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.
da Rosa G, de Freitas Daudt G, Roman IJ, Cargnelutti JF, Sangioni LA, Flores MM, Vogel FSF.Horses are intermediate hosts of Sarcocystis spp. capable of forming cysts in their musculature. This study aimed to detect sarcocysts and investigate the presence of nucleic acids from Sarcocystis spp. in samples of striated muscles from horses in the State of Rio Grande do Sul, Brazil, necropsied at the Veterinary Pathology Laboratory of the Federal University of Santa Maria. A total of 108 samples were collected from 24 horses and examined through direct examination. Microscopic tissue cysts were observed in three samples: tongue (2) and esophagus (1) from two animals. Extractions were perf...
Connolly K, Ekholm Fry N.An increasing number of universities and colleges in the United States are offering coursework on adaptive/therapeutic riding and the incorporation of horses in human service areas such as psychotherapy, education, occupational therapy, physical therapy, and speech-language pathology. The first study to identify coursework in these areas was published in 2018. In order to track development over time, we conducted a replication study to determine the prevalence of coursework on horses in human services at higher education institutions. Information gathered for the 2021-2022 academic year includ...
Andersen C, Jacobsen S, Uvebrant K, Griffin JF, Vonk LA, Walters M, Berg LC, Lundgren-Åkerlund E, Lindegaard C.Integrin α10β1-selected mesenchymal stem cells (integrin α10-MSCs) have previously shown potential in treating cartilage damage and osteoarthritis (OA) and in animal models . The aim of this study was to further investigate disease-modifying effects of integrin α10-MSCs. Methods: OA was surgically induced in 17 horses. Eighteen days after surgery, horses received 2 × 10 integrin α10-MSCs intra-articularly or were left untreated. Lameness and response to carpal flexion was assessed weekly along with synovial fluid (SF) analysis. On day 52 after treatment, horses were euthanized, and carp...
Pieroni C, Grassi A, Pantoli M, Berretti M, Messina S, Giovannini C, Lubas G, Diamanti D.The erythrocyte sedimentation rate (ESR) is a widely used diagnostic assay in human medicine but nowadays poorly applied in veterinary medicine. This test measures the speed (millimeters per hour) at which red blood cells settle in a whole anticoagulated blood tube. In human medicine, high ESR values are associated with various disorders, including infections, rheumatoid arthritis, oncologic diseases, and other inflammatory conditions. The ESR can also be influenced by some factors such as age and gender. In veterinary medicine, the ESR with the Westergren manual method was almost forgotten ov...
Cassone L.This article is intended to highlight toxicosis-associated pathology in horses that might be observed by a clinician in the living animal and at gross necropsy. When the clinician is aware of these pathologic changes (particularly when coupled with a suggestive environmental or herd history), then collaboration with a diagnostic laboratory can begin to help identify specific toxicants. Proper sampling and communication with the diagnostic laboratory will vastly improve the likelihood of a specific diagnosis; postmortem sampling and specimen submission are reviewed in the last section of this a...
Lin ST, Bolas NM, Peter VG, Pokora R, Patrick H, Foote AK, Sargan DR, Murray RC.Palmar/plantar osteochondral disease (POD) of the metacarpal/tarsal condyles is a common pathological finding in racehorses. Objective: To compare diagnoses, imaging details, and measurements of POD lesions between cone-beam computed tomography CT (CBCT), fan-beam CT (FBCT), and low-field magnetic resonance imaging (MRI) using macroscopic pathology as a gold standard. Methods: Cross-sectional study. Methods: Thirty-five cadaver limbs from 10 horses underwent CBCT, FBCT, MRI, and macroscopic examination. CT and MR images were examined for presence of POD, imaging details of POD, and measurement...
Wong ASM, Morrice-West AV, Hitchens PL, Whitton RC.Catastrophic musculoskeletal injuries (CMI) in horses are associated with both too little and too much high-speed exercise. In order to advise trainers on training and management strategies that minimize the risk of musculoskeletal injury (MSI), a better understanding of how training practices affect MSI in racehorses is needed. Data from prospective studies relating training data and MSI are complicated by the gradual development of pathology and the effect of this on the ability of horses to train consistently prior to the identification of an injury. To circumvent this, 66 Australian Thorou...
Auth AK, Hinnigan GJ, Smith MA, Owen KR.Low-field, magnetic resonance imaging (MRI) is an advanced imaging modality widely used to diagnose distal limb pathology in horses, but there are limited data regarding lesion distribution within the metacarpo/metatarsophalangeal joint (MCP/MTPJ) region in lame nonracehorses. The aim of this study was to describe the low-field MRI findings and lesion distribution in nonracehorses with MCP/MTPJ region pain. Clinical records from horses undergoing MRI of the MCP/MTPJ region between July 2016 and March 2023 were reviewed. Horses were included if pain causing lameness was localized to this region...
Leps A, Korsos S, Clarysse M, Vlaminck L.To document the long-term outcome of surgically treated primary and dental-related sinusitis in horses and to describe a simple protocol for postoperative management. All surgically treated sinusitis cases referred between January 2016 and June 2022 were reviewed. Cases diagnosed with primary and dental-related sinusitis and with a follow-up of at least 6 months after hospital discharge were included. Cases with other sinus pathology were excluded. 130 cases met the inclusion criteria. 104 out of 130 were treated with sinoscopy and 26/130 with sinusotomy. 86 out of 130 cases (66.2%) were diagn...
Jammes M, Cassé F, Velot E, Bianchi A, Audigié F, Contentin R, Galéra P.Osteoarthritis (OA) is a widespread osteoarticular pathology characterized by progressive hyaline cartilage degradation, exposing horses to impaired well-being, premature career termination, alongside substantial financial losses for horse owners. Among the new therapeutic strategies for OA, using mesenchymal stromal cell (MSC)-derived exosomes (MSC-exos) appears to be a promising option for conveying MSC therapeutic potential, yet avoiding the limitations inherent to cell therapy. Here, we first purified and characterized exosomes from MSCs by membrane affinity capture (MAC) and size-exclusio...
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...
Bardell D, Rocchigiani G, Ressel L, Milner P.Strangulating small intestinal disease (SSID) in horses carries a poor prognosis for survival, especially following resection of ischaemic tissue. The margins of a resection are principally based on visual appraisal of the intestine during surgery. We hypothesized that histological evaluation of resected tissue may identify occult changes indicative of prognosis. Small intestinal samples from 18 horses undergoing resection for SSID and 9 horses euthanised for reasons unrelated to gastrointestinal pathology were utilised. Histological appearance was used to generate a 'total damage score' (TDS)...
Loubière C, Moreau P, Marine R, Hélie P, Jean D.The objectives of this study were to quantify lymphocytes and eosinophils in the mucosa of the duodenum and rectum in asthmatic horses. Asthmatic horses were evaluated in a symptomatic (after 6 weeks of exposure to moldy hay) and asymptomatic status (3 and 7 months after being fed alfalfa pellets [n = 4] or treated with inhaled fluticasone [6]). Duodenal and rectal biopsies were endoscopically (n = 4 to 6) taken in each horse. Eosinophils were counted on slides stained with hematoxylin, eosin, phloxine, and saffron, and immunohistochemistry was used to evaluate T and B lymphocytes using CD3 an...
Lavado RA, Lewis J, Montgomery JB.Laminitis is a severely debilitating and life-threatening condition that occurs as a consequence of different primary triggering factors. Continuous digital hypothermia (CDH) is recommended in horses at risk of, or diagnosed with, acute laminitis due to its several physiological and biochemical alterations that may be positive for the prevention and early treatment of the condition, representing a low risk of adverse effects. Modulation of the inflammatory response, profound vasoconstriction, and prevention of tissue damage are the most notable protective effects of cryotherapy on the lamellae...
Lin ST, Bolas NM, Sargan DR, Restif O, Peter VG, Pokora R, Patrick H, Foote AK, Murray RC.Dorsoproximal osteochondral defects commonly affect the proximal phalanx, but information about diagnosis on computed tomography (CT) and magnetic resonance imaging (MRI) is limited. Objective: To assess CT and MRI diagnoses of osteochondral defects, describe the lesions and compare sensitivity and specificity of the modalities using macroscopic pathology as gold standard. Methods: Cross-sectional study. Methods: Thirty-five equine cadaver limbs underwent standing cone-beam CT (CBCT), fan-beam CT (FBCT), low-field MRI and pathological examination. CT and MR images were examined for proximal ph...
May-Davis S, Dzingle D, Saber E, Blades Eckelbarger P.This study examined the anomalous variations of the ventral process of C6 in modern E. ferus caballus. The aim was to provide an incremental grading protocol measuring the absence of the caudal ventral tubercle (CVT) in this ventral process. The findings revealed the most prevalent absent CVT (aCVT) was left unilateral (n = 35), with bilateral (n = 29) and right unilateral (n = 12). Grading was determined in equal increments of absence 1/4, 2/4, 3/4, with 4/4 representing a complete aCVT in 56/76, with a significance of p = 0.0013. This also applied to bilateral specimens. In those C6 osseous ...
Luff J, Weingart S, May S, Murphy B.The aetiology of oral squamous cell carcinoma (SCC) in horses is unknown, but papillomavirus infection as well as chronic periodontal disease are suspected to play a pathogenic role. In humans, some oropharyngeal cancers develop in association with human papillomaviruses. Equus caballus papillomavirus 2 (EcPV2) is suspected to play a causal role in the development of equine genital SCC. Given that association, we hypothesized that EcPV2 is associated with the development of oral SCC in horses. We performed standard polymerase chain reaction (PCR) and in-situ hybridization (ISH) for EcPV2 on 31...
Pimenta J, Pires I, Prada J, Cotovio M.Melanocytic tumors are an important neoplastic disease in human and veterinary medicine, presenting large differences regarding tumor behavior between species. In horses, these tumors present a prolonged benign behavior, with rare invasiveness and metastases. In humans and small animals, invasion and metastasis have been associated with an Epithelial-Mesenchymal Transition, where the loss of E-cadherin expression plays a key role in tumor progression. This process and the role of E-cadherin have not yet been evaluated in equine melanocytic tumors. This study aimed to assess the immunolabeling ...
de Melo UP, Ferreira C.Oral and dental diseases are common in horses, as evidenced by the results of incidence studies of dental diseases carried out on abattoir specimens or sports horses. Thus, periodic dental examinations in horses are essential to ensure the maintenance of dental health and proper use of ingested food. A retrospective study of the dental records of 416 Quarter Horses (256 males, 160 females), distributed in the western region of the Rio Grande do Norte, Brazil, was conducted. Horses were examined between July 2012 and August 2022. The variables collected were age, sex, type of diet, dental alter...
Talbot SE, Tallon R, Dunkel B.Gastric impactions (GI) have been identified as primary lesions (lone GI; LGI) or associated with other intestinal lesions (concurrent GI; CGI). Anecdotally, CGI resolve more rapidly with a better prognosis than LGI. Objective: To determine clinical, laboratory, and ultrasonographic findings, and short- and long-term survival in horses with GI. We hypothesized that LGI carries a worse prognosis than CGI. Methods: Seventy-one horses from 2 referral hospitals (2007-2022). Methods: Retrospective cohort study. Gastric impactions were defined as feed extending to the margo plicatus after ≥24 h...
De Paolis L, Armando F, Montemurro V, Petrizzi L, Straticò P, Mecocci S, Guarnieri C, Pezzolato M, Fruscione F, Passeri B, Marruchella G, Razzuoli E.Vulvar squamous cell carcinoma (VSCC) has been recently associated with Equus caballus papillomavirus type 2 (EcPV2) infection. Still, few reports concerning this disease are present in the literature. Objective: To describe a case of naturally occurring EcPV2-induced VSCC, by investigating tumour ability in undergoing the epithelial-to-mesenchymal transition (EMT). Methods: Case report. Methods: A 13-year-old Haflinger mare was referred for a rapidly growing vulvar mass. After surgical excision, the mass was submitted to histopathology and molecular analysis. Histopathological diagnosis was c...
Townsend KS, Johnson PJ, Kuroki K.Primary squamous cell carcinoma of the head and neck occurs in the skin or squamous epithelial lining tissues of the oral cavity, pharynx, larynx, and sinonasal tract. Although it is a common tumor in horses, distant metastatic spread to the lung is rare. This report describes a case of metastatic pulmonary squamous cell carcinoma in a 23-year-old Morgan gelding. The clinical signs displayed by this gelding in some ways mimicked the typical presentation of equine multinodular pulmonary fibrosis or thoracic lymphoma. The postmortem diagnosis in this case was head and neck squamous cell carcinom...
Malacarne BD, Martins RR, Paz CFR, Alves JVA, Dias LA, Cavalcante MA, Santos AM, Silva AGM, Leise BS, Carvalho AM, Faleiros RR.Although the external conformation of wild horse hooves has been proposed as an ideal model for domesticated modern horses, histological signs of laminitis have been reported among them. With the hypothesis that the lamellar tissue of horses of Iberian origin raised in semi-feral is healthier than those raised in an intensive management system (stall confinement and high-calorie diet intake), the objective was to compare their lamellar tissues. Lamellar tissue samples were taken from the forelimb hoof of eight domesticated Mangalarga Marchador (MM) horses and from six semi-feral Marajoara (MJ)...
Barton CK, Hughes KL, Cowan C, Nout-Lomas YS, Nelson BB.A 21-year-old Quarter Horse mare presented with a chronic, progressively worsening left pelvic limb lameness of 3 weeks duration. The initial examination identified a consistent lameness at a walk. Neurological examination showed sensory and gait abnormalities consistent with left femoral nerve dysfunction. The horse minimally advanced the leg cranially and had a shortened stride length at the walk. During the stance phase, the heels of the left hind foot did not contact the ground and the horse quickly took weight off of the limb. Diagnostic imaging (ultrasound and nuclear scintigraphy) exami...
Luethy D, Colmer S, Jodzio D, Bender S, Porter E, Hemmen Z, Fultz L, Craft W, Walker R, Johnson A, Holbrook T.Ultrasound-guided cervical centesis has gained popularity as a method for collecting cerebrospinal fluid (CSF) from standing horses. There are anecdotal reports of neck stiffness, regional swelling, sensitivity to palpation, and fever after the procedure. We report 2 horses with complications that occurred within days of C1-C2 centesis and ultimately resulted in euthanasia. Both C1-C2 centesis were performed routinely, with CSF cytologic analysis providing no evidence of blood contamination. Post-mortem examination revealed equine degenerative myeloencephalopathy as the primary disorder causin...
Steel C, Ahern B, Zedler S, Vallance S, Galuppo L, Richardson J, Whitton C, Young A.Radiographs underestimate the extent of bone injury in horses with third carpal bone (C3) fractures (Fx). We aimed to describe bone pathologies identified using computed tomography (CT) and compare the diagnostic value of digital radiography (DR) and CT in horses with C3 Fx. CT images of 15 racehorses with C3 Fx and 10 controls were reviewed (Part 1) then DR and CT images of 26 racehorses (24 Thoroughbred, 2 Standardbred) with C3 Fx (Part 2) were evaluated. Agreement on fracture geometry and concomitant bone lesions was tested between DR and CT using the kappa statistic (Part 2). For agreement...
Kumbhani TR, Raval SH, Parmar RS, Patel JG, Bechara VJ, Sindhi PI, Modh SP.A 6-year-old Marwari mare presented with recurrent vulvar growth. The growth was surgically excised, fixed and processed routinely. Microscopically, neoplasm showed proliferation of epithelial and myoepithelial cells with tubulopapillary pattern. On immunohistochemistry, myoepithelial cells showed strong immunoreactivity with smooth muscle actin alpha and p63. On basis of histopathology and immunohistochemistry, tumour was diagnosed as complex apocrine carcinoma. This case report describes first confirm vulvar complex apocrine carcinoma in equines.
Chalder R, Housby-Skeggs N, Clark C, Pollard D, Hartley C, Blacklock B.There are a growing number of horses, ponies, and donkeys aged 15 years or older in the United Kingdom, yet there have been no studies utilising a complete ophthalmic examination to investigate the prevalence of ophthalmic pathology within this population. Objective: To investigate the prevalence of ophthalmic pathology and associations with signalment, in a convenience sample of geriatric equids in the United Kingdom. Methods: Cross sectional. Methods: Horses, ponies, and donkeys aged 15 years or older based at The Horse Trust charity underwent a full ophthalmic examination including slit...
Tucker ML, Wilson DG, Bergstrom DJ, Carmalt JL.Computational fluid dynamics (CFD) has proven useful in the planning of upper airway surgery in humans, where it is used to anticipate the influence of the surgical procedures on post-operative airflow. This technology has only been reported twice in an equine model, with a limited scope of airflow mechanics situations examined. The reported study sought to widen this application to the variety of procedures used to treat equine recurrent laryngeal neuropathy (RLN). The first objective of this study was to generate a CFD model of an box model of ten different equine larynges replicating RLN a...
Bergmann W, Vernooij JCM, Grinwis GCM, Gröne A.Osteochondrosis dissecans (OCD) of articular process joints (APJs) is involved in cervical vertebral compressive myelopathy (CVM). Biomechanical forces, important in development of OCD, depend on joint conformation. Oval and flat APJ surfaces are considered normal. Objective: To identify and grade gross shape variation of cervical and cranial thoracic APJ surfaces and determine association with histological evidence of osteochondrosis. Methods: Case series. Methods: Eight hundred and four cervical and cranial thoracic APJ surfaces of 30 foals were evaluated for shape(s) and grades, and were co...
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...
Dixon PM, Tremaine WH, Pickles K, Kuhns L, Hawe C, McCann J, McGorum BC, Railton DI, Brammer S.Of 400 referred horses with dental disorders, 349 cases suffered from primary disorders of their cheek teeth, ninety of these from disorders of development or eruption, or displacements. These included 20 cases with rostral maxillary and caudal mandibular cheek teeth overgrowths, 16 with diastemata, 15 with grossly enlarged mandibular 'eruption cysts', 4 with grossly enlarged maxillary cheek teeth 'eruption cysts', 10 cases with supernumerary cheek teeth and 23 cases with displaced cheek teeth. These displacements were believed to be developmental in 16 cases and acquired in the remaining 7 ca...
Lazary S, Gerber H, Glatt PA, Straub R.The distribution of equine leucocyte antigens (ELA) in horses affected by equine sarcoid tumours was determined and compared with unaffected controls. ELA-haplotype W3,B1 occurred more frequently in affected riding horses of Irish, Swiss and French background. The combined data for the three breeds resulted in a chi 2 value of 20.35 (P less than 0.0005 after correction). Simultaneously, ELA-specificity W11 was more frequently found in horses of Irish background, while W5 was found in Swiss and French horses with sarcoids. The combined data for haplotype W3,B1 and/or W5 specificity demonstrated...
Cordes DO, Perry BD, Rikihisa Y, Chickering WR.Potomac horse fever was reproduced in 15 ponies by transfusion of whole blood originally from two natural cases and subsequently from ponies infected by the transfusions. Incubation periods varied from 9 to 15 days. Affected ponies developed varying degrees of fever, diarrhea, anorexia, depression, and leukopenia. Eleven affected ponies were killed, three died in the acute phase of the disease, and one did not show clinical signs. The most consistent post-mortem findings were fluid contents in the cecum and large colon, and areas of hyperemia (of inconstant degree and distribution) in mucosae ...
Choi YK, Kang MS, Yoo HS, Lee DY, Lee HC, Kim DY.Acute hemorrhagic myonecrosis accompanied by severe inter- and intrafascicular edema and hemorrhage of the right gluteal area was diagnosed in a 13-year-old male thoroughbred horse. Once the muscular and fascicular changes were subsided, the horse then developed acute respiratory problem. Histologically, the lung had diffuse severe hemorrhage with mild neutrophilic infiltration. The cause of death was acute respiratory failure that is believed to occur secondary to toxaemic event. Alpha and beta2 toxin secreting Clostiridum perfringens type A was isolated from the muscle and lung. The diagnosi...
Dowdall SM, Proudman CJ, Klei TR, Mair T, Matthews JB.Cyathostomins are the most common parasitic nematodes of horses. Larval stages, which inhabit the intestinal wall, are particularly pathogenic and can cause severe colitis and colic. Despite their clinical importance, diagnostic techniques for the prepatent stages do not exist. A method that could estimate mucosal infection intensity would have a major impact on the control and diagnosis of cyathostominosis. Here, serum IgG(T) responses to two larval antigen complexes of 25 and 20 kDa were quantified in horses with experimental infections, natural infections and in horses that presented with c...
Valberg SJ, Mickelson JR, Gallant EM, MacLeay JM, Lentz L, de la Corte F.The purpose of this study was to determine if chronic exertional rhabdomyolysis (ER) in Quarter Horses and Thoroughbreds represents one or several distinct myopathies. Eighteen Quarter Horses and 18 Thoroughbreds with ER were selected from cases presented to the Veterinary Hospital on the basis of a history of ER, assessment of muscle histopathology, and serum CK activity before and 4 h post exercise. In addition, 2 of 3 of the following parameters were evaluated: muscle glycogen concentrations, thyroid hormones (T3, T4), fractional excretion (FE) of sodium, potassium and chloride. The CK resp...
Draper ACE, Piercy RJ.Recurrent Laryngeal Neuropathy (RLN) is a highly prevalent and predominantly left-sided, degenerative disorder of the recurrent laryngeal nerves (RLn) of tall horses, that causes inspiratory stridor at exercise because of intrinsic laryngeal muscle paresis. The associated laryngeal dysfunction and exercise intolerance in athletic horses commonly leads to surgical intervention, retirement or euthanasia with associated financial and welfare implications. Despite speculation, there is a lack of consensus and conflicting evidence supporting the primary classification of RLN, as either a distal ("d...
Martineau D, Bowser PR, Wooster G, Forney JL.Sixty-seven adult walleye fish were examined by light and transmission electron microscopy. The fish were affected by a mesenchymal tumor previously termed Walleye Dermal Sarcoma that commonly affects up to 27% of the population seasonally. Biopsies from 24 fish were collected, and complete postmortem examinations were performed on 43 fish. Grossly, the tumors had the appearance of randomly distributed, often clustered, spherical nodules, 2-5 mm in diameter with a smooth and often ulcerated surface. The tumors arose from the superficial surface of scales and consisted of fibroblast-like cells ...
Da Silva AS, Garcia Perez HA, Costa MM, França RT, De Gasperi D, Zanette RA, Amado JA, Lopes ST, Teixeira MM, Monteiro SG.In this study, we reported the first outbreak of the infection by Trypanosoma vivax in horses in southern Brazil, a non-endemic region where bovines have only recently been found infected by this trypanosome species. We evaluated 12 horses from a farm in southern Brazil, where four horses displayed pale mucous membranes, fever, weight loss, and swelling of abdomen, prepuce, or vulva. The diagnosis of T. vivax was confirmed in four horses by morphological parameters of trypomastigotes in blood smears and species-specific PCR. All T. vivax-infected animals showed anemia, and most showed increase...
van Eps AW.Acute laminitis is a serious complication of many primary conditions in the horse. This article summarizes the most appropriate approach to management of the horse with acute laminitis, based on current information.
Holz CL, Sledge DG, Kiupel M, Nelli RK, Goehring LS, Soboll Hussey G.Histopathological differences in horses infected with equine herpesvirus type 1 (EHV-1) of differing neuropathogenic potential [wild-type (Ab4), polymerase mutant (Ab4 N752), EHV-1/4 gD mutant (Ab4 gD4)] were evaluated to examine the impact of viral factors on clinical disease, tissue tropism and pathology. Three of 8 Ab4 infected horses developed Equine Herpesvirus Myeloencephalopathy (EHM) requiring euthanasia of 2 horses on day 9 post-infection. None of the other horses showed neurologic signs and all remaining animals were sacrificed 10 weeks post-infection. EHM horses had lymphohistiocyti...
Schöniger S, Valentine BA, Fernandez CJ, Summers BA.Schwannomas are uncommonly recognized in horses. This study describes cutaneous schwannomas in 22 horses aged 8 to 25 years: 12 male, 7 female, and 3 of unknown sex. The horses had solitary cutaneous masses: 9 on the head, 3 on the neck, and the others on the shoulder, hip, thorax, abdomen, rump, extremities, or tail. The location of 1 tumor was unknown. The dermal tumors were well demarcated and expansile. Twelve had a multinodular pattern, whereas 10 formed a single nodule. Antoni A areas were observed in all tumors, and 10 tumors contained Antoni B areas. In Antoni A areas, the densely pack...
Rieger J, Kaessmeyer S, Al Masri S, Hünigen H, Plendl J.The cardiovascular system is the first functional organ in the embryo, and its blood vessels form a widespread conductive network within the organism. Blood vessels develop de novo, by the differentiation of endothelial progenitor cells (vasculogenesis) or by angiogenesis, which is the formation of new blood vessels from existing ones. This review presents an overview of the current knowledge on physiological and pathological angiogenesis in the horse including studies on equine endothelial cells. Principal study fields in equine angiogenesis research were identified: equine endothelial progen...
Cahill JI, Goulden BE.This study confirmed that neurogenic muscle pathology exists in intrinsic laryngeal muscles supplied by the recurrent laryngeal nerves in horses subclinically and clinically affected with laryngeal hemiplegia. An important additional observation was the occurrence in three out of four laryngeal hemiplegic horses of neurogenic muscle changes in a hindlimb muscle, the extensor digitorum longus, a muscle supplied by another long peripheral nerve. This finding suggests that a polynenropathy exists in laryngeal hemiplegic horses, and supports the classification of this disease as a distal axonopath...
Kimman TG, Binkhorst GJ, van den Ingh TS, Pol JM, Gielkens AL, Roelvink ME.Aujeszky's disease virus was isolated from the brain of a horse which had shown severe neurological signs, including excessive sweating, muscle tremors and periods of mania. Pathological examination revealed a non-suppurative meningoencephalitis. The virus was propagated in cell culture and inoculated into the conjunctiva and nostrils of two ponies. The ponies developed fever seven days after inoculation and subsequently started to behave abnormally, showing severe neurological signs on the ninth day after inoculation. One pony became excited and the other was depressed. One pony died on the n...
Kim DY, Taylor HW, Moore RM, Paulsen DB, Cho DY.Osteoarthritis (OA) is the most common joint disease in horses. Chondrocyte apoptosis has been implicated as a major pathological OA change in humans and experimental animals but no studies have been performed on equine OA. Articular cartilage was collected from three normal and five OA horses. Histopathological changes were scored by a modified Mankin grading system. A terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay was performed to identify chondrocyte apoptosis. Nitric oxide (NO) production from chondrocytes was indirectly evaluated by immunohistochemistr...
Sponseller ML, Binn LN, Wooding WL, Yager RH.Four field strains of western encephalitis virus were inoculated subcutaneously or intracranially (i/c) into recently weaned ponies. After s/c inoculation, 3 of the 4 strains produced an inapparent infection with a short period of viraemia. The 4th strain produced viraemia, fever, and signs of central nervous system disease. Viraemia occurred after intracranial inoculation with each strain; however, a variation in clinical response occurred, ranging from an inapparent infection to death. The disease pattern was characterized by three successive phases: viraemia, increased body temperature, and...
Ali AA, Refat NA, Algabri NA, Sobh MS.EHV-1 infection is responsible for huge economic losses in equines due to abortion and neonatal mortality. In this study, we describe 4 cases of abortion and neonatal deaths from pregnant mares and a she-donkey from different localities in Egypt during the period from May 2015 to October 2017. Attempts were made to isolate and identify EHV-1, in addition to compare the different pathological lesions in various tissues of the necropsied cases. EHV-1 was successfully isolated from two aborted fetuses and one dead neonatal foal from mares, beside one aborted fetus from a she-donkey. The positive ...
Webbon PM.The results of a survey are presented in which 589 limbs from 206 horses were dissected. In174 of the limbs lesions were found in either the superficial (131) or deep (43) digital flexor tendons. Changes occurring with age were also recorded. The sites of the abnormalities and their macroscopical appearance are described and the value of the results is considered in relation to the diagnosis and the treatment of clinical lesions.
Ramirez S, Lester GD, Roberts GR.The aim of this retrospective study was to determine the clinical usefulness of thoracic ultrasonography compared to thoracic radiography in evaluation of Rhodococcus equi pneumonia. Criteria for patient inclusion in this study were: (1) isolation of R. equi from transtracheal aspirate, (2) radiographic evaluation of the pulmonary parenchyma, and (3) sonographic evaluation of the pulmonary parenchyma. Seventeen foals met this criteria and their medical records were reviewed. Pyogranulomatous pneumonia was identified radiographically in 13 foals. Severe consolidative pneumonia with no detectabl...
Mair TS, Taylor FG, Harbour DA, Pearson GR.Combined immunodeficiency syndrome is an inherited disorder of the Arabian breed of horses. Affected foals usually die of infectious disease within the first few months of life, and the respiratory tract is the commonest site of infection. This report describes the clinical and pathological features of a case which showed signs of alimentary and respiratory infections. Intestinal infection by coronavirus (not previously recorded in cases of the syndrome) and cryptosporidia was identified. Histopathological evidence also suggested the presence of an adenovirus infection.
Martins TB, Kommers GD, Trost ME, Inkelmann MA, Fighera RA, Schild AL.Twenty-one cases of pythiosis in horses (n = 10), dogs (n = 9) and cattle (n = 2) were investigated. The aetiology in all cases was confirmed by immunohistochemistry. Data related to the clinical course and outcome and localization of the lesions were obtained from pathology reports. The equine lesions consisted of fibrotic tissue with multiple, often coalescing, areas of immature granulation tissue encircling eosinophilic cores. Affected dogs had gastrointestinal and/or cutaneous lesions with either or both of a granulomatous/pyogranulomatous or necrotizing eosinophilic inflammatory reaction....
Proudman CJ, Trees AJ.Until recently, the equine tapeworm Anoplocephala perfoliata was difficult to diagnose and considered to be of questionable pathogenicity. Here, Chris Proudman and Sandy Trees describe recent advances in the immunodiagnosis of this parasite that have facilitated epidemiological studies. These studies suggest that A. perfoliata may be an important cause of intestinal disease in the horse and demonstrate a dose-response relationship between infection intensity and risk of disease. If tapeworm infection is a risk factor for ileocaecal colic, the identification and treatment of infected individual...
The Journal of parasitologyApril 25, 2001
Volume 87, Issue 2 345-353 doi: 10.1645/0022-3395(2001)087[0345:COTOIO]2.0.CO;2
Dubey JP, Liddell S, Mattson D, Speert CA, Howe DK, Jenkins MC.Neospora hughesi was isolated in cell cultures inoculated with homogenate of spinal cord from a horse in Oregon. Tachyzoites of this Oregon isolate of N. hughesi were maintained continuously by cell culture passage and tachyzoites were infective to immunosuppressed mice. Gamma interferon gene knockout (KO) mice injected with tachyzoites developed fatal myocarditis and numerous tachyzoites were seen in lesions. Gerbils (Meriones unguiculatus) inoculated with tachyzoites developed antibodies (> or = 1:500) as indicated by the Neospora caninum agglutination test but did not develop clinical si...
Veraa S, Voorhout G, Klein WR.Infundibular changes are frequently encountered computed tomographic studies of the equine maxillary cheek teeth but the possible importance of this finding is not known. Infundibular caries is a possible cause for pulpitis and apical infection in some horses. Objective: To study the relationship between the 2 pathologies and the frequency of changes. Methods: The maxillary cheek teeth 108-208, 109-209 and 110-210 of 25 horses were evaluated using computed tomography and both the prevalence of infundibular and apical infection changes as the possible link with apical infection evaluated statis...
Taylor SD, Haldorson GJ, Vaughan B, Pusterla N.Gastric neoplasia of horses is incompletely described. Objective: Provide history, clinical signs, and clinicopathological and pathological findings associated with gastric neoplasia in horses. Methods: Twenty-four horses with gastric neoplasia. Methods: Retrospective study. History, clinical signs, and clinicopathological and pathologic findings in horses diagnosed histologically with gastric neoplasia were reviewed. Results: Horses ranged in age from 9 to 25 years (median 18 years at presentation). There was no apparent breed or sex predisposition. The most common presenting complaints were ...
Yoshikawa H, Yasu T, Ueki H, Oyamada T, Oishi H, Anzai T, Oikawa M, Yoshikawa T.To evaluate the possibility that Streptococcus equi subsp. zooepidemicus (S.z) the causative bacterial agent of equine shipping fever pneumonia (ESFP), as well as to investigate its pathogenesis, 10 horses (seven Thoroughbreds and three Anglo-Arab species, ranging from 2-4 years in age) were experimentally inoculated, via an endoscope, into bronchus of the lung lobe with a dose of 30 ml of 1-7 x 10(8) CFU/ml of S.z. After inoculation, autopsy and pathological examinations were sequentially conducted 30 min, 1, 2, 3, 4, 17, 20 hr and 2 weeks later. Pneumonia induced by the intrapulmonary inocul...
Sleutjens J, Cooley AJ, Sampson SN, Wijnberg ID, Back W, van der Kolk JH, Swiderski CE.The impact of cervical pathology on performance is of great importance to the horse industry. Accurate diagnosis of cervical disease with imaging modalities, including computed tomography (CT) and magnetic resonance imaging (MRI), requires thorough appreciation of normal cervical anatomy. Objective: (1) To describe in detail the anatomy of the equine cervical spine by comparing anatomical sections with corresponding MR and contrast-enhanced CT images in the sagittal, dorsal, and transverse plane. (2) To discuss the ability of MR and contrast-enhanced CT imaging to visualize anatomical structur...
