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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.
Dirofilariasis with arteriosclerosis in a horse. Arteriosclerosis caused by Dirofilaria immitis adult parasites was diagnosed in a 20-month-old Quarter horse stallion that died from cantharidin toxicosis. Microscopically, the pulmonary vascular changes were typical of those described as "proliferative endarteritis" in D immitis-infected dogs.
Equine hydatidosis: a new record for New Zealand. Cysts found in the liver of a horse which had never been out of New Zealand were used to infect two dogs which were slaughtered 35 days after infection. Large numbers of Echinococcus granulosus were recovered. These cestodes were compared with mature dog-sheep cestodes, using light and scanning electron microscopy and identified as the dog-horse strain of E.granulosus.
Equine adenovirus 1 isolated from cauda equina neuritis. Equine adenovirus 1 was recovered after four to six passages from two out of three cases of cauda equina neuritis (CEN) using kidney monolayers. Similar treatment of lumbo-sacral spinal cord from six normal horses did not yield adenovirus. All three cases of CEN had antibodies to the neuritogenic myelin protein P2 while immunofluorescence demonstrated that autologous IgG bound to the myelin of affected nerves. Adenovirus was not detected in neural tissue by immunofluorescence.
Aetiology and pathogenesis of congenital torticollis and head scoliosis in the equine foetus. In 214 cases of severe dystocia in mares, of which 141 (66 per cent) were Draught horses, deviation of the head and neck, with or without torticollis, malformed head and limbs were found to be the cause of dystocia. No evidence of a genetic lethal factor was found and torticollis was often combined with scoliosis of the head and, frequently, with malformation of one or more limbs. This is considered evidence of a common aetiology and pathogenesis of the syndrome of malformation. The malformations were found to be associated with an increased incidence of caudal and, particularly, transverse pr...
Ulcerative colitis and protein losing enteropathy associated with intestinal salmonellosis and histoplasmosis in a horse. Ulcerative colitis, protein losing enteropathy and intestinal histoplasmosis-salmonellosis were diagnosed in a six-year-old Quarterhorse stallion. For six months before examination, the horse experienced a slow continual loss of weight. During the 17 day period of hospitalisation the horse developed progressive generalised oedema. On the 12th day of hospitalisation a severe profuse watery diarrhoea began; the horse was killed five days later.
A health index to evaluate clinically a beta-hemolytic streptococcal infectious disease model in the horse. Quantification of the clinical manifestations of a disease has been a serious problem particularly as related to clinical trials or drug efficacy studies. Historically, this quantification has been limited to categorizing each patient into one of three or four groups, e.g. worse, no improvement, improved. This problem becomes serious when an investigation utilizes an experimentally induced animal disease model. A health index, which quantifies the clinical state of horses which have an experimentally induced beta-hemolytic streptococcal infection, is described. Aspects of experimental design a...
Congenital phalangeal hypoplasia in Equidae. Three cases of unilateral congenital phalangeal hypoplasia are described in 2 horses and 1 mule. Radiographic lesions include severe hypoplasia of the 3rd phalanx, and associated hypoplasia of the 2nd phalanx in 2 cases, and hypoplasia or aplasia of the navicular bone in 2 cases. All animals could ambulate but were lame. Two cases had palpable laxity at the level of the coronary band. Documented etiology was not determined for the dysgenesis, but possibilities include inherited transmission or an environmental teratogen.
[Findings of Corynebacterium equi Magnusson 1923 in connection with foal mortality in the Eastern Bohemia Region]. A case history of mass foal disease which affected ten of the total stock of 50 foals and killed eight is described. The disease was characterized by respiratory disorders and extensive pneumonias with abscess formation, metastatic abscesses in mesenterial lymph nodes and in other organs. As a result of the examination of two dead foals and three nasal smears from diseased animals, gram-positive bacteria were isolated from the lungs, pulmonary and abdominal abscesses and the nasal smears of the affected foals; with their cultivation, morphological and biochemical characteristics these bacteria...
Antigenic variation during persistent infection by equine infectious anemia virus, a retrovirus. The recurrent nature of equine infectious anemia has been attributed to relatively rapid antigenic variations in equine infectious anemia virus (EIAV) during persistent infection under selective immune pressures. This model was tested by serological and biochemical analysis of virus isolates recovered from separate febrile episodes in two experimentally infected ponies. Neutralization assays employing immune sera from the experimentally infected ponies demonstrated that distinct antigenic strains of virus predominate during sequential febrile episodes in a single pony. Analysis of the test str...
Haematological and biochemical values in horses naturally infected with Strongylus vulgaris. The concentrations of serum proteins (beta 1, beta 2, gamma, alpha 1, alpha 2 globulins and albumin) and absolute numbers of eosinophils, neutrophils and lymphocytes were examined in 64 naturally infected horses and ponies in which the number of larvae of Strongylus vulgaris in the cranial mesenteric artery and the severity of the lesion of verminous arteritis could be determined. The horses were grouped according to the number of larvae found and the severity of the arteritis. The results demonstrated that, although some significant deviation from a random distribution occurred in certain of ...
Acute diarrhea in horses of the Potomac River area: examination for clostridial toxins. Fecal specimens from horses in Montgomery County, Md, and in Fairfax and Loudoun counties, Va, were examined for Clostridium perfringens type A enterotoxin and for C difficile cytotoxin (92 and 108 specimens, respectively). The toxins were found in feces from horses that had experienced an acute diarrhea syndrome and from clinically normal horses. The toxins did not appear to be primary determinants of the diarrhea syndrome, although they may have contributed to the spectrum of clinical entities observed.
The regulatory peptide system of the large bowel in equine grass sickness. In recent years, distinct changes in regulatory peptides have been found in a number of gastrointestinal diseases. Grass sickness is a fatal disease of horses for which the etiology has yet to be fully ascertained. In this study, the peptide-containing nerves and ganglionic and mucosal endocrine cells of the ileum, colon and rectum were investigated in horses with sub-acute or chronic grass sickness and compared with normal controls using immunocytochemistry, at both the light and electron microscopical levels, and radioimmunoassay. A substantial loss of both peptide-containing cells and nerve...
Prevalence of Onchocerca cervicalis in equids in the Gulf Coast region. Microfilariae of Onchocerca cervicalis were detected in midventral skin biopsy samples in 64 of 84 (76%) mixed-breed ponies greater than 2 years old from the Gulf Coast area and in 42 of 51 (82.4%) horses from Louisiana breeding herds. The number of microfilariae per 8 mm of biopsied skin (ponies) ranged from 1 to 21,570. The number of microfilariae per 6 mm of biopsied skin (horses) ranged from 8 to 55,600.
Identification of swainsonine as a probable contributory mycotoxin in moldy forage mycotoxicoses. When infested with the fungus Rhizoctonia leguminicola, certain forages, e.g., red clover hay, can cause a "slobber syndrome" of varying severity when consumed by ruminants. The causative agent has been presumed to be slaframine [(1S,6S,8aS)-1-acetoxy-6-aminooctahydroindolizine], which is produced by R. leguminicola. In one serious outbreak of the slobber syndrome in horses, the red clover forage involved was carefully examined and found to contain R. leguminicola and slaframine. An identical hay sample is shown here by ion-exchange chromatographic and gas chromatographic-mass spectrometric an...
Genomic alterations associated with persistent infections by equine infectious anaemia virus, a retrovirus. The unique periodic nature of equine infectious anaemia (EIA) is believed to result from the ability of the infecting virus. EIAV, to undergo relatively rapid antigenic variations which circumvent host immune responses resulting in distinct virus populations in sequential clinical episodes in the persistently infected horse. This model was examined by oligonucleotide mapping comparisons of the RNA genomes of selected isolates of EIAV. Variations in oligonucleotide maps could be reproducibly demonstrated (i) after adaptation of the laboratory strain of EIAV to replication in a pony, (ii) after ...
Considerations of copper metabolism in osteochondrosis of suckling foals. Of 8 Thoroughbred foals in which osteochondrosis developed before weaning, 7 had serum copper and ceruloplasmin concentrations below normal. Three foals on one farm had serum zinc content high enough to suggest zinc toxicosis, and the liver of each foal contained abnormally high content of zinc. Four foals from the second farm had extremely low serum copper content, but normal serum zinc content. Evidence of environmental exposure to excess zinc was not found on either farm. The lesions in the zones of endochondral ossification of the afflicted foals were similar in many respects to those foun...
Serratia spp infection in 21 horses. Twenty-three isolations of Serratia spp were made from 21 horses at the University of Florida Veterinary Medical Teaching Hospital between Jan 1, 1979 and July 1, 1983. Three Serratia spp were involved in single-organism and mixed infections of various tissues. Eight horses of this group died. All horses that died had massive, mixed, gram-negative infection. The other 13 responded to treatment, including systemic antibiotic therapy. Most of these horses were stressed and under antibiotic therapy prior to the time of culture. Possible nosocomial infection, variable antibiotic sensitivity, and a...
Studies on equine prematurity 4: Effect of salt and water loss on the renin-angiotensin-aldosterone system in the newborn foal. Plasma renin substrate concentration was measured in 18, four-day-old pony foals after the administration of the natriuretic agent frusemide. Thirteen foals had been delivered spontaneously; labour had been induced in the remaining five mares. Plasma aldosterone concentration was measured in 12 of the spontaneously delivered foals. Renin substrate concentration had risen sharply within 15 mins (P less than 0.005) and peaked at 1 h. The response was consistently greater in the induced foals. Serum sodium concentration fell rapidly in the induced foals (P less than 0.002 by 60 mins) but was bett...
