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.
Cholleti H, Paidikondala M, Munir M, Hakhverdyan M, Baule C.Equine arteritis virus (EAV) causes a respiratory and reproductive disease in horses, equine viral arteritis. Though cell death in infection with EAV is considered to occur by apoptosis, the underlying molecular mechanism has not been extensively elucidated. We investigated the expression of mRNA of pro-apoptotic and caspase genes during EAV infection in BHK21 cells, a well-established cell type for EAV replication. Using a SYBR Green real-time PCR, mRNA of p53, Bax, caspase 3 and caspase 9 were found up-regulated in a time dependent manner in EAV infected cells. Western blot analysis for casp...
Pusterla N, Mapes S, Wademan C, White A, Ball R, Sapp K, Burns P, Ormond C, Butterworth K, Bartol J, Magdesian KG.The purpose of this study was to describe clinical, hematological and fecal PCR results from 161 horses involved in outbreaks associated with ECoV. The outbreaks happened at four separate boarding facilities between November 2011 and April 2012 in the States of CA, TX, WI and MA. Following the molecular detection of ECoV in the feces from the initial index cases, the remaining herdmates were closely observed for the development of clinical signs. Fecal samples were collected from sick and healthy horses for the PCR detection of ECoV. All four outbreaks involved primarily adult horses. Fifty-ni...
Montgomery K, Ortved K, DeVries J, Hackett R, Kern T, Irby N, Ducharme N.A 7-year-old Connemara stallion was presented with a 4 month history of blepharospasm, recurrent corneal ulcerations, mucopurulent ocular discharge, and keratoconjunctivitis sicca (KCS) in both eyes unresponsive to medical therapy. Ophthalmic examination revealed lackluster corneas, axial corneal scarring and pigmentation with associated neovascularization, and absolute KCS in both eyes. Computed tomography scan and endoscopic evaluation of the upper airway and guttural pouches revealed no structural abnormalities to indicate neurogenic KCS. The stallion was diagnosed with immune-mediated dacr...
Lange CE, Tobler K, Lehner A, Grest P, Welle MM, Schwarzwald CC, Favrot C.Equine penile papillomas, in situ carcinomas, and invasive carcinomas are hypothesized to belong to a continuum of papillomavirus-induced diseases. The former ones clinically present as small grey papules, while the latter 2 lesions are more hyperplasic or alternatively ulcerated. To test the hypothesis that these lesions are papillomavirus-induced, samples of 24 horses with characteristic clinical and histologic findings of penile papillomas or in situ or invasive squamous cell carcinomas were collected. As controls, 11 horses with various lesions--namely, Balanoposthitis (6 cases), melanoma ...
Yamout SZ, Magdesian KG, Tokarz DA, le Jeune SS.This is a report of a 12-year-old Swedish Warmblood gelding with a ruptured esophageal pulsion diverticulum associated with atypical clinical signs of colic and septic peritonitis on presentation. The location of this diverticulum at the hiatus was unique and was most likely responsible for the unusual presentation of this horse. Diverticule de Zenker intrathoracique chez un cheval. Ceci est un rapport d’un hongre de race Swedish Warmblood âgé de 12 ans présentant un diverticule de Zenker perforé associé à des signes cliniques atypiques de coliques et de péritonite septique à la pré...
Garcia-Etxebarria K, Jugo BM.Endogenous retroviruses (ERVs) are proviral phases of exogenous retroviruses that have become incorporated into the host genome. Little is known about ERVs in the horse genome. By combining 3 bioinformatic approaches, we detected 1947 putative ERVs in the horse genome. These equine ERVs are not scattered randomly across the genome and are especially abundant in the X chromosome. Based on phylogenetic relationships, some of these equine ERVs were classified into 15 previously uncharacterized families of Classes I, II and III. Compared with the cow and other species, the horse genome appears to ...
Elshafie EI, Sani RA, Hassan L, Sharma R, Bashir A, Abubakar IA.A cross-sectional study was designed to assess the seroprevalence and risk factors associated with Trypanosoma evansi infection among horses, using a total of 527 blood samples obtained from eight states in Peninsular Malaysia. A structured questionnaire was used to collect data on risk factors associated with T. evansi seroprevalence. The overall seroprevalence detected by card agglutination test for T. evansi (CATT/T. evansi) was 13.90% (73/527, CI: 11.2-17.1%). Female and exogenous horses showed a higher risk in association with the disease seroprevalence compared to other groups. The major...
Steelman SM, Chowdhary BP.Equine laminitis is a devastating disease that causes severe pain in afflicted horses and places a major economic burden on the horse industry. In acute laminitis, the disintegration of the dermal-epidermal junction can cause the third phalanx to detach from the hoof wall, leaving the horse unable to bear weight on the affected limbs. Horses that survive the acute phase transition into a chronic form of laminitis, which is often termed "founder". Some evidence suggests that chronic laminar inflammation might be associated with alterations in the endocrine and immune systems. We investigated th...
O'Leary JM, Barnett TP, Parkin TD, Dixon PM, Barakzai SZ.Although equine motorised dental instruments are widely used, there is limited information on their thermal effect on teeth. The recently described variation in subocclusal secondary dentine depth overlying individual pulp horns may affect heat transmission to the underlying pulps. Objective: This study compared the effect of 3 different equine motorised dental instruments on the pulpar temperature of equine cheek teeth with and without the use of water cooling. It also evaluated the effect of subocclusal secondary dentine thickness on pulpar temperature changes. Methods: A thermocouple probe ...
Back H, Kendall A, Grandón R, Ullman K, Treiberg-Berndtsson L, Ståhl K, Pringle J.A standardbred gelding with a history of 10 days pyrexia and lethargy was referred to the Equine Hospital at the Swedish University of Agricultural Sciences in Uppsala, Sweden.The horse had tachypnea with increased respiratory effort and was in thin body condition. Laboratory findings included leukocytosis, hyperfibrinogenemia and hypoxemia. Thoracic radiographs showed signs of pneumonia with a multifocal nodular pattern, which in combination with lung biopsy findings indicated Equine Multinodular Pulmonary Fibrosis (EMPF). EMPF is a recently described disease in adult horses with clinical s...
Kopke S, Angrisani N, Staszyk C.Recent studies reported on the very complex morphology of the pulp system in equine cheek teeth. The continuous production of secondary dentine leads to distinct age-related changes of the endodontic cavity. Detailed anatomical knowledge of the dental cavities in all ages is required to explain the aetiopathology of typical equine endodontic diseases. Furthermore, data on mandibular and maxillary pulp systems is in high demand to provide a basis for the development of endodontic therapies. However, until now examination of the pulp cavity has been based on either sectioned teeth or clinical co...
Cherry NA, Jones SL, Maggi RG, Davis JL, Breitschwerdt EB.Bartonella species bacteremia has been identified in numerous animal species. These bacteria cause, or have been associated with, a spectrum of clinical manifestations in dogs and human patients. The frequency of exposure to or infection with Bartonella spp. among healthy and sick horses has not been reported. Objective: To test healthy and sick horses and sick foals from the southeastern United States for serological, microbiological, and molecular evidence of Bartonella infection. Methods: Forty-seven healthy horses, 15 sick foals, 22 horses with musculoskeletal manifestations, and 8 horses ...
Hansson I, Johansson KE, Persson M, Riihimäki M.Nicoletella semolina, a member of the family Pasteurellaceae, can be isolated from the airways of horses with respiratory disorders. However, its role as a potential or opportunistic pathogen is not clear nor is its presence as part of the normal flora. We therefore investigated the presence and bacterial load of N. semolina in healthy and diseased horses. Samples from a healthy control group were compared with samples from the routine analysis of horses with a clinical history of respiratory disorders. A total of 1770 nose swabs and 1132 tracheal aspirate samples were analysed and subjected t...
Hunt RJ.Underrun heels are common and involve hoof capsule distortion in which the horn tubules of the heels undergo bending and lengthening, resulting in decreased strength and functionality. The syndrome varies in clinical presentation, depending on duration, severity of distortion, presence of secondary problems, and presence of lameness. Primary treatment goals are to maintain soundness and functional integrity of the foot and to establish a normal hoof capsule. Resolution of the problem is generally not achieved in horses in a heavy work schedule, and realistic goals in this situation are to main...
Redding WR, O'Grady SE.This article addresses nonseptic diseases associated with the hoof complex, namely keratoma, white line disease, canker, and neoplasia. Keratoma is an uncommon cause of lameness, which may be surgically removed. White line disease, a keratolytic process on the solar surface of the hoof, is treated with therapeutic farriery and resection of the hoof wall when appropriate. Equine canker is an infectious process that results in development of a chronic hypertrophy of the horn-producing tissues. Neoplasia involving the equine foot is rare, and melanoma is the most common type of neoplasm reported....
Botha CJ, Lewis A, du Plessis EC, Clift SJ, Williams MC.Twenty-eight horses in southern Mozambique died after exhibiting severe respiratory distress. At necropsy, the overinflated lungs did not collapse, had prominent rib impressions, and were fibrotic and emphysematous. Microscopically, prominent proliferation of nonciliated epithelial (Clara) cells in the terminal bronchioles and pulmonary fibrosis were observed, indicative of chronic pneumotoxicity. Transmission electron microscopy demonstrated hyperplasia, desquamation, and apical bulging of Clara cells into the bronchiolar lumen. The outbreak was attributed to ingestion of Crotalaria dura J.M....
O'Grady SE, Dryden VC.A club foot or flexural deformity may affect a horse at any stage of life from neonate through adulthood. The emphasis of this article is on defining and recommending the appropriate farriery for flexural deformities involving the deep digital flexor tendon and the distal interphalangeal joint. Clinical management of the flexural deformity is influenced by the severity, duration, and etiology of the club foot as well as the degree and source of lameness. Also discussed is the management of mismatched hoof angles, which remains a controversial subject for both farrier and veterinarian.
Borer KE, Bailey SR, Menzies-Gow NJ, Harris PA, Elliott J.Identification of ponies (Equus caballus) at increased risk of pasture-associated laminitis would aid in the prevention of the disease. Insulin resistance has been associated with laminitis and could be used to identify susceptible individuals. Insulin resistance may be diagnosed by feeding supplementary water-soluble carbohydrate (WSC) and measuring blood glucose and insulin concentrations. The aim of this study was to assess the glycemic and insulinemic responses of 7 normal (NP) and 5 previously laminitic (PLP), mixed breed, native UK ponies fed glucose, fructose, and inulin [1 g/(kg·d) fo...
Studzińska MB, Tomczuk K, Demkowska-Kutrzepa M, Szczepaniak K.Postmortem parasitic examinations of the large intestines of 725 slaughtered horses from individual farmers in southeastern Poland were carried out. The examinations were carried out monthly since February 2006 until January 2007 (except for August 2007 because of a technological stoppage in the slaughterhouse). The examinations included the intensiveness and extensiveness of the infestation of the Strongylidae belonging to the Strongylus genus. The Strongylidae were found in 26.5% of the examined horses. Strongylus vulgaris was the most dominant nematode and had a 22.8% prevalence, Strongylus...
Tadros EM, Frank N, Newkirk KM, Donnell RL, Horohov DW.The role of endotoxemia in the development of laminitis remains unclear. Although systemic inflammation is a risk factor for laminitis in hospitalized horses, experimental endotoxin administration fails to induce the disease. While not sufficient to cause laminitis by itself, endotoxemia might predispose laminar tissue to damage from other mediators during systemic inflammation. In "two-hit" models of organ damage, sequential exposure to inflammatory stimuli primes the immune system and causes exaggerated inflammatory responses during sepsis. Acute laminitis shares many characteristics with se...
Lafave MR, Butterwick DJ, Murray RP, Freeman T, Lau BH.The purpose of this study was to establish the content validity of the Rodeo SCAT for the sport of rodeo and bull riding. The study design was comprised of expert consensus and content validation. A modified Ebel procedure was employed to content validate the rodeo SCAT. Content validation using this method includes experts agreeing on the importance of each item that comprises the rodeo SCAT. This 3-stage process involved: 1) face validation by a local committee: 2) initial expert consensus measurement via distance; and 3) a face-to-face discussion for items that did not originally achieve 80...
Metcalfe LV, More SJ, Duggan V, Katz LM.Weight loss despite a good appetite is a frequent diagnostic challenge for equine veterinarians; however, there are few objective reports and little descriptive information regarding risk factors and prognostic indicators. Objective: To provide a descriptive epidemiological analysis of horses evaluated for weight loss despite a good appetite and evaluate relationships between historical and clinicopathological findings and final outcome (survival vs. nonsurvival) to identify risk factors and prognostic indicators. Methods: Medical records of horses referred for investigation of weight loss des...
Snyder JR, Olander HJ, Pascoe JR, Holland M, Kurpershoek CJ.Morphologic changes that develop sequentially in the large colon during experimentally induced ischemia were documented in 14 halothane-anesthetized horses. Colonic ischemia was induced by 4 types of vascular occlusion, 24 cm proximal and distal to the pelvic flexure. The effect of transmural (colonic wall) vascular compression combined with either venous occlusion (3 horses, group A) or venous and arterial occlusion (3 horses, group B) of the colonic vessels was studied for 1, 2, and 6 hours of occlusion. Also observed was the effect of reperfusion for 0.5 hour after release of the clamps for...
Lenard ZM, Lester NV, O'hara AJ, Hopper BJ, Lester GD.A 4-year-old Arab mare was diagnosed with disseminated cryptococcosis, including osteomyelitis of the proximal phalanx of the left hind limb, osteomyelitis with associated soft tissue granuloma of a rib and disseminated, large cryptococcal nodules in the lungs. The lesion in the dorsoproximal aspect of the proximal phalanx had a large area of cortical lysis with spiculated periosteal new bone and extensive soft tissue swelling. The affected rib had a pathological fracture. Cryptococcal osteomyelitis has not been previously reported in horses but should be considered as a differential diagnosis...
Cruz AM, Hurtig MB.Osteoarthritis and articular fractures are commonly responsible for early retirement from athletic performance. The subchondral bone (SCB) in those conditions is being recognized as an integral component in their pathophysiology. Early recognition of these potentially career-ending diseases may require understanding of the progression of changes occurring in SCB with time and exercise.
Ghosh S, Davis BW, Rosengren M, Jevit MJ, Castaneda C, Arnold C, Jaxheimer J, Love CC, Varner DD, Lindgren G, Wade CM, Raudsepp T.Disorders of sex development (DSD) and reproduction are not uncommon among horses, though knowledge about their molecular causes is sparse. Here we characterized a ~200 kb homozygous deletion in chromosome 29 at 29.7-29.9 Mb. The region contains genes which function as ketosteroid reductases in steroid hormone biosynthesis, including androgens and estrogens. Mutations in genes are associated with human DSDs. Deletion boundaries, sequence properties and gene content were studied by PCR and whole genome sequencing of select deletion homozygotes and control animals. Deletion analysis by PCR in ...
Valberg SJ, Soave K, Williams ZJ, Perumbakkam S, Schott M, Finno CJ, Petersen JL, Fenger C, Autry JM, Thomas DD.Sarcolipin (SLN), myoregulin (MRLN), and dwarf open reading frame (DWORF) are transmembrane regulators of the sarcoplasmic reticulum calcium transporting ATPase (SERCA) that we hypothesized played a role in recurrent exertional rhabdomyolysis (RER). Objective: Compare coding sequences of SLN, MRLN, DWORF across species and between RER and control horses. Compare expression of muscle Ca2+ regulatory genes between RER and control horses. Methods: Twenty Thoroughbreds (TB), 5 Standardbreds (STD), 6 Quarter Horses (QH) with RER and 39 breed-matched controls. Methods: Sanger sequencing of SERCA reg...
Sellon DC, Knowles DP, Greiner EC, Long MT, Hines MT, Hochstatter T, Hasel KM, Ueti M, Gillis K, Dame JB.Sarcocystis neurona is an apicomplexan parasite that is the primary etiologic agent of equine protozoal myeloencephalitis in horses. Protective immune responses in horses have not been determined, but interferon-gamma (IFN-gamma) is considered critical for protection from neurologic disease in mice. The role of adaptive and innate immune responses in control of parasites was explored by infecting BALB/c, IFN-gamma knockout (GKO), and severe combined immune deficient (SCID) mice with S. neurona (10(4) sporocysts/mouse). Immune competent BALB/c mice eliminated parasites within 30 days, with no s...
Santschi EM, Vrotsos PD, Purdy AK, Mickelson JR.To determine incidence of the Ile118Lys endothelin receptor B (EDNRB) mutation responsible for overo lethal white syndrome (OLWS) and its association with specific types of white patterning. Methods: 945 horses of white-patterned bloodlines and 55 solid-colored horses of other breeds. Methods: Horses were genotyped by use of allele-specific polymerase chain reaction to determine incidence of the Ile118Lys EDNRB mutation. Results: Genotypes detected were homozygous Ile118, homozygous Lys118, and heterozygous. All foals with OLWS were homozygous for the Ile118Lys EDNRB mutation, and adults that ...
O'Callaghan MW, Pascoe JR, Tyler WS, Mason DK.Lungs from 19 Thoroughbred racehorses with a history of exercise-induced pulmonary haemorrhage (EIPH) were studied using several forms of microscopy. Light microscopy of paraffin sections revealed three lesions in the caudodorsal region of the lungs from each horse. These correspond with the location of blue to brown stains seen at necropsy. These lesions include sequelae of bronchiolitis, hemosiderophages and increased connective tissue. Much of each of the lungs appeared normal, especially the more cranial or ventral portions. Foci of eosinophil infiltration were found in seven of the 19 lun...
Zipplies JK, Hauck SM, Schoeffmann S, Amann B, van der Meijden CH, Stangassinger M, Ueffing M, Deeg CA.Equine recurrent uveitis (ERU) is an incurable disease affecting the inner eye that leads to blindness, through activated T cells that pass the blood-retinal barrier and destroy the retina. Serum markers are a desirable choice for monitoring development of disease, as serum is easy accessible and the markers could serve to predict the beginning of disease or an imminent relapse. Methods: In this study, serum proteomes (depleted of high-abundance serum proteins) of horses with ERU and healthy controls were compared with the 2-D DIGE (two-dimensional gel electrophoresis) technique to identify di...
Guerrero Cota JM, Leale DM, Arzi B, Cissell DD.Temporomandibular joint (TMJ) disorders affect up to 12% of the human population, and naturally occurring TMJ diseases are increasingly recognized in animals. The TMJ disc plays a major role in TMJ disorders in people, but little is known about its role in TMJ pathology in animals. This study characterizes differences in properties of equine TMJ discs associated with age, disc region, and presence of TMJ osteoarthritis (OA). Discs were dissected from both TMJ's of sixteen horses euthanized for reasons unrelated to this study. Each joint was grossly evaluated and scored as normal, mild OA, or s...
Woolcock JB.Equine tonsillar tissue and the draining regional lymph nodes, as well as deep nasal swabs were examined bacteriologically. Group C streptococci, predominantly Streptococcus zooepidemicus, were shown to be present in all tissues. The most frequent site for isolation was the tonsil. Streptococcus equi was not located in any of the tissues sampled.
Pusterla N, Conrad PA, Packham AE, Mapes SM, Finno CJ, Gardner IA, Barr BC, Ferraro GL, Wilson WD.Over a 2-yr study period, we investigated possible endogenous transplacental transmission of Neospora hughesi in 74 mare and foal pairs following the diagnosis of neuronal neosporosis in a weanling foal. Presuckle and postsuckle serum of each foal, serum and colostrum of each periparturient mare, and serum of each mare and foal pair, collected at 3-mo intervals thereafter, were tested for N. hughesi using an indirect fluorescent antibody test (IFAT). Furthermore, whole blood and colostrum samples and placentae were tested for the presence of N. hughesi by real-time PCR. The mares' seroprevalen...
Kanoe M, Inoue S, Abe T, Anzai T, Kamada M, Imagawa H, Kanemaru T.Clostridium perfingens was isolated from four of 29 healthy foals and from all twelve foals with gastrointestinal diseases. The range of viable counts of C. perfringens in the faeces was 10(1)-10(5)/g and in the intestinal specimens 10(1)-10(7)/g. Of 41 isolates of C. perfringens, 37 were considered to be type A. Enterotoxin of the organism was demonstrated in the intestinal contents of five of eight foals with enteric diseases. These findings suggested that C. perfringens is a likely pathogen of foal intestinal diseases.
DeBowes RM, Leipold HW, Turner-Beatty M.Cerebellar abiotrophy is a degenerative condition of Arabian horses that produces signs of head tremors and ataxia. Affected foals demonstrate clinical signs between the time of birth and 6 months of age. The condition is untreatable, although some animals have reportedly improved to varying degrees. The disease is believed to be inherited; however, definitive evidence is lacking at this time.
Wilkins PA.The newborn foal can experience problems of the lower respiratory tract that are unique to the neonate. The transition to extrauterine life usually occurs rapidly and in a coordinated manner, but problems associated with the peripartum period, including placentitis, dystocia, infection, and trauma, can result in conditions that compromise gas exchange in the newborn foal. This article reviews the normal transition and presents some of the problems seen in these small patients.
Pusterla N, Tamez-Trevino E, White A, Vangeem J, Packham A, Conrad PA, Kass P.Equine protozoal myeloencephalitis is a commonly diagnosed neurological disease of horses in North America and is caused by infection with Sarcocystis neurona or Neospora hughesi. The aim of this study was to compare prevalence factors among horses seropositive or seronegative to N. hughesi and/or S. neurona. A total of 3123 submissions were included in the study, with horses originating from 49 States. Thirty-eight animals from 21 States tested seropositive for N. hughesi only, 840 horses from 40 States were seropositive for S. neurona only, 25 horses from 14 States were seropositive for both...
Purcell KL, Johnson PJ, Kreeger JM, Wilson DA.An 8-year-old Missouri Fox Trotter mare was examined because of intermittent, low-grade abdominal pain and weight loss for 3 months. Incomplete jejunal obstruction, caused by a granulomatous mass in the wall of the jejunum, was identified during exploratory celiotomy. Pythium insidiosum was identified as the cause of the granuloma. This case suggests that enteric pythiosis may develop in horses that are geographically distant from the Gulf Coast.
Worku Y, Wondimagegn W, Aklilu N, Assefa Z, Gizachew A.A prospective study was conducted to describe clinical epidemiology of equine colic in the Society for Protection of Animal Abroad and Donkey Sanctuary Project Clinic, at Debre Zeit, Ethiopia, from November 2014 to April 2015. The objectives were to describe clinical epidemiology of equine colic, to characterize the main types of equine colic, and to determine the major risk factors associated with equine colic. The method which was used in the study was attending clinical case of equine and assessing physiological parameters, fecal egg count, abdominal sounds, and rectal examination as well a...
Stancampiano L, Usai F, Marigo A, Rinnovati R.Strongyle infections have been traditionally regarded as a possible cause of colic in horses. Aim of the study was the comparison of parasitological status between subjects with or without colic syndrome, with particular attention to small strongyle infections. Coprological analyses were performed on 86 horses: 43 with colic and 43 controls. Strongyle eggs were found in 34/86 horses (prevalence 39.5%), the mean number of strongyles eggs per gram of faeces (EPG) was 145.34 (standard deviation 398.28). All those 34 positive animals had small strongyles infections. Negative binomial multiple regr...