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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.
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...
The prevalence of endocrinopathic laminitis among horses presented for laminitis at a first-opinion/referral equine hospital. Endocrinopathic causes of laminitis may be a common underlying causative pathogenesis in first-opinion or field cases presenting with laminitis, as opposed to laminitis produced in inflammatory research models. This study aimed to determine whether evidence of an underlying endocrinopathy was present in horses presented for laminitis to a first-opinion/referral veterinary teaching hospital. A second aim was to compare the signalment of horses and ponies with laminitis with the equine hospital population during the same period. All horses presenting for laminitis at Helsinki University Equine T...
Persistent, widespread papilloma formation on the penis of a horse: a novel presentation of equine papillomavirus type 2 infection. A 9-year-old gelding presented with approximately 100 papillomas that covered about 75% of the distal penis. Biopsy was performed, and histology showed evidence of viral cytopathic change and koilocytosis. Polymerase chain reaction using DNA extracted from biopsied tissue amplified equine papillomavirus type 2 (EcPV-2) DNA sequences. Sixteen months later, the horse was re-examined and the appearance of the papillomas was unchanged. Equine papillomavirus type 2 DNA sequences were again amplified from both biopsied tissue and swabs of the penis. Papillomavirus was localized to the lesions by imm...
Lower airway disease, now and in the future. Respiratory disease is an important cause of wastage in the Thoroughbred industry and is a cause of welfare problems in all types of horse. This review concerns developments in our understanding of equine respiratory disease since 1998 and illustrates how strategic funding from the Horserace Betting Levy Board has contributed to this understanding.
International disease monitoring, October to December, 2010. African swine fever in the Caucasus and Leningrad regions of Russia. Equine infectious anaemia in several EU member states. Foot-and-mouth disease in Bulgaria--the first in an EU member state since 2007. Highly pathogenic avian influenza H5N1 in the Far East. West Nile virus in southern Europe. These are among matters discussed in the international disease monitoring report for October to December 2010, prepared by Defra's Food and Farming Group, Veterinary Science Team.
Altered systolic left ventricular function in horses completing a long distance endurance race. It is unknown whether or not exercise-induced cardiac fatigue (EICF), as demonstrated in human athletes performing long duration exercise, occurs in endurance horses. Objective: To examine the effects of a long distance endurance race on left ventricular systolic function in horses. Methods: Echocardiography was performed before, and after, a 2 or 3 star international endurance race (106-132 km) in 11 horses. Systolic (s) and diastolic (d) interventricular and left ventricular free wall thickness (IVS and LVFW, respectively), left ventricular, left atrial and aortic internal diameter (LVID, LA...
Factors contributing to plasma TCO2 and acid-base state in Ontario Standardbred racehorses. Standardbred and Thoroughbred racehorses around the world are tested for performance enhancing substances. Among these are blood alkalising substances that raise plasma pH and total carbon dioxide (TCO(2)) concentration. However, many horses have an elevated TCO(2) due to dietary, environmental and health concerns without having been administered an alkalising substance. Objective: The purposes of this study were to determine the acid-base profile of a cross section of Standardbred horses in racing/race training in Ontario and the main independent variables that contributed to acid-base state....
Equine hospital data as a source for study of prevalence and heritability of osteochondrosis and palmar/plantar osseous fragments of Swedish Warmblood horses. Disturbances in skeletal development, primarily osteochondrosis (OC) and palmar/plantar osseous fragments (POF), have been commonly reported as problems in young horses. However, there are few reports of such findings for epidemiological analyses or breeding purposes. Objective: To evaluate equine hospital data as a possible source of information for genetic evaluations by estimating prevalence and heritability of OC in the stifle, hock and fetlock joints and of POF in the fetlock. Methods: Data on Swedish Warmblood (SWB) horses were obtained from a large equine hospital in south Sweden. Preva...
Risk factors for exercise-induced pulmonary haemorrhage in Thoroughbred racehorses. Risk factors for occult exercise-induced pulmonary haemorrhage (EIPH) are poorly defined or quantified. Objective: To investigate the importance of putative risk factors for EIPH amongst Thoroughbred racehorses in Australia. Methods: Tracheobronchoscopy was used to determine EIPH status of 744 Thoroughbred racehorses after flat racing in Melbourne, Australia. Horses were identified for study before racing, and over 50% of horses racing during the study period were examined. Statistical analysis included use of bivariate and multivariate logistic regression analysis to account for simultaneous ...
Elimination from elite endurance rides in nine countries: a preliminary study. Endurance is the fastest growing Féderation Équestre International (FEI) discipline and the large number of eliminations on veterinary grounds needs to be investigated. Objective: To document elimination rates and explore potential risk factors for elimination due to lameness or metabolic reasons in 9 countries representing 5 continents. Methods: Data for rides of ≥ 100 km ('elite endurance rides') in Australia, France, Italy, South Africa, Spain, United Arab Emirates (UAE), UK, Uruguay and USA were collected from the FEI website. Data were collected for all started horses on the country, ...
Physiological measurements and prevalence of lower airway diseases in Trotters with dorsal displacement of the soft palate. Dorsal displacement of the soft palate (DDSP) is one of the most common obstructive conditions of the upper respiratory tract in the racehorse. This condition has a complex aetiology which may be caused or exacerbated by pharyngeal inflammation. Additionally, lower respiratory airway diseases may be associated with DDSP thereby contributing to exercise intolerance in these horses. Objective: The aim of this study was to measure physiological variables during a standardised exercise test and to assess the prevalence and consequences of lower respiratory airway disease in horses with DDSP. Metho...
Prevalence of exercise-associated arrhythmias in normal performing dressage horses. Exercise-associated arrhythmias are important differentials when evaluating poor performance sport horses. However, most studies of arrhythmias have been conducted in racehorses and therefore there is a paucity of knowledge concerning the prevalence and significance of exercise-associated arrhythmias in riding horses. Objective: The objective of this study was to examine the prevalence of arrhythmias, particularly supraventricular premature complex (SVPCs) and ventricular premature complex (VPCs), associated with exercise in normal performing dressage horses. Methods: In total, 21 normal perfo...
Observations on development of natural infection and species composition of small strongyles in young equids in Kentucky. Early development and maturation of species of small strongyles have not been studied extensively. Most information is on the first appearance of strongyle eggs in feces of foals. However, species cannot be determined in this manner because of similarity of the morphological features of the eggs. To determine more definitive knowledge on development and species composition of natural infections of small strongyles, eight equid foals were necropsied and examined at various ages (31 to 92 days of age). The entire contents of the large intestine were examined, and all worms (6,671) recovered were...
Multiple congenital ocular anomalies in Icelandic horses. Multiple congenital ocular anomalies (MCOA) syndrome is a hereditary congenital eye defect that was first described in Silver colored Rocky Mountain horses. The mutation causing this disease is located within a defined chromosomal interval, which also contains the gene and mutation that is associated with the Silver coat color (PMEL17, exon 11). Horses that are homozygous for the disease-causing allele have multiple defects (MCOA-phenotype), whilst the heterozygous horses predominantly have cysts of the iris, ciliary body or retina (Cyst-phenotype). It has been argued that these ocular defects...
Glucose transport in the equine hoof. Several conditions associated with laminitis in horses are also associated with insulin resistance, which represents the failure of glucose uptake via the insulin-responsive glucose transport proteins in certain tissues. Glucose starvation is a possible mechanism of laminitis, but glucose uptake mechanisms in the hoof are not well understood. Objective: To determine whether glucose uptake in equine lamellae is dependent on insulin, to characterise the glucose transport mechanism in lamellae from healthy horses and ponies, and to compare this with ponies with laminitis. Methods: Study 1 investi...
Antibiotic resistance in faecal bacteria isolated from horses receiving virginiamycin for the prevention of pasture-associated laminitis. Enterococcus faecium, a major cause of potentially life-threatening hospital-acquired human infections, can be resistant to several antimicrobials, such that streptogramin quinupristin-dalfopristin (Q/D) is one of the few antibiotics still effective. Consequently use of the streptogramin virginiamycin as an animal growth promoter was banned in the EU in 1999 as some believed this contributed to the emergence of Q/D resistant E. faecium. Virginiamycin is advocated for preventing equine pasture-associated laminitis, but its effect on equine faecal bacterial Q/D resistance has not been determined...
Putative intestinal hyperammonaemia in horses: 36 cases. Intestinal hyperammonaemia (HA) has been infrequently reported in individual horses; however, there have been no studies describing clinical and laboratory data as well as short- and long-term outcome in a larger number of cases. Objective: To describe clinical and laboratory data and short- and long-term outcome in a large group of horses with intestinal HA. Methods: Multi-centred, retrospective study; case records of horses with HA were reviewed and any horse with a clinical or post mortem diagnosis of intestinal HA was included. Hyperammonaemia was defined as a blood ammonium (NH(4) (+)) co...
