Equine diseases encompass a wide range of health conditions that can affect horses, including infectious diseases, metabolic disorders, and genetic conditions. These diseases can impact the overall health, performance, and well-being of horses. Common equine diseases include equine influenza, equine herpesvirus, laminitis, and equine metabolic syndrome. Diagnosis and management of these diseases often require a combination of clinical evaluation, laboratory testing, and appropriate treatment strategies. This page gathers peer-reviewed research studies and scholarly articles that explore the etiology, pathophysiology, diagnosis, and treatment options for various equine diseases, providing valuable insights for veterinarians and researchers in the field.
Cornelissen BP, Buma P, Rijkenhuizen AB, Barneveld A.To localize and determine relative frequency of occurrence of calcitonin gene-related peptide (CGRP) and substance P (SP) fibers in the proximal sesamoid bones (PSB) and adjacent structures in sound horses. Methods: 4 foals and 3 adult horses. Methods: Medial PSB and adjacent ligaments of both forelimbs were collected, flushed, and fixed in buffered 4% formalin. The left PSB were cut into 5 longitudinal, sagittally oriented slabs, and the right PSB were cut into 5 transverse slabs. After decalcification in EDTA, slices were transferred to a 30% sucrose solution, deep frozen, sectioned (80 micr...
Lescun TB, Hawkins JF, Siems JJ.A 6-month-old warmblood filly had traumatic rupture in the gastrocnemius and superficial digital flexor muscles of the left hind limb. A modified Thomas splint-cast combination, which was custom fitted to the limb, was placed to prevent further disruption of the caudal reciprocal apparatus. The external coaptation device was removed after 21 days. The horse developed lesions consistent with osteochondrosis of the femoropatellar articulation within 8 weeks of the initial injury. Examination of the horse 6 months after injury revealed fibrous healing of the muscles and restoration of caudal reci...
Weiss DJ, Evanson OA, MacLeay J, Brown DR.To determine whether mucosal permeability is altered during the prodromal stages of alimentary laminitis. Methods: 15 healthy adult ponies. Methods: intestinal permeability was evaluated for control ponies (n = 5) and for ponies 4 to 12 (n = 5) and 20 to 28 (n = 5) hours after administration of carbohydrate overload. Mucosal permeability was determined by measuring the percentage of orally administered technetium Tc99m diethylenetriaminopentaacetate (99mTc-DTPA) excreted in urine during an 8-hour period, then measuring blood radioactivity at hourly intervals. Plasma endotoxin-like activity was...
Keegan KG, Wilson DA, Wilson DJ, Smith B, Gaughan EM, Pleasant RS, Lillich JD, Kramer J, Howard RD, Bacon-Miller C, Davis EG, May KA, Cheramie HS....To estimate sensitivity and accuracy of subjective evaluation of mild lameness in horses during treadmill locomotion and to correlate subjective evaluation with kinematic analysis. Methods: 19 lame and 5 clinically normal horses. Methods: Lameness was evaluated by subjective score and kinematic analysis before and after palmar digital nerve block (PDNB). Evaluations were made by 6 clinicians and 7 interns or residents. Within- and between-observer agreement analyses (kappa values) were calculated and compared, using a Student's t-test. Pearson's product-moment correlation coefficients were cal...
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...
Farkas R, Hall MJ.Veterinarians in Hungary were asked to complete a questionnaire on traumatic myiasis; of the 664 veterinarians contacted, 247 replied (37.2 per cent) and of these 209 (84.6 per cent) reported myiasis to be a problem among the livestock they treated. Infestation levels of > 10 per cent of animals were reported in sheep, cattle and horses. The myiasis season lasted from March to November with most cases reported in July and August. Significantly more respondents reported that fly larvae were present deep in wounds rather than superficially, consistent with infestations due to the obligate parasi...
Romeike A, Brügmann M, Drommer W.Despite extensive clinical research, the etiology of equine recurrent uveitis (ERU) is still unknown. After an immunologic pathogenesis was established in recurrent uveitis in humans, a similar pathogenic mechanism was assumed to exist in ERU. To investigate whether immunopathologic mechanisms are involved in ERU, 20 eyes of 15 horses with ERU were examined immunohistochemically with a T cell marker, B cell marker, and anti-major histocompatibility complex (MHC) class II antibodies. Twenty-six eyes of 20 horses were used for investigation of MHC class II antigen expression in normal equine eye...
Poonacha KB, Gregory CR, Vickers ML.The primary lesions of eastern equine encephalomyelitis (EEE) virus infection in the horse are limited to the brain and spinal cord. Intestinal lesions in addition to the changes in the central nervous system were found in a 6-month-old male Tennessee Walking Horse. One week prior to death, this colt was vaccinated for EEE virus, western equine encephalomyelitis virus, influenza virus, equine rhinopneumonitis virus, and tetanus. The clinical signs consisted of ataxia and rear-end weakness, with a body temperature of 102.8 F. Gross lesions consisted of yellowish discoloration, swelling, edema, ...
Krüger B, Siesenop U, Böhm KH.In 1993 and 1994 a highly increased occurrence of equine dermatophilosis was observed, and a study was initiated to determine phenotypic heterogeneity among 120 clinical isolates using biochemistry, antibiotic resistance profiles, membrane protein profiles and Western blotting. The biochemical examinations contained 1% equine serum in medium. Moreover, the API ZYM-test from bioMérieux was used. The biochemical reactions were suited to identify Dermatophilus congolensis but did not allow a differentiation among the various isolates. Antibiotic resistance in one or more isolates was observed ag...
Puffer BA, Watkins SC, Montelaro RC.We have identified an interaction between the equine infectious anemia virus (EIAV) late assembly domain and the cellular AP-2 clathrin-associated adapter protein complex. A YXXL motif within the EIAV Gag late assembly domain was previously characterized as a sequence critical for release of assembling virions. We now show that this YXXL sequence interacts in vitro with the AP-50 subunit of the AP-2 complex, while the functionally interchangeable late assembly domains carried by the Rous sarcoma virus p2b protein and human immunodeficiency virus type 1 p6 protein, which utilize PPPY and PTAPP ...
Zhang W, Lonning SM, McGuire TC.Most equine infectious anemia virus (EIAV)-infected horses have acute clinical disease, but they eventually control the disease and become lifelong carriers. Cytotoxic T lymphocytes (CTL) are considered an important immune component in the control of infections with lentiviruses including EIAV, but definitive evidence for CTL in the control of disease in carrier horses is lacking. By using retroviral vector-transduced target cells expressing different Gag proteins and overlapping synthetic peptides of 16 to 25 amino acids, peptides containing at least 12 Gag CTL epitopes recognized by virus-st...
Clegg PD, Jones MD, Carter SD.Loss of articular cartilage, which is the most important pathological lesion occurring in osteoarthritis, has been shown to be enzymatically mediated. The matrix metalloproteinases (MMPs) are a group of enzymes which have been implicated in this degradation of articular cartilage matrix. The use of pharmacological agents to inhibit this catabolic process in the joint is a potential route for therapeutic intervention. The gelatinase MMPs, MMPs-2 and 9, were purified by affinity chromatography from equine cell cultures. The ability of phenylbutazone, flunixin, betamethasone, dexamethasone, methy...
Grüninger B, Schoon HA, Schoon D, Menger S, Klug E.The morphology of endometrial blood vessels in uterine biopsy specimens from mares of varying age and reproductive status was examined by light (n = 117) and electron microscopy (n = 13), and additionally after elastase digestion (n = 86). Inflammatory vascular alterations were observed in 20.5% of the specimens. Smaller and larger arterial and venous vessels demonstrated mild to severe degenerative lesions. Unaltered vessels were detected only in maiden mares. Vessels in older maiden mares were frequently affected by angiosclerotic changes, characterized by mild to moderate perivascular and i...
Raidal SL, Bailey GD, Love DN.Flow cytometry was used to assess the phagocytosis of fluorescent-labelled bacteria by equine peripheral blood neutrophils and pulmonary alveolar macrophages. Cell populations were prepared from venous blood following ammonium chloride lysis and from washed bronchoalveolar lavage derived samples. Discrete clusters of cells, corresponding to different leucocyte groups, were readily identified on the basis of differing light scattering properties and could thus be discriminated, negating the need for prior cell separation. Cells able to associate with fluorescent-labelled bacteria (by attachment...
Leber R, Wiler R, Perryman LE, Meek K.V(D)J rearrangement is the molecular mechanism by which an almost limitless number of unique immune receptors is generated. V(D)J rearrangement involves two DNA breaks and religations resulting in two DNA joints; coding and signal joints. If V(D)J recombination is impaired (as in murine SCID (C.B-17 mouse] or RAG [Recombinase Activating Genes) deficient mice), B lymphocyte and T lymphocyte development is blocked and severe immunodeficiency results. The first animal model of SCID was reported in Arabian foals in 1973. Recently we demonstrated that the mechanistic defect in SCID foals is V(D)J r...
Peham C, Licka T, Mayr A, Scheidl M, Girtler D.Treadmills are widely used in equine motion analysis. For the evaluation of the trot of a horse, a trotting speed with low variation between motion cycles is necessary to make the measurements reproducible. The aim of this study is to show how an individual 'optimum' trotting speed for lameness quantification can be determined. In this study, the stability of a horse's gait pattern was evaluated by calculating the standard deviation (S.D.) of motion-cycle speed (MCS). In trot, eighteen horses were analysed at several speeds. The measurements were taken with the ExpertVision System (Motion Anal...
Coté N, Trout DR, Hayes MA.Binding between equine plasma alpha-2-macroglobulin (alpha 2M) and several cytokines known to participate in inflammatory reactions in other species was initially examined. Plasma was obtained from 5 horses with various abnormalities. Samples, both untreated and after reaction with methylamine, were incubated with exogenous, radiolabeled, porcine-derived transforming growth factor-beta-1 (125I-TGF-beta 1), recombinant human interleukin-1-beta (125I-IL-1 beta), and recombinant human tumor necrosis factor-alpha (125I-rhTNF-alpha). They were then subjected to nondenaturing polyacrylamide gel elec...
Kondo T, Fukunaga Y, Sekiguchi K, Sugiura T, Imagawa H.To examine antibodies against equine arteritis virus (EAV), an enzyme-linked immunosorbent assay (ELISA) using purified virus antigen was developed. The results of ELISA were compared with those of serum neutralization (SN) tests. The ELISA absorbance values and the SN titers in sera collected weekly from EAV-infected horses showed a similar pattern. The ELISA could detect antibody to EAV in horses experimentally infected with not only a homologous virus strain, which was used as the ELISA antigen, but also a heterologous strain. Using the ELISA, serum samples collected in 1996 from racehorses...
Caudron I, Grulke S, Farnir F, Aupaix R, Serteyn D.This study is part of a work to develop a radiographic method that defines objectively the individual conformation of an equine digit and its appropriate trimming. The authors used isolated distal limbs on a rotation support to study the influence of induced foot rotations on several angles measured from specific radiographs. The results of this work enabled the authors to quantify the rotation of the proximal phalanx compared to the distal, and to determine exactly the possible rotation in the distal interphalangeal joint. It was also observed that, faced with a forced rotation of the foot, t...
Marsh AE, Barr BC, Packham AE, Conrad PA.Neospora hughesi n. sp. was isolated from the central nervous system tissue of an adult equine (Equus caballus) from California. The tachyzoites are crescent-shaped, approximately 2 x 5 microm (1.8-3.0 x 4.0-7.0 microm), with characteristic apical complex structures consisting of an anterior polar ring, conoid, numerous rhoptries filled with a uniform electron-dense material, and 22 microtubules extending posteriorly from the polar ring. Comparison of N. hughesi to canine and bovine Neospora caninum isolates showed phenotypic differences in immunoreactive proteins. Molecular analysis of the sm...
Caudron I, Grulke S, Farnir F, Aupaix R, Serteyn D.This study is part of a work to develop a radiographic method that defines objectively the individual conformation of an equine digit and its appropriate trimming. The authors used isolated distal limbs fastened on a rotation support with variable inclinations to study the influence of induced asymmetric bearings on various angles measured from specific radiographs. The digit responded to asymmetric bearings by 1. deformation of the hoof; 2. rotation of the phalanges; and 3. joint asymmetry or local articular space narrowing. The two last situations occurred mainly in the distal interphalangea...
Ambrose NC, Mijinyawa MS, Hermoso de Mendoza J.Dermatophilus congolensis is a filamentous branching actinomycete that causes dermatophilosis, an exudative dermatitis in ruminants. The pathogenesis of this disease is poorly understood and virulence factors of D. congolensis have not been characterised. Culture filtrate (CF) of 14 D. congolensis isolates from cattle, 15 from sheep and four from horses were examined for proteolytic activity using azocasein as a non-specific substrate. The isolates were from a variety of geographical locations. All the isolates examined produced extracellular proteolytic activity. CF from 24 and 48 h cultures ...
Williamson RM, Beveridge I, Gasser RB.To compare the sensitivities of three coprological techniques for the diagnosis of Anoplocephala perfoliata infection in horses and to assess the value of the methods for diagnosis of horses at risk of clinical cestodiasis. Methods: Faecal samples were collected from necropsied horses with or without A perfoliata infection and examined using one sedimentation and two different flotation methods. The coprological results were compared with worm counts performed at necropsy of the horses and the degree of mucosal damage. In addition, the efficiency of recovery of A perfoliata eggs from faeces wa...
East LM, Steyn PF, Dickinson CE, Frank AA.A 5-year-old Arabian horse was admitted with a 5-day history of undulant pyrexia of unknown origin, inappetence, obtundation, and acute collapse. Physical examination results were unremarkable except for a grade II/VI left-sided systolic cardiac murmur and abdominal splinting. Mild chronic inflammatory changes were evident on clinicopathologic evaluation. Echocardiography revealed moderate aortic insufficiency. A solitary soft tissue opacity was found on thoracic radiography but not on ultrasonography. Palliative treatment was ineffective. Nuclear scintigraphy with WBC labeled with technetium ...
Malmgren L, Olsson Engvall E, Engvall A, Albihn A.This study was initiated in order to investigate the bacterial flora of the stallion genital tract by taking consecutive samples from normal stallions in regular use. The objective was to determine whether any growth of potential pathogens, particularly P. aeruginosa and K. pneumoniae, in fresh semen and urethra was associated with the presence of inflammatory cells in the semen and whether bacterial growth had any effect on sperm morphology and pregnancy results. Sixteen stallions, only used for A.I., housed at 3 different commercial stud farms, were used. A wide variety of microorganisms was...
Ward CL, Wood JL, Houghton SB, Mumford JA, Chanter N.Seventy-three bacterial isolates from 65 horses with and without evidence of lower airway disease were identified to assess whether the association with disease was accounted for by a small or large number of species. Just over half (50.5 per cent were Actinobacillus equuli, 17.8 per cent were A suis-like, 11 per cent were Pasteurella pneumotropica, 8.2 per cent were A lignieresii, 6.8 per cent were P haemolytica and 5.5 per cent were P mairii. These results suggest that a range of Actinobacillus and Pasteurella species can be isolated from the lower airways of horses, with many of the isolate...
Trostle S.A working knowledge of normal endoscopic anatomy and the effects of positioning must be mastered to take advantage of endoscopic procedures involving the gastrointestinal system. Endoscopic procedures involving the gastrointestinal system offer advantages over conventional surgery in that they are less invasive and provide direct visualization. Laparoscopy can be used to evaluate horses with abdominal pain before and after surgery. It can be used to evaluate and biopsy abdominal masses and parenchymal organs such as the spleen, liver, and kidney. Endoscopic gastrointestinal surgical procedures...
Frazer GS, Rossol TJ, Threlfall WR, Weisbrode SE.Endometrial fibrosis is a major cause of infertility in broodmares. Because of the proven anti-inflammatory effects of dimethyl sulfoxide (DMSO) and its influence on collagen, the effect of DMSO on the endometrium was investigated in mares. Solutions of DMSO (25%, 50%, or 75%) were infused into the uterus of clinically normal mares. Examination of serially obtained biopsy specimens revealed epithelial ulceration and stromal inflammation that were proportional to the DMSO concentration infused, but vasodilatation was not observed. In all mares, the endometrium had returned to normal by day 21 a...
Troncoso I, Calvanese R, Saravia F, Muñoz-Leal S, Zegpi NA, Ortega R.Equine coital rash (ECE) is a highly contagious benign infection that induces lesions on external genitals, and it is caused by the equine herpesvirus type 3 (EHV-3). Although the disease is globally distributed, its presence in Chile has not been documented from a genetic point of view. Here, we performed polymerase chain reaction screenings for EHV-3 in lesions of external genitals in four horses belonging to a riding station at Bulnes, Ñuble Region, Chile. We sequenced a fragment of the glycoprotein G (gG) gene from three horses with clinical signs of ECE. The sequences were identical betw...
Neuhauser S, Handler J.The aims of this study were to compare two different methods of quantifying the colour of the luminal surface of the equine endometrium and to relate the results to histopathological evidence of inflammation and fibrosis. The mucosal surfaces of 17 equine uteri obtained from an abattoir were assessed using a spectrophotometer and by computer-assisted analysis of photographs. Values were converted into L(*)a(*)b(*) colour space. Although there was significant correlation between the two methods of quantification, variations in 'brightness', 'red' and 'yellow' values were noted. Within a given u...
Sato T, Sato G, Shoji Y, Itou T, Sakai T.After RNA extraction from horsehair shafts and roots, the mRNAs of beta-actin, muscle-type phosphofructokinase, and transforming growth factor-beta1 were detected by reverse transcription polymerase chain reaction assay. Low amounts of RNA were present in the horsehair. These specific mRNA transcripts were readily detected when more than three hair roots were used. However, detection of the mRNA transcripts was difficult in the hair shaft. These findings indicate that the small amounts of residual RNA in horsehair roots can be utilized as samples for molecular biological analysis.
Donoghue S, Meacham TN, Kronfeld DS.Cumulative nutritional demands on good brood mares are unrivalled among domestic livestock, but little attention has been given to the influence of nutrition on their reproductive performance and efficiency. We suggest that part of the decline in racing performance of progeny of mares over 10 years of age may be caused by suboptimal nutrition. This article contrasts the concepts of minimal and optimal nutrient requirements, revives Hammond's concept of nutrient partitioning to the conceptus and mammary gland, and discusses energy and nutrient requirements during gestation and lactation. Furthe...
Kostiuk D.A 4-year-old Morgan stallion was presented with a 9-week history of diarrhea. Biopsy of nodules in the rectal mucosa yielded a diagnosis of eosinophilic enterocolitis. Treatment with steroids was instituted and the feces firmed within 2 days. Continued treatment with oral prednisone kept the feces at a normal consistency for 4 months.
Okai K, Taharaguchi S, Orita Y, Yokota H, Taniyama H.To contribute to early diagnosis and treatment of gastric ulcer of foals, we examined the gastric mucosa of healthy and affected foals using an endoscope. In healthy foals, the characteristic changes in the development of the squamous mucosa were seen mainly in the squamous mucosa, and maturation of the squamous mucosa in the greater curvature (GC-S) occurred more slowly than that of the squamous mucosa in the lesser curvature (LC-S). Epithelial desquamation in the LC-S and GC-S was observed between 6 and 90 days but was not observed in the LC-S at about 60 days, whereas it was observed in the...
Fussell D, Bizikova P, Breuhaus B, Harris RA, Moore AR, Chen L, Linder KE.Bullous amyloidosis is a rare disease in humans that has not been described in a veterinary species in the peer-reviewed literature. The human disease is characterised by haemorrhagic vesicles and bullae on the skin and mucosae, which form due to amyloid deposition. Objective: To describe the clinical features, laboratory analysis and histopathological features of an unique presentation of bullous disease in a horse. Methods: A 17-year-old thoroughbred mare presented for weight loss and severe oral cavity ulcers. Methods: Investigations involved haematological evaluation, chemistry profiles, g...
Cohen ND, Carey VJ, Donahue JG, Seahorn JL, Donahoe JK, Williams DM, Harrison LR.To identify factors associated with abortions of mares during late gestation attributed to mare reproductive loss syndrome (MRLS). Methods: Case-control study. Methods: 282 broodmares from 62 farms in central Kentucky, including 137 mares that had late-term abortions (LTAs) associated with MRLS, 98 mares from the same farms that did not abort, and 48 mares that aborted from causes other than MRLS. Methods: Farm managers were interviewed to obtain data on a wide range of management practices and environmental exposures for the mares. Data for case and control horses were compared to identify ri...
Mair TS, Stokes CR, Bourne FJ.Mast cells in the equine respiratory mucosa were studied at both light--and transmission electron--microscope levels. Mast cells were identified at all levels of the tract, with the greatest cell density in the nasopharynx. The majority (57 to 94 per cent) of this cell population were located within the connective tissue of the lamina propria. Up to 20 per cent of these cells were associated with the mucosal glandular tissue, whilst small numbers were present within the surface epithelium and in association with nodular lymphoid tissue. In the peripheral lung tissue 20 per cent of the mast cel...
Wilkins PA, Lowe JE.Right dorsal colon fistulas, 2.5 cm in diameter, were created in 2 healthy ponies, using a 2-stage surgical procedure. The first stage consisted of resection of portions of the 16th and 17th ribs on the right side, followed by surgical creation of a 6- to 8-cm-diameter adhesion between the right dorsal colon and the body wall. Fistulas were created approximately 2 weeks after the first surgery by sharp dissection through the adhesion into the lumen of the colon. The fistulas have been satisfactorily maintained for > 2 years by de Pezzer catheters (45 F). Ponies with fistulas have been used ...
May CE, Schulman ML, Howell PG, Lourens CW, Gouws J, Joone C, Monyai MS, le Grange M, Bezuidt OK, Harper CK, Guthrie AJ.Taylorella equigenitalis is the causative agent of contagious equine metritis (CEM), a sexually transmitted infection of horses. We report here the genome sequence of T. equigenitalis strain ERC_G2224, isolated in 2015 from a semen sample collected in 1996 from a Lipizzaner stallion in South Africa.
Watson RE, England JJ, Larson KA.A cell line, derived from a spontaneous equine connective tissue tumor (equine sarcoid), has been established. The morphological and growth characteristics indicative of malignant transformation of the cells include a disoriented, rapid growth and loss of contact inhibition. Further evidence of transformation is the agglutination of these cells by concanavalin A and their ability to divide in semisolid media.
Weiss DJ, Geor RJ, Burris SM, Smith CM.Pentoxifylline has been reported to improve peripheral vascular circulation by altering the flow properties of blood. To determine if the hemorrheological effects of pentoxifylline were mediated by alterations in neutrophil function and/or flow properties, we evaluated the drug's effects on equine neutrophils in vitro. Pentoxifylline, at a concentration of 1 x 10(-1) M, but not at concentrations of 1 x 10(-6) M to 1 x 10(-2) M, markedly suppressed neutrophil superoxide production, zymosan phagocytosis and adherence to nylon wool. Pentoxifylline failed to improve neutrophil filterability throug...