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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.
Diagnosis of equine influenza virus infections in quarantine stations in Australia, 2007. In August 2007, several horses showed pyrexia and respiratory signs while in post-arrival quarantine in Australia. Subsequent investigations diagnosed equine influenza by serology and PCR in two quarantine stations. A common origin in a shipment of horses from Japan was indicated.
Impact of the Australian equine influenza outbreak on a small business that was not infected. At the outbreak of equine influenza (EI) we chose to close our horse-based business, as we did not want to risk our horses contracting the disease and the demand for our services ceased. We report our experiences of the outbreak.
Longitudinal study describing the clinical signs observed in horses naturally infected with equine influenza. We describe the clinical signs and disease course during an outbreak of equine influenza (EI) in naïve horses in a police stables in Sydney, New South Wales, Australia.
Internet-based survey of horse owners for mortality and morbidity related to equine influenza in the 2007 Australian epidemic. Anecdotally, some sections of the horse community were under the impression that there was a high mortality rate in horses in 2007 because of the EI epidemic. A survey of horse deaths in the Hunter Valley of New South Wales (NSW) in 2007 indicated that there were few infections and deaths attributable to equine influenza (EI) infections in foals, but other authors found a very high seroprevalence across all age classes. This study aimed to generate objective information on mortality and morbidity rates associated with EI in Australian horses during the 2007 epidemic.
Overview of the epidemiology of equine influenza in the Australian outbreak. This overview of the equine influenza (EI) epidemic as it occurred in two Australian states, New South Wales and Queensland, in 2007 describes the functions and activities of the epidemiology teams that were engaged during the outbreak and also identifies key features of the epidemiology of EI during the outbreak.
Surveillance and prevention in a non-affected state: Victoria. The equine influenza outbreak detected in August 2007 in New South Wales and Queensland did not enter Victoria, which was, however, considered at risk because of its sizable border with New South Wales. Accordingly, Victoria implemented a response plan to prevent disease entry and enable early detection of any disease. Horse movement restrictions, surveillance strategies and public awareness formed a large part of this response.
Proof of freedom from equine influenza infection in Australia in 2007-08. The challenges faced in demonstrating Australia's freedom from equine influenza following the outbreak in 2007-08 and the responding strategy developed by the Proof of Freedom Working Group are presented.
Isolation and characterisation of an H3N8 equine influenza virus in Australia, 2007. Before 2007, equine influenza had never been diagnosed in Australia. On 22 August 2007, infection was confirmed in horses at Eastern Creek Animal Quarantine Station near Sydney. The virus subsequently isolated (A/equine/Sydney/2888-8/2007) was confirmed by sequence analysis of the haemagglutinin (HA) gene as an H3 virus of the variant American Florida lineage that is now referred to as Clade 1. The HA sequence of the virus was identical to that of a virus isolated from a contemporaneous outbreak in Japan and showed high homology to viruses circulating in North America.
Equine influenza: a clinical perspective in Centennial Parklands Equestrian Centre. The clinical signs of horses diagnosed with equine influenza (EI) at Centennial Parklands Equestrian Centre (CPEC) and the events surrounding their diagnosis are described. This was the site of the first case of EI diagnosed outside of the Eastern Creek Animal Quarantine Station. The clinical data demonstrate the rapid spread of the disease after a sufficient viral load had developed from the initial cases within CPEC.
Analysis of horse movements and events during the 2007 outbreak of equine influenza in New South Wales, Australia. To analyse horse event and horse movement registration data collected between September 2007 and December 2008 during the outbreak of equine influenza in New South Wales, Australia. Results: A total of 9356 events were registered, involving 504,382 horses and 242,952 riders. Registered horse movements totalled 224,084, involving 349,327 horses (excluding mobs) travelling 34.4 million km with an average of 154 km per journey. The number of recorded events and movements were low while movement controls were most stringent, then increased from December 2007 as restrictions were eased, to peak in ...
Role of the New South Wales Department of Primary Industries’ Laboratory Information Management System (LIMS) in the 2007 equine influenza emergency animal disease response. A Laboratory Information Management System (LIMS) was used to manage the laboratory data and support planning and field activities as part of the response to the equine influenza outbreak in Australia in 2007. The database structure of the LIMS and the system configurations that were made to best handle the laboratory implications of the disease response are discussed. The operational aspects of the LIMS and the related procedures used at the laboratory to process the increased sample throughput are reviewed, as is the interaction of the LIMS with other corporate systems used in the management...
Epidemic curve and hazard function for occurrence of clinical equine influenza in a closed population of horses at a 3-day event in southern Queensland, Australia, 2007. The risk of individuals becoming infected during an epidemic of infectious disease can vary as the disease progresses. Monitoring this risk may provide information about the dynamics of transmission. This study describes the epidemic curve for an epidemic of equine influenza (EI) in a closed population of horses predominantly immunologically naïve to EI at a 3-day event at Morgan Park in southern Queensland, Australia. The hazard function suggested that a subset of horses were at reduced risk of becoming infected. This highlights the importance, when modelling infectious disease in population...
Significant features of the epidemiology of equine influenza in New South Wales, Australia, 2007. Equine influenza (EI) was first diagnosed in the Australian horse population on 24 August 2007 at Centennial Park Equestrian Centre (CPEC) in Sydney, New South Wales (NSW), Australia. By then, the virus had already spread to many properties in NSW and southern Queensland. The outbreak in NSW affected approximately 6000 premises populated by approximately 47,000 horses. Analyses undertaken by the epidemiology section, a distinct unit within the planning section of the State Disease Control Headquarters, included the attack risk on affected properties, the level of under-reporting of affected pr...
Inheritance of cerebellar abiotrophy in Arabians. To determine the mode of inheritance for cerebellar abiotrophy (CA), a neurologic disease in Arabians. Methods: 804 Arabians, including 29 horses (15 males and 14 females) with CA. Methods: Most horses (n = 755) belonged to 1 of 4 paternal families. Among the 29 CA-affected horses, all had clinical signs consistent with the disease; the disease was confirmed histologically following euthanasia in 8 horses. From the pedigree information, inbreeding coefficients were calculated for 16 affected horses and compared with coefficients for a subgroup of 16 unaffected horses. Complex segregation analy...
Does immunotherapy protect equines from reinfection by the oomycete Pythium insidiosum? A cutaneous Pythium insidiosum reinfection was diagnosed in an equine in Brazil. Lesions with focal presentation appeared 2 years apart. The first infection and even immunotherapy were not likely to develop enough immune response to prevent reinfection. The use of adjuvants should be considered in the immunotherapy of pythiosis.
Diagnostic and epidemiologic analysis of the 2008-2010 investigation of a multi-year outbreak of contagious equine metritis in the United States. Contagious equine metritis (CEM) is a highly contagious venereal disease of horses caused by Taylorella equigenitalis. During testing for semen export purposes, a stallion in Kentucky was found to be T. equigenitalis culture positive in December of 2008. This finding triggered an extensive regulatory investigation to search for additional positive horses, determine the extent of the outbreak, identify the potential source of the outbreak, and ultimately return the United States to CEM-free status. The investigation included over 1000 horses located in 48 states. Diagnostic testing found a tota...
Infection of peripheral blood mononuclear cells with neuropathogenic equine herpesvirus type-1 strain Ab4 reveals intact interferon-α induction and induces suppression of anti-inflammatory interleukin-10 responses in comparison to other viral strains. The recent increase in incidence, morbidity, and mortality of neurological disease induced by equine herpesvirus type 1 (EHV-1) has suggested a change of virulence of the virus. The exact mechanisms by which EHV-1 induces neurologic disease are not known. Environmental, viral, and host risk factors might contribute to neurological manifestation. Here, we investigated innate interferon-α (IFN-α), interleukin-10 (IL-10) and IL-4 responses after infection of equine peripheral blood mononuclear cells (PBMC) with EHV-1 using an available cytokine multiplex assay. Three viral strains representing ...
Results of a haplotype-based GWAS for recurrent laryngeal neuropathy in the horse. Recurrent laryngeal neuropathy (RLN) is a major upper-airway disease of horses that causes abnormal respiratory noise during exercise and can impair performance. Etiopathogenesis remains unclear but genetic factors have been suspected for many decades. The objective of this study was to identify risk loci associated with RLN. To that end we genotyped 234 cases (196 Warmbloods, 20 Trotters, 14 Thoroughbreds, and 4 Draft horses), 228 breed-matched controls, and 69 parents with the Illumina Equine SNP50 BeadChip. Using these data, we quantified population structure and performed single-marker and...
The timeline of metalloprotease events during oligofructose induced equine laminitis development. The role of matrix metalloproteases (MMPs) and the timeline of proteolysis during laminitis development are incompletely understood. Objective: To determine the temporal progression of selected MMPs and protease regulators during laminitis development. Methods: Five clinically normal Standardbred horses received, via nasogastric intubation, an oligofructose (OF) bolus (10 g/kg bwt). Laminitis induction proceeded for 48 h followed by euthanasia. Lamellar biopsies were obtained prior to dosing and at intervals during the treatment period for analysis (12, 18, 24, 30 and 36 h and at 48 h followin...
Increased plasma fructosamine concentrations in laminitic horses. The use of plasma fructosamine concentration ([fructosamine]) as a marker of abnormal glucose homeostasis in laminitic horses has not been investigated. Objective: Plasma fructosamine concentration may be higher amongst laminitic horses than normal horses; this might relate to underlying insulin resistance. Objective: 1) To compare [fructosamine] between laminitic and normal horses. 2) To investigate associations between [fructosamine] at presentation in laminitic horses with a) single sample markers of insulin resistance and b) outcome. Methods: Plasma fructosamine concentration, fasting seru...
Immunoglobulin G antibody profiles against Anopheles salivary proteins in domestic animals in Senegal. Although domestic animals may not be permissive for Plasmodium, they could nevertheless play a role in the epidemiology of malaria by attracting Anopheles away from humans. To investigate interactions between domestic animals and mosquitoes, we assayed immunoglobulin G (IgG) antibodies directed against the salivary proteins of Anopheles gambiae in domestic animals living in Senegalese villages where malaria is endemic. By Western blotting, sera from bovines (n=6), ovines (n=36), and caprines (n=36) did not react with Anopheles whole saliva. In contrast, equine sera recognized proteins in both ...
Cardiac troponin I and the occurrence of cardiac arrhythmias in horses with experimentally induced endotoxaemia. The aim of this study was to determine whether experimentally-induced endotoxaemia induced elevations in plasma cardiac troponin I (cTnI) concentrations in horses and how this might affect the incidence of cardiac arrhythmias. Eight Standardbred horses received an intravenous continuous rate infusion of endotoxin (total dose 500 ng/kg) for 6 h while being monitored using electrocardiography (ECG). Blood samples were collected before the start of the endotoxin infusion, every 60 min during the infusion, then 1, 2, 3, 8, 10 and 24 h post-infusion, and analysed for cTnI concentrations. One horse ...
What’s in a name? Inflammatory airway disease in racehorses in training. The term 'inflammatory airway disease' (IAD) is often used to describe the syndrome of lower airway inflammation that frequently affects young racehorses in training around the world. In practice, this inflammation is generally diagnosed using a combination of endoscopic tracheal examination, including grading of amounts of mucus present and tracheal wash sampling. However, a recent consensus statement from the American College of Veterinary Internal Medicine concluded that bronchoalveolar lavage (BAL) sampling, rather than tracheal wash (TW) sampling, is required for cytological diagnosis of ...
Characterization of the interferon gamma response to Lawsonia intracellularis using an equine proliferative enteropathy challenge (EPE) model. Lawsonia intracellularis is the etiological agent of infectious intestinal hyperplasia for which several clinical diseases have been described including proliferative enteropathy (PE), intestinal adenomatosis, and ileitis. While initially recognized as the causative agent of PE in pigs, L. intracellularis is now viewed as an emerging cause of intestinal hyperplasia in a wide range of mammalian species, including horses. Equine proliferative enteropathy (EPE) has been reported worldwide though definitive diagnosis is difficult and the epidemiology of the disease remains poorly understood. Weanl...
Frequency of equine laminitis: a systematic review with quality appraisal of published evidence. Equine laminitis is a highly debilitating disease of the foot. Despite its perceived importance, epidemiological characteristics are poorly understood and the true frequency of the disease remains unclear. The objective of this study was to retrospectively assess previous research to identify publications which provide the best evidence of the frequency of naturally-occurring equine laminitis. A systematic review of English language publications was conducted using MEDLINE (1950-2010), CAB Direct (1910-2010) and IVIS (1997-2010). Additional publications were included by searching bibliographie...
Epizootic heamorragic disease. Epizootic haemorrhagic disease (EHD) is an infectious non-contagious viral disease transmitted by insects of the genus Culicoides which affects wild and domestic ruminants. The causative agent, the epizootic haemorrhagic disease virus (EHDV), belongs to the family Reoviridae, genus Orbivirus and shares many morphological and structural characteristics with the other members of the genus such as bluetongue, African horse sickness and equine encephalosis viruses. In recent years EHD outbreaks have been reported in countries bordering the European Union. They caused disease in cattle and severe r...
