using covariates determined on the day of admission. Predicted mortalit...
Actinobacillus and Pasteurella species isolated from horses with lower airway disease. Seventy-three bacterial isolates from 65 horses with and without evidence of lower airway disease were identified to assess whether the association with disease was accounted for by a small or large number of species. Just over half (50.5 per cent were Actinobacillus equuli, 17.8 per cent were A suis-like, 11 per cent were Pasteurella pneumotropica, 8.2 per cent were A lignieresii, 6.8 per cent were P haemolytica and 5.5 per cent were P mairii. These results suggest that a range of Actinobacillus and Pasteurella species can be isolated from the lower airways of horses, with many of the isolate...
The 1996 outbreak of African horse sickness in South Africa–the entomological perspective. During the 1996 summer season (January-April) in South Africa an estimated 500 horses died of African horse sickness (AHS); 80% of deaths were due to AHS virus serotypes 2 and 4. Nearly all cases occurred in the northern, north-eastern and central parts of South Africa. This study reports the first attempt to verify the involvement of the biting midge Culicoides imicola in a field outbreak of AHS in southern Africa. In light-trap collections made at 47 sites over 12 weeks, C. imicola comprised 94.2% of 4.78 million Culicoides. Culicoides imicola was the most prevalent of 34 species captured an...
Epidemiology of African horse sickness and the role of the zebra in South Africa. Zebra are the only equine species native to South Africa. These animals roamed over much of the country in the 17th century when horses and donkeys were first imported. The first cases of African horse sickness (AHS) then occurred in the horses of hunters who entered zebra territory. AHS continued to occur on a country-wide basis until the beginning of the 20th century, though the number of outbreaks decreased as the populations of zebra collapsed through overhunting. For most of the 20th century almost all free-living zebra have been confined to the north-eastern parts of South Africa which a...
Clinical, serologic, and histopathologic characterization of experimental Borna disease in ponies. Borna disease was originally described as an equine neurologic syndrome over 200 years ago, although the infectious etiology of the disorder was unproven until the early 20th century. Borna disease virus (BDV) was finally isolated from horses dying of the disorder, and that virus has been used to experimentally reproduce Borna disease in several species of laboratory animals. However, BDV has never been inoculated back into horses to experimentally and etiologically confirm the classic clinical, pathologic, and serologic characteristics of the disease in that species. Three ponies were intrace...
Changes in plasma protein concentrations in ponies with experimentally induced alimentary laminitis. To determine whether plasma protein concentrations were altered in ponies with alimentary laminitis. Methods: 12 adult ponies. Methods: Acute laminitis was induced in 6 ponies by oral administration of carbohydrate (85% corn starch, 15% wood flour); the other 6 ponies were used as controls. A physical examination was performed and blood samples were collected immediately before and 4, 8, 12, 24, and 28 hours after administration of carbohydrate. Plasma protein concentrations were determined by means of sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Results: 19 plasma proteins rang...
A cluster of equine granulomatous enteritis cases: the link with aluminium. A cluster of 6 cases of equine granulomatous enteritis is described. Aluminium was demonstrated in the tissues and lesions of these horses and in the intimal bodies of intestinal vessels. The relationship between granulomatous lesions, aluminium, acidity and invading microorganisms, particularly parasites, is presented and discussed.
Halicephalobus gingivalis (Stefanski, 1954) from a fatal infection in a horse in Ontario, Canada with comments on the validity of H. deletrix and a review of the genus. Although the original description given by Stefanski (1954) was satisfactory, Anderson & Bemrick (1965), in describing H. deletrix (= Micronema deletrix), claimed Stefanski's description was "inadequate" and the species a "species inquirenda". Thus, infections in horses and humans have been assigned to H. deletrix. We believe the species reported in horses and humans is H. gingivalis and that H. deletrix is its synonym. H. gingivalis is separated herein from forms found free-living. The genital tract in the advanced fourth stage of H. gingivalis is didelphic and amphidelphic and terminal e...
Getah virus infection of Indian horses. An outbreak of disease, characterized by depression, anorexia, fever, limb oedema and lymphocytopenia, occurred on a farm for thoroughbreds in India in 1990. Twenty-six of the 88 horses on the farm were affected, predominantly adults. Signs were present in affected horses for 7-10 days, and the outbreak lasted 21 days. Seven of the 26 affected horses were tested for exposure to Getah virus using paired serum samples, acute and convalescent. Four of the 7 horses seroconverted to Getah virus, and the other three showed a 4-fold or greater rise in titre. The clinical and laboratory findings were ...
Equine TIMP-1 and TIMP-2: identification, activity and cellular sources. Matrix metalloproteinases (MMPs) are the main enzymes involved in connective tissue turnover. Regulation of MMPs is achieved by controlling production, activation of the pro-enzymes together with the presence of inhibitors, such as, tissue inhibitors of metalloproteinases (TIMPS). The presence of TIMPs in equine synovial fluid was assessed by the ability of the fluid to inhibit equine MMP-9 activity using a gelatin degradation ELISA. The cellular source of the TIMPs was determined using culture supernatants of resident articular cells (chondrocytes and synovial fibroblasts) and invading inflam...
Cytology of 100 samples of abdominal fluid from 100 horses with abdominal disease. A total of 100 samples of abdominal fluid (AF) from 100 horses with abdominal disease were evaluated by cytology. Cytology results were subsequently correlated with the final outcome of the disease. The horses were classified into 4 groups: Group I, horses that were treated with conventional (nonsurgical) therapy and recovered; Group II, horses that had surgery and survived; Group III, horses that had surgery but died; and Group IV, horses that were subjected to euthanasia prior to surgery. Statistical analysis showed that both nucleated cell count and total neutrophils were significantly high...
Farm and animal exposures and pediatric brain tumors: results from the United States West Coast Childhood Brain Tumor Study. Nineteen counties from San Francisco and Los Angeles, California and Seattle, Washington were the United States sites for a large population-based case-control study of childhood brain tumors (CBTs), sponsored by the National Cancer Institute. CBT patients who were 1 year and were first on a farm when they were < 6 months of age also had increased risk for CBTs (OR = 3.9, 95% CI = 1.2-13). A somewhat increased risk for CBTs was found for children of mothers who ever had worked on livestock farms compared with mothers who never had worked on a farm (OR = 7.4, 95% CI = 0.86-64, based on five...
Complications of balloon catheterization associated with aberrant cerebral arterial anatomy in a horse with guttural pouch mycosis. A 3-year-old Quarter Horse gelding was treated for left guttural pouch mycosis by ligation and balloon catheterization of the left internal carotid artery. Catheter advancement was shorter (10 cm) than the normally reported distance (13-15 cm), but was observed endoscopically during placement as it coursed within the internal carotid artery through the guttural pouch. The horse developed a persistently abnormal respiratory pattern after catheter placement, failed to gain consciousness, developed pulmonary edema, and died 5.5 hours postoperatively. Postmortem examination revealed an aberrant le...
Pathophysiology of acquired dental diseases of the horse. Periodontitis, infundibular necrosis, and periapical infection are dental diseases commonly affecting adult horses. Routine dental examinations and care may help to prevent these diseases. Further investigation of the treatment of horses with these diseases using local antimicrobial therapy, restorative dentistry, and endodontic therapy is needed. An understanding of the pathogenesis of these diseases aids in diagnosis and treatment. Gingival hyperplasia and odontogenic tumors are uncommon but should remain in a list of differential diagnoses when examining a horse with pertinent clinical sign...
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...
Retinal degeneration associated with vitamin E deficiency in hunting dogs. A group of Walker Hounds and Beagles that were fed a diet of table scraps were examined because of slow, progressive loss of vision. Clinical and microscopic features of the disease were correlated to the dogs' micronutrient status. Sensory retinal degeneration, predominantly in the central tapetal fundus, was found in all dogs, and severity of changes varied with age of the dog. Plasma, serum, and tissue concentrations of vitamin E were low in affected dogs (10 to 40% of control values). Lipofuscin accumulation was found on microscopic examination in retinal pigment epithelium, smooth muscle ...
