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Topic:Tumor
Tumors in horses are abnormal growths of tissue that result from uncontrolled cell division. They can be benign or malignant and may affect various tissues and organs within the equine body. Common types of tumors in horses include sarcoids, melanomas, and squamous cell carcinomas. The presence and progression of tumors can impact a horse's health, performance, and quality of life. Diagnosis often involves clinical examination, imaging techniques, and histopathological analysis. This page compiles peer-reviewed research studies and scholarly articles that explore the types, diagnosis, treatment options, and prognostic factors associated with tumors in equine medicine.
Association Between Matrix Metalloproteinase-9 (MMP-9) Immunohistochemical Expression and Clinicopathological Features in Equine Melanoma. Equine melanoma is one of the most important oncological diseases in horses and exhibits a distinct biological behavior compared with melanoma in other species. Matrix metalloproteinase-9 (MMP-9) has been associated with tumor aggressiveness and metastasis in human and canine melanoma, but its expression in equine melanoma remains unknown. Objective: Evaluate the immunohistochemical expression of MMP-9 in equine melanomas and investigate its association with clinicopathological features. Methods: 68 formalin-fixed, paraffin-embedded equine melanomas from 48 gray horses were evaluated immunohis...
Diagnosed causes of sinonasal disease in 1600 horses and associations with clinical signs, computed tomographic findings and case outcome. The diagnosis of equine sinonasal disorders has been greatly enhanced by using computed tomographic (CT) imaging. Objective: To explore associations between specific diagnoses and clinical and CT findings and between specific diagnoses and case outcome in equine sinonasal disease. Methods: Retrospective case series. Methods: Data were collected from medical records from 19 equine hospitals on cases of sinonasal disease, all of which underwent CT imaging. Case outcome was obtained from clinical records, and/or by contacting clients and referring veterinarians. Logistic regression analysis was u...
Proof of concept for low dose and delayed release of tigilanol tiglate in the treatment of equine sarcoids. Intra-tumoural administration of tigilanol tiglate has been shown effective in local treatment of cutaneous equine neoplasias. The drug causes rapid oncolysis and tumour slough, but may also be associated with comorbidities in sensitive and/or intricate anatomical sites due to its initial pro-inflammatory mode of action. Here we describe two approaches to optimise and further de-risk treatment of equine sarcoids with tigilanol tiglate, especially in difficult locations. Firstly, we provide preliminary clinical and observational data on the efficacy of low dose administration of tigilanol tigla...
Selective oncolytic activity of newcastle disease virus in equine sarcoid primary cells: a preclinical investigation. Equine sarcoids are the most common skin tumors in horses and are characterized by local invasiveness, high recurrence rates, and inconsistent responses to current therapies. Oncolytic virotherapy represents a promising alternative approach that exploits defects in antiviral signaling pathways in tumor cells. Newcastle disease virus (NDV), an avian paramyxovirus that is nonpathogenic in mammals, has demonstrated tumor-selective activity in several species; however, its effects on equine sarcoids have not been previously investigated. In this study, primary cell cultures derived from equine sar...
Genetic variants of EcPV2 E6 and E7 in equine genital and oronasal squamous cell carcinoma. Since its discovery in 2008, equine papillomavirus type 2 (EcPV2) has been detected in up to 100% of equine genital and up to 40% of equine oronasal squamous cell carcinomas (SCCs). Preliminary sequence data point to the existence of EcPV2 E6 and E7 oncogene variants compared to the British reference sequence from 2008. Objective: To Identify E6 and E7 sequence variations in EcPV2-positive tumours of horses from Continental Europe and Iceland. Methods: Cross-sectional study. Methods: EcPV2 E6 and E7 were amplified from DNA of 60 EcPV2-positive SCCs/SCC precursor lesions. Amplicons were gel-pur...
Intratracheal Leiomyosarcoma in a 13-Year-Old German Riding Pony Mare. A 13-year-old German Riding Pony mare was referred for evaluation of progressive respiratory noise and mixed dyspnoea, which rapidly deteriorated to respiratory distress. Clinical examination revealed marked rattling inspiratory and expiratory tracheal sounds and severe, rattling, vesicular lung sounds. Arterial blood gas analysis demonstrated moderate hypoxaemia (partial pressure of arterial oxygen 76 mmHg at rest). Upper airway endoscopy identified a pink, cauliflower-like pedunculated mass originating from the dorsal tracheal wall approximately 15 cm cranial to the tracheal bifurcation, cau...
Leptomeningeal dissemination of a poorly differentiated carcinoma involving the trigeminal ganglion in a horse: a case report. Neoplastic conditions involving cranial nerves are uncommon in horses and represent a significant diagnostic challenge. Leptomeningeal dissemination is a recognized mechanism of tumor progression in aggressive neoplasms but is rarely reported in this species. A 15-year-old mixed-breed horse with a history of periocular squamous cell carcinoma treated by enucleation three years earlier developed progressive neurological signs. Initial differential diagnoses included metastatic neoplasia and equine protozoal myeloencephalitis. Due to rapid neurological deterioration, euthanasia and necropsy were...
Oxidative Stress and Immunomarkers in Equine Dermal Melanomatosis: Single-Case Comparison with Healthy Individual. Dermal melanomatosis is a common tumor in grey horses, characterized by cutaneous/subcutaneous lesions with metastatic potential. While clinically well-described, oxidative stress involvement remains poorly understood. This case report compared oxidative stress markers and antioxidant enzymes' activities in total protein extracts from melanomatosis lesions (grey horse) versus healthy control skin (black horse), alongside histopathology and immunohistochemistry, to correlate oxidative imbalance and tumor behavior. Melanomatosis tissue exhibited decreased antioxidant defenses confirmed by catala...
Intratumoral para-toluenesulfonamide as a tumor-ablative therapy for equine cutaneous tumors: a case series of three horses. Equine neoplasia, including sarcoids, melanomas, and squamous cell carcinomas, presents therapeutic challenges due to recurrence and limitations of conventional treatments. Para-toluenesulfonamide (p-TLS) is a tumor-ablating agent that is associated with localized tumor necrosis and subsequent lesion resolution. It has been evaluated in human clinical settings as an intratumoral treatment of malignant airway obstruction caused by non-small cell lung cancer. This study aimed to describe the clinical outcomes and tolerability of intratumoral p-TLS in equine neoplasia. Three equine cases, includi...
Clinical and pathologic findings of splenic tumours in four horses: a case series. Splenic tumours are rare in horses, with limited published literature consisting primarily of individual case reports and one hepato-splenic lymphoma case series. This case series analyses the clinical presentation, diagnostic findings and clinical outcomes of four cases of splenic neoplasia that presented to a university referral hospital over a three year period (2022-2025). Methods: Presented are two cases of primary splenic lymphoma, and two cases of metastatic melanoma. Three cases (75%) presented with chronic, non-specific clinical signs including weight loss, colic and ventral oedema. O...
Electrochemotherapy Following Surgical Cytoreduction for the Treatment of Recurrent Equine Sarcoids: A Retrospective Study of 23 Lesions. Despite the wide range of therapeutic options currently available for equine sarcoids, recurrence of these lesions remains a major clinical challenge. Consequently, the identification of effective strategies for the management of recurrent sarcoids remains an important objective in equine oncology. The aim of this retrospective study was to evaluate the clinical outcome of surgical cytoreduction combined with intraoperative electrochemotherapy in horses affected by recurrent equine sarcoids. Medical records of horses treated between July 2018 and August 2025 at the Veterinary Teaching Hospital...
Mammary neuroendocrine tumor in a mare. A 10-y-old American Paint Horse mare was presented to the Equine Field Services at Virginia-Maryland College of Veterinary Medicine (Blacksburg, VA, USA) for evaluation of mastitis and a possible abscess in the right mamma. Histologic evaluation of a mammary biopsy revealed a densely cellular, infiltrative neoplasm with cells arranged in packets supported by thin stroma. In a neuroendocrine immunohistochemistry panel, the neoplastic cells did not immunolabel for neuron-specific enolase or synaptophysin, positively immunolabeled for chromogranin A, and had moderate scattered immunolabeling for ...
Integrated transcriptomic profiling reveals oncogenic pathways and chimeric transcripts in equine sarcoid lesions with predominant BPV1 detection. Sarcoids are the most common cutaneous tumors in horses, representing up to 90% (35%-90%) of skin neoplasms. Mostly caused by Bovine Papillomavirus (BPVs) infections, sarcoids are highly resistant to therapy and prone to recurring, posing a significant threat to equine health. The aim of this study is to explore molecular pathogenetic mechanisms underlying the development of equine sarcoids, by applying transcriptomic approach. After testing samples for viral DNA, both mRNA and small RNA expression was analyzed via high-throughput Illumina sequencing comparing 12 sarcoids and 12 healthy skin s...
An unusual presentation of a sarcoid in Australia. Sarcoids are a common skin tumour affecting all equids. To date, only one case of a sarcoid in the oral cavity of the horse has been reported. In the present case, an oral sarcoid was identified using histology and polymerase chain reaction to detect bovine papillomavirus type 2 DNA. The lesion was known to be incompletely surgically excised and did not recur over a 15-month period. This case report describes the first oral sarcoid identified in Australia.
Topical betulinic acid for treatment of equine melanoma and sarcoid. Betulinic acid, a natural pentacyclic triterpenoid, has demonstrated anti-inflammatory and anti-tumor properties in vitro, including activity against equine melanoma and sarcoid. However, there is limited in vivo evidence evaluating its clinical efficacy. The objective of this study was to assess the safety and efficacy of a compounded 1% betulinic acid cream for the treatment of equine cutaneous melanoma and sarcoid. Unassigned: This prospective, randomized, double-blinded, placebo-controlled clinical trial enrolled client-owned horses with melanoma or sarcoid tumors. Horses received either a...
Visceral disseminated hemangiosarcoma causing severe bicytopenia in a mare. Hemangiosarcoma is an uncommon but highly aggressive malignant vascular neoplasm in horses, most often identified as a disseminated process at postmortem examination. This report describes an adult Warmblood mare presenting with acute hemorrhagic diarrhea, severe anemia, and thrombocytopenia associated with disseminated hemangiosarcoma likely originating in the transverse colon with metastasis to the liver and lungs. This case highlights gastrointestinal hemangiosarcoma as a potential differential diagnosis in horses with unexplained bicytopenia and hemorrhagic enteropathy.
Unusual, fatal neck cancer in a foal: immunohistological investigations and differential diagnosis. Neck masses may represent a diagnostic challenge for equine veterinarians, since they may involve different structures with a similar clinical appearance. Whereas neck masses in foals mostly result from non-neoplastic conditions, including various congenital abnormalities, neoplastic cervical masses have been rarely documented. This report describes the unusual case of a rapidly growing neck cancer in a four-month-old colt, resulting in a fatal outcome. Gross and immunohistological findings were most consistent with a poorly differentiated thymic carcinoma with sarcomatoid features and multifo...
Germline Pathogenic Variant in the APC Gene Suggestive of Gardner Syndrome in a Pony. A 12-year-old pony mare was presented for evaluation of dental disease and nasal discharge. At presentation, clinical signs included bilateral nasal discharge, cutaneous masses, and numerous hard enlargements involving the bones of the skull, maxilla, mandible, and cervical vertebrae. Oral exam revealed advanced dental disease with hard enlargements adjacent to and between numerous cheek teeth. Radiographs and computed tomography confirmed the presence of severe dental disease and proliferative bone lesions disseminated along the skull, hyoid apparatus, and cranial cervical vertebrae. The bony...
In Vitro Characterization of an Equinized Anti-PD-L1 Antibody for Cancer Immunotherapy in Horses. Horses develop spontaneous tumors, typically in old age. Although local tumor control can be achieved using conventional therapies, systemic therapies are required to treat recurrent and/or metastatic tumors. Immune checkpoint inhibitors, such as anti-PD-L1 antibodies, have been approved for the treatment of various tumor types in humans; however, little is known about the immunosuppressive roles of the PD-1/PD-L1 pathway in horses, and the therapeutic potential of these inhibitors remains to be elucidated. Previously, we reported that the rat monoclonal anti-PD-L1 antibody 6C11-3A11 cross-rea...
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...
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 ...
Spontaneous regression of equine sarcoids is an exceptional event. Sarcoids are benign, yet locally aggressive skin tumours that commonly affect horses and other equid species. The lesions are induced by bovine papillomavirus types 1, 2, and probably 13 in conjunction with other factors including trauma and a genetic predisposition. Although sarcoids have a substantial impact on the health and welfare of affected equids, information on the immune response to bovine papillomavirus infection and resulting sarcoids is limited. However, there is evidence that sarcoid disease is associated with an impaired immune response to bovine papillomavirus infection. This o...
Cannabidiol-induced cellular and matrix-associated responses in primary equine sarcoid cells. Sarcoids are locally invasive skin tumors in equids, associated with bovine papillomavirus. Objective: Address potential applications of cannabidiol (CBD) in veterinary medicine. We evaluated the response of equine sarcoid cells to CBD in vitro, focusing on viability, invasiveness, and matrix remodeling. Methods: Three primary sarcoid cell lines. Methods: Cells were treated with CBD (20, 6.75, 2.25, 0.75 μM) and incubated for 6, 24, 48, 72 hours. Cell viability, cytotoxicity, and apoptosis were assessed using the ApoTox-Glo Assay. Based on these results, further analyses were performed for ...
Association between ultraviolet-related TP53 mutations and immune microenvironment in equine ocular squamous cell carcinoma. This study investigates the molecular and immune characteristics of equine ocular squamous cell carcinoma (eoSCC). Immunohistochemistry (IHC) and next-generation sequencing (NGS) were used to detect protein expression and TP53 mutations, respectively. T lymphocytes (CD3+), regulatory T cells (FoxP3+), B lymphocytes (CD20+), and macrophages (IBA-1+) were quantified. A total of 29 cases of eoSCC were evaluated, consisting of 3/29 carcinomas in situ (CISs) and 26/29 squamous cell carcinomas (SCCs). p53 positivity by IHC was detected in 19/29 cases while by NGS, 21 TP53 mutations were found in 13/...
Hemithyroidectomy due to a large, solid follicular thyroid adenoma in a 19-year-old thoroughbred mare. This case report describes the successful hemithyroidectomy of the largest equine solid follicular adenoma described in the veterinary literature to date. A 19-year-old thoroughbred mare was referred to Oakhill Veterinary Centre for the surgical removal of a large, left-sided thyroid gland measuring 26cm in diameter. Pre-operative considerations, the hemithyroidectomy surgical technique as well as the intra- and post-operative complications encountered, are discussed. Following surgery the horse had no long-term complications and continues to thrive four and a half years post-operatively.
Acquired and Degenerative Conditions of the Cervical Vertebral Column in Horses. The cervical vertebral column in horses plays a crucial role in movement, posture, and performance and disorders affecting it can cause pain, ataxia, or lameness. This review discusses major acquired (traumatic, infectious, neoplastic) and degenerative (osteoarthritis, foraminal stenosis, intervertebral disc disease) conditions. Acquired lesions often arise from trauma, bacterial infection, or neoplasia, with clinical signs ranging from neck pain to neurologic deficits. Degenerative disorders, particularly osteoarthritis of articular process joints, are common in the caudal cervical spine and ...
Engineered biopolymeric hydrogels for in vitro modeling of equine sarcoid tumors in comparative oncology. Developing advanced preclinical in vitro cancer models is essential for understanding tumor biology, improving drug discovery, and enhancing the clinical translation of new therapies. Papillomaviruses (PVs) cause diverse lesions in humans and animals; notably, bovine papillomavirus (BPV) is the main cause of equine sarcoid, the most common skin tumor in horses. Its pathogenesis involves viral infection, fibroblast transformation, and extracellular matrix (ECM) remodeling. These processes highlight the limitations of conventional two-dimensional (2D) culture systems, which fail to replicate the...
Current and Future Central Nervous System Surgery-Part 1: Cervical Spinal Cord Compression. Ventral cervical stabilization remains the primary surgical approach, in general, for horses with spinal cord compression. Advancements in volumetric imaging offer a more comprehensive understanding of central nervous system dysfunction elucidating that other modes of compression exist. Minimally invasive instrumentation and computer-assisted surgery are expanding therapeutic possibilities for cervical vertebral compressive myelopathy, radiculopathy, vertebral fractures, and intracranial or intraspinal masses. Emerging techniques-such as articular process joint fixation, targeted decompression...
