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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.
Splenic infarction and splenectomy in a jumping horse. Primary splenic disease in the horse is rarely recognised as a
clinical entity. A few cases of splenic abscesses (Swan 1968),
splenic haematoma (Spier et al. 1986; McGorum et al. 1996),
and splenic rupture (Finocchio 1971; Steiner 1981; Dyke and
Friend 1988) have been reported. One case of primary
splenomegaly associated with recurrent colic has been
described in the veterinary literature and a splenectomy was
performed which corrected the problem (Varra and Nelson
1976). We are aware of only one report of splenomegaly
associated with splenic infarction in horses (Scott et al. 1978);
...
Spontaneous production of nitric oxide (NO), prostaglandin (PGE2) and neutral metalloproteinases (NMPs) in media of explant cultures of equine synovial membrane and articular cartilage from normal and osteoarthritic joints. Nitric oxide (NO), prostaglandin E2 (PGE2), and the activity of neutral metalloproteinases (NMPs) were measured in conditioned media of equine synovial membrane and articular cartilage explant cultures from horses with normal joints (n = 7) and from horses affected with moderate (n = 7) or severe osteoarthritis (n = 14) as judged by macroscopic appearance. Normal articular cartilage appeared glossy and bluish-white, was of normal thickness and showed no evidence of discolouration, fibrillation or other cartilage discontinuity. Slight discolouration and fibrillation or minor clefts of the carti...
Esophageal obstruction in horses: a retrospective study of 34 cases. The major purpose of this investigation was to describe the causes, possible complications, and prognoses of horses with esophageal obstruction. Of 34 cases presenting with esophageal obstruction, 28 cases were due to impaction of ingesta. Obstruction due to pre-existing esophageal disease occurred in 4 horses with megaesophagus, in 1 horse with stricture in the upper third of the esophagus, and in 1 horse with esophageal diverticulum. There was no significant difference in the contamination of the trachea between horses that subsequently developed aspiration pneumonia and those that did not. ...
Functional and histopathological evidence of cardiac parasympathetic dysautonomia in equine grass sickness. The parasympathetic terminal cardiac ganglia were examined in three normal horses and in five horses with grass sickness. Histopathological changes, consistent with those observed in other ganglia of horses with grass sickness, were identified in the terminal cardiac ganglia of the affected horses. A functional analysis of cardiac autonomic control by time domain analysis (TDA) of heart rate variability was applied to eight horses with grass sickness, and double-paired to 16 normal horses on the basis of their age, sex and breed, and the time of day at which the electrocardiographs were obtain...
Diarrhoea associated with cryptosporidial oocyst shedding in a quarterhorse stallion. Cryptosporidial oocyst shedding was detected in a 2.5-year-old Quarterhorse stallion with diarrhoea. Based on the detection of cryptosporidial oocysts, and the absence of other aetiological agents or enteropathogens, cryptosporidiosis was presumptively diagnosed. This case was unusual because cryptosporidial oocyst shedding is primarily found in some immunocompromised or immature horses, and has not been reported in healthy mature horses.
A retrospective evaluation of the causes of death of 448 insured French horses in 1995. Epidemiological studies should allow comparisons to be made of the prevalence of disease in populations from different countries, but the population characteristics and health problems in French horses are not well established. We have conducted a retrospective evaluation of the causes of death and vital characteristics of insured horses in France for the year 1995, with a view to comparison with published data from other countries. Files on 448 deceased horses were provided by nine insurance companies. Most of the animals were used for breeding (60%), followed by leisure (20%), eventing and r...
Polysaccharide storage myopathy in Morgan, Arabian, and Standardbred related horses and Welsh-cross ponies. Polysaccharide storage myopathy is an equine neuromuscular disorder characterized by accumulation of glycogen-related polysaccharide inclusions within skeletal muscle fibers. The pathologic criteria for diagnosis of this disorder are somewhat controversial; however, periodic acid-Schiff-positive, amylase-resistant inclusions are considered pathognomonic. Although these inclusions are most often found in affected horses related to the Quarter Horse, draft horse, and Warmblood breeds, this report describes these characteristic inclusions in muscle of five horses from nonrelated breeds (two Morga...
Calcium regulation by skeletal muscle membranes of horses with recurrent exertional rhabdomyolysis. To determine whether an alteration in calcium regulation by skeletal muscle sarcoplasmic reticulum, similar to known defects that cause malignant hyperthermia (MH), could be identified in membrane vesicles isolated from the muscles of Thoroughbreds with recurrent exertional rhabdomyolysis (RER). Methods: Muscle biopsy specimens from 6 Thoroughbreds with RER and 6 healthy (control) horses. Methods: RER was diagnosed on the basis of a history of > 3 episodes of exertional rhabdomyolysis confirmed by increases in serum creatine kinase (CK) activity. Skeletal muscle membrane vesicles, prepared by ...
Tissue sites of persistent infection and active replication of equine infectious anemia virus during acute disease and asymptomatic infection in experimentally infected equids. Equine infectious anemia virus (EIAV) infection of horses is characterized by recurring cycles of disease and viremia that typically progress to an inapparent infection in which clinical symptoms are absent as host immune responses maintain control of virus replication indefinitely. The dynamics of EIAV viremia and its association with disease cycles have been well characterized, but there has been to date no comprehensive quantitative analyses of the specific tissue sites of EIAV infection and replication in experimentally infected equids during acute disease episodes and during asymptomatic ...
Comparative pathophysiology of nonglandular ulcer disease: a review of experimental studies. Ulceration of the nonglandular, stratified squamous mucosa of the equine and porcine stomach is a common event in both species, although in pigs the fatality rate is significant and it is an economically important disease. Because the barrier function of this mucosa in horses and pigs appears similar, it is probable that similar pathophysiological mechanisms may be responsible for the initiating lesions and reparative events. Recent studies of ulcer pathogenesis in the pig have shown that feed preparation or prolonged fasting can result in disruption of the normal stratification of gastric con...
Role of duodenal reflux in nonglandular gastric ulcer disease of the mature horse. Gastric contents were sampled in horses via nasogastric tube to determine changes in pH and bile salt concentrations during feeding and fasting periods. The horses were rotated through 4 feeding protocols. (1) hay; (2) hay with twice daily grain meals; (3) and (4) fasting preceded by either hay only or hay and grain. Sequential, hourly samples were collected from 3 horses prepared with gastric cannulas. Horses were fed hay twice daily and grain mix either twice daily or in small aliquots dispensed every 90 min. The horses were sampled during normal feeding or after 14 h of feed deprivation. Ga...
Induction and maintenance of gastric ulceration in horses in simulated race training. Gastric ulceration is a prevalent condition of racehorses. A number of models of gastric ulceration have been described, but none mimic the conditions of a horse in training. The objectives of this study were to determine whether gastric ulcers could be induced and maintained in a group of horses in simulated race training. In addition, serum cortisol was measured on a weekly basis to investigate the possibility that stress may be important in the pathogenesis of gastric ulceration. Thirty horses used in the trial were fed Bermuda grass hay and 6 kg of a concentrate diet, and exercised 6 days/...
Normal equine gastroduodenal secretion and motility. This article represents an attempt to provide an overview of the current knowledge of equine gastroduodenal secretory and motor activity, with respect to how these functions are controlled and interact. First, the equine gastric mucosal anatomy is discussed in comparison with other monogastric species, with some attention directed at the large nonglandular portion in relation to its function, or lack thereof. Next, control of gastric acid secretion, as assessed by the collection of gastric contents from a cannula or continuous measurement of their changes in pH, is reviewed, pointing out that ...
Cross-sectional study of gastric ulcers of the squamous mucosa in thoroughbred racehorses. Although gastric ulcers have been identified relatively frequently in racing Thoroughbreds, there have been no large scale studies to determine their effect on health and performance. Two hundred and two Thoroughbred horses in active race training were selected by the attending veterinarians for gastro-endoscopic examination. Images of the stomach mucosa were stored in a digitised format for subsequent evaluation. The number of ulcers and a score of severity were determined. Gastric ulceration of the squamous mucosa was identified in 82% of horses. Seventy-three (39%) horses displayed clinical...
Intrapelvic hemangiosarcoma in a horse. No abstract available
Causes of poor performance of horses during training, racing, or showing: 348 cases (1992-1996). To determine results for horses undergoing a high-speed treadmill examination, including videoendoscopy of the pharynx and larynx before and during exercise, echocardiography before and after exercise, and electrocardiography before, during, and after exercise, because of poor performance. Methods: Retrospective study. Methods: 348 horses. Results: A definitive diagnosis was obtained for 256 (73.5%) horses. One hundred forty-eight horses had dynamic obstruction of the airway during exercise, 33 had clinically important cardiac arrhythmias alone, 22 had a combination of dynamic airway obstructi...
Risk factors for disease associated with influenza virus infections during three epidemics in horses. To identify risk factors associated with respiratory tract disease in horses during 3 epidemics caused by influenza virus infections. Methods: Cross-sectional and prospective longitudinal observational studies. Methods: 1,163 horses stabled at a Thoroughbred racetrack. Methods: Investigations were conducted during a 3-year period. An epidemic of respiratory tract disease caused by influenza virus infections was identified in each year. Routine observations and physical examinations were used to classify horses' disease status. Data were analyzed to identify factors associated with development ...
Descriptive epidemiologic study of disease associated with influenza virus infections during three epidemics in horses. To describe 3 epidemics of respiratory tract disease caused by influenza virus infections in a large population of horses. Methods: Cross-sectional and prospective longitudinal observational studies. Methods: All horses stabled at a Thoroughbred racetrack. Methods: During a 3-year period, descriptive information was collected as horses arrived at the racetrack and throughout race meetings. Routine observations and physical examinations were used to classify horses' disease status. Cause of epidemics was established by use of serologic testing and identification of influenza virus in nasal secr...
Survey of retinal haemorrhages in neonatal thoroughbred foals. Twenty-seven of 167 neonatal thoroughbred foals (16 per cent) were found to have retinal haemorrhages after a careful examination of the entire fundus. Experience in differentiating haemorrhages from other lesions, and the selection of foals from normal populations, were considered to have an important effect on their apparent incidence. Bilateral haemorrhages were more common and there was a significantly higher incidence in female foals. The numbers of haemorrhages ranged between one and 20; 36 per cent of eyes with retinal haemorrhages had the small punctate type and 56 per cent had the spl...
Role of peridomestic birds in the transmission of St. Louis encephalitis virus in southern California. In response to the 1984 St. Louis encephalitis (SLE) epidemic in the Los Angeles Basin of southern California (USA), an investigative program was initiated to evaluate the interactive components of the SLE virus transmission cycle. From 1987 through 1996 (10 yr), 52,589 birds were bled and their sera tested for SLE and western equine encephalomyelitis (WEE) virus antibodies by the hemagglutination inhibition (HAI) test. Eighty-three percent of the birds tested were house finches (Carpodacus mexicanus) (48.7%) and house sparrows (Passer domesticus) (34.6%); 1.1% of these birds were positive for...
A function for guttural pouches in the horse. Athletic animals must keep their brains cool during exertion because this organ can be damaged irreversibly by hyperthermia. But how horses do this has remained a mystery, as they don't appear to have thermoregulatory dervices like those found in other animals. They do, however, have a unique anatomical arrangement of their internal carotid arteries, which supply blood to the brain: these are enveloped by a pair of air-filled guttural pouches. Here we show that horses use their guttural pouches to cool these important arteries during exercise, keeping the brain from overheating.
