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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.
Twenty cases of equine osteoarthrosis detected at autopsy. A pathological study was performed on osteoarthrosis detected at autopsy in 20 horses whose ages ranged from 21 days to 17 years old. They were asymptomatic on the joints except in 3 animals, and autopsied after death or sacrificed due to accidental fracture or other diseases. Lesions of osteoarthrosis were recognized in all horses, which tended to increase in incidence and severity according to age. Lesions were concentrated at hinged joints such as the elbow, fetlock, and hock. Synovial fossae and ulcerative lesions were observed on each opposite articular cartilage, forming the so-called mi...
Phenothiazine in the origin of benzimidazole resistance in population-B equine strongyles. Clinical trials on a central Kentucky Thoroughbred Farm (B) during 1960-1961 involved nine test treatments of mares, yearlings and weanlings (n = 124), and compared efficacies of phenothiazine (PTZ), piperazine (PPZ), mixtures of PTZ + PPZ and thiabendazole (TBZ) for (1) percent reduction and (2) complete clearance or graded reduction of strongyle egg per gram (epg) counts. Three grades of PTZ (N.F. green, micronized purified and 2-3 microns purified) at the dose rate of 55 mg kg-1 were ineffective in six tests; reduction of strongyle epg count were low grade (26%) and complete clearance was f...
Amino acids in different layers of the matrix of the normal equine hoof. Possible importance of the amino acid pattern for research on laminitis. A method was developed for separating different layers of the matrix of the equine hoof wall by dissection, and the layers were then analyzed with respect to their amino acid composition. The results were used to compare the biochemistry of hard keratinization (e.g., in the hoof wall matrix) and soft keratinization (e.g., in the epidermis of the skin). Hard keratinization differed from soft keratinization not only by its previously well known high incorporation of cystine, but also by considerable incorporation of tyrosine and threonine into the outer layers of the keratogenous zone and by the...
Immunogenicity and allergenicity of Culicoides imicola (Diptera: Ceratopogonidae) extracts. Summer seasonal recurrent dermatitis (SSRD) or "sweet itch" is a seasonally occurring allergic dermatitis of horses provoked by biting midges. The allergic skin reactions have been attributed to allergens present in various Culicoides species. C. imicola is the suspected etiological agent of SSRD in Israel. Whole body extracts of this midge induced hypersensitivity reactions upon injection into susceptible horses and in this study attempts were made to define components of C. imicola which have immunogenic and allergenic properties. Immunogenic potency was evaluated by raising antisera to whol...
Pasture-associated seasonal respiratory disease in two horses. Two horses on separate farms developed severe obstructive pulmonary disease in successive years during the early summer months. In both cases clinical remission of the respiratory distress was achieved by moving the animals to different environments. The suggested aetiology for this outdoor chronic respiratory disease is a pulmonary allergy to pollen. Both animals were also shown to suffer from classical chronic obstructive pulmonary disease, i.e., obstructive pulmonary disease in the presence of hay and, or, straw.
Is there a morning-evening difference in egg production of bloodworms, strongyle parasites of equines? To test a claim that counts of the eggs of large strongyles or bloodworms, parasites of equines, are greater in morning fecal samples than in those from later in the day, and therefore, may be indicators of circadian variations in these worms, samples from one pony and nine horses were analyzed for strongyle eggs. Samples were collected twice per day, about 7:30 and again about 19:30, during two, 24-day periods. Individual counts varied from 0 to 1184. The mean of all 7:30 counts was 212.52; that of 19:30 counts was 236.03. The difference is not significant, and does not support the idea of ci...
[Current information on the subject of African horse sickness (AHS)]. The objective of the present review was to summarize current knowledge of African horse sickness (AHS), based on available literature (which is nonetheless relatively scant) and recent information obtained from the O.I.E. Brief description is made of the biology of AHS virus (an arbovirus, transmitted by Culicoides imicola), isolation of the agent, diagnosis by serotyping procedures, and preventive measures (such as protection of horses from insect infestation, or vaccination programs) which may be taken. The recent outbreaks in Spain, Portugal, and Morocco, have demonstrated that much more re...
Ectopic ureter in the horse: Three cases and a review of the literature. Ureterovesicular anastomosis resulted in resolution of the clinical signs of urinary incontinence in three horses with unilateral ectopic ureter. Follow-up of two of the horses ten months and three years later indicated no further urinary tract problems; the third horse died four days after surgery from intestinal infarction.Diagnosis can be readily confirmed by antegrade or retrograde ureterography, or endoscopic visualization of the ectopic ureteral openings. Nephrectomy appears indicated in cases of unilateral ectopic ureter with associated ipsilateral urinary tract infection or hydronephro...
Detection of African horsesickness (AHS) in recently vaccinated horses with inactivated vaccine in Qatar. Two 7-year old Arabian racing horses were reported to show typical AHS symptoms in Qatar and died shortly after. The horses had been vaccinated with formol inactivated vaccine approximately 10 days before the onset of the disease. Blood samples from these horses were collected and AHS virus isolated from one sample after intracerebral (i.c.) inoculation into suckling mice. The virus identity was confirmed by complement fixation test (CFT) using the virus antigen and reference type 9 of AHS virus hyperimmune serum. The serotype of the isolated virus was identified by serum neutralization test (...
Isolation of Clostridium perfringens from foals. Clostridium perfingens was isolated from four of 29 healthy foals and from all twelve foals with gastrointestinal diseases. The range of viable counts of C. perfringens in the faeces was 10(1)-10(5)/g and in the intestinal specimens 10(1)-10(7)/g. Of 41 isolates of C. perfringens, 37 were considered to be type A. Enterotoxin of the organism was demonstrated in the intestinal contents of five of eight foals with enteric diseases. These findings suggested that C. perfringens is a likely pathogen of foal intestinal diseases.
[Enzootic viral abortion on a stud farm in east Switzerland]. An outbreak of abortion due to the equine herpesvirus-1 (EHV-1) in the eastern part of Switzerland is reviewed. Seven of eleven pregnant mares aborted within twenty-three days in January 1989. Four weeks later another foal died a few minutes after parturition. Three mares delivered live foals in February, March and April without any complications. The examination of the eight dead foals revealed an EHV-1 Infection. The clinical signs and the pathology are discussed. Severe complications during the early post-parturient time are in contrast to the uncomplicated outcome mentioned by other author...
Feedtrough dirt as a source of Clostridium botulinum type C intoxication in a group of farm horses. Four horses from the same farm developed clinical signs of botulism during the winter months; three of these horses died. One horse survived an initial attack and recovered over a three-week period, but died during a second attack. The horse that survived took six weeks to recover. Clinical and postmortem examination ruled out other causes of disease. Confirmation of the diagnosis was made by isolation of Clostridium botulinum type C toxin from the dirt in the bottom of an oak feedtrough used by all horses, and from the colonic contents of one of the horses that died. To our knowledge, this is...
Temperature sensitivity of equine herpesvirus isolates: a brief review. This article reviews the findings on temperature sensitivity of equine herpesvirus isolates with an emphasis on equine herpesvirus 3, etiological agent of equine coital exanthema. The hypothesis is presented that the relative apathogenic nature of this herpesvirus may be an indirect result of its inability to synthesize and/or process glycoproteins needed by the virus to produce infectious virions at the normal body temperature of its natural host. It is suggested that equine herpesvirus 3 is the more evolved and naturally attenuated member of the equine herpesviruses.
Equine infectious anemia virus (EIAV) humoral responses of recipient ponies and antigenic variation during persistent infection. Three ponies were inoculated with plasma containing 10(4.8) TCID50 of equine infectious anemia virus (EIAV) and observed for 165 to 440 days. Each pony developed a febrile response within 3 weeks of infection during which a plasma viremia greater than or equal to 10(3.5) TCID50/ml was observed. Analyses of four isolates from sequential febrile episodes in a single pony were conducted by two-dimensional tryptic peptide maps and with monoclonal antibodies in immunoblots. Structural and antigenic alterations were observed in the envelope glycoproteins gp90 and gp45, with greatest variation in gp9...
Leiomyosarcoma of the duodenum in two horses. Two horses affected by chronic, intermittent colic were found, at post-mortem examination, to have localized annular thickening of a segment of the duodenum. Histological examination of the lesion in both cases revealed a tumour composed of bundles of oval or spindle-shaped cells that stained as muscle with van Gieson stain. The histological diagnosis was leiomyosarcoma. The tumour had caused partial bowel obstruction in both horses.
Skeletal muscle changes associated with equine myotonic dystrophy. A progressive neuromuscular disorder in young horses, clinically apparent as early as 1 month of age, is characterized by generalized myotonia, muscle stiffness, muscle weakness and atrophy. Myotonia is identified by percussion dimpling and myotonic EMG discharges. Changes in one case included testicular hypoplasia, cataract formation, and glucose intolerance, indicating a systemic involvement. Pathologic changes in skeletal muscles from three affected foals were examined. Sarcoplasmic masses, ringed fibers, internal positioning of sarcolemmal nuclei, and nuclear rowing were among the primary ...
Zoonotic cutaneous leishmaniasis due to Leishmania (Viannia) braziliensis associated with domestic animals in Venezuela and Brazil. After outbreaks of cutaneous leishmaniasis in Solano State, Venezuela, 5% of the population had parasitized ulcers while after similar outbreaks in Mesquita, Rio de Janeiro State, Brazil, 9% had the disease. In these foci children, including some under six years of age, were affected. There was no significant difference in the occurrence of the disease according to sex or type of employment. In Solano, 3% of dogs and 28% of donkeys had parasitized lesions, while in Mesquita these indices were 19.8% and 30.8% respectively. The parasite from man, dogs and equines was identified as Leishmania (Vi...
[Histochemical and biochemical changes in skeletal muscles of rhabdomyolysis-sensitive racehorses following exertion. III: Elevated activity of various antioxidant enzymes]. In this communication, the results of a histochemical and biochemical enzyme study on gluteus medius muscle of horses, sensitive to exertional myopathy, during attacks of rhabdomyolysis are presented. For the biochemical study the biopsy specimens investigated were selected by means of histological and enzyme histochemical staining methods. Dissected specimens were used which contained groups of muscle fibres with a high or low activity of glucose-6-phosphate dehydrogenase. The activity of glucose-6-phosphate dehydrogenase, phosphogluconate dehydrogenase, glutathione reductase, glutathione per...
Equine infectious anemia: prospects for control. Equine infectious anemia has been managed in most countries by the imposition of testing and quarantine regulations. In the United States, about 700,000 of the more than 7,000,000 horses are tested annually. As long as the status of greater than 90% of the horse population remains unknown and horses are transported and congregate in a relatively unrestricted manner, EIA will continue to exact its toll. Therefore, it is incumbent on the scientific community to continue to develop and refine practical and sensitive diagnostic tests for EIA which will be used in an expanding market, to reduce the...
[The occurrence of feed-induced stomach ulcers in horses]. Ponies were fed hay (n = 21) or mixed feed (n = 27; 128 g crude protein, 175 g crude fibre/kg dry matter) for at least 14 days (treatment against parasites with ivermectin before the experimental period). The feeding level was 18 g dry mater/kg body weight/day. After the feeding period (the experiments were conducted to investigate the water and electrolyte content of the alimentary tract in dependence on feed, feeding time and physical exercise) the ponies were slaughtered and the stomachs were visually controlled for the occurrence of ulcers. In the hay group no gastric ulcers were observed,...
Equine postanaesthetic myositis: a possible role for free radical generation and membrane lipoperoxidation. A method for the evaluation of total plasma antihydroxyl and antiperferryl activity is described. This method was applied to horse plasma obtained during halothane anaesthesia. In horses suffering from postanaesthetic myositis, a significant decrease in the antiperferryl activity was observed during anaesthesia particularly when the muscular compression produced by the weight of the horse was released. In the affected muscles, strong oxidants could therefore be generated during the reperfusion of the ischaemic muscles and might initiate membrane lipid peroxidation. This phenomenon could possib...
Neonatal viral diarrhoeas. Diarrhoea continues to be one of the more common and
important causes of economic loss in young animals (Anon
1978). Virus particles identified as rotaviruses, coronaviruses,
calci-like viruses, astroviruses, parvoviruses, and several others
have been detected by direct electron microscopy of ultracen-
trifuged samples of diarrhoeic faeces from young animals and
human infants over the past 20 years. Despite numerous stud-
ies on the many aetiological agents associated with neonatal
viral diarrhoea in recent years (Tzipori 1985), the challenge
for today’s new veterinary graduate is s...
Serum uric acid concentrations in horses heterozygous for combined immunodeficiency. Serum uric acid concentrations were determined in horses known to be carriers of combined immunodeficiency gene(s) and in presumed noncarrier horses. Uric acid concentrations were significantly higher (P less than 0.005) in carrier horses than in presumed noncarrier horses. However, there was some overlap in serum uric acid concentrations between carrier and presumed noncarrier horses.
Equine coital exanthema (EHV-3 virus) infection in India. A progenital disease encountered at one equine stud farm at Bangalore in Southern India during 1987 was investigated and confirmed as equine coital exanthema on the basis of characteristic lesions and clinical symptoms, isolation of equine herpes virus-3 (EHV-3) from the scabs collected from animals having active lesions and demonstration of neutralizing antibodies in the sera of recovered mares and stallion. This is the first authenticated report of the occurrence of equine coital exanthema in India due to EHV-3.
