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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.
Accuracy of Computed Tomography in Diagnosing Temporomandibular Joint Osteoarthritis Relative to Histopathological Findings-An Ex Vivo Study of 41 Horses. Computed tomography (CT) is used to support the diagnosis of equine temporomandibular joint (TMJ) disease; however, its diagnostic accuracy remains unclear. This study aimed to evaluate the relationship between CT findings and histopathological manifestations of osteoarthritis (OA) in equine TMJs. A total of 82 TMJs were CT-imaged, sampled, grouped into age-related and OA-related groups, and analyzed for frequency distributions, correlations, and CT-based TMJ OA diagnosis. CT findings were observed in 79% of joints, including 'CT anatomical variations' considering to reflect age-related remode...
Verminous mastitis caused by Cephalobus cubaensis infection in a mare. A 7-y-old American Quarter Horse mare was presented to a veterinary hospital for ongoing reproductive monitoring and management of endometritis. During physical evaluation, several nodular lesions of unknown origin and duration were discovered in the mammae. Histologically, biopsies from the lesions were confirmed as severe granulomatous mastitis with intralesional rhabditid nematodes. A putative diagnosis of or infection was assigned, and ivermectin (1.2 mg/kg PO) treatment was given every 2 wk. When lesions persisted after the initial dose of ivermectin, PCR testing of and gene targe...
Macroscale and microscale mechanical and biochemical properties of the equine superficial digital flexor tendon are regionally dependent. To examine regional mechanical and biochemical differences across the length of the equine superficial digital flexor tendon (SDFT). Unassigned: Equine SDFTs were collected postmortem from 9 donors and divided into proximal, middle, and distal regions based on the location of the musculotendinous and osteotendinous junctions. Tensile testing was performed on samples to obtain macroscale mechanical properties, and atomic force microscopy was done to obtain microscale mechanical properties. Biochemical assays and histological staining were done to assess glycosaminoglycan (GAG), collagen, and DN...
Structural Features of the Equine Small Intestinal Mesenteric Attachment Predisposing to Rupture. Rupture of equine small intestine with formation of a pouch of ingesta within the mesentery has been reported in clinical colic cases. Multiple ex-vivo studies using anastomosed jejunum observed rupture into the mesentery, distant to the anastomosis. Both scenarios suggest the jejunum is predisposed to rupture at the mesenteric attachment. The aim of the study is to 1) document the location at which equine jejunal segments rupture when subjected to high intraluminal pressures, 2) identify predisposing anatomical features that may confer weakness at the point of rupture and 3) demonstrate jejun...
Edema and Structural Remodeling in Equine Suspensory Ligament Injury: A Severity Gradient Associated with Microvascular Dysfunction. Suspensory ligament injury is a major cause of lameness in sport horses, yet its underlying mechanisms remain incompletely understood. The aim of this study was to characterize histopathological alterations of the equine suspensory ligament and to evaluate their association with imaging features. A comparative descriptive study was performed on sport horses with forelimb lameness, combining clinical evaluation, ultrasonography, magnetic resonance imaging, and histopathological analysis. Ligament samples were collected post-mortem from anatomically defined regions selected based on imaging find...
Rostral hard palate swelling (lampas) in horses: true or fiction? This study aimed to determine the occurrence of swellings (lampas) in the rostral portion of the hard palate in young, adult, and elderly horses and to characterize them histologically. One hundred and twenty horses of different ages were evaluated by oral inspection. Horses were classified with lampas when the mucosa of the hard palate extended beyond the occlusal surface of the upper incisors and samples of palatal mucosa were collected. Ten other horses without rostral hard palate alterations, euthanized for unrelated causes, were included as the control group. Histological analysis include...
Persistence of Sarcocystis neurona and histopathology in horses with equine protozoal myeloencephalitis. Currently, little is known about the exact role of immunopathology in equine protozoal myeloencephalitis (EPM), including the ability to persist after anti-protozoal treatment. The main objectives of this study were to determine whether is present in the CNS in horses with EPM, including previously treated cases, and to evaluate the associated histopathology and immune response. For this study, control ( = 10) and horses with EPM ( = 9) were confirmed based on our inclusion criteria. Based on our preliminary data, we classified horses with EPM and clinical signs for >6 months as...
Malignant Ovarian Teratoma in a Lusitano Filly: Diagnostic Challenges and Clinical Significance. An 8-month-old Lusitano filly (a young female horse) was referred with a five-day history of abdominal distension, respiratory distress, and hyporexia. Clinical and ultrasonographic examinations revealed ventral edema, anemia, leukocytosis, hypoalbuminemia, and bilateral pleural effusion. The filly subsequently developed progressive clinical deterioration, including persistent hyporexia, scant fecal output, and acute colic with nasogastric reflux, followed by sudden respiratory decompensation, collapse, and death. Post-mortem examination revealed a large, multilobulated abdominal mass involvin...
Histological properties of the distal sesamoidean impar ligament in racing Thoroughbreds and Quarter horses. The distal sesamoidean impar ligament (DSIL) is a key component of the equine podotrochlear apparatus, yet its role in conditions such as caudal heel pain and navicular syndrome remains poorly understood. The objective of this study was to characterize the histological properties of the DSIL and evaluate how it is influenced by breed and age. Eighty-four cadaveric forelimb DSIL samples were collected from young, athletic Quarter horses (QHs), Thoroughbreds (TBs), and older, retired Quarter horses. Samples were stained and assessed for vessel size and count, number of nerve fascicles, and the r...
Coexistence of seminoma and leiomyoma in the testis of an Arabian-Barbe stallion: A case report. Testicular tumors are rare in horses, with seminoma being the most frequently described in the literature. In Morocco, many stallions used for Tbourida are intentionally kept intact, as uncastrated horses are traditionally viewed as symbols of prestige and cultural pride. This cultural practice increases the likelihood of detecting testicular pathology in mature stallions. Unassigned: A 15-year-old Arabian-Barbe stallion used in Tbourida was presented for evaluation after the owner noticed a slow, progressive enlargement of the right testis over a period of more than 1 year. Clinical examinati...
Septic Endophthalmitis Following Suprachoroidal Cyclosporine Implant Placement in Two Horses With Equine Recurrent Uveitis. This article presents the clinical and histopathological findings from two horses that developed severe postoperative complications following suprachoroidal procedures routinely employed in the management of equine recurrent uveitis (ERU). Case 1 was a 5-year-old warmblood stallion that initially received a unilateral suprachoroidal triamcinolone injection, followed later by bilateral suprachoroidal cyclosporine implant (CSI) placement. At 9 weeks postoperatively, the right eye (which had undergone both procedures) developed secondary glaucoma necessitating enucleation. Case 2 was a 14-year-ol...
Equine genital and ocular squamous cell carcinomas: clinical, histopathological, molecular and viral characterization with proposed histopathological classification system. Equine squamous cell carcinomas (eSCCs) are common, and a proportion are likely induced by papillomavirus 2 (EcPV-2). Accurate prediction of clinical outcomes is challenging with no recognized prognostic criteria or consistent histopathological classification scheme for eSCC. The aims of this study were to histopathologically subtype a large case series of eSCCs (genital and ocular) and correlate them with p16 and HER-2 expression, equine papillomavirus infection status, and various clinical and histopathological parameters to predict tumour behavior and prognosis. One hundred and eighty-five...
Metastatic adenocarcinoma in the parotid gland in a horse – clinical and pathological findings. This case report details the findings of a metastatic adenocarcinoma of the parotid gland, a rare neoplasm in horses with limited treatment options. A 12-year-old, Criollo breed, gelding was presented with an enlarged left parotid gland that had been previously treated for 6 months without response to treatment. Based on the results of the diagnostic procedures performed, the horse underwent a total sialadenectomy and died of hypovolemic shock in the recovery room. Post-mortem examination revealed metastatic neoplastic infiltration of the submandibular lymph nodes and the lymphatic network at ...
Postmortem characterization of cranial nuchal bursa and ligament in healthy horses reveals subclinical gross and histopathologic abnormalities. To investigate the presence of subclinical cranial nuchal bursitis and characterize its histopathologic features and association with Borrelia burgdorferi. Unassigned: This was a prospective descriptive cadaver study on a convenience population of horses in a B burgdorferi-endemic region (15 horses: 5 geldings and 10 mares of various breeds; 4 to 29 years old). Horses without history or clinical signs of cranial nuchal bursitis underwent euthanasia and tissue donation. Cranial nuchal bursa, synovial fluid, and nuchal ligament were collected postmortem. The bursa and ligament were evaluated via...
Modified Medial Canthoplasty for Correction of Euryblepharon in Two Horses. To describe a medial canthoplasty surgical procedure in two horses for correction of euryblepharon, secondary to microphthalmia, and following excision of retrobulbar fat prolapse. Methods: A 1 year old thoroughbred mare was presented for small globes and chronic ocular discharge bilaterally. Ophthalmic examination revealed microphthalmos, euryblepharon, medial canthal pocket syndrome, and dacryocystitis bilaterally with no visual impairments. A 2 year old Appaloosa gelding was presented for evaluation of a smooth, subconjunctival mass anterior to the right globe in the medial canthus. Oph...
Genetic background of the Transylvanian endemic equine recurrent rhabdomyolysis. To investigate the pathophysiology, prevalence and severity of equine exertional rhabdomyolysis in a mountainous region of Transylvania, Romania, this study considered genetic and histological factors. We determined the occurrence and frequency of a mutation in the glycogen synthase gene 1 (GYS1), associated with equine polysaccharide storage myopathy type 1 (PSSM1), in two adjacent populations, one with a significantly high prevalence of the disease (high altitude villages, HV) and the other with a rare prevalence (valley villages, VV). We genotyped GYS1 in 41 animals (HV = 31, VV = 10) and f...
Equine Corneal Stromal Invasive Squamous Cell Carcinoma: Clinical and in Vivo Confocal Microscopic Features of 7 Cases. To describe the clinical and in vivo confocal microscopy (IVCM) characteristics of horses with corneal stromal invasive squamous cell carcinoma (CSI-SCC). Methods: Retrospective study of 7 horses with histopathologically confirmed unilateral CSI-SCC. Methods: Horses with corneal CSI-SCC were examined by laser scanning IVCM. Signalment, clinical findings, and histopathology results were compared with IVCM findings. Results: Clinical ocular lesions in all horses included a heavily vascularized, opaque, gray or tan, anterior or midstromal opacity invading the cornea from the limbus. The corneal ...
Pulmonary fibrosis in horses associated with spontaneous Crotalaria juncea intoxication. We report an outbreak of Crotalaria juncea intoxication in horses exhibiting progressive weight loss and respiratory distress in northeastern Brazil. Necropsy revealed firm, non-collapsed lungs with extensive interstitial fibrosis, bronchiolar epithelial hyperplasia with club cells proliferation, and marked pulmonary arterial remodeling. Hepatic lesions consisted primarily of centrilobular necrosis, probably resulting from hypoxic injury related to anemia and prolonged agonic death. Pasture inspection identified significant invasion by shrubs of C. juncea in various phenological stages.
Functional and histopathologic evidence of laryngeal reinnervation using the spinal accessory nerve in horses. To evaluate functional and histopathologic outcomes of standing selective laryngeal reinnervation using the spinal accessory nerve (SAN) in horses with experimentally induced recurrent laryngeal neuropathy (RLN). Methods: Five Thoroughbred mares. Methods: Prospective cohort study. Methods: The horses underwent left recurrent laryngeal neurectomy followed 8 weeks later by selective laryngeal reinnervation using the SAN. Follow-up evaluations at 4.5, 6, 8, and 12 months included treadmill exercising endoscopy, ultrasonography of intrinsic laryngeal muscles, and percutaneous electrical stimul...
Confocal laser endomicroscopy: exploring endometrial image quality in relation to the oestrous cycle of mares. Assessment of the endometrium is an essential component of a breeding soundness examination in mares. The current reference standard for evaluating equine endometrial health is histopathological assessment of an endometrial biopsy, however, inconsistencies may arise when a single blinded biopsy is used. Confocal laser endomicroscopy (CLE) is non-invasive and enables real-time in-vivo imaging of the endometrium across multiple locations within the uterine lumen. An initial study revealed variation in CLE image quality between mares. Objective: This study aimed to compare the quality of endometr...
Standing superficial keratectomy provides long-term control of epithelial and stromal equine immune-mediated keratitis. To describe the demographics and treatment outcomes of horses definitively diagnosed with epithelial or stromal immune-mediated keratitis (IMMK) by use of in vivo confocal microscopy (IVCM) and/or histopathology. Unassigned: Medical records of horses presented to the Cornell University Equine Hospital definitively diagnosed with epithelial or stromal IMMK with IVCM and/or histopathology between 2020 and 2024 were reviewed. Patient signalment, affected eye(s), diagnostics, treatments, and outcomes were assessed. Unassigned: 22 horses met the inclusion criteria. The mean age was 16.9 years (SD, ...
Amniotic Mesenchymal Stromal/Stem Cell-Derived Extracellular Vesicles for Equine Chronic Degenerative Endometritis Treatment. Equine chronic degenerative endometritis (CDE) is a progressive process characterized by endometrial fibrosis that could be responsible for alterations of uterine environment and foetal-maternal communication. Objective: The aim of this study was to try to restore this communication by intrauterine administrations of amniotic cell-derived extracellular vesicles (AMC-EVs) in a case series. Methods: Twelve mares were selected on the basis of their reproductive history of early embryonic loss or abortion and clinical suspicion of CDE subsequently verified with histopathological examination of end...
Clear cell squamous cell carcinoma in the third eyelid of a horse. Squamous cell carcinoma (SCC) is the most common ocular and periocular neoplasm of horses, typically arising from the limbus, third eyelid mucosa or mucocutaneous junctions of the upper and lower eyelids. Tumours are locally invasive, prone to recurrence and may rarely metastasize. Histological evaluation is required for definitive diagnosis and atypical SCC subtypes may be diagnostically challenging. Here we describe a clear cell SCC in the third eyelid of a 16-year-old female Quarter Horse. The red and invasive mass was surgically excised for histological evaluation. The lesion consisted of ...
Two cases of primary hepatic neoplasia in young horses: Diagnostic challenges and clinical implications. Primary hepatic neoplasms are rare in horses and often have a poor prognosis due to non-specific clinical signs and delayed diagnosis. This report describes two cases of primary hepatic neoplasia in young horses. The first case was a yearling Hanoverian filly presenting with non-specific clinical signs, including poor weight gain and inappetence, ultimately diagnosed with hepatoblastoma based on ultrasonographic findings and histopathological examination. The second case was a three-year-old Polish Sport Horse stallion that died suddenly, with post-mortem examination revealing advanced cholang...
A rare and unusual case of advanced complete molar pregnancy in an Arabian mare: first report. Molar pregnancy is a rare condition in women, referring to the development of fetal membranes with or without an embryo. A 22-year-old mare referred to the veterinary faculty clinic due to the delayed parturition. In the ultrasound examination, the uterine membranes were seen suspended in fluids without any trace of the fetal organs. The mare underwent caesarean section, a mixture of brown fluid with fragments of fetal membranes was removed, but no fetus or any remnants of the fetus were found in the uterus. In the histopathological examinations, the fetal membranes showed severe degenerative ...
Widespread Osteolysis as an Uncommon Manifestation of Equine Sarcoidosis. Equine sarcoidosis is an uncommon disease characterized by granulomatous inflammation presenting in a spectrum of body system involvement and severity. Musculoskeletal manifestations are sporadically reported but without correlation between imaging and pathologic findings. In a mature Quarter Horse mare eventually diagnosed with a progressive form of sarcoidosis, phalangeal osteolysis discovered on radiography prompted further evaluation, revealing diffuse, discrete osteolysis throughout the axial skeleton. Due to disease progression, humane euthanasia was elected, and computed tomography and ...
Detection of vasculogenic mimicry in equine ocular, oronasal, and genital squamous cell carcinoma. Squamous cell carcinoma (SCC) is the most common malignant tumor disease in horses. It predominantly affects the ocular, oronasal, and anogenital region. Equine SCC is difficult to treat, also because important aspects of SCC development and metastasis are still unclear. We previously provided evidence that equine SCC cells can adopt a stem cell-like phenotype as a hallmark of malignant progression. Here, we investigated whether equine SCCs harbor endothelial-like tumor cells that form an alternative network of pseudo-vessels better known as vasculogenic mimicry (VM). Following histopathologic...
Histomorphometric Analysis of the Endometrium of Jennies (Equus asinus) and Mares (Equus caballus) in Estrus: Anatomical Differences and Possible Reproductive Implications. Assisted reproductive techniques are often extrapolated from horses to donkeys, despite poorer fertility outcomes in jennies. This issue has been attributed to unknown uterine species-specific differences. This study compared, through histomorphometry, the endometrium of jennies and mares. Endometrial biopsies (N = 12) were taken from reproductively sound jennies (n = 6) and mares (n = 6) in estrus. Histomorphometric analysis evaluated luminal (LE, µm) and glandular epithelium height (GE, µm), glandular lumen diameter (LD, µm), glandular area (GA, µm), the number of glands (#G), and glandu...
Listeria monocytogenes septicemia in foals: A case series (1986 to 2024). Listeriosis is caused by , a Gram-positive, facultative anaerobic, intracellular rod bacterium that can infect a wide variety of species. Listeriosis occurs in a diverse range of domestic and wild animals but is most commonly a disease of ruminants. Clinical signs include meningoencephalitis, typhlocolitis, septic arthritis, and abortions. Listeriosis in horses has been reported in several countries but is an uncommon diagnosis. This report describes clinical, bacteriological, histopathological, and immunohistochemical findings in 6 foals with neonatal septicemia from which was isolated. Key ...
Full Clinical Pathological and Bacteriological Investigation of a Giant Nasal Polyp Associated With the Developing Apex of the Permanent Fourth Premolar (Triadan 108) in a 3-year-old Connemara Filly: A Case Report. A 3-year-old Connemara X filly was referred to a UK equine hospital for further investigation of unilateral nasal discharge and facial swelling. Diagnostic imaging documented the presence of a heterogenous, soft tissue opacity with areas of focal mineralisation within the right paranasal sinuses, completely obliterating the nasal cavity, in addition to endodontic disease and significant periapical pathology associated with the right permanent fourth premolar (Triadan 108). Subsequent histopathologic examination confirmed the mass as a fibro-inflammatory polyp.
