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Topic:Histopathology
Histopathology in horses involves the microscopic examination of tissue samples to study the manifestations of disease. This field provides insights into the structural and cellular changes that occur in equine tissues as a result of various pathological conditions. Common applications of histopathology in equine medicine include the diagnosis of neoplastic, inflammatory, and degenerative diseases. Techniques such as tissue staining and immunohistochemistry are employed to identify specific cellular components and pathological markers. This page aggregates peer-reviewed research studies and scholarly articles that explore the methodologies, findings, and implications of histopathological investigations in equine health.
Periocular sarcoid with bone invasion in a Thoroughbred mare. A periocular nodular sarcoid was diagnosed on the right upper eyelid and medial canthus of a 12-year-old Thoroughbred mare. Enucleation was performed and during the procedure the mass was noted to be firmly adhered to the underlying frontal bone. Partial ostectomy of the dorsal orbital rim was performed. Histopathology revealed invasion of the cortical lamellar bone and the bone marrow by neoplastic spindle cells and extension of these cells to multiple surgical margins. Recurrence at the level of the surgical site and its surroundings occurred 3 months after the procedure. The horse was eutha...
Molecular detection, histopathological analysis, and immunohistochemical characterization of equine infectious anemia virus in naturally infected equids. Equine infectious anemia (EIA), a disease caused by equine infectious anemia virus (EIAV), is considered an obstacle to the development of the horse industry. There is no treatment or vaccine available for EIA, and its pathogenesis, as well as the immune response against the virus, is not fully understood. Therefore, an immunohistochemistry assay was developed for the detection of viral antigens in tissues of equids naturally infected with EIAV. Sections of organs of six equids from Apodi-RN, Brazil, that tested positive for EIA by serological tests (ELISA and AGID) were fixed in 10% formalin ...
First case of fatal equine meningoencephalitis caused by Halicephalobus gingivalis in Mexico. Aberrant nematode larval migration in the CNS of horses is rare but frequently fatal; one of the main etiological agents involved in this illness is Halicephalobus gingivalis. This soil nematode has been associated with several fatal equine meningoencephalitis reports worldwide; however, it had never been diagnosed in horses of Mexico. A 10 year-old Andalusian horse presented dysphagia, fever, weakness, prostration and ataxia; the patient expired during the medical attention. Post mortem examination was performed and no gross alterations were found. Histopathology revealed meningoencephalitis...
Molecular and cellular evidence of natural Venezuelan equine encephalitis virus infection in frugivorous bats in Colombia. Venezuelan equine encephalitis virus (VEEV) is an alphavirus that causes encephalitis with a high impact on public health in Latin America. However, only in Guatemala, Trinidad and Tobago, and Mexico have found antibodies in VEEV in bats, using immunohistochemistry, the sensitivity and specificity are improved; thus, it is better for demonstrating natural infection in bats as potential hosts. This study aimed to determine the presence of VEEV in tissues of frugivorous bats. Methods: A prospective descriptive cross-sectional study with a non-probabilistic sampling was carried out in 12 localiti...
Scapula fracture secondary to metastatic pulmonary carcinoma in a horse: Clinical, sonographic, radiographic, computed tomographic, and pathologic findings. A 20-year-old Quarter horse gelding was referred for evaluation of an acute onset non-weight-bearing right forelimb lameness. Marked soft tissue swelling was apparent over the right scapula and shoulder region; no crepitus was palpable. A complete transverse fracture of the scapular neck was suspected based on ultrasonography and radiographs were obtained to confirm the presumptive diagnosis. A complete, oblique fracture of the right scapular neck with mild cranial and proximal displacement of the distal fragment was detected. Computed tomography of the upper right forelimb was performed post-...
Immersion Foot Syndrome in 6 Equids Exposed to Hurricane Floodwaters. Prolonged exposure to water, known as immersion foot syndrome in humans, is a phenomenon first described in soldiers during World War I and characterized by dermal ischemic necrosis. In this report, we describe the pathologic findings of a condition resembling immersion foot syndrome in 5 horses and 1 donkey with prolonged floodwater exposure during Hurricane Harvey. At necropsy, all animals had dermal defects ventral to a sharply demarcated "water line" along the lateral trunk. In 5 animals, histologic examination revealed moderate to severe perivascular dermatitis with vasculitis and coagula...
Pregnancy loss due to amnionitis in anglo-arabian mare-Case report. The amnion is a layer of the foetal membrane that has mechanical protection function and allows expansion and growth. The diseases that affect amnion have rarely been reported in horses. Amnionitis and funiculitis have been implicated as components of abortions as observed in abortions caused by the mare reproductive loss syndrome. Here, we report an abortion at 240-day gestation of a 7-year-old Anglo-Arabian mare with a history of previous stillbirth. Blood samples from both mare and foetus were collected for serological testing. Fragments from the placenta were taken for macroscopic and hist...
Magnetic resonance imaging and histopathological evaluation of equine oblique sesamoidean ligaments. Pathology involving the oblique sesamoidean ligaments (OSLs) is commonly diagnosed during magnetic resonance imaging (MRI) of the equine distal limb. Presence of striations within the ligament and magic angle artefact can result in an incorrect diagnosis of pathological change. No studies have been performed using histopathology, the gold standard, to corroborate their imaging diagnosis. Objective: (a) To determine which MRI characteristics are associated with normal vs abnormal OSLs and (b) to evaluate the ability of MRI to correctly identify abnormal vs normal oblique sesamoidean ligaments u...
Ovarian histopathology, pre- and post-operative endocrinological analysis and behavior alterations in 27 mares undergoing bilateral standing laparoscopic ovariectomy. Determining if ovariectomy will abolish unwanted behaviors can be challenging in mares without ultrasonographic ovarian abnormalities and/or endocrine values not consistent with a granulosa cell tumor. The objective of the study was to identify mares that have a positive improvement in unwanted behaviors after elective standing laparoscopic ovariectomy and to determine if the change is associated with any pre- and post-operative endocrine profiles and/or with ovarian histological findings. During the study period 27 mares underwent a bilateral standing laparoscopic ovariectomy. Pre- and post-o...
An atypical presentation of leiomyosarcoma causing extremity compartment syndrome of the crural region in a Dutch Warmblood mare: a case report. A 12-year-old Warmblood mare was presented with an acute onset left hindlimb lameness associated with generalised soft tissue swelling of the entire limb and medial saphenous vein (MSV) thrombophlebitis. A presumptive diagnosis of extremity compartment syndrome (ECS) was made. Due to the clinical deterioration, emergency fasciotomy of the crural fascia and biopsy was performed. Histological and immunohistochemical examination of the samples confirmed a diagnosis of leiomyosarcoma likely originating from the tunica media of the MSV. This report is the first to describe an unique combination of ...
A Study on the Potential Role of Occlusal Fissure Fractures in the Etiopathogenesis of Equine Cheek Teeth Apical Infections. Thirty-nine equine cheek teeth diagnosed as having anachoretic apical infections and also having occlusal fissure fractures, but without occlusal pulpar exposure, that had been orally extracted without causing occlusal damage and 10 control teeth were used in this study. The teeth were individually imaged by computed tomography, occlusally stained with methylene blue and visually reexamined, then sectioned subocclusally at 5 mm intervals until the fissure fractures could no longer be detected. A limited histological study was then performed on 7 apically infected and 5 control teeth. Standard ...
Equine pastern vasculitis in a horse associated with a multidrug-resistant Pseudomonas aeruginosa isolate. Equine pastern vasculitis is an uncommon disorder in horses. Underlying causes are difficult to assess, especially bacterial infections. Conclusions: A 13-year-old French saddle gelding horse presented for evaluation of a six weeks history of pastern dermatitis. Histopathological examination of skin biopsy samples revealed small vessel vasculitis. A pure growth of a multidrug-resistant Pseudomonas aeruginosa (MRPA) was obtained from a deep skin biopsy. Clinical remission was observed after a six week course of enrofloxacin and lesions did not recur. Conclusions: To the best of the authors' kno...
Multinodular Malignant Cutaneous Mast Cell Tumor in a Horse With Generalized Pruritus and Reactive Fibrosis: A Case Report. Mast cell tumor (MCT) has long been considered as an uncommon neoplasm in horses. Cytological and behavioral evidence of its malignancy is usually lacking, and only a few reports have described MCT displaying malignant behavior. An 18-year-old Friesian stallion presented with a one-year history of intermittent and progressive skin lesions on the left forelimb associated with intense, generalized pruritus and apathy temporarily responsive to glucocorticoids and antibiotics. The horse was alert and responsive with poor body condition and marked generalized pruritus. The left forelimb was markedl...
Molecular and genomic characterization of a novel equine molluscum contagiosum-like virus. Cases of pox-like lesions in horses and donkeys have been associated with poxviruses belonging to different genera of the family . These include the orthopoxviruses vaccinia virus (VACV), horsepoxvirus (HPXV) and cowpoxvirus (CPXV), as well as a potentially novel parapoxvirus and molluscum contagiosum virus (MOCV). However, with the exception of VACV, HPXV and CPXV, the genomic characterization of the causative agents remains largely elusive with only single short genome fragments available. Here we present the first full-length genome sequence of an equine molluscum contagiosum-like virus (EM...
Correlation Between Peritonitis and Incisional Infections in Horses. Surgical site infection of abdominal incisions is an important complication after laparotomy with increased risk of incisional hernia formation in horses. This study aims to evaluate the healing process of abdominal incisions and correlate peritonitis with the occurrence of surgical site infection and incisional hernias. Nine horses underwent standardized laparotomy, intestinal exploration, and induced septic peritonitis. Standardized relaparotomy was performed two (n = 3), four (n = 3), and six (n = 3) months later to evaluate the abdominal cavity for adhesions and to collect the sutured v...
Description of the D4/D4 genotype in Miniature horses with dwarfism. Four causative mutations (D1, D2, D3*, and D4) of chondrodysplastic dwarfism have been described in the equine () gene. Homozygotes for one of these mutations and heterozygotes for any combination of these mutations exhibit the disproportionate dwarfism phenotype. However, no case description of homozygotes for D4 (D4/D4) has been reported in the literature, to our knowledge. We report 2 Miniature horses with the genotype D4/D4 in the gene. Clinically, the 2 dwarfs had a domed head that was large compared to the rest of the body, mandibular prognathism, and short and bowed limbs, mainly in t...
Rhinosinusitis in an Australian mare caused by Flavodon flavus, a recently recognized invasive fungal pathogen of the horse. We describe herein the clinical, endoscopic, computed tomography (CT), pathologic, and microbiologic features of an infection caused by an under-recognized fungal pathogen, , in a 25-y-old Australian Quarter Horse. The horse had a unilateral obstructive nasal mass, resulting in stertor and dyspnea. On endoscopy, the mass was tan, multinodular, and completely obstructed the nasal passage. CT analysis revealed a large, soft tissue-attenuating and partially mineralized mass in the right nasal passage and dorsal-conchofrontal sinus, expanding into adjacent paranasal sinuses with associated bone ly...
Surgical management of penile sarcoid in a stallion. This report describes surgical management and breeding implications of a case of penile sarcoid associated with penis laceration in a 4-year-old Kurdish stallion. A large fleshy mass on the distal end of the penis that resulted in urethral meatus deviation and dysuria was detected in a physical examination. No evidence of local extent or metastasis was detected. Under general anaesthesia, the involved distal portion of the penis was removed through partial phallectomy. Histopathological examination of the mass confirmed a fibroblastic sarcoid. Partial phallectomy was successful for management ...
High-field (3 Tesla) MRI of the navicular apparatus of sound horses shows good agreement to histopathology. Magnetic resonance imaging and the correlation to histopathological findings of the equine palmar foot of lame horses have been described previously, using 0.27 and 1.5 T systems. Compared to these, 3 T systems provide superior spatial resolution and imaging contrast. The aim of our prospective anatomic study was to characterize the imaging anatomy of the navicular region on 3 T MRI in comparison to histopathological findings. We hypothesized that 3 T MRI allows a good visualization of the entire navicular apparatus and reliable measurements of navicular cartilage and cortical bone thickness. ...
Clinical and histopathological comparative study of two equine-derived bone graft: a human study. To compare the performance of collagenated bone graft substances with different collagen ratios after sinus floor augmentation. Methods: The cross-sectional study was conducted at Hacettepe University, Ankara, Turkey, from September 2011 to September 2013. Sinus floor augmentation was done with two different equinederived xenografts in patients before dental implant application. Of the two randomised groups, one was treated with 100% collagenated bone mix (Group A), and the other half with 90% collagenated bone mix + 10% collagen gel (Group B).Six months after sinus augmentation, prior to dent...
Impact of alpha-tocopherol deficiency and supplementation on sacrocaudalis and gluteal muscle fiber histopathology and morphology in horses. A subset of horses deficient in alpha-tocopherol (α-TP) develop muscle atrophy and vitamin E-responsive myopathy (VEM) characterized by mitochondrial alterations in the sacrocaudalis dorsalis medialis muscle (SC). Objective: To quantify muscle histopathologic abnormalities in subclinical α-TP deficient horses before and after α-TP supplementation and compare with retrospective (r)VEM cases. Methods: Prospective study; 16 healthy α-TP-deficient Quarter Horses. Retrospective study; 10 retrospective vitamin E-responsive myopathy (rVEM) cases . Methods: Blood, SC, and gluteus medius (GM) biops...
Paving the way for more precise diagnosis of EcPV2-associated equine penile lesions. There is growing evidence that equine papillomavirus type 2 (EcPV2) infection is causally associated with the development of equine genital squamous cell carcinomas (SCCs). Early stages of disease present clinically as plaques or wart-like lesions which can gradually progress to tumoural lesions. Histologically these lesions are inconsistently described as benign hyperplasia, papilloma, penile intraepithelial neoplasia (PIN), carcinoma in situ (CIS) or SCC. Guidelines for histological classification of early SCC precursor lesions are not precisely defined, leading to potential misdiagnosis. Th...
Ganglioglioma of the Right Cerebrothalamus in a 7-Year-Old Quarter Horse Cross Gelding. Intracranial neoplasia in horses is rare compared to other species. Detailed information such as neurological, electroencephalographic, and histopathological examination of horses with intracranial neoplasia associated with seizures is scarce in the literature. Furthermore, ganglioglioma has not been reported in the horse. A 7-year-old Quarter horse cross Paint gelding was examined due to recurrent seizure-like episodes of 1-year duration. The seizures had been increasing in frequency and length, occurring up to 20 times a day at the time of presentation. Neurological examination revealed inte...
Multiple excisions of an equine sarcoid and the repercussions. A 13-year-old Morgan crossbred mare was presented in May 2018 with a 10-cm mass on the medial aspect of the left hind fetlock. In September and November 2018 and June 2019 the mass was incompletely excised and continued to grow. A diagnosis of spindle cell tumor, consistent with equine sarcoid, was made based on histopathology from the last excision. . Une jument Morgan croisée âgée de 13 ans a été présentée en mai 2018 avec une masse de 10 cm sur l’aspect médial du boulet arrière gauche. En septembre et novembre 2018 ainsi qu’en juin 2019, la masse avait été excisée de manièr...
History, clinical findings and outcome of horses with radiographical signs of equine odontoclastic tooth resorption and hypercementosis. The progression of equine odontoclastic tooth resorption and hypercementosis (EOTRH) has not been completely evaluated, and currently, the only effective treatment is extraction of severely affected teeth. We aim to describe how the disease relates to the history and clinical findings and to report on the outcome in individual horses. This case series comprises data collected from 20 horses (age 14-29 years old) with radiographic findings of EOTRH in their incisor and/or canine teeth. Most horses affected with EOTRH in this study were admitted for dental problems, but some for other complaints...
Assessing pathological changes within the nucleus ambiguus of horses with recurrent laryngeal neuropathy: An extreme, length-dependent axonopathy. Equine recurrent laryngeal neuropathy (RLN) is a naturally occurring model of length-dependent axonopathy characterized by asymmetrical degeneration of recurrent laryngeal nerve axons (RLn). Distal RLn degeneration is marked, but it is unclear whether degeneration extends to include cell bodies (consistent with a neuronopathy). With examiners blinded to RLN severity, brainstem location, and side, we examined correlations between RLN severity (assessed using left distal RLn myelinated axon count) and histopathological features (including chromatolysis and glial responses) in the nucleus ambiguu...
Clinical, ultrasonographic, and histopathologic findings in seven horses with Descemet’s membrane detachment: A case series. To describe ultrasonography as a diagnostic method of in vivo Descemet's membrane detachment (DMD) in horses. Methods: Seven horses (three Icelandic horses, two Dutch Warmblood horses, one Appaloosa, and one Welsh Pony), presenting with moderate-to-severe focal or diffuse corneal edema, in whom DMD was suspected on ultrasonographic examination and confirmed with histopathology, were studied. Methods: A retrospective analysis of case records of horses with suspected DMD was performed. Results: Median age at presentation was 14 years (range 11-24). Clinical signs in eyes with DMD were unilatera...
Determination of magnetic motor evoked potential latency time cutoff values for detection of spinal cord dysfunction in horses. Transcranial magnetic stimulation (TMS) and recording of magnetic motor evoked potentials (MMEP) can detect neurological dysfunction in horses but cutoff values based on confirmed spinal cord dysfunction are lacking. Objective: To determine latency time cutoff for neurological dysfunction. Methods: Five control horses and 17 horses with proprioceptive ataxia. Methods: Case-control study with receiver operating characteristic curve analysis, based on diagnostic imaging, TMS, and histopathological findings. Horses were included if all 3 examinations were performed. Results: Diagnostic imaging an...
Myenteric networks of interstitial cells of Cajal are reduced in horses with inflammatory bowel disease. Inflammatory bowel disease (IBD) is a well-recognised but poorly understood disease complex in the horse. Clinical signs may vary but often include weight loss, diarrhoea and colic. The effect this disease process may have on the gastrointestinal pacemaker cells (the interstitial cells of Cajal), enteric neurons and glial cells has not been previously evaluated in the horse. Objective: To compare the density of the interstitial cells of Cajal (ICC), enteric neurons and glial cells in horses with IBD to those of normal horses using immunohistochemical markers. Methods: Retrospective, quantitati...
A study of residual lesions in horses that recovered from clinical signs of chronic equine dysautonomia. Equine dysautonomia (ED) causes degeneration and loss of autonomic neurons. Approximately 50% of chronic cases recover, but it is unclear how they survive neuronal loss. Objective: To assess lesions, autonomic neuron numbers, interstitial cells of Cajal (ICC), and neurodegeneration in recovered cases. Methods: Thirteen cases (group ED), euthanized 10.3 ± 5.2 (1-16) years from diagnosis and 6 age-matched controls (group C). Methods: Prospective, case control; routine post mortem examination, neuron counts in peripheral and enteric ganglia and immunohistochemical assessment of neural networ...
