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.
Buergelt CD.The few data collections that evaluate the involvement of organ systems in horse diseases are in agreement that the locomotor, gastrointestinal and nervous systems are the sites of primary disease in the vast majority of sick horses. When compared with diseases of these organ systems, equine cardiovascular diseases occur infrequently. The most detailed and comprehensive survey of equine cardiac pathology was reported in 1972 by Else and Holmes, who summarized the gross and microscopic cardiac findings from 1500 abattoir horses. This paper reviews the pathology of the cardiovascular diseases ty...
Rothschild CM, Oaks JL, Schaupp JK, Rurangirwa FR, Sellon DC, Hines MT.Helcococcus ovis, a recently described organism cultured from sheep, was isolated in pure culture from a pulmonary abscess in a horse. This is the first report of this organism in horses and the first report in veterinary medicine to clearly demonstrate a pathogenic role for this organism.
Rapisarda G, Marino F, Ferrara G, Gioffrè F, Galofaro V.Here we present a case of preputial benign fibrous histiocytoma in a 7-year-old mule. This case was treated surgically. Pathologic analysis and diagnosis of these lesions were based on a combination of light microscopy and immunohistochemistry. Histologically, the tumour was composed primarily of a storiform pattern of fibroblastic and poligonal cells. In immunohistochemistry, except for consistent immunoreactivity for vimentin, nearly all tumour cells were positive for CD68, S-100 protein, pan-cytokeratin, alpha-smooth muscle actin, and desmin. Benign fibrous histiocytoma of the prepuce in mu...
Alghamdi AS, Foster DN, Troedsson MH.Seminal plasma (SP) is known to have immunosuppressive properties in several species. Equine SP has been reported to reduce or inhibit chemotaxis, phagocytosis and complement activity in vitro. The type and amount of the SP component that suppresses sperm-polymorphonuclear neutrophil (PMN) binding in vitro was determined, and the effect of such suppression on the fertility of mares inseminated in the presence of uterine inflammation, was analyzed. Sperm cells were suspended in either SP, semen extender or a mixture of both, and each was mixed with PMN-rich uterine secretions collected at 12 h ...
Staszyk C, Gasse H.In order to display the collagen-fiber arrangement in the equine periodontal ligament an inexpensive and easy staining procedure with fluorescein was applied to paraffin sections. After fluorescein labeling a section was suitable for successful examination with three special microscopical systems: a) fluorescence microscopy b) phase contrast microscopy and c) polarized light microscopy. Collagen fibers were clearly displayed as compact structures in the fluorescence microscope. This distinct feature of the fluorescent image generated an almost three-dimensional impression of the fiber arrangem...
Borst GH, van der Weij PJ, Vos JH.Acute idiopathic gastric rupture resulted in sudden death of a 4.5-months-old healthy Friesian foal. No morphological lesions were present which could explain the preceding gastric impaction. In this case hypodypsia may have been (partially) responsible for the impaction as only a mechanical drinking apparatus, unsuitably for horses, was available.
Rickards KJ, Page CP, Cunningham FM.Heaves is an allergic airway disease in horses characterised by reversible airway obstruction, bronchial hyperresponsiveness and airway inflammation associated with a Th(2) response. Cyclic nucleotide-dependent signalling pathways can regulate lymphocyte function. In this study, we examined lymphocyte PDE activity comparing horses with heaves to healthy control animals. Total PDE activity and the effects of isoenzyme selective inhibitors were measured before, 5 and 24 h after the start of a 7 h allergen challenge. Allergen challenge had no effect on either total cAMP PDE activity or its inhibi...
Yoon JH, Brooks RL, Khan A, Pan H, Bryan J, Zhang J, Budsberg SC, Mueller PO, Halper J.Fluoroquinolone antibiotics have been used widely in humans and domestic animals, including horses, because of their broad-spectrum bactericidal activity, and relative safety. The use of fluoroquinolones, however, is not without risk. Tendonitis and spontaneous tendon rupture have been reported in people during or following therapy with fluoroquinolones. We have studied the effects of enrofloxacin, a fluoroquinolone antibiotic used commonly in domestic animals, on tendon cell cultures established from equine superficial digital flexor tendons. Effects on cell proliferation and morphology were ...
McClure SR, VanSickle D, Evans R, Reinertson EL, Moran L.Extracorporeal shock-wave therapy (ESWT) may stimulate healing of desmitis in multiple species. The objective of this study was to evaluate the ultrasonographic and histologic appearance of collagenase-induced suspensory ligament (SUL) desmitis in untreated ligaments and ligaments treated with ESWT in horses. Four mature horses had SUL desmitis induced in both forelimbs. Beginning 3 weeks after induction of the lesions, one ligament per horse was treated 3 times at 3-week intervals with ESWT. The percent lesion, echogenicity and fiber alignment scores of the SULs were evaluated at 3-week inter...
Althaus H, Müller N, Busato A, Mellor PS, Torsteinsdottir S, Marti E.Insect bite dermal hypersensitivity (IBH) is an allergic dermatitis of horses caused by bites of Culicoides spp. and sometimes Simulium spp. The aim of the investigation presented here was to identify allergens causing IBH. A cDNA library expressing recombinant Culicoides nubeculosus proteins was screened using affinity-purified serum from an IBH-affected horse. Screening of the library resulted in identification of one immunoreactive clone. The sequence of the cDNA insert was determined and revealed a 600 bp insert with an open reading frame coding for a 78 amino acid long protein, called rCu...
Davis EG, Sang Y, Blecha F.beta-Defensins are cysteine-rich endogenously produced antimicrobial peptides that play an important role in innate immune defense. Although, previous investigations have identified beta-defensins in several mammalian species, no reports have identified equine beta-defensins. Using a strategy of database searching for expressed sequence tags (EST) we identified putative expression of equine beta-defensins in hepatic tissue. Based on this information, sequence specific primers were designed for the equine gene enabling the identification of the full-length cDNA sequence of equine beta-defensin-...
Buckley P, Dunn T, More SJ.Pony Club is one of the leading junior equestrian organisations in the world, and was established to teach young people the many aspects of horsemanship. The aim of this study was to gain an understanding of the health and performance of Pony Club horses from the perspective of their owners. In-depth interviews were conducted with Pony Club members at two sites in Australia, and topics relating to participants' background with horses, horse attributes valued by participants, horse health and performance, and Pony Club-related matters. The in-depth interviews were taped, transcribed and analyse...
Boxell AC, Gibson KT, Hobbs RP, Thompson RC.To assess the occurrence of gastrointestinal parasites in horses in Perth. To apply polymerase chain reaction (PCR) for the identification of some species of encysted larval cyathostomes. Methods: Between February and September of 2000, the gastrointestinal tracts of 29 horses submitted to a local knackery and Murdoch University Veterinary hospital in Perth were examined post mortem for the presence of gastrointestinal parasites. Methods: The gastrointestinal tract was divided into six sections, which were screened for the presence of parasites such as Gasterophilus sp, Anoplocephala sp and Pa...
Li Y, Yao J, Chang M, Nikolic D, Yu L, Yager JD, Mesecar AD, van Breemen RB, Bolton JL.Catechol-O-methyltransferase (COMT) plays an important role in the inactivation of biologically active and toxic catechols. It has been shown that COMT is genetically polymorphic with a wild-type and variant form where a valine has been substituted with a methionine. Several, but not all, epidemiological studies have shown that women, homozygous with the variant form, have an increased risk of developing breast cancer. Previously, we showed that 4-hydroxyequilenin (4-OHEN), a cytotoxic/genotoxic equine catechol estrogen metabolite, is both a substrate of COMT and an irreversible inhibitor of t...
Hughes KJ, Malikides N, Hodgson DR, Hodgson JL.To compare a fast Romanowsky cytological stain (Diff-Quik) and Leishman's stain for the detection of mast cells in samples from the lower airways of racehorses, and to compare the proportion of mast cells and eosinophils in the total inflammatory cells in tracheal aspirate (TA) with those in paired bronchoalveolar lavage (BAL) samples. Methods: Retrospective case series of 48 young Thoroughbred and Standardbred racehorses. Methods: Fifty-one paired TA and BAL samples were collected after treadmill exercise from 48 horses with poor racing performance. Two slides were prepared from each sample; ...
Foote CE, Gilkerson JR, Whalley JM, Love DN.To examine the prevalence of equine herpesvirus 1 antibody in mares and foals on a large Hunter Valley Thoroughbred stud farm in New South Wales before and after the introduction of an inactivated whole virus vaccine. Methods: Cross-sectional serological surveys performed in February 1995 and 2000 to determine the prevalence of EHV-1 antibody-positive mares and foals. A further cross-sectional survey was carried out in 2001 to complement the 2000 data. Methods: Two hundred and twenty-nine mares and their foals were sampled in 1995 and 236 mares and their foals were sampled in 2000. The study p...
Schembri MA, Major DA, Suttie JJ, Maxwell WM, Evans G.To investigate cryopreservation-induced capacitation-like changes in equine spermatozoa frozen in three different media using chlortetracycline (CTC) fluorescence staining analysis. Methods: Semen collected from three stallions was diluted in one of three centrifugation media and, after centrifugation and removal of supernatant, extended in corresponding freezing media containing additional egg yolk, glycerol, lactose and Equex paste. The semen was frozen in 5 mL straws and the spermatozoa assessed for motility and membrane quality after thawing. Results: Following centrifugation, spermatozoa ...
Begg LM, O'Sullivan CB.To report the prevalence and distribution of gastric ulceration within a group of racehorses and to describe the endoscopic appearance of gastric antrum and pyloric ulceration. Methods: Retrospective clinical study. Methods: Medical records from gastroscopic examinations of 345 racehorses (331 Thoroughbreds and 14 Standardbreds) were reviewed. Prevalence, distribution and severity of gastric ulcers were recorded. Lesions involving the squamous mucosa and the glandular mucosa of the antrum and pylorus were graded and compared. Results: Gastric ulceration was found in 86% of racehorses. The squa...
Van Hoogmoed LM, Nieto JE, Spier SJ, Snyder JR.To evaluate the efficacy of a customized solution to attenuate intestinal injury following 20% low-flow ischemia and reperfusion in the jejunum of horses. Methods: 10 healthy adult horses. Methods: Two 30.5-cm-long segments of jejunum were exteriorized through a ventral midline incision and the mesenteric artery and vein supplying that portion of the intestine were instrumented with flow probes. Blood flow was decreased to 20% of baseline for 90 minutes followed by 90 minutes of reperfusion. In 5 horses, 60 mL of the customized solution was placed in the lumen of each segment (treatment-group ...
Arnoczky SP, Lavagnino M, Gardner KL, Tian T, Vaupel ZM, Stick JA.To determine the effects of oxytetracycline on matrix metalloproteinase-1 (MMP-1) mRNA expression and collagen gel contraction by equine myofibroblasts in an effort to explain the mechanistic basis for the pharmacologic treatment of flexural deformities in foals. Methods: Cultured myofibroblasts from the accessory ligament (distal check ligament) of 6 foals. Methods: Collagen gel scaffolds seeded with equine myofibroblasts were cultured in individual culture dishes containing complete media (Dulbecco's modified Eagle medium with 10% fetal bovine serum) and oxytetracycline (0, 12.5, 25, or 75 m...
Farstvedt EG, Hendrickson DA, Dickenson CE, Spier SJ.Two horses were examined for large head wounds suspected to be the result of trauma and characterized by extensive necrosis of the skin and subcutaneous tissue, with abundant purulent exudate. Corynebacterium pseudotuberculosis was isolated from the facial wounds in both horses. Histopathologic examination revealed severe suppurative cellulitis and panniculitis with fistulous tracts and granulation tissue in 1 horse. Both horses were treated with local wound care, nonsteroidal anti-inflammatory drugs, and administration of antimicrobials. The concept of moist wound care was used in the second ...
Björnsdóttir S, Arnason T, Lord P.A survival analysis was used to compare the culling rate of Icelandic horses due to the presence of radiographic and clinical signs of bone spavin. A follow-up study of 508 horses from a survey five years earlier was performed. In the original survey 46% of the horses had radiographic signs of bone spavin (RS) and/or lameness after flexion test of the tarsus. The horse owners were interviewed by telephone. The owners were asked if the horses were still used for riding and if not, they were regarded as culled. The owners were then asked when and why the horses were culled. During the 5 years, 9...
Zerbe H, Engelke F, Klug E, Schoon HA, Leibold W.An endometritis model was used to investigate the influence of degenerative endometrial changes (endometrosis) on functional parameters of uterine neutrophils in the horse. Six hours after intrauterine application of recombinant human interleukin-8 (rhIL-8), the uteri of 15 mares were flushed with phosphate-buffered saline. Quantitative and qualitative flow cytometric assays were then made to determine the absolute numbers, viability, phenotype, generation of reactive oxygen species (ROS), and phagocytic activity of immigrated polymorphonuclear neutrophilic granulocytes (PMN). Recombinant hIL-...
de Grauw JC.Diseases affecting synovial joints are a major cause of chronic disability both in humans and in companion animal species, most notably dogs and horses. As progressive deterioration of the articular cartilage is the hallmark of degenerative joint disease or osteoarthritis, research efforts traditionally tended to focus primarily on cartilage pathology. However, in recent years it has become clear that synovial joints should be considered intricate organs in their own right, with each of the constituent tissues (cartilage, bone, and synovial membrane) interacting with each other both in health ...
Herzog A, Höhn H, Klug E, Hecht W.In a 7 months old foal with a male pseudohermaphroditism the cytogenetic investigation revealed a XO/XYY-mosaic with a centric fusion of the Y-chromosomes.
Swanson CR, Muir WW.The influence of positive end-expiratory pressure (PEEP) on the alveolar-arterial O2 tension difference [P(A-a)O2], physiologic right-to-left shunt fraction, physiologic dead space-to-tidal volume ratio, and hemodynamic variables was studied in halothane-anesthetized horses maintained in dorsal recumbency during controlled ventilation. Dobutamine was used to minimize the adverse cardiovascular consequences of PEEP. Six adult horses were anesthetized, using xylazine (2.2 mg/kg of body weight, IM), guaifenesin (50 mg/kg, IV), thiamylal Na (4.4 mg/kg, IV), and halothane (1.5 to 2% inspired) in 10...
Shirakawa T, Ide M, Taniyama H, Tobiwatari K, Senba H, Oishi H, Matsui T, Ono T.A 1-month-old male thoroughbred foal, which had difficulty in walking, was killed and examined by histological, histochemical and ultrastructural methods. The muscles of the trunk and upper hind limbs were chiefly affected, and changes in the affected muscles resembled those in muscular dystrophy in man. The type of muscular dystrophy present in this foal and the significance of this disease in thoroughbred horses are discussed. The dystrophy in this foal resembled the limb-girdle type or myotonic dystrophy of muscular dystrophy in man.
Ertelt A, Stumpff F, Merle R, Kuban S, Bollinger L, Liertz S, Gehlen H.Asymmetric dimethylarginine (ADMA) is a cardiac biomarker in humans, symmetric dimethylarginine (SDMA) a renal biomarker in humans, cats, and dogs. The purpose of this prospective study was to investigate if measuring serum ADMA and SDMA concentrations via ELISA allows detection of cardiac disease in horses in a routine laboratory setting. In this context, reference values in horses were established. Methods: Seventy-eight horses with no known medical history were compared to 23 horses with confirmed structural cardiac disease with/or without arrhythmias. Horses underwent physical examination,...
Gay CC, Sullivan ND, Wilkinson JS, McLean JD, Blood DC.The case histories and clinical findings of 15 ponies with hyperlipaemia are presented. The disease was characterised by hyperlipidaemia with inappetance, progressing somnolence, muscle fasciculation, diarrhoea, and ventral oedema as the predominant clinical findings. Post mortem examinations of 12 ponies showed extensive lipidosis and vascular thrombosis with widespread secondary changes. Most cases occurred in late pregnant and early lactating mares in the summer months and it is postulated that the disease was initiated in this group by a falling nutritional plane in the face of high nutrie...
Estrada A, Samper JC, Lillich JD, Rathi RR, Brault LS, Albrecht BB, Imel MM, Senne EM.A 3-year-old Quarter Horse halter stallion was referred for routine semen evaluation. Physically, the stallion's reproductive organs appeared normal. Repeated semen evaluations did not reveal any spermatozoa. Because high activities of alkaline phosphatase are detected in the epididymal fluid and indicative of complete ejaculation, alkaline phosphatase activities were analyzed in several samples, which yielded activities far less than reference values and suggested a blockage of the reproductive tract. Endoscopic evaluation of the urethra and the bulbourethral, prostate, and urethral gland duc...
Araújo JA, Curcio B, Alda J, Medeiros RM, Riet-Correa F.Two outbreaks of Hypochaeris radicata-induced Australian stringhalt involving two farms and seven horses from southern Brazil are reported here. Subsequently, the disease was experimentally reproduced in a feeding trial with one colt fed H. radicata from the suspect paddocks. Fresh H. radicata was fed to the experimental animal for 50 days at an average daily dosage of 9.8 kg. Initially, the plant was collected from the paddock where the clinical disease occurred and was fed for 19 consecutive days producing mild clinical signs. However, on days 20-23 fresh plant was collected from a neighbori...
The UK has never experienced an outbreak of African horse sickness but, as Matthew Robin of the Fyrnwy Equine Clinic explains, there is still a risk of a case occurring.
Allen WE, Kessy BM, Noakes DE.Two experimental procedures were investigated in order to assess their usefulness in diagnosing occlusion of the equine uterine tube. The starch grain test, which involves the injection of a starch suspension onto the ovary and the subsequent recovery of starch from the cervix, proved to be safe and reliable. Each tube could be investigated separately. It was found that when starch was injected onto the ovulating ovary on the day of ovulation, there was a delay of four to seven days before starch was recovered from the cervix. The phenolsulphonphthalein (PSP) test, which involves the depositio...
Bertone AL, McIlwraith CW, Jones RL, Norrdin RW, Radin MJ, Lebel JL.To evaluate the effects of 5 treatments on clinical responses, synovial fluid analysis, radiographic changes, bacteriologic culture results of the synovial fluid and synovial membrane, microscopic characteristics of the synovial membrane, and articular cartilage histochemistry, Staphylococcus aureus organisms (1.6 X 10(6) colony-forming units) were inoculated into the tarsocrural joints of 12 horses (n = 24 joints; 2 joints/horse). Each horse was given phenylbutazone (2 g) orally, every 24 hours, beginning 24 hours after inoculation. Two horses (ie, 4 joints) were not given other treatment (co...
Kitchen DL, Merritt AM, Burrow JA.To determine gastric secretory responses in horses treated with histamine and to determine the dose of histamine needed to elicit maximal gastric secretion. Methods: 6 adult horses with an indwelling gastric cannula. Methods: Gastric contents were collected in 15-minute periods, and volume, pH, hydrogen ion concentration, hydrogen ion output, sodium concentration, and sodium output were determined. Values were determined without any treatment (baseline), after administration of pyrilamine maleate (1 mg/kg of body weight, i.v., given during a 15-minute period), and during 1-hour infusions of hi...
Greatorex JC.The clinical manifestations, diagnosis and differential diagnosis of "verminous aneurysm" formation at the root of the cranial mesenteric artery and coeliac artery resulting from Strongylus vulgaris larvae migration are described. Forty-nine of 57 cases were successfully treated with low molecular weight dextran (dextran 70).
Gratzek AT, Kaswan RL, Martin CL, Champagne ES, White SL.Topical cyclosporine A was safely used in a series of 11 cases of equine keratitis and keratouveitis and appeared to be an effective anti-inflammatory agent in 9 cases. The clinical diagnoses included interstitial keratouveitis, endotheliitis, multifocal punctate keratopathy and a melting stromal ulcer. In most cases, the presence or absence of insidious bacterial infection was not conclusively determined. Topical cyclosporine A had no deleterious effects in this series of cases. The authors suggest that topical cyclosporine in both aqueous and lipid base vehicles should be investigated and ev...
Moore JN, Allen D, Clark ES.This article reviews research findings relating to the pathophysiology of acute laminitis in horses. The data presently available suggest that the onset of the condition may be due to constriction of the postcapillary vessels in the digit, leading to increased capillary hydrostatic pressure and movement of fluid into the interstitial space.
Mottironi VD, Perryman LE, Pollara B, Mickey MR, Swift R, McGrath P.Combined immunodeficiency disease (CID) is a genetic disorder of T and B lymphocyte production which results in a nonfunctional immune system. It is inherited as an autosomal recessive trait and has been reported in humans and in horses of the Arabian breed. Arabian horses known to have the CID gene and horses of unknown carrier status were tested using a microlymphocytotoxicity technique. Computer chi 2 analysis distinguished six serologically defined specificities. The study of unrelated horses and a limited number of families showed that the specificities behave as codominant alleles segreg...
Lyons ET, Tolliver SC.Macrocyclic lactones (MLs) revolutionized parasite control in horses and other animals. They are unique in that they are effective against arthropods and nematodes. The first of the widely used avermectins was ivermectin. In 1983, it was marketed for use in horses as an injectable formulation but was withdrawn in 1984 after about a year and half on the market because of adverse problems. It was replaced by a paste formulation and an oral/stomach tube liquid formulation. Ivermectin is highly active on bots, ascarids, large and small strongyles, pinworms, strongyloides, stomach worms, and some o...
Govaere J, Ducatelle R, Hoogewijs M, De Schauwer C, de Kruif A.This report describes a bilateral seminoma in a stallion. After slaughter, histological examination revealed that the tumour consisted predominantly of polyhedral tumour cells with large nuclei, obvious nucleoli and a small border of cytoplasm. The mitotic index was low and Ki67 staining revealed 4% nuclear staining. To our knowledge, this paper is the first using Ki67 staining as a method to evaluate the mitotic rate in a testicular seminoma in the stallion.
Nixon AJ, Pool RR.Osteochondral fragments from the axial proximoplantar/proximopalmar region of the proximal phalanx were removed from 38 joints in 30 horses. Ninety-three percent of the horses were Standardbreds, and 28 of the 30 had a low-grade lameness. All but 1 of the horses had hind limb involvement. A total of 43 fragments were removed. Most (71%) of the fragments involved the medial aspect of the joint and had to be dissected from a covering of synovial tissue. Histologically, the circumference of most fragments consisted of a transition zone at the attachment of the joint capsule, a region of nonarticu...
Singha H, Malik P, Saini S, Khurana SK, Elschner MC, Mertens K, Barth SA, Tripathi BN, Singh RK.Burkholderia mallei is a Gram-negative coccobacillus which causes glanders-a fatal disease of equines that may occasionally be transmitted to humans. Several cases of outbreaks have been reported from India since 2006. This paper presents draft genome sequences of two B. mallei strains isolated from equines affected by glanders in India.