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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.
Concurrent ivermectin and Solanum spp. toxicosis in a herd of horses. Representatives from a herd of horses with acute onset of neurologic signs after administration of ivermectin presented for evaluation and treatment. Objective: Describe clinical signs of horses intoxicated by ingestion of Solanum sp. and administered ivermectin. Methods: Six of 11 affected unrelated horses presented for evaluation and treatment. The remaining 5 affected horses were treated at the farm. Four additional horses, housed separately, were unaffected. Methods: Case series is presented. Serum ivermectin concentrations were evaluated in the 6 hospitalized horses. The remnants of the t...
Intestinal ischemia-reperfusion injury in horses: pathogenesis and therapeutics. This article discusses the potential role of oxidative injury to the intestinal tract of horses and the therapeutic approaches that have been investigated to decrease cellular damage secondary to ischemia-reperfusion (IR) injury. Equine colic is a major concern for horse owners and veterinary practitioners. Strangulating and obstructive lesions of the small and large intestines commonly require intervention in patients via exploratory celiotomy. However, the application of information from experimentally induced IR injury in horses to clinical cases of naturally occurring equine colic is not c...
Phylogenetic and structural studies of a novel equine papillomavirus identified from aural plaques. Papillomaviruses (PVs) infect a wide range of animal species and show great genetic diversity. To date, excluding equine sarcoids, only three species of PVs were identified associated with lesions in horses: Equus caballus papillomavirus 1 (EcPV1-cutaneous), EcPV2 (genital) and EcPV3 (aural plaques). In this study, we identified a novel equine PV from aural plaques, which we designated EcPV4. Cutaneous samples from horses with lesions that were microscopically diagnosed as aural plaques were subjected to DNA extraction, amplification and sequencing. Rolling circle amplification and inverse PCR...
Strain impact on equine herpesvirus type 1 (EHV-1) abortion models: viral loads in fetal and placental tissues and foals. Equine herpesvirus-1 (EHV-1) continues to cause both sporadic and epidemic abortions despite extensive vaccination. Lack of progress in the development of protective vaccines may be hindered by the lack of equine abortion models that employ contemporary EHV-1 strains. The objective of our experiments was to compare a contemporary EHV-1 strain with a previously described challenge strain, and to quantify EHV-1 loads in various maternal and fetal tissues. Infection experiments were performed in two groups of 7 pregnant pony mares at 270-290 days of gestation with a contemporary EHV-1 strain (Uni...
Atypical myopathy: a review and description of the outbreak in the Netherlands during autumn 2009 and spring 2010. This article reviews the literature on equine atypical myopathy (AM), an acute, severe rhabdomyolysis that occurs in horses at pasture. The prevalence, mortality, clinical signs, pathology, potential aetiology, typical aspects, diagnosis, treatment, and prognosis are described. Horse management, characteristic weather conditions, and possible preventive measures are also discussed. In addition, the characteristics of 54 highly probable or confirmed cases of equine AM occurring between autumn 2009 (27 cases) and spring 2010 (27 cases) in the Netherlands are described. Of the 54 affected horses,...
Effects of the addition of endotoxin during perfusion of isolated forelimbs of equine cadavers. To examine the effect of endotoxins on metabolism and histopathologic changes of isolated perfused equine forelimbs. Methods: Forelimbs (comprising the metacarpus and digit) were collected from cadavers of 12 healthy adult horses after slaughter at an abattoir (14 limbs; 1 forelimb of 10 horses and both forelimbs of 2 horses). Methods: Forelimbs were perfused for 10 hours with autologous blood, with and without the addition of endotoxin (80 ng of lipopolysaccharide [LPS]/L). Two limbs of the endotoxin exposure group and 2 nonperfused limbs were loaded to failure of the suspensory apparatus of ...
Evidence that in vitro susceptibility of CD3+ T lymphocytes to equine arteritis virus infection reflects genetic predisposition of naturally infected stallions to become carriers of the virus. We investigated the correlation between in vitro susceptibility of CD3(+) T lymphocytes to equine arteritis virus (EAV) infection and establishment of persistent infection among 14 stallions following natural infections. The data showed that carrier stallions with a CD3(+) T lymphocyte susceptibility phenotype to in vitro EAV infection may be at higher risk of becoming carriers than those that lack this phenotype (P = 0.0002).
Feed restriction enhances the depressive effects of erythromycin on equine hindgut microbial metabolism in vitro. Equine typholocolitis is a sporadic diarrheal disease causing high mortality rates. One of the risk factors responsible for this is the oral application of the macrolide antibiotic erythromycin. The aim of the present in vitro study was to investigate whether erythromycin in combination with feed restriction provokes changes in microbial hindgut metabolism and could therefore be involved in the pathogenesis of equine typhlocolitis. As application of erythromycin and feed restriction are risk factors for equine typhlocolitis, both factors were chosen to investigate their individual and combined...
Extensive myenteric ganglionitis in a case of equine chronic intestinal pseudo-obstruction associated with EHV-1 infection. A 7-year-old male trotter horse with a history of recurrent colic displayed clinical findings consistent with chronic intestinal pseudo-obstruction (CIP). At laparotomy, an impaction of the descending colon associated with marked atrophy of the right dorsal colon was found. The horse was humanely destroyed and tissues collected at necropsy examination revealed diffuse enteric ganglionitis comprising an infiltrate of CD3(+) T lymphocytes and plasma cells. At all levels of the intestinal tract the number of myenteric ganglia and of normal ganglion cells was decreased significantly. There were ch...
Distribution of insulin receptor and insulin-like growth factor-1 receptor in the digital laminae of mixed-breed ponies: an immunohistochemical study. Hyperinsulinaemia has been implicated in the pathogenesis of laminitis; however, laminar cell types responding to insulin remain poorly characterised. Objective: To identify laminar cell types expressing insulin receptor (IRc) and/or insulin-like growth factor-1 receptor (IGF-1R); and to evaluate the effect of dietary nonstructural carbohydrate (NSC) on their expression. Methods: Mixed-breed ponies (n = 22) received a conditioning hay chop diet (NSC ∼6%); following acclimation, ponies were stratified into lean (n = 11, body condition score [BCS]≤4) or obese (n = 11, BCS ≥7) groups and ea...
Differential expression of TAR DNA-binding protein (TDP-43) in the central nervous system of horses afflicted with equine motor neuron disease (EMND): a preliminary study of a potential pathologic marker. Equine motor neuron disease (EMND) is a neurodegenerative disorder of unknown etiology affecting horses worldwide. Trans-Active Response DNA Binding Protein of 43 kDa (TDP-43) has been reported in the central nervous system (CNS) of several neurodegenerative conditions in humans including Amyotrophic Lateral Sclerosis (ALS) and assumed to play role in the disease. We examined whether horses afflicted with EMND express the TDP-43 in CNS. Ten horses with EMND and 6 controls of different ages and breed we enrolled. Detection of presence of TDP-43 protein in the CNS was analyzed by immunohistoche...
Right dorsal displacement of the large colon as a cause of surgical colic in three foals in New Zealand. Over a 3-year period between July 2008 and July 2011, 10 exploratory laparotomies were performed on foals in a Waikato referral facility in New Zealand. Results: Right dorsal displacement of the large colon (RDDLC) was identified during four exploratory laparotomies in three foals that presented for mild-to-moderate colic that was non-responsive to medical management. One foal required a repeat laparotomy 7 weeks post initial surgery, and RDDLC was again diagnosed. Methods: Right dorsal displacement of the large colon in foals. Conclusions: Further investigation may identify risk factors or ma...
Successful therapeutic management of concurrent subclinical Eimeria leukarti and Babesia (Theileria) equi infection in a mare. The occurrence of Eimeria leukarti infection in equine is being sporadically documented despite its cosmopolitan prevalence. A Marwari mare, aged 3 years and 6 months and owned by a socio-economically weaker class of labourer of royal families, was suffering from non specific enteric disorders. Detailed systemic clinical examination of mare confirmed subclinical enteric infection with E. leukarti and piroplasms of Babesia (Theileria) equi in the circulating erythrocytes. She was therapeutically managed with synchronous administration of specific and supportive therapy with success. Non speci...
Familial narcolepsy in the Lipizzaner horse: a report of three fillies born to the same sire. The occurrence of sleep disorder in three half sibling Lipizzaner is described. Sleepiness, swaying, stumbling, carpal joints buckling and falling down onto the carpal joints had been present since early foal age in all of them. Clinical signs had gradually reduced since the age of 2 years in cases 1 and 3. Sleepiness was induced by going out from the stable in adulthood. A physostigmine test was performed in all three affected horses and produced positive results in cases 1 and 3. The result of the test in case 2 was unclear due to the almost continuous sleepiness of the foal. Hypocretin-1 co...
Reaginic antibodies from horses with recurrent airway obstruction produce mast cell stimulation. Reaginic antibodies (IgE and some IgG subclasses) and mast cells play important roles in the induction of type I immediate hypersensitivity reactions. These antibodies bind through their Fc fragment to high affinity receptors (FcεRI) present in the membrane of mast cells and basophils. The cross-linking of the receptor initiates a coordinated sequence of biochemical and morphological events that results in exocytosis of secretory granules containing pre-formed inflammatory mediators, secretion of newly formed lipid mediators, and secretion of cytokines. Previously, several studies have invest...
Contact with horses is a risk factor for tick-borne lymphadenopathy (TIBOLA): a case control study. Tick-borne lymphadenopathy (TIBOLA) is an emerging infection caused by Rickettsia slovaca. We describe here the seasonal, age and gender characteristics as well as the association with horse contact as risk factors for acquiring TIBOLA in comparison with another, more frequent tick-borne disease, Lyme borreliosis.We analysed a dataset of 855 patients diagnosed with either Lyme (n = 805) or TIBOLA (n = 50) disease using Fisher's exact tests and generalized linear models. Then we performed a matched case-control study in which all TIBOLA patients were paired with one Lyme patient matching in age...
Analysis of several factors of variation of gestation loss in breeding mares. The files for ultrasound diagnosis of gestating mares belonging to the French equine herd recorded for 3 consecutive years were joined with the files for foal birth of these same mares, allowing the statistical analysis of factors of pregnancy loss. For 28 872 positive diagnoses of gestation, 2898 losses were recorded, that is, a global rate of gestation interruption of 9.12%. The etiology of these interruptions is mainly extrinsic: the year and month of insemination, as well as region for climatic reasons. The intrinsic causes that are implicated are breed of the father (heavy breeds except t...
Histological and morphometric lesions in the pre-clinical, developmental phase of insulin-induced laminitis in Standardbred horses. Lamellar pathology in experimentally-induced equine laminitis associated with euglycaemic hyperinsulinaemia is substantial by the acute, clinical phase (∼48h post-induction). However, lamellar pathology of the developmental, pre-clinical phase requires evaluation. The aim of this study was to analyse lamellar lesions both qualitatively and quantitatively, 6, 12 and 24h after the commencement of hyperinsulinaemia. Histological and histomorphometrical analyses of lamellar pathology at each time-point included assessment of lamellar length and width, epidermal cell proliferation and death, base...
The role of equine herpesvirus type 4 glycoprotein k in virus replication. Equine herpesvirus 4 (EHV-4) is an important equine pathogen that causes respiratory tract disease among horses worldwide. Glycoprotein K (gK) homologues have been identified in several alphaherpesviruses as a major player in virus entry, replication, and spread. In the present study, EHV-4 gK-deletion mutant has been generated by using bacterial artificial chromosome technology and Red mutagenesis to investigate the role of gK in EHV-4 replication. Our findings reported here show that gK is essential for virus replication in vitro and that the gK-negative strain was not able to be reconstitut...
Characterisation of retroviruses in the horse genome and their transcriptional activity via transcriptome sequencing. The recently released draft horse genome is incompletely characterised in terms of its repetitive element profile. This paper presents characterisation of the endogenous retrovirus (ERVs) of the horse genome based on a data-mining strategy using murine leukaemia virus proteins as queries. 978 ERV gene sequences were identified. Sequences were identified from the gamma, epsilon and betaretrovirus genera. At least one full length gammaretroviral locus was identified, though the gammaretroviral sequences are very degenerate. Using these data the RNA expression of these ERVs were derived from RNA ...
Copy number expansion of the STX17 duplication in melanoma tissue from Grey horses. Greying with age in horses is an autosomal dominant trait, associated with loss of hair pigmentation, melanoma and vitiligo-like depigmentation. We recently identified a 4.6 kb duplication in STX17 to be associated with the phenotype. The aims of this study were to investigate if the duplication in Grey horses shows copy number variation and to exclude that any other polymorphism is uniquely associated with the Grey mutation. Results: We found little evidence for copy number expansion of the duplicated sequence in blood DNA from Grey horses. In contrast, clear evidence for copy number expansio...
Subclinical fungal endometritis in an 8-year-old Hanoverian mare. Clinical and subclinical endometritis are leading causes of reduced reproductive efficiency in the mare. Clinical endometritis is relatively easy to diagnose during routine physical and ultrasonographic reproductive examinations, whereas the diagnosis of subclinical endometritis requires a more detailed work-up. The goal of this paper is to review the various options, and describe the regimen chosen in a mare with subclinical fungal endometritis. Endométrite fongique subclinique chez une jument hanovrienne âgée de 8 ans. L’endométrite clinique et subclinique sont les principales causes d...
Plasma neurofilament pNF-H concentration is not increased in acute equine grass sickness. Although a presumptive diagnosis of acute grass sickness (AGS) can be made on the basis of clinical signs, a definitive ante mortem diagnosis currently requires histological examination of enteric ganglia. Development of an accurate noninvasive ante mortem diagnostic test is therefore warranted. The objective of this study was to determine whether quantification of the plasma concentrations of the heavily phosphorylated form of major neurofilament subunit NF-H (pNF-H), which mirror the degree of axonal degeneration in some human and animal neurodegenerative disorders, could distinguish AGS-aff...
The emerging pathophysiology of age-related testicular degeneration with a focus on the stallion and an update on potential therapies. Studies in laboratory rodents are shedding light on the pathophysiology of testicular ageing and now suggest a complicated basis for age-related declines in testicular function. A highly significant contributor to infertility may involve failure of specific and complex testicular microenvironments (niches) comprised of a variety of cellular and molecular components. Our laboratory has applied testis tissue xenografting to the study of testicular ageing in the stallion. Using this technique, we have confirmed that the disease is tissue autologous. As would be expected from a tissue autologous d...
Comparison of the fecal microbiota of healthy horses and horses with colitis by high throughput sequencing of the V3-V5 region of the 16S rRNA gene. The intestinal tract houses one of the richest and most complex microbial populations on the planet, and plays a critical role in health and a wide range of diseases. Limited studies using new sequencing technologies in horses are available. The objective of this study was to characterize the fecal microbiome of healthy horses and to compare the fecal microbiome of healthy horses to that of horses with undifferentiated colitis. A total of 195,748 sequences obtained from 6 healthy horses and 10 horses affected by undifferentiated colitis were analyzed. Firmicutes predominated (68%) among health...
Complete genome sequence of Corynebacterium pseudotuberculosis strain 1/06-A, isolated from a horse in North America. Corynebacterium pseudotuberculosis causes disease in several animal species, although distinct biovars exist that appear to be restricted to specific hosts. In order to facilitate a better understanding of the differences between biovars, we report here the complete genome sequence of the equine pathogen Corynebacterium pseudotuberculosis strain 1/06-A.
Hyperlipidaemia in trypanosomiasis of naturally infected horses: possible cachexia-anorexia syndrome? Trypanosomiasis caused by Trypanosoma evansi commonly produces wasting disease with signs of emaciation and cachexia mainly at the end stage. The present study was conducted to explore the possible hyperlipaemia or hyperlipidaemia and its association with cachexia-anorexia in equine trypanosomiasis. Out of the fifteen confirmed animals, none of the plasma sample was opaque. There was a significant increase in plasma triglyceride, total cholesterol and blood urea nitrogen and a highly significant increase in low-density lipoprotein (LDL) levels. A mild increase in high-density lipoprotein (HDL)...
Genome-wide linkage and association analysis identifies major gene loci for guttural pouch tympany in Arabian and German warmblood horses. Equine guttural pouch tympany (GPT) is a hereditary condition affecting foals in their first months of life. Complex segregation analyses in Arabian and German warmblood horses showed the involvement of a major gene as very likely. Genome-wide linkage and association analyses including a high density marker set of single nucleotide polymorphisms (SNPs) were performed to map the genomic region harbouring the potential major gene for GPT. A total of 85 Arabian and 373 German warmblood horses were genotyped on the Illumina equine SNP50 beadchip. Non-parametric multipoint linkage analyses showed g...
Fusobacterium necrophorum, and not Dichelobacter nodosus, is associated with equine hoof thrush. The aim of this study was to determine which of the two species, Fusobacterium necrophorum or Dichelobacter nodosus, are associated with hoof thrush in horses. Fourteen hoof samples, collected from eight horses with thrush and 14 samples collected from eight horses with healthy hooves, were examined for the presence of F. necrophorum, Fusobacterium equinum and D. nodosus. Only isolates with phenotypic characteristics representing Fusobacterium could be cultured. Total DNA extracted from the 28 hoof samples was amplified by using DNA primers designed from gene lktA, present in F. necrophorum su...
