Pathology in horses involves the study of diseases and abnormalities affecting equine health, encompassing a range of conditions that can impact various systems within the horse's body. This field examines the causes, mechanisms, and effects of diseases, as well as the structural and functional changes they induce in equine tissues and organs. Common pathological conditions in horses include laminitis, colic, equine infectious anemia, and respiratory disorders. Understanding these diseases involves evaluating clinical signs, diagnostic methods, and treatment options. This page compiles peer-reviewed research studies and scholarly articles that explore the etiology, pathogenesis, and clinical implications of pathological conditions in horses.
Asakawa MG, Jamieson CA, David F, Johnson JP, Mehmood W, Oikawa MA.A 5-year-old Arabian broodmare with acute colic was diagnosed with lymphocytic ganglioneuritis of the coeliac-mesenteric ganglia and lymphocytic‒plasmacytic enterocolitis resembling inflammatory bowel disease. No significant pathogens were identified by aerobic culture or histopathological examination. The ganglia were multifocally infiltrated with small lymphocytes that were immunopositive for CD3 and negative for CD20 and CD79a antigens, indicating CD3+ T-lymphocyte-mediated coeliac-mesenteric ganglioneuritis. The findings suggest immune-mediated inflammatory bowel disease resulting in dis...
Albers L, Albers J, Dullin C, Staszyk C, Bienert-Zeit A.In clinical practice, early diagnosis of Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH) and other resorptive incisor diseases is difficult to achieve. The radiographic appearance of subtle pathological changes has not been described in detail and might be confused with age-related changes. Objective: The study was performed to define typical radiographic signs of early incisor lesions and to evaluate the reliability of the radiographic findings. Methods: Descriptive and comparative study using post mortem clinical, radiographic, macroscopic and µCT examination. Methods: The...
Sreenivasan CC, Uprety T, Reedy SE, Temeeyasen G, Hause BM, Wang D, Li F, Chambers TM.Antibodies to influenza D virus (IDV) have been detected in horses, but no evidence of disease in the field has been reported. To determine whether IDV is infectious, immunogenic, and pathogenic in horses, four 2-year-old horses seronegative for both influenza A (H3N8) and D viruses were intranasally inoculated with 6.25 × 107 TCID50/animal of D/bovine/California/0363/2019 (D/CA2019) virus, using a portable equine nebulizer system. Horses were observed daily for clinical signs including rectal temperature, nasal discharge, coughing, lung sounds, tachycardia, and tachypnea. No horses exhibited...
Storms N, Medina Torres C, Franck T, Sole Guitart A, de la Rebière G, Serteyn D.Laminitis is a pathology of the equine digit leading to a failure of the dermo-epidermal interface. Neutrophil activation is recognized as a major factor in SIRS-associated laminitis. Less is known about the role of neutrophil activation in laminitis associated with metabolic disorders. The aim of this descriptive study was to observe whether myeloperoxidase is increased in the laminae during early stage laminitis in three horses subjected to a prolonged euglycemic hyperinsulinemic clamp (pEHC). After 48 h of pEHC-treatment, horses were subjected to euthanasia. Two healthy horses are used as c...
Alberti E, Stucchi L, Lo Feudo CM, Ferrucci F, Zucca E.Pulmonary artery stiffness (PAS) is an index of pulmonary artery elasticity that permits to evaluate the pulmonary vascular bed in humans. It can early detect an increase in pulmonary artery stiffness as a consequence of remodeling of the vessel wall caused by chronic pulmonary and congenital heart diseases. This remodeling can occur also in horses with chronic respiratory diseases. Thus, PAS could be a useful echocardiographic parameter also in horses. However, in literature, there are no studies regarding PAS in horses. The aim of this study is to evaluate the feasibility of PAS in horses. F...
Uldahl M, Bundgaard L, Dahl J, Clayton HM.This study addresses the presence and location of oral lesions in 342 dressage, show jumping, and eventing horses examined at an obligatory veterinary inspection before competing in the Danish National Championship in 2020. Ulcers in the lip commissures were photographed for subsequent pathological analysis. If a lesion was found at the lip commissures on one side, there was an increased risk of finding a similar lesion on the other side (ulcer: p < 0.0001; scarring/depigmentation: p < 0.0001; fissure: p = 0.002; erosion/contusion: p < 0.0001). At the lip commissures, external (cutaneous) ulce...
Hobbs KJ, Porter E, Wait C, Dark M, MacKay RJ.Magnetic resonance imaging is increasingly available for evaluation of horses with suspected pituitary adenomas; however, published studies describing the MRI features of normal equine pituitary glands are currently lacking. This retrospective, descriptive, anatomic study describes the MRI appearance and size of presumed normal equine pituitary glands and assesses potential correlations between pituitary size, brain size, and patient weight. These findings serve as a reference for MRI evaluation of the equine pituitary gland. Inclusion criteria consisted of adult horses (2-15 years old), over ...
Diana A, Freccero F, Giancola F, Linta N, Pietra M, Luca V, Salamanca G, Cipone M, Chiocchetti R.Ultrasonographic morphometry of wall layers is commonly used in veterinary patients with suspected small intestinal disease, however published studies comparing this method with histopathology in horses are limited. This prospective, methods comparison study compared the qualitative and quantitative characteristics of small intestinal wall layers using ex vivo high-frequency ultrasound versus histopathology in a sample of 16 horses. Transverse section images of duodenum, distal jejunum, and ileum were acquired with a high-frequency linear transducer (7-15 MHz). Transverse histological cryosec...
Henker LC, Lorenzett MP, Piva MM, Wronski JG, de Andrade DGA, Borges AS, Driemeier D, Oliveira-Filho JP, Pavarini SP.Holoprosencephaly is a central nervous system malformation, characterized by incomplete or total lack of division of prosencephalon hemispheres, which is commonly accompanied by craniofacial malformations. A 9-month-gestation aborted American Quarter Horse fetus was submitted for postmortem examination. The fetus lacked haircoat and had severe facial malformations including marked shortening/absence of the maxillary, incisive and nasal bones, bilateral anophthalmia, and pre-maxillary agenesis. The prosencephalon was small and nearly spherical, represented by a single lobe, with no visible sepa...
Grillos AS, Roach JM, de Mestre AM, Foote AK, Kinglsey NB, Mienaltowski MJ, Bellone RR.Warmblood Fragile Foal Syndrome Type 1 (WFFS) is an autosomal recessive disorder reported previously only in warmbloods and thought to be caused by a variant in the gene procollagen-lysine,2-oxoglutarate 5-dioxygenase 1 (PLOD1, c.2032G>A, p.Gly678Arg). Given the presentation of this Thoroughbred case, we hypothesised that a similar genetic mechanism caused this phenotype. Objective: To describe the pathological and genetic findings on a foal presenting to a veterinary practice in the UK with skin lesions similar to other Ehlers-Danlos Syndromes, including those documented for warmbloods with W...
Addis A, Canciani E, Campagnol M, Colombo M, Frigerio C, Recupero D, Dellavia C, Morroni M.Different xenogeneic inorganic bone substitutes are currently used as bone grafting materials in oral and maxillo-facial surgery. The aim of the present study was to determine the physicochemical properties and the in vivo performance of an anorganic equine bone (AEB) substitute. AEB is manufactured by applying a process involving heating at >300 °C with the aim of removing all the antigens and the organic components. AEB was structurally characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier-transformed infrared (FT-IR) spectros...
Nitzsche AM, Fey K, Büttner K, Gröf M, Staszyk C.Pituitary pars intermedia dysfunction (PPID) is a common neurodegenerative disease mainly in horses older than 15 years. The domestic equine population is following the same demographic change as that seen in humans; it is aging and veterinarians are asked to attend to geriatric horses more frequently. Common problems seen regularly in older equines are dental disorders and especially periodontal disease. As a systemic and endocrine disease, associated with delayed wound healing and impaired immune function, PPID should be considered before major dental treatment in aged equines is started. Po...
Morrell JM, Rocha A.One of the most commonly encountered challenges in equine breeding is endometritis, which can be difficult to resolve and causes considerable economic losses to the industry. It is a multifactorial condition, developing as an exaggerated form of the normal physiological response to breeding. Seminal plasma proteins, spermatozoa, bacteria and debris initiate an inflammatory response; the resulting fluid and neutrophils are then cleared from the uterus along with the debris. However, in some mares, the response is prolonged or exaggerated, with much fluid formation and neutrophil infiltration le...
Gomaa N, Elemiri M, Hegazy Y, Zeineldin M, Nassif M, Alcala-Canto Y, Barbabosa-Pliego A, Rivas-Caceres RR, Abdelmegeid M.A retrospective cohort study was conducted on two Egyptian horse farms with most of horses were suffered from abdominal pain to describe the associations between the occurrence of mycotoxicosis and equine colic. The farms owner complain was an unexpected increase in number of colic cases and deaths among horses. The association between colic and risk factors (sex, type of food either dry or mixed with roughages and hematobiochemical parameters) was compared using independent sample T-test. The associations between possible prognostic indicators for colic caused by mycotoxicosis was estimated u...
Loynachan AT.Pulmonary malformations are rare equine congenital anomalies. Over a 3-year timeframe, three cases of left sided pulmonary agenesis were diagnosed in perinatal foals. All three cases were associated with concurrent ipsilateral diaphragmatic herniation and hypoplasia of the right lung lobe. All three foals died immediately following parturition due to perinatal asphyxia associated with the congenital malformations. To the author's knowledge, this is the first report of pulmonary agenesis in the horse.
Amat JAR, Patton V, Chauché C, Goldfarb D, Crispell J, Gu Q, Coburn AM, Gonzalez G, Mair D, Tong L, Martinez-Sobrido L, Marshall JF, Marchesi F....The mechanisms and consequences of genome evolution on viral fitness following host shifts are poorly understood. In addition, viral fitness -the ability of an organism to reproduce and survive- is multifactorial and thus difficult to quantify. Influenza A viruses (IAVs) circulate broadly among wild birds and have jumped into and become endemic in multiple mammalian hosts, including humans, pigs, dogs, seals, and horses. H3N8 equine influenza virus (EIV) is an endemic virus of horses that originated in birds and has been circulating uninterruptedly in equine populations since the early 1960s. ...
Bessonnat A, Hélie P, Grimes C, Lavoie JP.There is a remodeling of the central airways in horses with severe asthma but whether a similar process occurs in horses with the mild or moderate asthma (MMA) is unknown. Objective: To evaluate lesions affecting the central airways of horses with MMA. Methods: Twelve horses with MMA and 8 control horses. Methods: Case-control retrospective study of horses classified as MMA affected or controls based on history and bronchoalveolar lavage fluid cytology. Endobronchial biopsies were analyzed using histomorphometry and a semiquantitative histologic scoring system. Results: Histomorphometry identi...
Ochala J, Finno CJ, Valberg SJ.Myosinopathies are defined as a group of muscle disorders characterized by mutations in genes encoding myosin heavy chains. Their exact molecular and cellular mechanisms remain unclear. In the present study, we have focused our attention on a -related E321G amino acid substitution within the head region of the type IIx skeletal myosin heavy chain, associated with clinical signs of atrophy, inflammation and/or profound rhabdomyolysis, known as equine myosin heavy chain myopathy. We performed Mant-ATP chase experiments together with force measurements on isolated IIx myofibres from control horse...
Sakurai M, Isshiki S, Sasaki N, Sakai Y, Yamada Y, Morimoto M.A 7-year-old male Thoroughbred horse exhibited recurrent falls followed by convulsive seizures. The horse was clinically diagnosed with epilepsy and phenobarbital treatment was initiated. However, as seizure control was unsuccessful, the animal was euthanized. At necropsy, yellow-brown linear lesions were found extensively at the U-fibres and cingulate gyrus within the cerebral white matter. Histopathologically, linear demyelination and occasional cavitation were observed. Glial cells with yellow-brown pigment granules, which were autofluorescent, positive to the periodic acid-Schiff reaction ...
Uzal FA, Arroyo LG, Navarro MA, Gomez DE, Asín J, Henderson E.Enteritis, colitis, and enterocolitis are considered some of the most common causes of disease and death in horses. Determining the etiology of these conditions is challenging, among other reasons because different causes produce similar clinical signs and lesions, and also because some agents of colitis can be present in the intestine of normal animals. We review here the main bacterial and viral causes of enterocolitis of horses, including Salmonella spp., Clostridium perfringens type A NetF-positive, C. perfringens type C, Clostridioides difficile, Clostridium piliforme, Paeniclostridium so...
Jasiński T, Zdrojkowski Ł, Kautz E, Juszczuk-Kubiak E, Ferreira-Dias G, Domino M.Endometrosis is an important mares' disease which considerably decreases their fertility. As classic endometrial classification methods might be insufficient for tissue pathological evaluation, further categorization into active/inactive and destructive/non-destructive types was developed by Hoffmann and others. This study aimed to compare NF-κB pathway genes transcription among histopathological types of endometrosis, following Hoffmann and co-authors' classification. Endometrial samples, collected postmortem from cyclic mares ( = 100) in estrus or diestrus, were classified histologically an...
Munday JS, Orbell G, Fairley RA, Hardcastle M, Vaatstra B.Equine sarcoids are common mesenchymal neoplasms of horses that are caused by cross-species infection by . While bovine papillomavirus (BPV) 1 and 2 are the most common causes, there are differences between countries regarding which of these BPV types cause the majority of sarcoids. Additionally, no causative PV can be detected in a subset of sarcoids, suggesting that other PV types could be rarer causes of these neoplasms. In the present study, consensus PCR primers and PCR primers specific for the five types currently known to cause mesenchymal neoplasia (BPV1, BPV2, BPV13, BPV14, and Ovis ...
Sander J, Terhardt M, Janzen N.In horses, congenital defects of energy production from long-chain fatty acids have not been described so far. In contrast, inhibition of fatty acid degradation caused by the toxins hypoglycin A and methylenecyclopropylglycine from various maple species are observed frequently. These non-proteinogenic aminoacids are passed on placentally to fetuses or with collostrum or milk to newborn foals. Nevertheless, newborn foals become very rarely symptomatic. Vertical transmission apparently is not sufficient to induce clinical disease without a particular genetic constellation being present. One of t...
Marčeková P, Mad'ar M, Styková E, Kačírová J, Sondorová M, Mudroň P, Žert Z.Equine hoof canker and bovine digital dermatitis are infectious inflammatory diseases of the hooves with an unknown etiology. However, anaerobic spirochetes of the genus Treponema are considered to be potential etiological agents. The aim of this study was to find a suitable way to isolate DNA and to detect the presence of treponemal DNA in samples of equine hoof canker and bovine digital dermatitis. DNAzol®® Direct and column kits were used to isolate DNA from samples of equine hoof canker and bovine digital dermatitis. The presence of Treponema spp. was detected using PCR and Sanger sequen...
Dupuis-Dowd F, Lavoie JP.Airway smooth muscle remodelling in severe equine asthma includes both thickening of airway smooth muscle, resulting from hyperplasia and hypertrophy, and changes in contractility. However, airway smooth muscle changes have not been studied in milder forms of the disease. Objective: To investigate bronchial smooth muscle remodelling in horses with mild and moderate asthma (MEA). Methods: Retrospective case-control study. Methods: The endobronchial biopsies from 18 horses with MEA referred to the Equine Hospital of the Université de Montréal and from seven healthy age-matched control horses w...
Agreste FR, Moreira JJ, Fülber J, Bogossian PM, Chaible LM, Silva LCLC, Michelacci YM, Baccarin RYA.The synovial membrane (SM) presents itself with distinctive characteristics during arthroscopic procedures in cases of osteoarthritis (OA) as well as osteochondritis dissecans (OCD) in horses. Most of the arthroscopic findings of the SM are limited to a description of a nonspecific inflammation state. In the present study, the macroscopic and histological aspects of the SM in OA and OCD horses were compared to those of healthy horses. The expression of interleukin (IL) in SM was also investigated. Besides, the concentrations of ILs and keratan sulfate (KS) in the synovial fluid (SF), and the m...
Ruppert S, Lee JK, Marsh AE.A 6-year-old female captive zebra (Equus zebra) had a three-year history of slow progressive neurologic signs that recently worsened with hind limb ataxia, head tilt, and circling. Gross examination including the brain and spinal cord were unremarkable. On histopathology, the brain and brainstem had multiple random areas of severe lymphoplasmacytic meningoencephalitis associated with numerous 15-25 μm in diameter protozoal cysts with a discernible outer wall containing numerous 2 × 4 μm oval to crescent-shaped organisms. Immunohistochemistry and PCR identified the presence of Neospora or...
Palozzo A, Traversa D, Marruchella G, Celani G, Morelli S, Petrizzi L.Cutaneous habronemosis in horses is caused by larvae of the spirurid nematodes Habronema microstoma and Habronema muscae. These lesions, also known as "summer sores'', are often severe and disfiguring. Although Habronema-caused lesions at the coronary grooves have been described, cases of hoof cracks with secondary summer sores have never been reported. The present case describes clinic-pathological and surgical features of a quarter crack case complicated by cutaneous habronemosis at the dermal layers. A 15-year-old, Andalusian stallion was referred to the Veterinary Teaching Hospital of the ...
Kopper JJ, Willette JA, Kogan CJ, Seguin A, Bolin SR, Schott HC.Rates of detecting ≥1 potential enteric pathogens (PEP) or toxins (PEP-T) in feces, blood, or both of horses ≥6 months of age with enteric disease and impact of multiple detections on outcome of horses with colitis has not been reported. Objective: To determine detection rates of PEP/PEP-T in feces, blood, or both of horses with enteric disease and effect of detecting multiple agents on outcome of horses with colitis. Methods: Thirty-seven hundred fifty-three fecal samples submitted to IDEXX Laboratories and 239 fecal and blood samples submitted to Michigan State University's Veterinary D...
Leventhal HR, Hassebroek AM, Carvallo F, McKenzie HC.A 14-y-old pony mare was referred after 30-d duration of intermittent pyrexia, anorexia, weight loss, and change in manure consistency. Physical examination revealed a palpable but reducible ventral abdominal mass. Transabdominal ultrasonography revealed multiple distended, hypomotile, and thickened small intestinal loops in close approximation with numerous, well-defined, hyperechoic masses. There was a large amount of echogenic peritoneal fluid; abdominocentesis revealed a neutrophilic and macrophagic inflammatory exudate, and a mixed bacterial population was cultured. Given the poor prognos...
Ludwig A, Gatineau S, Reynaud MC, Cadoré JL, Bourdoiseau G.This aetiological study of guttural pouch mycosis (GPM) in the horse was based on the retrospective study of 21 horses brought into the National Veterinary School of Lyon (France) between 1998 and 2002. Biopsies were taken from the lesions caused by GPM during endoscopic examination. In 87% of the cases, direct examination gave positive results, whereas 43% of the cultures were found to be negative. The main fungi observed were Aspergillus fumigatus (in three cases), A. versicolor (in two cases, together with other fungi), and A. nidulans and A. niger (one case each). In six cases, the Aspergi...
Belknap JK.The black walnut extract (BWE) model was developed after the discovery that horses bedded on shavings from black walnut trees commonly developed laminitis. The first investigators that consistently induced laminitis with black walnut shavings established that it was only the heartwood of the tree that induced laminitis. The BWE model of laminitis has allowed investigators to determine many of the early pathologic signaling events likely to occur in the developmental and acute clinical stages of the disease process, and has brought inflammatory injury to the forefront of laminitis research. The...
Walker C, Love DN, Whalley JM.The mouse models of the respiratory and abortion forms of equine herpesvirus 1 (EHV-1) infection have been used to investigate the vaccine potential of various EHV-1 immunogens, the effect of antiviral agents on EHV-1 infection and the pathogenicity of EHV-1 strain variants and deletion or insertional mutants. This review examines the similarities and differences in the pathogenesis of primary EHV-1 infection in the natural host, the horse, and in the mouse by comparing tissue tropism, clinical signs of infection, the effects of EHV-1 on pregnancy, haematological changes following infection, v...
Hampson BA, de Laat MA, Mills PC, Walsh DM, Pollitt CC.It has been proposed that the feral horse foot is a benchmark model for foot health in horses. However, the foot health of feral horses has not been formally investigated. Objective: To investigate the foot health of Australian feral horses and determine if foot health is affected by environmental factors, such as substrate properties and distance travelled. Methods: Twenty adult feral horses from five populations (n = 100) were investigated. Populations were selected on the basis of substrate hardness and the amount of travel typical for the population. Feet were radiographed and photographed...
Pool RR, Meagher DM.Many lesions of the musculoskeletal system of racing horses are either acute traumatic lesions or are chronic biomechanically induced lesions that become suddenly unstable and provoke acute clinical signs. The latter lesions along with those of DJD are much more common and are of much greater overall economic importance to the racing industry than are the acute traumatic injuries. Chronic biomechanical lesions occur at predictable sites and are the result of an imbalance between repetitive microtrauma sustained in athletic performance and adaptive repair mechanisms of skeletal tissues. The dis...
Pollock PJ, Reardon RJ, Parkin TD, Johnston MS, Tate J, Love S.There are potential advantages to imaging the upper portion of the respiratory tract (URT) of horses during ridden exercise. With the advent of a wireless endoscope, this is now possible. However, there has been no detailed validation of the technique and findings have not been compared to ridden speed. Objective: To assess the combined use of a Dynamic Respiratory Scope (DRS) and global positioning system (GPS) receiver for examining the URT of a group of Thoroughbred racehorses randomly selected from a single flat racehorse training establishment. Methods: Horses were selected randomly from ...
Williamson RM, Gasser RB, Middleton D, Beveridge I.The intestinal tracts of 130 horses were examined for infection with Anoplocephala perfoliata at necropsy. Fifty horses (38.5%) harboured the tapeworm, and the site of attachment of each worm was recorded using predetermined anatomical landmarks. The worms were attached in four regions of the gastrointestinal tract: 17% of the worms were found at the ileocaecal junction, 81% on the caecal wall, 1.7% in the terminal ileum and 0.2% in the ventral colon. The severity of lesions produced at the sites of attachment was related to the number of worms attached. Due to the small area of the ileocaecal...
Stierstorfer B, Eichhorn W, Schmahl W, Brandmüller C, Kaaden OR, Neubauer A.An outbreak of neurological disease occurred in a well-managed riding school. Ataxia and paresis were observed in several horses, five of which became recumbent and were euthanized. Post-mortem analysis revealed scattered haemorrhages along the spinal cord, that were reflected by multiple haemorrhagic foci on formalin-fixed sections, with the thoracic and lumbar segments being the most affected. Pathohistologically, perivascular mononuclear cuffing and axonal swelling, especially in the white matter, were evident. Parallel to the course of disease, alterations in myelin sheets and activation o...
Miller RI, Campbell RS.Pythiosis (204 cases, 77%), basidiobolomycosis (48 cases, 18%), and conidiobolomycosis (14 cases, 5%) were diagnosed morphologically from 266 horses with phycomycosis. All lesions were cutaneous ulcerative granulomas and three horses with pythiosis had metastatic lesions in regional lymph nodes. Lesions of pythiosis contained characteristic yellow, coral-like coagula and had a fibrotic surface containing sinus tract openings. Basidiobolomycosis was characterized by infrequent small yellow coagula and a yellow line of fungal invasion beneath an edematous surface. Lesions of conidiobolomycosis h...
Birch HL, Smith TJ, Poulton C, Peiffer D, Goodship AE.Partial rupture occurs most often to the superficial digital flexor tendon (SDFT) of the forelimb at the mid-metacarpal level. In this study, we tested the hypothesis that the mid-metacarpal region of the SDFT has the smallest cross sectional area (CSA) and a similar collagen content to other regions and, therefore, represents a weak point in the tendon. The SDFT was collected from the forelimbs of 9 horses. Each tendon was marked at 7 different levels from the origin of the accessory ligament to the phalangeal region. The CSA, water content and collagen content was measured at each level. The...
Stegelmeier BL, Gardner DR, James LF, Molyneux RJ.Houndstongue (Cynoglossum officinale), a noxious weed that contains pyrrolizidine alkaloids (PAs), infests pastures and fields in the western United States and Europe. The purpose of this study was to develop techniques to better diagnose PA poisoning and describe the progression of gross and microscopic lesions caused by houndstongue intoxication. Six horses were gavaged daily with a suspension of houndstongue containing 5 or 15 mg/kg total PA for 14 days. Two horses were treated similarly with ground alfalfa as controls. Liver biopsy samples and serum biochemical and hematologic values were ...
Machado TS, Correia da Silva LC, Baccarin RY, Michelacci YM.Alternative methods to evaluate the joint condition in asymptomatic osteochondrosis dissecans (OCD) and other joint diseases may be useful. Objective: To investigate possible changes in synovial fluid composition that may lead to joint conditions in asymptomatic OCD, in mature horses. Methods: Animals aged >2 years, of different breeds, with OCD in the intermediate ridge of distal tibia, symptomatic or not, were studied. Synovial fluid samples (10 healthy; 11 asymptomatic OCD; 25 symptomatic OCD) were collected by arthroscopy from 29 horses. Glycosaminoglycans (GAGs) were analysed by a comb...
Muller S, Grzybowski M, Sager H, Bornand V, Brehm W.This report describes a case of nodular posthitis caused by Halicephalobus gingivalis in a 24-year-old warmblood horse. Macroscopic examination revealed a multinodular, partially ulcerated mass on the external lamina of the prepuce. Nematode migration from unfixed biopsy material in phosphate-buffered saline revealed adult nematodes with the typical morphological features of H. gingivalis: distinctive rhabditiform oesophagus with corpus, isthmus and bulb and the dorsoflexed ovary. The main histopathological features consisted of submucosal confluent granulomatous foci containing cross- and tan...
Bowen RA, Bosco-Lauth A, Syvrud K, Thomas A, Meinert TR, Ludlow DR, Cook C, Salt J, Ons E.Over the last years West Nile virus (WNV) lineage 2 has spread from the African to the European continent. This study was conducted to demonstrate efficacy of an inactivated, lineage 1-based, WNV vaccine (Equip WNV) against intrathecal challenge of horses with a recent isolate of lineage 2 WNV. Twenty horses, sero-negative for WNV, were enrolled and were randomly allocated to one of two treatment groups: an unvaccinated control group (T01, n=10) and a group administered with Equip WNV (T02, n=10). Horses were vaccinated at Day 0 and 21 and were challenged at day 42 with WNV lineage 2, Nea Sant...
Schott HC, Esser MM.Clinicopathologic evaluation of renal function and renal disease in sick adult horses remains grounded in detection of azotemia, assessment of serum and urine electrolyte concentrations, and evaluation of urinalysis findings, including specific gravity, reagent strip analysis, and sediment examination. Because increases in serum or plasma urea nitrogen and creatinine concentrations are insensitive indicators of a decreased glomerular filtration rate, there is considerable interest in identifying novel biomarkers of renal function or injury in blood and urine, with serum symmetric dimethylargin...
Oladunni FS, Sarkar S, Reedy S, Balasuriya UBR, Horohov DW, Chambers TM.Equid herpesvirus 1 (EHV-1) is a viral pathogen of horse populations worldwide spread by the respiratory route and is known for causing outbreaks of neurologic syndromes and abortion storms. Previously, we demonstrated that an EHV-1 strain of the neuropathogenic genotype, T953, downregulates the beta interferon (IFN-β) response in equine endothelial cells (EECs) at 12 h postinfection (hpi). In the present study, we explored the molecular correlates of this inhibition as clues toward an understanding of the mechanism. Data from our study revealed that EHV-1 infection of EECs significantly red...
Jasiński T, Zdrojkowski Ł, Kautz E, Juszczuk-Kubiak E, Ferreira-Dias G, Domino M.Endometrosis is an important mares' disease which considerably decreases their fertility. As classic endometrial classification methods might be insufficient for tissue pathological evaluation, further categorization into active/inactive and destructive/non-destructive types was developed by Hoffmann and others. This study aimed to compare NF-κB pathway genes transcription among histopathological types of endometrosis, following Hoffmann and co-authors' classification. Endometrial samples, collected postmortem from cyclic mares ( = 100) in estrus or diestrus, were classified histologically an...
Chaffin MK, Fuenteabla IC, Schumacher J, Welch RD, Edwards JF.The medical records of 11 horses with idiopathic muscular hypertrophy (MH) of the small intestine were reviewed to determine the clinical and pathological features of the disease. The median age of affected horses was 10.0 years (range 5-18 years). No breed or sex predisposition was apparent. Ten horses (91%) had chronic (23 days to 2.4 years) signs of mild, intermittent colic, and 1 horse had signs of severe colic of only 3 days' duration. Partial anorexia and chronic weight loss of variable duration (1-6 months) were prominent historical findings in 5 (45%) horses. Diagnostic tests, with the...
Williams JH, van Niekerk S, Human S, van Wilpe E, Venter M.Since 2007, West Nile virus (WNV) has been reported in South African horses, causing severe neurological signs. All cases were of lineage 2, except for one case that clustered with lineage 1 viruses. In the present study, gross and microscopic lesions of six South African lineage 2-infected horses and the one lineage 1 case are described. Diagnoses were confirmed by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) of central nervous system (CNS) tissue and one by RT-PCR of a brain virus isolate. The CNS of all cases was negative by RT-PCR or immunohistochemistry (IHC) for Afr...
Mollenhauer HH, Rowe LD, Cysewski SJ, Witzel DA.Ultrastructural studies were made of myocardium, diaphragm, appendicular muscle, liver, and kidney of 3 ponies acutely poisoned with a single oral dose of monensin (4 mg/kg of body weight). These ponies developed severe signs of toxicosis and were killed 28 to 72 hours after treatment. Severe mitochondrial damage (swelling) and lipoidosis in myocardial tissues were observed in 2 of the 3 ponies; similar, but less severe, changes were observed in the 3rd pony. The hepatocytes of the 3 ponies were characterized by increased amounts of smooth endoplasmic reticulum, large numbers of lipid droplets...
Cottrell DF, McGorum BC, Pearson GT.Autonomic dysfunction constitutes a prominent clinical feature of equine grass sickness (EGS). Significant injury to the nervous control of the alimentary system is life threatening, partly because of dysphagia but also because of the failure of the unique regulatory mechanisms in equine digestion involving water and electrolyte balance. The neuropathology also indicates the presence of a somatic polyneuropathy. The morphological features of EGS are similar to those of excitotoxic neuronal degeneration, which resembles neuronal apoptosis. It is difficult to ascertain from published accounts th...
Henning K, Sachse K, Sting R.The isolation and identification of a chlamydial agent from an equine fetus is reported. The fetus was aborted by a mare with respiratory disease and fever in the 9th month of pregnancy. The serum of the mare was investigated by the compliment fixation test. Specific antibodies were detected for chlamydial antigen in a titer of > 1:40 and for equine herpes virus 1 antigen in a titer of 1:32. Pathological lesions were not found in the organs of the fetus. Chlamydiae were detected in the placenta by ELISA and subsequently isolated by cell culture. Using PCR technique the agent was identified ...
Suthers JM, Pinchbeck GL, Proudman CJ, Archer DC.The pattern of long-term survival and specific factors associated with long-term survival have not previously been evaluated in horses with a strangulating large colon volvulus (LCV). Objective: To provide data on the long-term survival of horses with LCV and to identify pre-, intra- and post operative variables associated with survival. Methods: Clinical data and long-term follow-up information were obtained from 116 horses with a strangulating LCV (≥360°) undergoing general anaesthesia. Two multivariable Cox proportional hazards models for post operative survival time were developed: Mode...
Lyons ET, Drudge JH, Tolliver SC.Experimentally induced infections of Parascaris equorum in worm-free pony foals required 14 to 17 days for migration of the larvae through the liver and lungs, and 79 to 110 days to become gametogenically functional. Treatment of experimentally infected or naturally exposed foals during the parenteral phase of development, using levamisole at 8 mg/kg, a mixture of levamisole at 8 mg/kg plus piperazine at 88 mg base equivalent/kg, or dl-tetramisole at 10 mg/kg, was quite efficacious in (1) reducing the number of P. equorum larvae recovered from the small intestines of the foals at necropsy, or ...
Horses affected by chronic piroplasmosis may develop poor performance and muscle atrophy. Here we investigate the pathological and immunopathological aspects of myopathy occurring in chronic equine piroplasmosis. The study included 16 horses serologically positive for equine piroplasms presenting with clinical signs and supporting serum biochemical evidence of a myopathy. Skeletal muscle was evaluated by histopathology, immunohistochemistry, indirect immunofluorescence, and molecular detection of piroplasms and inflammatory cytokines in skeletal muscle. Histologic lesions included muscle fiber...
Lin ST, Foote AK, Bolas NM, Peter VG, Pokora R, Patrick H, Sargan DR, Murray RC.Fissure in the third metacarpal/tarsal parasagittal groove and proximal phalanx sagittal groove is a potential prodromal pathology of fracture; therefore, early identification and characterisation of fissures using non-invasive imaging could be of clinical value. Thirty-three equine cadaver limbs underwent standing cone-beam (CB) computed tomography (CT), fan-beam (FB) CT, low-field magnetic resonance imaging (MRI), and macro/histo-pathological examination. Imaging diagnoses of fissures were compared to microscopic examination. Imaging features of fissures were described. Histopathological fin...
Mungall BA, Pollitt CC.To investigate the role of matrix metalloproteinase (MMP) activity in the pathophysiology of equine laminitis, the techniques of in situ zymography and quantitative SDS-PAGE zymography were used to analyse the lamellae and plasma and serum of horses with carbohydrate overload-induced laminitis. The gelatinase activity localised within the epidermal lamellae of laminitic hooves did not differ significantly from normal hooves. In laminitis sections there was an increase in vascular gelatinase activity, possibly associated with the perivascular cuffing of polymorphonucleocytes. Both plasma and se...
Sandin A, Skidell J, Häggström J, Girma K, Nilsson G.Necropsy records from 702 horses, less than one year old, that were subjected to necropsy between 1924 and 1996 were used to estimate the prevalence of gastric ulceration in younger horses and to evaluate some potential risk factors that may contribute to the development of gastric ulceration. Information concerning breed, gender, age, season of death, clinical signs of colic, medical treatment, parasitism and documentation of diseases in different organs were recorded, as well as size, number and anatomical distribution of ulcers. Gastric ulcers were found in 96 of 702 young horses (14%) and ...
Pinchbeck GL, Clegg PD, Boyde A, Barr ED, Riggs CM.Palmar/plantar osteochondral disease (POD) is a common, debilitating condition in Thoroughbred racehorses; however, training- and racing-related factors associated with this disease are unknown. Objective: To determine horse-, racing- and training-related risk factors for POD. The general hypotheses were that early training and racing, and increased intensity of racing and training, lead to increased severity of POD. Methods: The metacarpo/metatarsophalangeal joints of 164 Thoroughbred racehorses were examined at post mortem and graded for third metacarpal and metatarsal POD. The relationships...
