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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.
Effects of season and lower ambient temperature on the structure of the sweat glands in anhidrotic horses. Histological studies of the sweat glands of anhidrotic horses in the Hong Kong summer and under conditions of reduced thermal stress, both natural and controlled, were undertaken to determine if glandular regeneration occurs. Clinical data were collected for comparison with the histological results in each instance. Horses were assigned to one of three categories on the basis of the resulting change in the number of thin glandular profiles in a cooler environment. Group 1, which was classed as normal, had a low initial value, which was maintained. Group 2, typical of mild and moderately affect...
Radiographic measurement from the lateromedial projection of the equine foot with navicular disease. Radiographic measurements from the lateromedial projection of the equine foot were compared in three groups of horses. Group 1 consisted of 143 normal horses, group 2 were 60 horses with clinical navicular disease and group 3 were 161 horses with clinical and radiographic navicular disease. Several measurements tended to be larger in group 3 than group 1. An enlargement of the navicular bone was observed in proximodistal and dorsopalmar directions. Partial enlargement of the pedal bone was observed in groups 2 and 3. Few differences were observed between age classes. All horses aged four years...
Origin of the hemagglutinin on A/Equine/Johannesburg/86 (H3N8): the first known equine influenza outbreak in South Africa. A severe influenza outbreak occurred in horses in South Africa in 1986. The causative agent was identified as an influenza virus [A/Equine/Johannesburg/86 (H3N8)]. Antigenic analyses of the hemagglutinin (HA) with ferret antisera and monoclonal antibodies showed that the Eq/Johannesburg/86 virus is similar to recent equine H3 viruses. The nucleotide sequence analysis on the HA genes of Eq/Johannesburg/86 and other equine H3 influenza viruses, together with the epidemiological data, clearly demonstrated that the Eq/Johannesburg/86 virus was derived from a virus that had been circulating in hors...
Serum vitamin E and blood glutathione peroxidase values of horses with degenerative myeloencephalopathy. Serum vitamin E and blood glutathione peroxidase values were determined in 40 horses with a histologically confirmed diagnosis of degenerative myeloencephalopathy and in 49 age-matched control horses with normal neurologic function. Significant differences were not detected in serum vitamin E or blood glutathione peroxidase values between horses affected with degenerative myeloencephalopathy and control horses. These findings fail to support a reported role of vitamin E deficiency as a cause of equine degenerative myeloencephalopathy.
Lipopigments in veterinary pathology: pathogenesis and terminology. The lipopigments are a heterogenous group of pigments whose pathogenesis and terminology is confused. Whereas there is epidemiological and observational evidence that ceroid is derived from degeneration and peroxidation of unsaturated lipid, the assumption that all so-called lipopigments are similarly formed, is questioned. In particular, recent studies have distanced the pathogenesis of the pigment found in the ceroid-lipofuscinoses from that perceived for ceroid. The importance of protein rather than lipid in the pathogenesis of the pigment of ceroid-lipofuscinosis and of age pigment from th...
[Histochemical changes in skeletal muscles of racehorses susceptible to rhabdomyolysis after exertion. II. Later myopathological and regeneration phenomena]. Needle biopsies from m. gluteus medius of 22 horses which had suffered from repeated attacks of exertional myopathy were studied at various times after an attack, to determine if metabolic alterations can be demonstrated by enzyme histochemistry. Morphological changes and activity of 25 enzymes were studied. Immediately after onset of an attack, some large rounded fibres with a defect of the oxidative phosphorylation were seen. After some hours these fibres lost their glycolytic enzyme activity, followed by disappearance of mitochondrial enzyme activity with accumulation of Ca2+-containing sub...
Survival of day-4 embryos from young, normal mares and aged, subfertile mares after transfer to normal recipient mares. The estimated embryonic loss rate between Days 4 and 14 after ovulation for young, normal mares (9%) was significantly lower (P less than 0.01) than the estimated embryonic loss rate for aged subfertile mares (62%). Fertilization rates, which were based on the recovery of embryos at Day 4 after ovulation, were 96% and 81% (P less than 0.1) for normal and subfertile mares, respectively. Day-4 embryos were collected from the oviducts of normal and subfertile donors mares. These embryos were transferred to the uteri of synchronized, normal recipient mares to test the hypothesis that the high inci...
Surgery of the penis and prepuce. Treatments of penile and preputial injuries, anomalies, tumors, "summer sores," paraphimosis, phimosis, and priapism are presented. Surgical procedures described include preputiotomy, reefing, penile retraction, amputation, and relocation. Treatment of hemospermia by means of urethrotomy is discussed.
Displacements, malpositions, and miscellaneous injuries of the mare’s urogenital tract. Although they are pivotal events in the continued production of new generations of horses, breeding and foaling are not without risk to the mare. This article reviews the accidents that can occur and result in injury, displacement, and malpositions of the urogenital tract of the mare.
Surgical management of foaling injuries. The great variety of pathologic conditions associated with the peripartum period in the mare emphasizes the need for close observation and evaluation of the mare's condition during this period. The temperament and strength of the mare and violence of parturition undoubtedly produce extreme intraabdominal pressures that result in (or enhance preexisting) pathologic changes. Although the exact etiology of many of these disease processes is unknown, careful observation with properly timed medical and/or surgical intervention could reduce the losses associated with the peripartum period.
Surgery for abnormal vulvar and perineal conformation in the mare. Reproductive failure in mares can present a challenge to the attending veterinarian. Although many causes of failure to conceive or to carry to term may be easy to diagnose and treat effectively, others may be difficult. In some cases, more than one problem will be present, and both medical therapy and surgical intervention will be required to achieve a successful outcome. Pneumovagina and its sequelae remain a common cause of reproductive failure in mares. Depending on the case involved, different surgical techniques may be required to correct the problem.
Hereditary junctional mechanobullous disease in a foal. Mechanobullous disease was diagnosed in a male Belgian foal that had sloughed hooves at 30 hours and at 6 and 12 days of age. Histologic and electron microscopic studies disclosed that lesions were the result of separation of the basal epithelial cell layer from the lamina densa of the basement membrane zone along the lamina lucida. Results of immunofluorescence on tissue specimens were negative for immunoglobulin deposition. The breeding history of the foal's dam indicated that the foal was produced from breeding of the mare to its full sibling stallion. This same mare had produced a female f...
Non-isotopic immunoassay drug tests in racing horses: a review of their application to pre- and post-race testing, drug quantitation, and human drug testing. We have introduced large scale non-isotopic immunoassay testing into pre- and post-race drug testing in racehorses. The technologies utilized are Particle Concentration Fluorescence Immuno Assay (PCFIA) and the one-step Enzyme Linked Immuno Sorbent Assay (ELISA). These technologies are rapid, inexpensive, and highly effective. On introduction into post-race testing in the Western United States, these ELISA tests exposed several previously undetected patterns of drug abuse. The drugs detected were buprenorphine, oxymorphone, mazindol, sufentanil and cocaine. This led to the suspension of a larg...
Susceptibility of cats to infection with Ehrlichia risticii, causative agent of equine monocytic ehrlichiosis. Eight adult cats were inoculated IV (n = 6) or SC (n = 2) with Ehrlichia risticii-infected P388D1 (continuous murine macrophage) cells or with E risticii released from P388D1 cells. Three additional cats were inoculated with organism-free P388D1 cultured monocytes, and 1 cat, which served as a medium control was inoculated with balanced salt solution. Clinical signs of illness were observed in the IV inoculated cats from which E risticii was isolated. One cat developed intermittent diarrhea between postinoculation days (PID) 8 and 18, and the other cat developed lymphadenopathy, acute depressi...
Molecular pathogenesis of equine coital exanthema: identification and expression of infected cell polypeptides at the restricted temperature during equine herpesvirus 3 infection. Equine herpesvirus 3 (EHV-3)-infected equine cells display a kinetics of infected cell polypeptide (ICP) synthesis at 34 degrees C that is typical of coordinate cascade gene regulation of herpesviruses. In contrast, when infected cell cultures are incubated at the restricted temperature of 39 degrees C, the shift from early (beta) gene expression to late (gamma) gene expression is perturbed, i.e., there is an accumulation of early (beta) gene products and a decrease in, or absence of, late (gamma) gene products. Some of the affected late (gamma) gene products may be glycoproteins since these I...
Effects of atropine in ponies with recurrent airway obstruction. The effects of atropine on lung function and airway reactivity in two groups of ponies were measured. Principal ponies had a history of recurrent airway obstruction when housed in a barn and fed hay; control ponies had no history of airway obstruction. Principal and control ponies were paired, and measurements were made when principal ponies were in clinical remission (period A) and during an acute attack of airway obstruction (period B). Atropine did not alter pulmonary resistance (RL), dynamic compliance (Cdyn), or airway responsiveness in either group of ponies at period A or in the control...
Leukoencephalomalacia in a horse induced by fumonisin B1 isolated from Fusarium moniliforme. Each of two horses was dosed by stomach tube with culture material on maize of Fusarium moniliforme MRC 826. One horse developed severe hepatosis and mild oedema of the brain after 6 doses of 2.5 g of culture material/kg body mass/day in 7 days. The second horse, in a similar experiment but at a dosage rate of 1.25 g/kg/day, developed mild hepatosis and moderate oedema of the brain. In both animals the brain oedema was particularly noticeable in the medulla oblongata. The mycotoxin fumonisin B1 was extracted and purified from the culture material of F. moniliforme MRC, 826 which contained appr...
Prevalence of Anoplocephala perfoliata in horses and ponies in Clwyd, Powys and adjacent English marches. The prevalence of Anoplocephala perfoliata in 103 horses and ponies from Clwyd, Powys and the adjacent English marches, slaughtered during January 1987, was 69 per cent.
Hematochezia attributable to cranial mesenteric arterial aneurysm with connecting tracts to cecum and ileum in a horse. A cranial mesenteric arterial aneurysm with fistulous tracts to the cecum and ileum was discovered in a Missouri Fox Trotter stallion. The principal clinical sign was hematochezia, observed at 7- and 10-day intervals. The lesion may have been attributable to arteritis caused by fourth-stage larvae of Strongylus vulgaris.
[2 cases of colonic pbstipation in ponies, probably as a sequela of a treatment with Taktic]. Within a one-year period two ponies were operated on because of colon impaction. The two ponies had each been treated with Amitraz (Taktik) quite recently. In view of findings reported in the literature, the colon impaction in these two ponies was very likely to have been due to treatment with Taktik.
[Pathogenesis and drug therapy of acute laminitis in horses: a literature review]. Impairment of the microcirculation in the distal part of the foot is an important factor in the aetiology of equine laminitis. To prevent the development of chronic laminitis and the resulting complications, two new therapeutical principles were tested in the treatment of acute laminitis. Thrombosis which frequently occurs in the corium of the foot, could be controlled by administration of anticoagulants such as heparin. Alpha-receptor blocking agents such as phenoxybenzamine were used, to improve the peripheral blood flow. The use of these drugs and that of anti-inflammatory agents during the...
Clinical, histopathological, and immunological responses of ponies to Ehrlichia sennetsu and subsequent Ehrlichia risticii challenge. Ehrlichia risticii has a close antigenic relationship to E. sennetsu. Sera of ponies experimentally infected with E. risticii, the etiologic agent of Potomac horse fever, consistently reacted with E. sennetsu, a human pathogen, in indirect fluorescent-antibody (IFA) testing, while human E. sennetsu convalescent serum reacted with E. risticii by IFA testing and immunoferritin labeling of cells infected in vitro. Two ponies injected intravenously with live E. sennetsu did no develop clinical illness. Subsequent injection with live E. sennetsu did not develop clinical illness. Subsequent injectio...
Kairi virus identified from a febrile horse in Argentina. A virus isolated from the blood of a febrile horse in Argentina was identified as a strain of Kairi virus. This is the fifth Bunyamwera serogroup virus isolated from livestock and wild animals in the Americas. Bunyamwera serogroup viruses have been isolated from febrile humans in the Americas and Africa.
Preferred landing sites of Culicoides species (Diptera: Ceratopogonidae) on a horse in Israel and its relevance to summer seasonal recurrent dermatitis (sweet itch). Six hundred and twenty culicoides of five species were collected from a bait horse at Kannot, Israel, between April and September 1986. Seventy-two per cent of the midges were collected from the belly and 27 per cent from the dorsal aspect of the body, ie, the sweet itch summer seasonal recurrent dermatitis (SSRD) zone. Midges were active mainly from half an hour prior to half an hour after sunset. Only Culicoides puncticollis, C imicola and C schultzei group were collected in considerable numbers. While C imicola was present continuously throughout the season, the appearance of the two other ...
BCG emulsion immunotherapy of equine sarcoid. Of 61 horses with sarcoids treated with intralesional injection of a double emulsion incorporating inactivated bacillus Calmette Guérin organisms, 36 (59 per cent) showed complete regression and 11 (18 per cent) showed partial regression. The majority of cases required only one treatment. Not all sarcoids were responsive to this therapy; those not responding were usually large or on horses with multiple sarcoids.
Prevalence of Eimeria leuckarti (Flesch, 1883) and intensity of faecal oocyst output in a herd of horses during a summer grazing season. The prevalence of Eimeria leuckarti infection and the intensity of faecal oocyst output were determined in a herd of 14 mares and their foals in northwest Germany using a sedimentation technique at weekly intervals during a summer grazing season from May to September. None of the mares, but all foals shed oocysts on at least one occasion. The patent periods lasted up to 16 weeks. The mean intensity of oocyst output (0.1-33 o.p.g.) was very low. No clinical signs of gastrointestinal disorder were noticed in any of the foals during this study.
Equine neutrophil locomotion in response to Streptococcus zooepidemicus. The neutrophil is involved in the defence of the mare's uterus against micro-organisms. The ability of Streptococcus zooepidemicus and its growth products to induce shape changes or directional locomotion (chemotaxis) of equine neutrophils was investigated; no effect was found.
