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.
Sorrell MS, Fish RE, Taylor KH.Horses and ponies are used infrequently in research but may be valuable animal models for studying both equine-specific diseases and biomedical applications. We report here 2 cases of pediculosis in random-source ponies. Infestation and clinical signs were not present during a 4-wk quarantine period or for 3 to 9 mo thereafter but became apparent coincident with the ponies' movement from pasture to indoor housing. These 2 geldings presented with pruritus associated with excoriating lesions on the neck, and infestation with Bovicola (Werneckiella) equi Denny, 1842 was diagnosed. Ponies were tre...
Liao D, Shen J.In the present article, we summarize our studies of antrycide-resistance of Trypanosoma brucei evansi in four aspects in the last recent several years, the analysis of quinapyramine-sensitive situation of T. b. evansi in China, biological characteristics of T. b. evansi population in quinapyramine-resistance and biological materials of quinapyramine-resistance in T. b. evansi population. Firstly, the correlative assays of effective dosage of quinapyramine on T. b. evansi disease between in vivo and in vitro methods showed that their relationship was parabolic with positive correlation. On the ...
Da Silva AS, Garcia Perez HA, Costa MM, França RT, De Gasperi D, Zanette RA, Amado JA, Lopes ST, Teixeira MM, Monteiro SG.In this study, we reported the first outbreak of the infection by Trypanosoma vivax in horses in southern Brazil, a non-endemic region where bovines have only recently been found infected by this trypanosome species. We evaluated 12 horses from a farm in southern Brazil, where four horses displayed pale mucous membranes, fever, weight loss, and swelling of abdomen, prepuce, or vulva. The diagnosis of T. vivax was confirmed in four horses by morphological parameters of trypomastigotes in blood smears and species-specific PCR. All T. vivax-infected animals showed anemia, and most showed increase...
Morán G, Folch H, Araya O, Burgos R, Barria M.Reaginic antibodies, mainly of the IgE and some IgG subclasses, play an important role 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. Previously, several studies have investigated the role of reaginic antibodies in the pathogenesis of RAO. However, whereas immunological aspects of RAO have been extensively studied, the precise sequence of events is still not well understood and role of IgE in this disease still remains controversial. Therefo...
Orsini JA, Parsons CS, Capewell L, Smith G.This retrospective study investigated the factors associated with a poor outcome (death by euthanasia or from other causes) in horses treated for laminitis at a tertiary care hospital. Cases (n = 247) were defined as patients with laminitis that were euthanized or that died of other causes during hospitalization. Controls (n = 344) were patients with laminitis that survived to be discharged from the hospital. In the final multivariate analysis, the factors significantly associated with an increased risk for death and their respective odds ratios (OR) were as follows: Thoroughbred (OR = 1.57); ...
Szczerba-Turek A, Siemionek J, Wasowicz K, Szweda W, Raś A, Platt-Samoraj A.BPV-1 is now recognized as a main etiological agent of equine sarcoids. The etiopathogenesis of the equine sarcoids is equivocal and is not yet fully understood. The aim of the present study was to analyse a partial sequence of the L1 gene of BPV associated with equine sarcoids in Polish horses. After clinical diagnosis, 40 skin lesions obtained from 29 horses were collected. The amplicons of a fragment of BPV L1 DNA were detected using PCR with MY09/MY11 primers in 31 specimens. All of them were recognized as BPV-1. Phylogenetic analysis has allowed the amplicons of partial L1 gene to be divi...
Ireland JL, Clegg PD, McGowan CM, McKane SA, Pinchbeck GL.Geriatric horses (aged≥15 years) represent a substantial proportion of the equine population, yet very few studies have investigated the prevalence of diseases within the UK equine geriatric population. Objective: To describe the provision of routine preventive health care measures, prevalence of clinical signs of disease and the prevalence of owner reported diseases. Additionally, the effect of increasing age on the provision of preventive health care and the presence or absence of clinical signs and disease was assessed. Methods: A cross-sectional study was conducted, surveying a randomly ...
Sinding MF, Berg LC.The aetiological factors behind impinged or overriding of dorsal spinous processes ('kissing spine syndrome', KSS) are not clearly understood. Back conformation, breed, age, training and gender may play important roles in this condition. Radiographic changes vary and abnormalities are seen in many clinically normal horses, but the conclusion of previous studies in mature horses is that interspinous spaces <4 mm are considered too narrow and potentially indicative of KSS. Objective: To evaluate whether narrowing of the interspinous space was present in a population of normal Warmblood foals....
Ueno T, Nambo Y, Tajima Y, Umemura T.Broad ligament haemorrhage in peripartum mares is a life-threatening disease and there are few reports on the aetiology and pathogenesis of broad ligament haematoma. Objective: To obtain information regarding the sites for the early diagnosis and pathogenesis of broad ligament haematoma of mares. Methods: Thirty-one mares that died of broad ligament haematoma peripartum were examined pathologically for bleeding sites. The arterial distribution of 5 young mares with several parities served as negative controls. Results: Age and/or multiparity were the predisposing factors for the disease. Arter...
Waggett BE, McGorum BC, Wernery U, Shaw DJ, Pirie RS.While previous studies have demonstrated an association between equine grass sickness (EGS) and the presence of Clostridium botulinum within ileal contents and faeces, no such associations with other intestinal-derived anaerobic bacteria have been extensively investigated. Objective: The prevalence of C. perfringens in the ileal contents and faeces of EGS horses is greater than control horses; the detection of C. perfringens in faeces by ELISA could be diagnostically beneficial in a clinical setting. Methods: The prevalence of C. perfringens in faeces from EGS horses and healthy grazing contro...
Eustace RA.The terminology relating to laminitis is confusing. This article describes how equine veterinarians, by using their eyes and fingers alone, can diagnose and evaluate a case of chronic laminitis. This evaluation will enable veterinarians to give a statistically significant prognosis that can be further refined by measurements taken from plain, weight-bearing lateromedial radiographs of the affected hooves. Should invasive techniques such as digital venography also be used, the results of both techniques are complementary.
van Eps A, Collins SN, Pollitt CC.Supporting limb laminitis poses a threat to all horses suffering from severe unilateral lameness. Despite its devastating effects, relatively little is known about the precise pathologic processes that lead to its development. This article reviews the potential mechanisms of supporting limb laminitis, and the authors present some preliminary data based on advanced imaging and computer-based modeling techniques aimed at further elucidating the etiology of this unique form of laminitis. Gaining a better understanding of the pathologic processes that lead to supporting limb laminitis is essential...
van Eps A, Collins SN, Pollitt CC.Supporting limb laminitis poses a threat to all horses suffering from severe unilateral lameness. Despite its devastating effects, relatively little is known about the precise pathologic processes that lead to its development. This article reviews the potential mechanisms of supporting limb laminitis, and the authors present some preliminary data based on advanced imaging and computer-based modeling techniques aimed at further elucidating the etiology of this unique form of laminitis. Gaining a better understanding of the pathologic processes that lead to supporting limb laminitis is essential...
Geor RJ.Epidemiologic studies indicate that most laminitis cases occur in horses and ponies kept at pasture, hence the term 'pasture-associated laminitis'. Clinical cases of laminitis most often occur under conditions that favor accumulation of rapidly fermentable nonstructural carbohydrates (fructans, simple sugars, or starches) in pasture, and animals with an equine metabolic syndrome (EMS) phenotype (insulin resistance, abnormal insulin dynamics, +/- obesity) seem to be at highest risk for developing the condition. Although the mechanisms linking consumption of pasture forage with development of la...
Metz GE, Ocampos GP, Serena MS, Gambaro SE, Nosetto E, Echeverría MG.To perform genetic analysis of the ORF5 of equine arteritis virus (EAV) may provide new insights into the genetic evolution and origin of the Argentinean EAV sequences. Methods: A total of 76 sequences were analyzed by neighbor joining (NJ), maximum parsimony and maximum likelihood algorithms. The analysis of the selective pressures was performed using the Tajima's test. Results: The trees showed similar topologies. Two clades were identified: the first clade was formed by strains isolated mainly from a donkey, whereas the second clade presented four large groups from different geographic regi...
Bubeck KA, García-Lopez JM, Jenei TM, Maranda LS.To compare heat generation during insertion, pullout strength, and associated microdamage between a self-tapping positive profile transfixation pin (STTP) and nontapping positive profile transfixation pin (NTTP). Methods: 30 pairs of third metacarpal bones (MC3s) from adult equine cadavers. Methods: One MC3 of each pair was assigned to the STTP group; the other was assigned to the NTTP group. The assigned pin was inserted into the diaphysis in a lateral to medial direction. Bone temperature increase during pilot-hole drilling and pin insertion was recorded at 1 mm from the final thread positio...
Lopes MA, Salter CE, Vandenplas ML, Berghaus R, Hurley DJ, Moore JN.To investigate whether expression of inflammation-associated genes in leukocytes from horses with gastrointestinal tract (GIT) diseases correlated with the type of disease and outcome. Methods: 10 healthy horses and 50 horses with GIT disease. Methods: A blood sample was collected from each healthy horse or horse with GIT disease (during admission to the hospital). Leukocytes were isolated, diluted to a standard concentration, and frozen until RNA extraction. Expression of 14 genes associated with inflammation was quantified by use of a real-time quantitative reverse transcription PCR assay. R...
Sanz MG, Sellon DC, Potter KA.A 25-year-old Appaloosa gelding was evaluated for chronic weight loss and diarrhea. A clinical diagnosis of protein loosing enteropathy was made and the gelding was euthanized. Histology revealed neoplastic lymphocytes infiltrating the mucosa of the small and large intestine. Immunohistochemistry was positive for CD3, consistent with epitheliotropic T-cell lymphoma. Lymphome T intestinal épithéliotrope primaire comme cause de diarrhée chez un cheval. Un hongre appaloosa âgé de 25 ans a été évalué pour perte de poids et diarrhée chronique. Un diagnostic clinique d’entéropathie avec...
Burns TA, Geor RJ, Mudge MC, McCutcheon LJ, Hinchcliff KW, Belknap JK.Insulin resistance has been associated with risk of laminitis in horses. Genes coding for proinflammatory cytokines and chemokines are expressed more in visceral adipose tissue than in subcutaneous adipose tissue of insulin-resistant (IR) humans and rodents. Objective: To investigate adipose depot-specific cytokine and chemokine gene expression in horses and its relationship to insulin sensitivity (SI). Methods: Eleven light breed mares. Methods: Animals were classified as IR (SI=0.58+/-0.31x10(-4) L/min/mU; n=5) or insulin sensitive (IS; SI=2.59+/-1.21x10(-4) L/min/mU; n=6) based on results o...
de la Rebière de Pouyade G, Serteyn D.Despite ongoing research and a widening range of treatment options, laminitis remains a severely damaging condition with poorly understood pathophysiology. Results obtained from cytokine regulation studies during the last decade have highlighted the inflammatory nature of laminitis. This review will describe the role of systemic activation and local infiltration of neutrophils in laminar tissues in the induction of laminitis. Particular emphasis is placed on the role of neutrophil activation in subsequent vascular dysfunction and oxidative and proteolysis imbalances that are pathways previousl...
Vanderstraeten E, Bogaert L, Bravo IG, Martens A.Squamous cell carcinoma (SCC) represents the most common malignant tumour of the eye and external genitals in horses. Comparable to humans, papillomaviruses (PV) have been proposed as etiological agents of cancer in horses and recently, Equine papillomavirus type 2 (EcPV2) has been identified in genital SCCs. Hitherto it had never been demonstrated in ocular SCCs. The first goal of this study was to determine the prevalence of EcPV2 DNA in tissue samples from equine genital and ocular SCCs, genital papillomas and penile intraepithelial neoplasia (PIN) lesions, using EcPV2-specific PCR. The sec...
Roberts H.Helen Roberts of Defra's International Disease Monitoring team sets out the situation regarding equine infectious anaemia in Europe, the threat to the UK and the expectations of disease control measures in light of an outbreak being detected.
Hardy J, Léveilé R.Guttural pouches are unique anatomic structures in Equidae. Conditions affecting the guttural pouches present with clinical signs that are not observed in other domestic species, and treatment of some of these conditions can be challenging. This article describes the anatomy and examination of the guttural pouches and reviews the presenting signs and treatment of the more common conditions affecting them, including empyema, tympany, mycosis, and stylohyoid arthropathy.
Tully LJ, Murphy AM, Smith RK, Hulin-Curtis SL, Verheyen KL, Price JS.To explore whether genetic susceptibility is a potential risk factor for superficial digital flexor (SDF) tendinopathy in Thoroughbred (TB) racehorses. Objective: To identify informative single nucleotide polymorphisms (SNPs) that capture genetic diversity across a range of candidate genes and to investigate, in a case-control study, their association with SDF tendinopathy in UK National Hunt TB racehorses in training. Methods: Case-control candidate gene association study. Methods: This study used in silico gene assembly and DNA sequencing to screen candidate genes for SNPs. Seven candidate g...
Dik KJ, van den Broek J.From progeny lists of 30 Dutch Warmblood sires, 586 3-year-old females by these stallions were randomly selected, each progeny group aimed at 20 animals for statistical reasons. The front feet of the sires and female progeny were examined radiographically using lateromedial and dorsopalmar upright pedal projections. The radiological features associated with navicular disease were classified 0-4 using a standardised classification, grades 3 and 4 representing the more severe changes. The shape of the proximal articular border of the navicular bone outline on the dorsopalmar view was classified ...
Dumoulin M, Pille F, Van den Abeele AM, Haesebrouck F, Oosterlinck M, Gasthuys F, Martens A.The objective of this study was to evaluate an automated blood culture system for the isolation of microorganisms from infected equine synovial fluid (SF). Samples were collected from 220 severely inflamed synovial joints and classified as either presumably infected (group A: n=149) or not infected (group B: n=71), based on a combination of clinical history, clinical signs and cytological analysis of the SF. Samples were inoculated into blood culture bottles and after incubation were subcultured onto agar media to confirm the results and to facilitate full bacterial identification. Microorgani...
Blanke A, Aupperle H, Seeger J, Kubick C, Schusser GF.Clinical, anatomical and histological aspects of the equine acoustic organ have been poorly investigated and illustrated in literature so far. It is understood that an intact acoustic organ and hearing function are of vital importance for the well-being of flight animals like horses. The knowledge of the acoustic organ is usually transferred analogously from other mammals to horses. The purpose of this study was to provide a detailed and complete histological description of the healthy equine auditory organ, and to determine its congruity to other mammalians. Anatomical dissections and histolo...
Halliwell RE, Fleischman JB, Mackay-Smith M, Beech J, Gunson DE.Twenty-five horses with chronic pulmonary disease were skin tested with allergenic extracts of 24 molds, 4 thermophilic actinomyces, barn dust, hay dust, soya-bean mill dust, and grain mill dust. The results were compared with those obtained on 25 normal horses. Between the 2 groups of horses, there was a highly significant difference in positive skin test results at 30 minutes and 4 hours.
Schumacher J.Hematuria and pigmenturia of horses are discussed in this article. Equine urine is normally straw colored. Discolored urine can be caused by contamination with red blood cells, hemoglobin, myoglobin, oxidizing agents normally found in urine, and plant-derived pigments.
Hilbe M, Guscetti F, Wunderlin S, Ehrensperger F.Equine and feline dysautonomias are characterized histopathologically by degenerating neurons with chromatolysis, pyknotic and sometimes eccentric nuclei, and loss of Nissl substance in the peripheral autonomic ganglia. Because it may be difficult to distinguish pathological from post-mortem changes in affected ganglia by histopathological examination, synaptophysin was evaluated as an immunohistochemical marker. Degenerating neurons showed strong intracytoplasmic labelling indicating abnormal accumulation of synaptophysin. It was concluded that synaptophysin immunohistochemistry is a helpful ...
Hinrichs K, Williams KA.Horse oocytes with expanded (EX) cumuli appear to have greater meiotic competence than do horse oocytes with compact (CP) cumuli but are thought to come from atretic follicles. We evaluated the relationships among cumulus expansion, follicle viability, initial chromatin configuration, and meiotic competence of horse oocytes. Follicle walls were sectioned for histological examination, and the follicles were scraped to obtain the oocytes. Half of the oocytes were evaluated immediately and half were matured for 24 h in vitro. Cumulus expansion was significantly associated with follicle atresia. I...
Weideman H, Schoeman SJ, Jordaan GF, Kidd M.This study investigated if environmental factors had an effect on the incidence of epistaxis related to exercise-induced pulmonary haemorrhage (EIPH) among racehorses in southern Africa. Data covering the period 1986-2001 and involving 778 532 race runs were analysed. This included the following information: date of race, age, sex, name of breeder, trainer, distance, jockey, state of going, weight carried, racing centre and altitude. Veterinarians employed by the Jockey Club suspended officially entered horses that presented with epistaxis (frank bleeding from the nostrils) after racing. On-co...
Ramos RT, Silva A, Carneiro AR, Pinto AC, Soares Sde C, Santos AR, Almeida SS, Guimarães LC, Aburjaile FF, Barbosa EG, Dorella FA, Rocha FS....The bacterium Corynebacterium pseudotuberculosis is of major veterinary importance because it affects livestock, particularly sheep, goats, and horses, in several countries, including Australia, Brazil, the United States, and Canada, resulting in significant economic losses. In the present study, we describe the complete genome of the Corynebacterium pseudotuberculosis Cp316 strain, biovar equi, isolated from the abscess of a North American horse.
Andersen C, Jacobsen S, Walters M, Lindegaard C.Osteoarthritis (OA) is a significant health issue in humans as well as horses. Experimental models of equine carpal OA have been used to investigate OA pathogenesis and potential therapeutic candidates. A 5-scale scoring system (OARSI) for macroscopic pathological cartilage changes already exists, but there is a need for a scoring system with better differentiation of severity. The aim of this study was therefore to develop and validate such a scoring system. Results: New scoring system were developed for cartilage erosions (Copenhagen Equine Total Cartilage Score, CEqTCS) along with synovial ...
Noschka E, Vandenplas ML, Hurley DJ, Moore JN.The results of recent studies indicate that inflammatory responses occurring in the early stages of equine laminitis lead to downstream events that eventually result in failure of the bond between the hoof wall and the distal phalanx. In order to gain further insights into the molecular mechanisms involved in the development of laminitis, an equine-specific cDNA microarray consisting of transcripts for more that 3000 genes was used to assess temporal changes in gene expression in laminar tissues at 1.5, 3 and 12 h after administration of either a laminitis-inducing agent (black walnut heartwoo...
Howard-Martin M, Morton RJ, Qualls CW, MacAllister CG.A 1-day old, full-term foal with a history of colic died 2 hours after admission. Necropsy revealed an extremely flaccid, fluid-filled intestinal tract. Histopathologically, the superficial intestinal mucosa was completely necrotic, with minimal inflammatory response. Numerous large, gram-positive rods covered the villi. Clostridium perfringens was isolated on bacteriologic culturing of the intestinal tract contents and was identified as type C by toxin neutralization tests.
Reilly GA, Cassidy JP, Taylor SM.Detailed pathological examinations of two horses with subacute fatal diarrhoea suggested an association between the diarrhoea and damage to the colonic and caecal mucosae caused by large numbers of cyathostome larvae (larval cyathostomiasis). The affected animals deteriorated rapidly, and died after a short illness.
Halldórsdóttir S, Lazary S, Gunnarsson E, Larsen HJ.Three hundred and three horses, exported from Iceland to Norway, Sweden, Denmark, Switzerland or Germany were tested for their distribution of leucocyte antigens. One hundred and thirty-six horses were affected with summer eczema. The panel of sera recognised the internationally accepted ELA-specificities A 1 to A10, and the nine work shop specificities W 11 to W 15 and W 18 to W 21. Also, some local specificities, characterised in Switzerland (Be I, Be III, Be 8, Be 25, Be 26, Be 27), and two non major histocompatibility complex (MHC)-linked antigens (Ely 1:1, Ely 2) were included. Only one a...
Ayala I, Rodríguez MJ, Martos N, Zilberschtein J, Ruíz I, Motas M.Fatal brodifacoum poisoning in a pony is described; this condition has not previously been reported in ponies. Discussion of what factors in the pony's history and treatment may have predisposed to the severity and ultimate death is provided. Cet article décrit un empoisonnement mortel au brodifacoum chez un poney, condition jamais rapportée auparavant. La discussion porte sur les liens entre les divers éléments de l’anamnèse et les traitements reçus par rapport à la sévérité de la condition et ultimement à la mort de l’animal. (Traduit par Docteur André Blouin)
Semevolos SA.This article reviews current knowledge of osteochondritis dissecans (OCD) development in horses, including normal cartilage development, early osteochondrosis pathogenesis, and factors that result in healing or advancement to OCD fragments. Discussion includes current theories, detection, and therapeutic options.
McGorum BC, Mayhew IG, Amory H, Deprez P, Gillies L, Green K, Mair TS, Nollet H, Wijnberg ID, Hahn CN.Equine motor neuron disease (EMND) was diagnosed in 3 horses maintained on lush, grass-based pasture. This contrasted with North American studies which identified limited or no access to green herbage as an important risk factor for EMND. Objective: Grazing horses that have an apparently adequate intake of pasture herbage to meet normal equine vitamin E requirements can develop EMND. Methods: Owners of 32 European horses diagnosed with EMND completed a questionnaire regarding intrinsic, managemental, nutritional and environmental factors that could potentially be risk factors for EMND, and als...