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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.
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 ...
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 ...
An outbreak of equine leukoencephalomalacia at Oaxaca, Mexico, associated with fumonisin B1. Equine leukoencephalomalacia (ELEM), swine pulmonary oedema and human oesophageal cancer have been associated with fumonisine B1 (FB1) ingestion. For the first time in this study it is reported that FB1 was identified as being associated with an outbreak of ELEM at Oaxaca, Mexico. Symptoms of ELEM and Equine Venezuelan Encephalitis (EVE) are similar and a different diagnosis is obligatory. In the geographical area (Oaxaca, Mexico) where donkeys died showing a neurological syndrome, 14 corn samples were collected. With the use of TLC (Thin layer chromatography) and HPLC (High performance liquid...
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...
Renal failure, laminitis, and colitis following severe rhabdomyolysis in a draft horse-cross with polysaccharide storage myopathy. A Thoroughbred-Percheron crossbred gelding developed a fulminant cascade of sequelae following a severe episode of rhabdomyolysis. Complications may occur with rhabdomyolysis of any etiology. In warmblood horses with Percheron bloodlines, rhabdomyolysis may be secondary to polysaccharide storage disease, and aggressive therapy should be undertaken promptly to avoid the complications.
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.
A case-control study of grass sickness (equine dysautonomia) in the United Kingdom. A case-control study was performed to investigate the epidemiology of grass sickness in the United Kingdom from 1992 to 1995. Data were collected by means of postal questionnaire when cases of grass sickness were identified. Sets of three questionnaires were posted to owners of, or veterinary surgeons attending, cases of grass sickness, with a request to provide information on the case, on one healthy animal on the same premises as the case and on another healthy animal on other premises. Controls were matched to cases by date of onset. After univariate analyses, the probability of grass sickn...
Inhaled leukotrienes cause bronchoconstriction and neutrophil accumulation in horses. Leukotrienes have been shown to mimic many of the pathophysiological processes in allergic airway disease. In this study the bronchoconstrictor effect of inhaled LTD4, and radiolabelled neutrophil accumulation in response to inhalation of LTB4, have been examined in the horse. In separate studies, solutions of LTD4 and LTB4 were administered to the airways of normal animals by nebulisation. LTD4, but not LTB4, caused a dose-dependent increase in pleural pressure which was maximal at three to four minutes and had returned to baseline by 15 to 20 minutes. On a molar basis LTD4 was 305 to 970 tim...
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...
Fusion pore expansion in horse eosinophils is modulated by Ca2+ and protein kinase C via distinct mechanisms. Using the patch-clamp technique, we studied the role of protein phosphorylation and dephosphorylation on the exocytotic fusion of secretory granules with the plasma membrane in horse eosinophils. Phorbol 12-myristate 13-acetate (PMA) had no effect on the amplitude and dynamics of degranulation, indicating that the formation of fusion pores is insensitive to activation of protein kinase C (PKC). Fusion pore expansion, however, was accelerated approximately 2-fold by PMA, and this effect was abolished by staurosporine. Elevating intracellular Ca2+ to 1.5 microM also resulted in a 2-fold accelera...
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...
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... 
