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.
Ramzan PH, Powell SE.Sagittal fracture of the proximal phalanx (P1) is an important musculoskeletal injury of the performance horse. Although widely considered to be monotonic in nature, there is emerging evidence that some P1 fractures may have stress-injury aetiology. Three cases are described in which imaging features found were suggestive of prodromal bone injury. All cases returned to full performance use after a period of rest. The authors conclude that it is possible that some P1 fractures in the Thoroughbred racehorse may develop through stress/fatigue injury pathways. It is proposed that intervention prio...
Wright A, Beard L, Bawa B, Bras J.Equine dysautonomia, also known as equine grass sickness (EGS), is a well documented disease in several countries. To the authors' knowledge, EGS has not been reported previously in North America. This report describes EGS in a 6-year-old female mule in the USA. Failure initially to consider EGS resulted in a delayed diagnosis. EGS should be considered as a differential diagnosis and appropriate diagnostic tests performed in similar cases in North America.
Thorpe CT, Clegg PD, Birch HL.Tendon injury is one of the most common causes of wastage in the performance horse; the majority of tendon injuries occur to the superficial digital flexor tendon (SDFT) whereas few occur to the common digital extensor tendon. This review outlines the epidemiology and aetiology of equine tendon injury, reviews the different functions of the tendons in the equine forelimb and suggests possible reasons for the high rate of failure of the SDFT. An understanding of the mechanisms leading to matrix degeneration and subsequent tendon gross failure is the key to developing appropriate treatment and p...
Teeter MG, Arroyo LG, Bakker JD, Hayes MA, Viel L, Runciman RJ.Arterial calcification is found frequently in the pulmonary artery of racehorses, but the aetiology is unknown. Calcification might be associated with increased wall stress due to arterial geometry (shape) and exercise-induced hypertension. Objective: High wall stress levels are found in the regions associated with calcified lesion formation, exacerbated as transluminal pressure increases to levels associated with exercise. Methods: The pulmonary arteries of 5 horses, unaffected by calcification, were dissected and pressurised to resting and exercising physiological transluminal pressures and ...
Hendrix SM, Baxter GM, McIlwraith CW, Hendrickson DA, Goodrich LR, Frisbie DD, Trotter GW.Summary Reasons for performing study: Medial meniscal injuries and subchondral cystic lesions (SCL) are known to occur independently within the medial femorotibial (MFT) joint in horses. However, there are no reports of a potential clinical relationship between these 2 types of lesions. Objective: To: 1) document the concurrent presence or sequential development of medial meniscal and SCL of the medial femoral condyle within the MFT joint; and 2) determine the prognosis with both types of lesions. Methods: Retrospective case series of horses with both a medial meniscal and SCL of the medial fe...
Saenz RA, Quinlivan M, Elton D, Macrae S, Blunden AS, Mumford JA, Daly JM, Digard P, Cullinane A, Grenfell BT, McCauley JW, Wood JL, Gog JR.A key question in pandemic influenza is the relative roles of innate immunity and target cell depletion in limiting primary infection and modulating pathology. Here, we model these interactions using detailed data from equine influenza virus infection, combining viral and immune (type I interferon) kinetics with estimates of cell depletion. The resulting dynamics indicate a powerful role for innate immunity in controlling the rapid peak in virus shedding. As a corollary, cells are much less depleted than suggested by a model of human influenza based only on virus-shedding data. We then explore...
Unger-Torroledo L, Straub R, Lehmann AD, Graber F, Stahl C, Frey J, Gerber V, Hoppeler H, Baum O.The lethal toxin of Clostridium sordellii (TcsL) evokes severe, mostly fatal disease patterns like toxic shock syndrome in humans and animals. Since this large clostridial toxin-induced severe muscle damaging when injected intramuscularly into mice, we hypothesized that TcsL is also associated with equine atypical myopathy (EAM), a fatal myodystrophy of hitherto unknown etiology. Transmission electron microscopy revealed skeletal and heart muscles of EAM-affected horses to undergo degeneration ultrastructurally similar to the damage found in TcsL-treated mice. Performing immunohistochemistry, ...
Ntafis V, Fragkiadaki E, Xylouri E, Omirou A, Lavazza A, Martella V.Severe outbreaks of diarrhoeic syndrome occurred in young foals at the same stud farm during two consecutive breeding periods namely spring 2006 and 2007. Rotavirus-like particles were detected by electron microscopy in the faeces of the affected foals and group A rotavirus infection was confirmed by Reverse-Transcription (RT)-PCR with selected sets of rotavirus-specific primers. Sequence analysis of the genes encoding the outer capsid rotavirus proteins VP7 and VP4 enabled classification of the viruses as G3AP[12] and revealed that the viruses were highly similar to recently reported equine r...
Serteyn D, Piquemal D, Vanderheyden L, Lejeune JP, Verwilghen D, Sandersen C.Osteochondrosis (OC) is a developmental disease that affects growing horses and that severely affects their ability to perform. The genetic basis of its pathogenesis is poorly understood. The aim of the study was to analyze the transcript profile of leukocytes from horses affected with OC. Two transcriptome libraries were constructed from leukocytes of OC-affected and non-OC-affected horses using digital gene expression analysis (DGE) and real-time PCR. Statistical analysis allowed selection of 1,008 tags upregulated in the non-OC-affected group and 1,545 tags upregulated in the OC-affected gr...
Neuhaus S, Bruendler P, Frey CF, Gottstein B, Doherr MG, Gerber V.Equine recurrent airway obstruction (RAO) shares many characteristics with human asthma. In humans, an inverse relationship between susceptibility to asthma and resistance to parasites is suspected. Objective: Members of a high-incidence RAO half-sibling family (F) shed fewer strongylid eggs compared with RAO-unaffected pasture mates (PM) and that RAO-affected horses shed fewer eggs than RAO-unaffected half-siblings. Methods: Seventy-three F and 73 unrelated, age matched PM. Methods: Cases and controls kept under the same management and deworming regime were examined. Each individual was class...
Di Meo GP, Neglia G, Perucatti A, Genualdo V, Iannuzzi A, Crocco D, Incarnato D, Romano G, Parma P, Iannuzzi L.Gonadal dysgenesis and heterosexual conditions are often associated with sex chromosome abnormalities. In this study we report on 2 cases of abnormal sex development involving numerical sex chromosome aberrations in both horse and sheep. A 17-month-old Standardbred filly was sent to an equine fertility centre as an embryo donor due to its reduced size, being much smaller than a racehorse filly of the same age, which excluded it from an athletic career. External genitalia were clinically normal but manual palpation of the reproductive tract showed the presence of a small underdeveloped uterus a...
Gerber V, De Feijter-Rupp H, Wagner J, Venta P, Harkema JR, Robinson NE.Airway mucus accumulation is associated with indoor irritant and allergen exposure in horses with recurrent airway obstruction (RAO). Epidermal growth factor receptor (EGFR) and a chloride channel (calcium activated, family member 1; CLCA1) are key signalling molecules involved in mucin gene expression. Objective: We hypothesised that exposure to irritants and aeroallergens would lead to increased expression of the mucin gene eqMUC5AC and increased stored mucosubstance in the airways of RAO-affected horses, associated with increased neutrophils and CLCA1 and EGFR mRNA levels. Methods: We perfo...
Van Eps AW, Pollitt CC.The histopathology of laminitis during its transition from the acute to the chronic phase has not been previously documented. Studying hoof lamellar tissues 7 days after induction of laminitis may provide insight into the intractable nature of the chronic phase of the disease. Objective: To induce laminitis and investigate hoof wall lamellar tissues 7 days after dosing. Methods: Laminitis was induced using oligofructose in 6 normal Standardbred horses. The dorsal hoof lamellar tissues of these and 12 normal horses were processed and examined by light microscopy. Serial sections of a lamellar t...
Yasuda K, Scott DW, Erb HN, McDonough SP.Infiltrative lymphocytic mural folliculitis (ILMF) is a histopathological reaction pattern reported to occur in a small number of equine inflammatory dermatoses. However, the prevalence of ILMF in a variety of equine dermatoses has not been reported. Skin biopsy specimens from 250 horses with inflammatory dermatoses and from 27 horses with physically healthy skin were therefore evaluated. ILMF was present in 82% of the diseased skin specimens examined. ILMF was not seen in physically healthy skin. It appears that ILMF is frequently seen in a wide variety of equine inflammatory dermatoses and t...
Lobsiger L, Müller N, Schweizer T, Frey CF, Wiederkehr D, Zumkehr B, Gottstein B.The present case report describes a novel etiological agent of cutaneous leishmaniasis that appears for the first time in a cow. A similar agent had recently been described as causing autochthonous infections in horses of Germany and Switzerland. The infection in the cow was initially diagnosed upon clinical and immunohistological findings. Subsequent comparative sequence analysis of diagnostic PCR products from the internal transcribed spacer 1 (ITS1) of ssrRNA classified the respective isolate as neither Old World nor New World Leishmania species, but yielded complete identity of the analyse...
Byrne BA, Rand CL, McElliott VR, Samitz EM, Brault SA.Dermatophilosis caused by Dermatophilus congolensis causes exudative dermatitis in a variety of species. The infection is generally limited to the cutaneous tissues, where infection is acquired from the environment and bacteria penetrate into keratinized epithelium through epithelial disruption. A 3-year-old pony filly was examined for enlarging mandibular lymph nodes during the preceding 10 months. Biopsy of the node revealed mixed and granulomatous inflammation and thick, filamentous Gram-positive bacteria. Dermatophilus congolensis, confirmed by biochemical testing and sequencing of the rib...
Brum MC, Anjos BL, Nogueira CE, Amaral LA, Weiblen R, Flores EF.An outbreak of severe cutaneous disease associated with an orthopoxvirus in horses in southern Brazil is described. Fourteen Crioulo mares and foals from a husbandry farm developed papules, and vesicles progressing to proliferative and exudative lesions on the muzzle, external nares, and external and internal lips. The vesicles eroded, and the proliferative lesions eventually bled and progressed to moist crusts and scars. The clinical signs lasted approximately 6-12 days, after which the animals progressively recovered. Direct electron microscopy of skin biopsies revealed brick-shaped, 250-300...
McDowell KJ, Webb BA, Williams NM, Donahue JM, Newman KE, Lindemann MD, Horohov DW.A new abortigenic disease, now known as mare reproductive loss syndrome (MRLS), significantly affected the horse industry in the Ohio River Valley of the United States in late April and early May of 2001 and 2002. In 2001, approximately 25% of all pregnant mares aborted within several weeks (over 3,000 mares lost pregnancies), and abortion rates exceeded 60% on some farms. Mare reproductive loss syndrome struck hard and without warning, it was caused by something in the environment, it was not transmitted between animals, and it was not associated with any known abortigenic agent or disease. T...
Peel AJ, Bouts T, Flach E, Rivers S, Routh A.Pituitary pars intermedia dysfunction (PPID), also known as Equine Cushing's disease, is most often diagnosed in older horses and ponies. To the authors' knowledge, there have been no reports of its diagnosis in captive nondomestic equids. A 13-yr old onager (Equus hemionus onager) at the Zoological Society of London (ZSL) Whipsnade Zoo showed clinical signs suggestive of PPID, including hirsutism, fat redistribution, weight loss, laminitis, and chronic infections. A dexamethasone suppression test was performed to confirm PPID. Subsequently, adenomatous hyperplasia and microadenoma of the pars...
Leiva M, Peña T, Armengou L, Cesarini C, Monreal L.Septicemia in humans is described as a leading cause of uveitis, which eventually can induce blindness. Objective: Uveal inflammatory findings could be related to sepsis severity in newborn foals and might be used as an indirect indicator for survival. Methods: Seventy-four septic foals, 54 nonseptic foals, and 42 healthy foals. Methods: Prospective observational clinical study. A detailed blinded, ophthalmic examination was performed by boarded ophthalmologists on all admitted newborn foals. Foals were grouped as septic (when blood culture resulted positive or the sepsis score was > or =14...
Pusterla N, Gebhart C.Equine proliferative enteropathy (EPE) is a disease of foals caused by the obligate intracellular organism Lawsonia intracellularis. This emerging disease affects mainly weanling foals and causes fever, lethargy, peripheral oedema, diarrhoea, colic and weight loss. The diagnosis of EPE may be challenging and relies on the presence of hypoproteinaemia, thickening of segments of the small intestinal wall observed on abdominal ultrasonography, positive serology and molecular detection of L. intracellularis in faeces. Although the clinical entity, diagnostic work-up and treatment of EPE are well e...
Kraus MS, Jesty SA, Gelzer AR, Ducharme NG, Mohammed HO, Mitchell LM, Soderholm LV, Divers TJ.To compare cardiac troponin I (cTnI) concentrations determined by use of a point-of-care analyzer with values determined by use of a bench-top immunoassay in plasma samples obtained from clinically normal horses with and without experimentally induced cardiac disease, and to establish a reference range for plasma equine cTnI concentration determined by use of the point-of-care analyzer. Methods: 83 clinically normal horses, 6 of which were administered monensin to induce cardiac disease. Methods: A blood sample was collected from each of the 83 clinically normal horses to provide plasma for an...
Brink P, Skydsgaard M, Teige J, Tverdal A, Dolvik NI.To develop a scoring system for histopathologic changes in the synovium of tarsocrural joints (TCJs) of horses with osteochondritis dissecans (OCD) and to test for association between histopathologic changes and joint effusion or lameness. Methods: 93 horses with OCD of the intermediate ridge of the tibia of 1 or both TCJs (134 joints) and 38 control horses without disease of TCJs (38 joints). Methods: For OCD-affected horses, pretreatment lameness, TCJ effusion, and results of pelvic limb flexion test were scored. Synovial biopsy specimens were obtained from TCJs of OCD-affected horses during...
Cymerys J, Dzieciatkowski T, Słońska A, Bierla J, Tucholska A, Chmielewska A, Golke A, Bańbura MW.Equine herpesvirus-1 (EHV-1) infections cause significant economic losses for equine industries worldwide as a result of abortion, respiratory illness, and neurologic disease in all breeds of horses. The occurrence of abortions caused by EHV-1 has repeatedly been confirmed in Poland, but neurological manifestations of the infection have not been described yet. Also it is unknown how the infection of neurons with non-neuropathogenic strains is regulated. To further understand the virus-neuron interaction we studied two strains of EHV-1 in murine primary neuron cell cultures. Both strains were i...
Galvin N, Corley K.A retrospective study was carried out to investigate the causes of disease and death in a population of foals in Ireland during their first 12 months post partum. Foaling and veterinary records from 343 foals on four farms born between January 1, 2004 and May 30, 2008 were reviewed. Among 343 foals, 22 did not survive to 12 months of age. Over the five-year period, the incidence of stillbirth was 1.5% (5/343), mortality 5% (17/338) and overall morbidity was 88.5% (299/338). Morbidity was calculated to include all new conditions brought to the attention of the attending veterinary surgeon, no m...
Cassimeris L, Armstrong C, Burger QC, Stokes S, van Eps A, Galantino-Homer H.The euglycemic hyperinsulinemic clamp model (EHC) of equine endocrinopathic laminitis induces rapid loss of lamellar tissue integrity, disrupts keratinocyte functions, and induces inflammation similar to natural disease. Continuous digital hypothermia (CDH) blocks tissue damage in this experimental model, allowing identification of specific genes or molecular pathways contributing to disease initiation or early progression. Archived lamellar tissues (8 horses, 48 h EHC treatment, including CDH-treated front limbs) were used to measure relative expression levels of genes encoding keratin 17 (KR...
Traub-Dargatz JL, Gay CC, Evermann JF, Ward AC, Zeglen ME, Gallina AM, Salman MD.Epidemiologic and etiologic data about diarrhea in foals were collected under a planned prospective recording and monitoring study. The survey and monitoring procedures included a survey to obtain an overview of current horse management practices on participating farms, a daily health record survey to obtain information on mares and their foals, and collection of feces from 19 of 144 diarrheic foals and 10 age-matched nondiarrheic foals for electron microscopy, ELISA for rotavirus, and bacteriologic culture. Coronavirus was detected in the feces of diarrheic as well as clinically normal foals....
Okumura M, Fujinaga T, Yamashita K, Tsunoda N, Mizuno S.Ceruloplasmin (Cp) was isolated from fresh equine plasma by precipitation, cellulose chromatography, and improved ion-exchange chromatography. Purified equine Cp is a glycoprotein having a molecular weight of approximately 115,000. In electrophoresis, equine Cp migrated to the alpha 1-globulin region, its isoelectric point was about 4.15 and consisted of about 890 amino acid residues. Serum Cp concentration was measured by use of the single radial immunodiffusion method. In clinically normal horses, the mean (+/- SD) serum Cp concentration of newborn foals was 2.87 +/- 0.40 mg/ml and that of 3...
Lam K, Parkin T, Riggs C, Morgan K.The analysis of data in clinical records could be useful to epidemiologists in planning analytical studies and identifying new research initiatives. This paper describes the method used to develop a systematic, replicable technique for compressing many words of text into fewer content categories on the basis of explicit rules of user-defined coding, and systematically sorting a large volume of records accurately and reliably. The method was used to categorise the reasons for retirement from racing in Hong Kong of 3727 thoroughbred racehorses between the 1992/93 and 2003/04 racing seasons into ...
Ploeg M, Saey V, van Loon G, Delesalle C.The aorta can rupture at the aortic root or aortic arch. In most breeds, the aortic root is the likely site and rupture leads to aortocardiac fistula with communication between the aorta and the right atrium, right ventricle and/or the interventricular septum. There is a high prevalence of aortic rupture in young Friesian horses and rupture occurs at the aortic arch with pseudoaneurysm and potentially aortopulmonary fistulation. Echocardiographic and post-mortem techniques must be adapted to identify aortic arch rupture that is not generally identified with standard approaches. Given the narro...
Rynhoud H, Meler E, Gibson JS, Price R, Maguire T, Farry T, Bennett E, Hartono J, Soares Magalhães RJ.To detect methicillin resistant Staphylococcus aureus (MRSA) and S. pseudintermedius (MRSP) swab samples were collected from dogs, cats and horses from South East Queensland (SE QLD). MRSP carriage in dogs was 8.7% and no MRSP was isolated from cats and horses; no MRSA was isolated. Risk factors for carriage included previous hospitalisation, previous bacterial infection, consultation type, average precipitation, and human population density. The probability of MRSP carriage was highest in Brisbane city, Sunshine Coast and Gympie. This suggests that MRSP carriage in dog populations from SE QLD...
Seltenhammer MH, Sundström E, Meisslitzer-Ruppitsch C, Cejka P, Kosiuk J, Neumüller J, Almeder M, Majdic O, Steinberger P, Losert UM, Stöckl J....The Grey horse phenotype, caused by a 4.6 kb duplication in Syntaxin 17, is strongly associated with high incidence of melanoma. In contrast to most human melanomas with an early onset of metastasis, the Grey horse melanomas have an extended period of benign growth, after which 50% or more eventually undergo progression and may metastasize. In efforts to define changes occurring during Grey horse melanoma progression, we established an in vitro model comprised of two cell lines, HoMel-L1 and HoMel-A1, representing a primary and a metastatic stage of the melanoma, respectively. The cell lines ...
Blazyczek I, Hamann H, Ohnesorge B, Deegen E, Distl O.The objective of the present study was to analyze the mode of inheritance of guttural pouch tympany (GPT) using pedigrees of Arabian horses. Complex segregation analyses were employed to test for the significance of nongenetic transmission and for monogenic, polygenic, and mixed monogenic-polygenic modes of inheritance. Horses affected by GPT comprised 27 Arabian purebred foals. Of these 27 animals, 22 were patients at the Clinic for Horses, School of Veterinary Medicine Hannover, Hannover, Germany, between 1994 and 2001 and 5 Arabian foals were from stud farms. Information on the pedigrees of...
Kubacki J, Lechmann J, Fraefel C, Bachofen C.We present the genome sequence of equid alphaherpesvirus 1 (EHV-1) sequenced directly from the nasal swab of a Swiss horse that attended an international equestrian event in Valencia, Spain, the origin of an outbreak of neurological disorders in horses in several European countries in February 2021.
Sharp EL, Farrell HE, Borchers K, Holmes EC, Davis-Poynter NJ.Equid herpesvirus 2 (EHV-2), in common with other members of the subfamily Gammaherpesvirinae, encodes homologues of cellular seven-transmembrane receptors (7TMR), namely open reading frames (ORFs) E1, 74 and E6, which each show some similarity to cellular chemokine receptors. Whereas ORF74 and E6 are members of gammaherpesvirus-conserved 7TMR gene families, E1 is currently unique to EHV-2. To investigate their genetic variability, EHV-2 7TMRs from a panel of equine gammaherpesvirus isolates were sequenced. A region of gB was sequenced to provide comparative sequence data. Phylogenetic analysi...
Schale S, Howe D, Yeargan M, Morrow JK, Graves A, Johnson AL.Infection by 2 or more protozoa is linked with increased severity of disease in marine mammals with protozoan encephalitis. Objective: To assess whether horses with equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona also have evidence of infection with Neospora hughesi or Toxoplasma gondii. We hypothesized that horses with EPM would be more likely than horses with cervical vertebral stenotic myelopathy (CVSM) to be positive for antibodies to multiple protozoan parasites. Methods: One hundred one horses with neurologic disease: 49 with EPM and 52 with CVSM. Methods: Case rev...
Husted L, Sanchez LC, Baptiste KE, Olsen SN.Risk factors for the development of gastric squamous ulcers include various management procedures, such as intermittent feed deprivation that can occur during weight management regimens or stall and dry lot confinement. Objective: To investigate the effect of intermittent feed deprivation relative to continuous feed intake on proximal intragastric pH, specifically in the region of the squamous mucosa of the lesser curvature. Methods: In 6 horses, pH electrodes were placed just inside of the oesophageal sphincter in the stomach for each of two 72 h protocols (A and B) in a randomised, cross-ove...
Mungall BA, Pollitt CC, Collins R.In situ gelatin zymography is a technique, which utilises a gelatin-based emulsion overlay to detect and, more importantly, localise the gelatinase activity in underlying tissue. Gelatinase A [matrix metalloproteinase-2 (MMP-2)] and gelatinase B [matrix metalloproteinase-9 (MMP-9)] are present in equine hoof homogenates and supernatants from cultured hoof explants by SDS-PAGE gelatin zymography, and it has been assumed that the enzymes are derived solely from matrix and epithelia and not from other sources such as leucocytes. Using in situ zymography, gelatinases are shown to be localised with...
Littlejohn A, Walker EM.The sex, coat colour, age, province and month of occurrence of every case of babesiosis was recorded in a horse population of 5856 in South Africa and Rhodesia. A total of 115 cases were recorded during the period 1973-01-01 to 1973-12-31. Chisquared tests were used to evaluate the significance of frequencies. Significant biases in the distribution of cases of babesiosis were found with regard to season (P < 0,05), sex (P < 0,001) and coat colour (P < 0.01).
Morris EA, Treadwell BV.The effect of interleukin 1 (IL-1) on equine articular cartilage was investigated, using a cartilage explant culture system. Measurement of [35S]O4 incorporation revealed synthesis of matrix proteoglycan by cartilage to be decreased 45, 59.7, and 37.5% after 1, 3, and 5 days, respectively, in culture in the presence of 5 U of IL-1/ml. There was no change in proteoglycan degradation as determined by measurement of [35S]O4 release into the culture medium. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of cartilage-conditioned medium indicated that exposure of cartilage to IL-1 caused ...
Sánchez-Matamoros A, Sánchez-Vizcaíno JM, Rodríguez-Prieto V, Iglesias E, Martínez-López B.African horse sickness (AHS) is one of the most important vector-borne viral infectious diseases of equines, transmitted mainly by Culicoides spp. The re-emergence of Culicoides-borne diseases in Europe, such as the recent bluetongue (BT) or Schmallenberg outbreaks, has raised concern about the potential re-introduction and further spread of AHS virus (AHSV) in Europe. Spain has one of the largest European equine populations. In addition, its geographical, environmental and entomological conditions favour AHSV infections, as shown by the historical outbreaks in the 1990s. The establishment of ...
Gallagher LM, Crane J, Fitzharris P, Bates MN.To confirm that working with horses is an occupational respiratory hazard and observed associations are not attributable to confounding. Methods: A postal survey of the respiratory health of 659 horse trainers and a comparison group of 506 vegetable growers was conducted. Data were analysed using logistic regression. Results: Relative to vegetable growers, horse trainers reported higher rates of chronic bronchitis [odds ratio (OR) = 6.8, 95% confidence interval (CI): 2.2-21.4] and organic dust toxic syndrome/farmers' lung (ODTS/FL) (OR = 3.5, 95% CI: 1.8-6.8). Grinding oats, spreading hay, and...
Hayes HM.Data from 16 North American veterinary university teaching facilities, 5009 cryptorchid horses, were analysed using relative risk methodology. In five breeds (Thoroughbred, Standardbred, Morgan, Tennessee Walking horse and Arabian), cryptorchism was diagnosed significantly (P less than 0.05) less frequently than expected by their representation in the hospital population. Three breeds, (Percheron, American Saddle horse and American Quarterhorse), plus ponies (as a group) and crossbred horses were significantly over-represented within the series. The over-representation of Quarter-horses was ev...
Tessier C, Holcombe SJ, Derksen FJ, Berney C, Boruta D.Nasopharyngeal collapse has been observed in horses as a potential cause of exercise intolerance and upper respiratory noise. No treatment is currently available and affected horses are often retired from performance. Objective: To determine the effect of bilateral glossopharyngeal nerve block and stylopharyngeus muscle dysfunction on nasopharyngeal function and airway pressures in exercising horses. Methods: Endoscopic examinations were performed on horses at rest and while running on a treadmill at speeds corresponding to HRmax50, HRmax75 and HRmax, with upper airway pressures measured with ...
Brindley MA, Zhang B, Montelaro RC, Maury W.Wild-type strains of equine infectious anemia virus (EIAV) prevent superinfection of previously infected cells. A variant strain of virus that spontaneously arose during passage, EIAV(vMA-1c), can circumvent this mechanism in some cells, such as equine dermis (ED) cells, but not in others, such as equine endothelial cells. EIAV(vMA-1c) superinfection of ED cells results in a buildup of unintegrated viral DNA and rapid killing of the cell monolayer. Here, we examined the mechanism of resistance that is used by EIAV to prevent superinfection and explored the means by which EIAV(vMA-1c) overcomes...
Cutler TJ, MacKay RJ, Ginn PE, Gillis K, Tanhauser SM, LeRay EV, Dame JB, Greiner EC.Equine protozoal myeloencephalitis is a common neurologic disease of horses in the Americas usually caused by Sarcocystis neurona. To date, the disease has not been induced in horses using characterized sporocysts from Didelphis virginiana, the definitive host. S. neurona sporocysts from 15 naturally infected opossums were fed to horses seronegative for antibodies against S. neurona. Eight horses were given 5x10(5) sporocysts daily for 7 days. Horses were examined for abnormal clinical signs, and blood and cerebrospinal fluid were harvested at intervals for 90 days after the first day of chall...
House JA.AHS is a noncontagious vector-borne disease of Equidae caused by Orbiviruses. Species susceptibility in decreasing order is horses, mules, donkeys, and zebras. The main vectors of AHS are culicoides. The disease is endemic in sub-Saharan Africa, but epizootics have occurred outside of this area on several occasions. The most recent outbreaks outside of the endemic area were in Spain, Morocco, and Portugal between 1987 and 1990. AHS causes mortality up to 95% and is classically divided into four clinical forms: the pulmonary, cardiac, mixed, and horse fever forms. Pathologic changes are subcuta...
McGorum BC, Pirie RS.Equine dysautonomia (ED; also known as equine grass sickness) is a neurological disease of unknown cause, which primarily affects grazing adult horses. The clinical signs reflect degeneration of specific neuronal populations, predominantly within the autonomic and enteric nervous systems, with disease severity and prognosis determined by the extent of neuronal loss. This review is primarily focused on the major clinical decision-making processes in relation to ED, namely, (1) clinical diagnosis, (2) selection of appropriate ancillary diagnostic tests, (3) obtaining diagnostic confirmation, (4)...
French KR, Pollitt CC.Acute laminitis is characterised by hoof lamellar dermal-epidermal separation at the basement membrane (BM) zone. Hoof lamellar explants cultured in vitro can also be made to separate at the basement membrane zone and investigating how this occurs may give insight into the poorly understood pathophysiology of laminitis. Objective: To investigate why glucose deprivation and metalloproteinase (MMP) activation in cultured lamellar explants leads to dermo-epidermal separation. Methods: Explants, cultured without glucose or with the MMP activator p-amino-phenol-mercuric acetate (APMA), were subject...
Varner DD, Blanchard TL, Brinsko SP, Love CC, Taylor TS, Johnson L.Numerous techniques may be used for evaluation of the different reproductive disorders of the stallion. Approaches may vary from real-time ultrasonography and biopsy for evaluating testicular tumors to use of special assays for evaluating sperm or plasma for presence of antisperm antibodies. This communication addresses techniques used to evaluate five relatively uncommon, but perplexing, disorders of breeding stallions: (1) seminal vesiculitis, (2) hemospermia associated with idiopathic urethral defects, (3) acrosomal dysfunction, (4) abnormal spermatozoal chromatin, and (5) azoospermia.
Frank N, Sojka JE, Latour MA.To measure and compare the concentration and composition of very low-density lipoprotein (VLDL) in plasma and selected lipids in serum of horses fed mixed grass hay ad libitum or denied feed for 36 hours. Methods: 4 healthy adult mares. Methods: Mares were either fed mixed grass hay ad libitum or denied feed for 36 hours beginning at 8:00 AM. Blood samples were collected every 2 hours during the study period and analyzed for nonesterified fatty acid (NEFA), triglyceride (TG), VLDL, and glucose concentrations and composition of VLDL. Results: Withholding feed significantly increased mean serum ...
Carrasco L, Sánchez C, Gómez-Villamandos JC, Laviada MD, Bautista MJ, Martínez-Torrecuadrada J, Sánchez-Vizcaíno JM, Sierra MA.African horse sickness (AHS) is a disease of equids, characterized by severe pulmonary oedema and caused by an orbivirus. To determine the role of pulmonary intravascular macrophages (PIMs) in the development of pulmonary microvascular changes in this disease, five horses were given an intravenous inoculation of 10(6)TCID50of serotype 4 of AHS virus. Viral replication was detected in endothelial cells, PIMs, interstitial macrophages and fibroblasts. Alveolar and interstitial oedema, and changes in pulmonary microvasculature, consisting mainly of the sequestration of neutrophils and the formati...
Monath TP, McLean RG, Cropp CB, Parham GL, Lazuick JS, Calisher CH.Brain tissues were obtained from 5 horses with clinical encephalomyelitis during an epizootic in southwestern Michigan in August-September 1980. These tissues were tested for virus by intracerebral inoculation of suckling mice and by examination of frozen sections and impression smears by the indirect fluorescent antibody (FA) technique. Eastern equine encephalomyelitis virus was isolated and detected by FA technique in brains of 3 horses which died or were euthanatized within approximately 24 hours of onset of the disease but not from 2 horses at 2 and 3 days after onset. The latter 2 animals...
Emmons RW, Woodie JD, Laub RL, Oshiro LS.Main Drain virus, which is thought to be transmitted normally among rabbits and various rodents by its natural vector, Culicoides variipennis, was isolated repeatedly from brain tissue of a sick horse from Sacramento County, California, and was implicated as the causative agent. Signs of illness were incoordination and ataxia, stiff neck, head pressing, inability to swallow, fever, and tachycardia.
McQueen CM, Whitfield-Cargile CM, Konganti K, Blodgett GP, Dindot SV, Cohen ND.Rhodococcus equi (R. equi) is an intracellular bacterium that affects young foals and immuno-compromised individuals causing severe pneumonia. Currently, the genetic mechanisms that confer susceptibility and/or resistance to R. equi are not fully understood. Previously, using a SNP-based genome-wide association study, we identified a region on equine chromosome 26 associated with culture-confirmed clinical pneumonia. To better characterize this region and understand the function of the SNP located within TRPM2 that was associated with R. equi pneumonia, we performed RNA-Seq on 12 horses repres...
