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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.
Renal mucus gland cystadenomas in a horse. A 35-year-old horse was submitted to the necropsy service at the University of Kentucky Livestock Disease Diagnostic Center. At necropsy, multiple 1-4-cm-diameter cystic structures were incidentally identified unilaterally in the right renal medulla and the cortex. On histologic examination, the cystic structures compressed the normal renal architecture, were lined by tall columnar epithelium that formed occasional papillary projections, and contained large amounts of mucicarmine and periodic acid-Schiff-positive mucinous material. The masses were diagnosed as renal mucus-gland cystadenomas. T...
Equine giant cell tumor of soft parts: a series of 21 cases (2000-2007). In horses, giant-cell tumors of soft parts are rare neoplasms, with the majority of reported cases occurring within the hind limb muscles and soft tissues in older horses. The following article documents 21 cases of equine giant-cell tumors of soft parts clinically examined within the state of Colorado from 2000 to 2007. The majority of cases occurred in male horses aged 10 years or older. Nine (43%) arose within the hind limbs. Key histologic features included numerous multinucleated giant cells and hemosiderin-laden macrophages admixed with a spindle-cell proliferation. The majority demonstr...
Expression of anti-Müllerian hormone (AMH) in equine granulosa-cell tumors and in normal equine ovaries. Anti-Müllerian hormone (AMH), also known as Müllerian inhibiting substance (MIS), is expressed by granulosa cells in females of many mammalian species, and circulating AMH concentrations have been used to monitor granulosa-cell tumors (GCT) in women. The objective was to characterize expression of AMH in equine GCT, and in normal equine ovaries, based upon immunohistochemistry (IHC), using a polyclonal primary antibody directed against human AMH. Equine GCT (n=27) and normal equine ovaries (n=10) were examined by IHC. In addition, sera from four mares with GCT were characterized for AMH bioa...
Electrochemotherapy in veterinary oncology. Electropermeabilization is a method that uses electric field pulses to induce an electrically mediated reorganization of the plasma membrane of cells. Electrochemotherapy combines local or systemic administration of chemotherapeutic drugs such as bleomycin or cisplatin that have poor membrane permeability with electropermeabilization by direct application of electric pulses to the tumors. Preclinical studies have demonstrated excellent antitumor effectiveness of electrochemotherapy on different animal models and various tumor types, minimal toxicity, and safety of the procedure. Based on resul...
Penile and preputial squamous cell carcinoma in the horse: a retrospective study of treatment of 77 affected horses. The most common penile and preputial neoplasm in the horse is the squamous cell carcinoma (SCC), but no large surveys of treatment and effects of the grade of the tumour, based on the degree of differentiation, on outcome of affected horses are available. Objective: Analysis of treatment of male horses affected with SCC of the external genitalia and long-term results of treatment. Methods: Seventy-seven cases of SCC were evaluated. Data recorded included treatment, outcome, post operative histopathology and retrospective tumour grading. Results: Treatments included: cryosurgery, excision, part...
Penile and preputial tumours in the horse: a retrospective study of 114 affected horses. Preputial and penile tumours are more common in horses than in other domestic animals, but no large surveys of male horses with tumours of the external genitalia are available. Objective: To present a retrospective analysis of male horses with neoplasms of the external genitalia. Methods: The penile and preputial tumours of 114 horses were evaluated. Data recorded included age, gelding or stallion and breed; type and site of lesion; involvement of regional lymph nodes; histopathology (including grading of squamous cell carcinoma); and results of radiographic examination of the thorax. Results:...
A subset of equine sarcoids harbours BPV-1 DNA in a complex with L1 major capsid protein. Bovine papillomavirus type 1 or 2 (BPV-1, BPV-2) are accepted causal factors in equine sarcoid pathogenesis. Whereas viral genomes are consistently found and expressed within lesions, intact virions have never been detected, thus permissiveness of sarcoids for BPV-1 replication remains unclear. To reassess this issue, an immunocapture PCR (IC/PCR) was established using L1-specific antibodies to capture L1-DNA complexes followed by amplification of the viral genome. Following validation of the assay, 13 sarcoid-bearing horses were evaluated by IC/PCR. Samples were derived from 21 tumours, 4 per...
Surgical management of a progressive iris melanocytoma in a Mustang. A 7-year-old gray Mustang gelding weighing 454 kg was presented for evaluation of a brown mass within the left eye (OS) of 1 year's duration with recent enlargement. Results: A nonpainful, 8 mm diameter, brown, vascularized mass was identified in the anterior chamber of the OS. Ocular B-scan ultrasound confirmed iris involvement and corneal endothelial contact. Histopathology confirmed the presumptive diagnosis of a uveal melanocytic neoplasm, and revealed 1-3 mitotic figures per high power (400x) field. Results: The mass was removed via sector iridectomy without complications, but without com...
Expression of anti-Müllerian hormone (AMH) in the equine testis. Anti-Müllerian hormone (AMH) induces regression of Müllerian ducts during male fetal development; in the human male, it is expressed in Sertoli cells during fetal development (and through puberty). The objective was to characterize expression of AMH in the fetal, neonatal, prepubertal, and adult equine testis, as well as in equine cryptorchid testes, in select testicular neoplasms, and in intersex gonads, based upon immunohistochemistry (IHC). Testes were removed from equine fetuses at 5.5, 10, and 11 months of gestation, at 12 months of age, and from adult stallions. In addition, cryptorchi...
Benign peripheral nerve sheath tumor of the perianal region in a young pony. A 20 x 10 cm, lobulated mass was present in the perianal region of a 4-year-old Dales pony. Histopathology revealed an unencapsulated, loose arrangement of sheets and whorls of narrow mesenchymal cells, situated in the deep dermis. Intervening areas had a myxomatous appearance. The whorls were often arranged around a central structure resembling an axon or a vascular structure. Immunohistochemistry revealed that the elongated mesenchymal cells and central axon-like structures expressed vimentin, S-100, and neuron-specific enolase, but not pancytokeratin, glial fibrillary acid protein, and the ...
Immunotherapy of equine sarcoid: dose-escalation trial for the use of chimeric papillomavirus-like particles. Equine sarcoids are fibrosarcoma-like skin tumours with a prevalence of approximately 1-2 %. Strong evidence exists for a causative role of bovine papillomavirus (BPV) type 1 or type 2 in the development of sarcoids. No effective treatment of equine sarcoid is available and after surgical excision relapse of the tumours is very frequent. We developed chimeric virus-like particles (CVLPs) of BPV 1 L1-E7 for the immunotherapy of equine sarcoid. In a phase I clinical trial 12 horses suffering from equine sarcoid with an average number of more than 22 tumours per animal were vaccinated in a dose-e...
Vaccination of sarcoid-bearing donkeys with chimeric virus-like particles of bovine papillomavirus type 1. Equine sarcoids are fibroblastic skin tumours affecting equids worldwide. While the pathogenesis is not entirely understood, infection with bovine papillomavirus (BPV) type 1 (and less commonly type 2) has been implicated as a major factor in the disease process. Sarcoids very seldom regress and in fact often recrudesce following therapy. Nothing is known about the immune response of the equine host to BPV. Given that the viral genes are expressed in sarcoids, it is reasonable to assume that vaccination of animals against the expressed viral proteins would lead to the induction of an immune re...
Loss of expression of protein kinase a regulatory subunit 1alpha in pigmented epithelioid melanocytoma but not in melanoma or other melanocytic lesions. Pigmented epithelioid melanocytoma (PEM) is a recently described entity comprising most cases previously described as "animal-type melanoma" and epithelioid blue nevus (EBN) occurring in patients with the multiple neoplasia syndrome Carney complex (CNC). Mutations of the protein kinase A regulatory subunit type 1alpha (R1alpha) (coded by the PRKAR1A gene) are found in more than half of CNC patients. In this study, we investigated whether PEM and EBN are related at the molecular level, and whether changes in the PRKAR1A gene status and the expression of the R1alpha protein may be involved in th...
Primary intraocular primitive neuroectodermal tumor (retinoblastoma) causing unilateral blindness in a gelding. A 14-year-old gray gelding was presented for investigation of a visible, pale-colored ocular mass in the right eye. An intraocular mass was identified clinically and ultrasonographically as originating from the superior nasal quadrant of the ciliary body and retina. The mass occupied the majority of the vitreous chamber and some of the superior anterior chamber of the eye. The affected eye was blind. Following exenteration, a primary intraocular primitive neuroectodermal tumor (i.e. a retinoblastoma/medulloepithelioma), a rarely described intraocular mass in adult horses, was identified by pat...
Calcified tumours of the paranasal sinuses in three horses. Three horses, a 10-year-old Thoroughbred mare, a 9-year-old Thoroughbred gelding and a 6-year-old Arab gelding, with calcified tumours of the paranasal sinuses, are described. All horses presented with purulent nasal discharges and facial distortion. Exophthalmos, blepharospasm and ocular discharge were also a feature in individual horses. A presumptive diagnosis of a calcified tumour was made on the basis of clinical signs and radiographic and endoscopic findings. The tumours ranged from 15 to 25 cm in diameter. A large frontonasal bone flap was used to expose the tumours, which were cleaved ...
Omental leiomyoma in a male adult horse. A well-circumscribed mass 70 x 35 x 28 cm in size and 41 kg in weight was detected at necropsy in a male adult horse within the omentum major without any association to the gastrointestinal tract. The tumor consisted of multiple white-to-yellow lobules and displayed a firm consistency. In addition, multiple cysts filled with blood-like fluid, and multifocal areas of necrosis were observed. Histologically, the mass consisted of slightly pleomorphic spindloid-shaped cells arranged in interlacing bundles containing elongated nuclei with blunt ends. The majority of tumor cells revealed a positive ...
Papillary renal adenoma of distal nephron differentiation in a horse. A 20-year-old thoroughbred mare had a mass in the right kidney. The mass was encapsulated with fibrous capsule and composed of variably-sized papillary projections lined by a single layer of flattened to cuboidal neoplastic epithelial cells with no cytological and nuclear atypia. Immunohistochemically, the neoplastic cells were broadly positive for cytokeratin AE1/AE3 and granular staining for alpha-1-antitrypsin was focally detected; this immunohistochemical property was similar to that of the normal distal nephron. From these results, this case was diagnosed as papillary renal adenoma of dis...
Imaging features and decision making in retrobulbar neuroendocrine tumours in horses–case report and review of literature. A 25-year-old Haflinger gelding was evaluated for chronic-progressive unilateral exophthalmos. Ultrasonographic investigation and magnetic resonance (MR) imaging revealed a retrobulbar space-occupying mass to be the cause of eyeball displacement. Ultrasonographic features were not sufficient to specify the type and extension of the lesion. Magnetic resonance scans, however, clearly displayed an infiltrative intracranial growth pattern but sparing of orbital soft tissues. Based on MR appearance, tentative diagnosis of an orbital soft tissue neoplasia was made and subsequently confirmed by histo...
Bovine papillomavirus load and mRNA expression, cell proliferation and p53 expression in four clinical types of equine sarcoid. Equine sarcoids, the most common skin tumours in horses, are induced by bovine papillomavirus (BPV). Their clinical appearance varies from small stable patches to aggressively growing masses. Differences in BPV load and mRNA expression and Ki67 and p53 immunostaining among four clinical types (fibroblastic, occult, nodular and verrucous sarcoids) were evaluated to test the hypothesis that the clinical behaviour of equine sarcoids correlates with BPV activity. Viral load and expression of the BPV E2, E5, E6 and E7 genes were determined using quantitative real-time PCR. The proliferative fractio...
Dental benign cementomas in three horses. Cementoma is a very rare odontogenic neoplasm of mesenchymal origin. Clinically, in 3 horses, multiple bony enlargements of the upper and lower jaw extending into the oral cavity were observed. Radiographically, multiple, well-circumscribed, radiopaque masses surrounding the roots of the upper and lower incisors or an upper premolar tooth were present. Due to malocclusion and local pain, single teeth were extracted in each case. Grossly, a hard grayish-white mass surrounding the root of the incisors and the premolars was identified. Histopathologically, the tumors consisted of excessive deposi...
Bilateral occurrence of granulosa-theca cell tumors in an Arabian mare. An Arabian mare was referred for right granulosa-theca cell tumor (GTCT) evaluation. The mare was presented 4.5 years later for a left GTCT, after successfully conceiving and delivering a normal foal in the interim. The concurrent or nonconcurrent occurrence of bilateral GTCT in mares appears to be rare. Une jument Arabe a été référée pour l’évaluation d’une tumeur de la granulosa et de la thèque du côté droit (TGT). La jument avait été présentée 4,5 ans plus tôt pour une TGT du côté gauche, ayant entre temps conçu et mis au monde un poulain normal. La présence, simultan...
Long-term outcome associated with intratumoral chemotherapy with cisplatin for cutaneous tumors in equidae: 573 cases (1995-2004). To determine outcome associated with cutaneous tumors treated via intratumoral chemotherapy with cisplatin and identify risk factors affecting local tumor control and complications in equidae. Methods: Retrospective case series. Methods: 573 equidae with 630 cutaneous tumors. Methods: Medical records of horses, mules, donkeys, and ponies with cutaneous tumors treated via intratumoral chemotherapy with cisplatin were analyzed. Results: 549 horses, 13 mules, 8 donkeys, and 3 ponies with 630 histologically confirmed cutaneous tumors were included. Tumors included sarcoids (n = 409), squamous cell...
Histomorphological and immunohistochemical characterization of equine granulosa cell tumours. Benign (n=33) and malignant metastasizing (n=1) granulosa cell tumours (GCTs) from 34 mares aged 3-21 years, and normal (control) ovaries from nine mares aged 3-10 years, were examined histologically and immunohistochemically (for inhibin alpha, glutathione S-transferase alpha [GSTalpha], c-erbB-2 oncoprotein [cerb], cytokeratin, vimentin, desmin and alpha-actin), the results being related where appropriate to clinical signs and endocrinological data. Availability permitting, serum samples from GCT-affected mares before and several weeks after ovariectomy were examined for the following hormon...
Confocal laser scanning analysis of an equine oral mast cell tumor with atypical expression of tyrosine kinase receptor C-KIT. A 20-year-old female horse showed a nodular, firm, focal ulcerated mast cell tumor at the right dorsobuccal face of the tongue. Histologically, the nonencapsulated tumor consisted of dense, infiltrating aggregates of well-differentiated, Cresyl violet-positive mast cells accompanied by numerous eosinophils. Furthermore, they exhibited a strong, diffuse, intracytoplasmatic immunohistochemical signal for tryptase and a faint membrane-associated and perinuclear signal for tyrosine kinase receptor KIT. Confocal laser scanning microscopy confirmed an aberrant spatial colocalization of KIT in the Go...
Three equine cases of mixed hepatoblastoma with teratoid features. Hepatoblastoma was diagnosed in 3 Thoroughbreds at the University of Kentucky Livestock Disease Diagnostic Center (LDDC) since 1997. Case #1 involved a fetus with a well-demarcated, multilobulated, solitary mass that extended from the left liver lobe. Case #2 was observed in a neonate with a primary hepatic mass and multiple metastases in the skin, brain, meninges, and stylohyoid bone. Case #3 was a solitary hepatic mass incidentally discovered in a neonate at necropsy. Microscopically, the masses were similarly composed of sheets and cords of fetal and embryonal epithelial cells that frequent...
Equine osteosarcoma: a series of 8 cases. In horses, osteosarcoma is a rare tumor, with the majority of reported cases occurring in the head, and, more specifically, in the mandible of young horses. The following report documents 8 cases of equine osteosarcoma, the majority occurring in male horses aged 7 years or older with a lack of metastasis identified in any horse. Six arose in the maxilla or mandible and one in the proximal tibia. The predominant subtype was fibroblastic osteosarcoma with fewer osteoblastic type tumors. All had osteoid and most had a chondromucinous matrix. Surgical excision was attempted in the majority of case...
Colonic ganglioneuromatosis in a horse. Ganglioneuromas are complex tumors that arise in peripheral ganglia and are composed of well-differentiated neurons, nerve processes, Schwann cells, and enteric glial cells. The term ganglioneuromatosis (GN) denotes a regional or segmental proliferation of ganglioneuromatous tissue. This report describes an 8-year-old mixed breed horse with GN in a 25-cm segment of small colon. Grossly, the lesion consisted of numerous sessile to pedunculated nodules extending from the serosal surface. Histologic examination revealed the nodules to consist of fascicles of spindle-shaped cells consistent with S...
A subcutaneous mass on the neck of a horse. A 25-year-old Arabian gelding was presented for investigation of a subcutaneous neck mass. Fine-needle aspirates and impression smears revealed mast cells with widely varying degrees of cytoplasmic granulation and scattered eosinophils. Histopathology revealed a poorly circumscribed mass composed of sheets and bundles of mast cells with a large population of eosinophils. The mast cells were separated into numerous lobules by a heavy collagenous stroma, and multifocal collagen necrosis was present. Strong reactivity of the tumor cells for both Giemsa and toluidine blue stains confirmed the diag...
