Neoplasms in horses refer to abnormal tissue growths that can be benign or malignant, affecting various body systems. These growths arise from uncontrolled cellular proliferation and can occur in different forms, including tumors and cancerous lesions. Equine neoplasms can impact the skin, gastrointestinal tract, reproductive organs, and other areas, with common types including melanomas, sarcoids, and squamous cell carcinomas. Diagnosis often involves clinical examination, imaging, and histopathological analysis. Treatment and prognosis vary depending on the type, location, and stage of the neoplasm. This page compiles peer-reviewed research studies and scholarly articles that explore the etiology, diagnosis, treatment options, and outcomes associated with neoplasms in equine patients.
Leiva M, Felici F, Carvalho A, Ramis A, Peña T.An 11-year-old Arabian mare was presented for investigation of a visible, pale-colored intraocular mass in the right eye. Results: An intraocular mass was detected clinically and ultrasonographically as originating from the superior temporal quadrant of the ciliary body and iris and causing secondary glaucoma. The echodense mass was occupying the majority of the vitreous chamber and extended into the anterior chamber. The left eye appeared normal. Results: Enucleation was recommended for therapeutic and diagnostic purposes. No adjuvant treatment was given. Histopathological examination demonst...
Durham AC, Pillitteri CA, San Myint M, Valli VE.Lymphoma is the most common malignant neoplasm in the horse. Single case reports and small retrospective studies of equine lymphomas are reported infrequently in the literature. A wide range of clinical presentations, tumor subtypes, and outcomes have been described, and the diversity of the results demonstrates the need to better define lymphomas in horses. As part of an initiative of the Veterinary Cooperative Oncology Group, 203 cases of equine lymphoma have been gathered from 8 institutions. Hematoxylin and eosin slides from each case were reviewed and 187 cases were immunophenotyped and c...
Potocki L, Lewinska A, Klukowska-Rötzler J, Bugno-Poniewierska M, Koch C, Mählmann K, Janda J, Wnuk M.It is widely accepted that equine sarcoid disease, the most common skin associated neoplasm in equids, is induced by bovine papillomavirus (BPV-1). Although BPV-1 DNA has been found in almost all examined sarcoids so far, its detailed impact on the horse's host cell metabolism is largely unknown. We used equine fibroblast cell lines originating from sarcoid biopsies to study BPV-1-associated changes on DNA methylation status and oxidative stress parameters. Sarcoid-derived fibroblasts manifested increased proliferation in vitro, transcriptional rDNA activity (NORs expression) and DNA hypometh...
Facemire PR, Facemire LM, Honnold SP.A 2-year-old gelding presented with a history of lethargy and anorexia. Physical examination revealed pleural and abdominal fluid, as well as several masses in the scrotum. The horse became acutely dyspneic despite 7 days of supportive care. Because of the poor prognosis, the owners elected euthanasia. Gross necropsy findings included multiple masses in the scrotum and inguinal canals and along the dorsal peritoneal cavity. The neoplasm infiltrated the kidneys, liver, spleen, mesenteric lymph nodes, mesentery, and abdominal surface of the diaphragm. Histologically, the neoplasm is composed of ...
Recknagel S, Nicke M, Schusser GF.To evaluate the diagnostic value of peritoneal fluid (PF) cytology for clinical diagnosis of abdominal neoplasia in horses. Methods: Ten horses with histopathologically confirmed abdominal neoplasia, in which a PF analysis was performed, were included in this retrospective study. PF was analyzed for total protein concentration and a nucleated cell count was performed. Using cytological criteria of malignancy, the PF samples were evaluated regarding their probability of malignancy. Results: Cytologic classification of cells according to criteria of malignancy allowed a positive cytologic diagno...
Strazzullo M, Corteggio A, Altamura G, Francioso R, Roperto F, D'Esposito M, Borzacchiello G.Sarcoids are peculiar equine benign tumours. Their onset is associated with Bovine Papillomavirus type -1 or -2 (BPV-1/2) infection. Little is known about the molecular interplay between viral infection and neoplastic transformation. The data regarding papillomavirus infections in human species show the inactivation of a number of tumour suppressor genes as basic mechanism of transformation. In this study the putative role of the tumour suppressor gene Fragile Histidine Triad (FHIT) in sarcoid tumour was investigated in different experimental models. The expression of the oncosuppressor protei...
Antonello AM, Pivoto FL, Camillo G, Braunig P, Sangioni LA, Pompermayer E, Vogel FS.Neospora spp. is a intracellular protozoan phylogenetically closely related to Toxoplasma gondii and Sarcocystis neurona, and it can infect horses leading to the development of reproductive or neurological diseases. We determined the presence of antibodies to Neospora sp. in mares at their parturition time and determine the frequency of vertical transmission in healthy foals to verify the importance of transplacental transmission. The samples were analyzed by indirect immunofluorescence antibody test, showing that seroprevalence in mares is higher than in foals and seropositive mares are likel...
Labelle AL, Metzler AG, Wilkie DA.Neoplasia, for which surgical excision is a frequent treatment, is the most common disease of the equine nictitating membrane. There is little long-term follow-up information available to the practitioner regarding the long-term effects of nictitating membrane excision on ocular health. No information is available to compare recurrence of primary neoplasia of the nictitating membrane after excision with local or general anaesthesia. Objective: To evaluate the long-term complications of nictitating membrane resection in horses; recurrence of neoplasia of the nictitating membrane when nictitatin...
Dobromylskyj MJ, Copas V, Durham A, Hughes TK, Patterson-Kane JC.A 9-year-old Haflinger mare presented to the Liphook Equine Hospital with a history of weight loss, azotemia, and repeated episodes of ascites over a period of 10 days. The horse was euthanized after exploratory laparotomy revealed large numbers of variably sized masses distributed throughout the peritoneal cavity. Macroscopically, some masses were papillary, while others were nodular. Histologically, the masses were comprised of large to giant, variably shaped, and occasionally multinucleated neoplastic cells with marked anisokaryosis and anisocytosis and a high mitotic rate. Small to moderat...
Underwood C, van Eps AW, Ross MW, Laverman P, van Bloois L, Storm G, Schaer TP.Liposomes are phospholipid nanoparticles that extravasate at sites of increased vascular permeability. They have potential in equine medicine for targeted drug delivery and diagnostic imaging of infectious, inflammatory and neoplastic lesions. Objective: This study evaluates the safety and biodistribution of i.v. polyethyleneglycol(PEG) liposomes in normal horses. Methods: PEG-liposomes were prepared by the film hydration method and labelled using (99m) Tc-hexamethyl-propylene-amine-oxime. A single dose of 0.24 µmol/kg bwt (99m) Tc-PEG-liposomes and 2.4 µmol/kg bwt unlabelled PEG-liposomes...
Conwell RC, Hillyer MH, Mair TS, Pirie RS, Clegg PD.This retrospective study was conducted in the UK and identifies the most frequent causes, diagnoses, treatment and prognoses for short- and long-term survival in 54 cases of horses with haemoperitoneum. Clinical signs of haemorrhagic shock and colic were common, and abdominal ultrasound was very useful for the identification of haemoperitoneum. Causes of haemoperitoneum included uterine injury (22 per cent), involvement of specific blood vessels (20 per cent), splenic injury (19 per cent), neoplasia (13 per cent) and other (4 per cent). No source was identified in 22 per cent of cases. Fifty-s...
Castleman WL, Toplon DE, Clark CK, Heskett TW, Farina LL, Lynch TM, Bryant UK, Del Piero F, Murphy B, Edwards JF.This multi-institutional report describes 8 cases of rhabdomyosarcoma in horses. Four neoplasms were in the tongue and other areas of the mouth or head, 2 were in the abdominal wall, and 1 each was in right shoulder muscles and heart. Four rhabdomyosarcomas that were less than 10 cm in diameter were treated by surgical excision or radiation with no recurrence. Two neoplasms greater than 10 cm in diameter in the abdominal wall and the right shoulder were considered inoperable and led to decisions to euthanize the horses. Two neoplasms were incidental findings at necropsy. All the neoplasms were...
Burns RE, Pesavento PA, McElliott VR, Ortega J, Affolter VK.Three horses presented with variably painful, nonulcerated masses of the head or neck that were diagnosed as glomus tumours. Grossly, they were fleshy, pink to tan masses ranging from 0.4 to 9 cm in diameter, involving either the deep dermis and subcutis or the subcutis and underlying skeletal muscle. Microscopically, neoplastic epithelioid cells were arranged in sheets, cords and packets within lobules. The neoplastic cells frequently abutted and formed nodular bulges into large endothelium-lined vascular spaces, especially around the tumour periphery. Large nerve branches were associated wit...
Knowles S, Blas-Machado U, Butler AM, Gomez-Ibañez SE, Lowder MQ, Fayrer-Hosken RA.An 11-year-old Oldenburg mare presented with a 3-month history of weight loss and swelling of the posterior right mandible. Physical examination and radiographs showed a soft-tissue mass in the right mandible with foci of mineralization, periosteal proliferation, and a retained molar. The tumor increased in size over several weeks, and the mare was euthanized. On necropsy, a 24 cm × 15 cm × 15 cm firm, white mass had obliterated the posterior right mandible. The mass was multinodular with discrete clusters of blood-filled cystic spaces. Histologically, the mass was composed of neoplastic ...
Van Den Top JG, Ensink JM, Gröne A, Klein WR, Barneveld A, Van Weeren PR.Penile and preputial tumours are not uncommon in the horse, but can cause discomfort and lead to serious complications. Several types of tumour of the male external genitalia have been described. The most common type is the squamous cell carcinoma (SCC), which is found mainly in older horses. Reports of a breed predilection for penile tumour formation are equivocal, but castration, coat colour, poor hygiene and various infectious agents have all been suggested to predispose to the development of some types of tumour (e.g. SCC, papilloma and melanoma). Careful assessment of the primary tumour i...
Hermeyer K, Seehusen F, Gehlen H, Peters M, Wohlsein P.Cutaneous malignant lymphomas are rare in horses and comprise predominantly T-cell-rich B-cell lymphomas. They are characterized by multiple tumour nodules affecting predominantly female horses with a survival rate of months to years. At the final stage, metastases to regional lymph nodes occur, whereas widespread organ involvement is rarely reported. In this case report, a cutaneous T-cell-rich B-cell lymphoma in a 7-year-old standardbred gelding with metastases is described. Clinically, multiple cutaneous and subcutaneous nodules, enlarged superficial lymph nodes, rapid weight loss, and vent...
Pusterla N, Conrad PA, Packham AE, Mapes SM, Finno CJ, Gardner IA, Barr BC, Ferraro GL, Wilson WD.Over a 2-yr study period, we investigated possible endogenous transplacental transmission of Neospora hughesi in 74 mare and foal pairs following the diagnosis of neuronal neosporosis in a weanling foal. Presuckle and postsuckle serum of each foal, serum and colostrum of each periparturient mare, and serum of each mare and foal pair, collected at 3-mo intervals thereafter, were tested for N. hughesi using an indirect fluorescent antibody test (IFAT). Furthermore, whole blood and colostrum samples and placentae were tested for the presence of N. hughesi by real-time PCR. The mares' seroprevalen...
Nell B, Walde I.Diseases of the vitreous, fundus and optic nerve are described and illustrated according to their ophthalmological appearance. Vitreal alterations are commonly of developmental, degenerative, age related, traumatic or inflammatory origin and of minor clinical relevance. In contrast, those affecting the fundus, may be accompanied by visual deficits or blindness. Fundic lesions of inflammatory (multifocal or peripapillary chorioretinitis, haemorrhage, retinal detachment) and traumatic origin have to be differentiated from congenital (congenital stationary night blindness, colobomatous defects, r...
Giuliano EA.Neoplastic adnexal disease represents one of the most frequently encountered and therapeutically challenging ophthalmic problems of horses. This paper reviews current concepts in equine periocular neoplasia. Specifically, a literature-based review of the aetiopathogenesis of the most common tumours to affect the equine eyelid (squamous cell carcinoma, sarcoid, melanoma and lymphosarcoma) is provided. Current and emerging treatment modalities, including photodynamic therapy, are reviewed.
Govaere J, Maes S, Saey V, Blancke W, Hoogewijs M, Deschauwer C, Smits K, Roels K, Vercauteren G, de Kruif A.This paper describes a case of uterine fibrosarcoma in an 18-year-old Warmblood mare. The mare had exhibited bloody fluid accumulation inside the uterus and vaginal haemorrhagic discharge since the previous foaling. The mare was euthanized, and on pathological examination, in addition to the uterine neoplasia, multiple metastases were found in the lungs, liver and spleen. The histological and immunohistochemical examination determined that the tumour was a fibrosarcoma. To our knowledge, this is the first paper to describe a uterine fibrosarcoma in a mare.
Romero A, Rodgerson DH, Fontaine GL.A 3-year-old Thoroughbred was presented for evaluation of hematuria post exercise. On physical examination, an enlarged kidney was identified, as well as serum biochemical abnormalities such as an elevated creatine kinase (CK) and hypoalbuminemia. The kidney was removed laparoscopically and a nephroblastoma was identified. Un Thoroughbred âgé de 3 ans est présenté pour évaluation de l’hématurie après l’effort. À l’examen physique, un rein enflé est identifié ainsi que des anomalies biochimiques sériques comme une créatine kinase (CK) élevée et l’hypoalbuminémie. Le rein...
Shahriar F, Moore J.Thymic malignancy is rare in horses. Thymic epithelial tumor was diagnosed in an 18-year-old mare with invasion and metastasis to the pericardium and heart. At necropsy, the cranial thoracic cavity was obliterated by a large mass located in the thymic region and the right atrium was also expanded and effaced by a similar mass. Histologically, the neoplasm was composed of sheets of spindle cells with intraparenchymal Hassall's corpuscles and formation of pseudorosettes around blood vessels compatible with type A thymic epithelial tumor according to World Health Organization classification. The ...
Snook ER, Wakamatsu N.A 17-year-old, Thoroughbred mare was presented for necropsy with a large, invasive oral mass determined via immunohistochemistry to be a soft tissue sarcoma of neural origin. Oral sarcomas are rare in veterinary medicine, and to the authors' knowledge, this is the first oral sarcoma of neural tissue origin reported in a horse.
Haralambus R, Burgstaller J, Klukowska-Rötzler J, Steinborn R, Buchinger S, Gerber V, Brandt S.Sarcoids are nonmetastasising, yet locally aggressive skin tumours that constitute the most frequent neoplasm in equids. Infection by bovine papillomaviruses types 1 and 2 (BPV-1, BPV-2) has been recognised as major causative factor in sarcoid pathogenesis, but a possible correlation of intralesional virus load with disease severity has not been established thus far. Objective: Given the pathogenic role of BPV-1 and BPV-2 in sarcoid disease, we suggest that intralesional viral DNA concentration may reflect the degree of affection. Methods: Severity of disease was addressed by recording the tum...
Millward LM, Hamberg A, Mathews J, Machado-Parrula C, Premanandan C, Hurcombe SD, Radin MJ, Wellman ML.A 6-year-old female Rocky Mountain horse was presented for evaluation of draining tracts and distal limb subcutaneous edema on the left front and left hind limbs that had been present for 2 weeks. Direct smears of fluid collected by fine-needle aspiration of subcutaneous fluid from both limbs were highly cellular with a predominance of eosinophils accompanied by numerous, moderately atypical, variably granulated mast cells. The cytologic diagnosis was mast cell tumor (MCT) with prominent eosinophilic infiltration with a differential diagnosis of eosinophilic granuloma. Histologic evaluation of...
Cribb NC, Bouré LP.To describe laparoscopic removal of a large testicular teratoma in a standing horse. Methods: Clinical report. Methods: Thoroughbred horse (11 months) with a testicular teratoma. Methods: A unilateral cryptorchid testicle could not be removed by an inguinal approach under general anesthesia because of it s large size. After recovery from general anesthesia, ultrasound evaluation revealed a 24 x 19 cm fluid-filled testicular mass. The mass was removed by paralumbar fossa laparoscopy with the horse in a standing position. After fluid aspiration of the mass, the mesorchium and ductus deferens wer...
Herbach N, Breuer W, Hermanns W.Post-mortem examination was performed on a horse that died after exhibiting signs of colic. Gross findings included haemoperitoneum and a large round encapsulated mass located in the sublumbar area cranial to the left kidney. On sectioning the mass was solid red to brown and small nodules of similar tissue were noted at the periphery of the mass. The spleen was firm and three nodules were found in one thyroid gland. Microscopically, the abdominal mass, adjacent nodules, the spleen and one thyroid nodule consisted of clusters and cords of round to oval neoplastic cells, separated by a fine coll...
Tura G, Savini F, Gallina L, La Ragione RM, Durham AE, Mazzeschi M, Lauriola M, Avallone G, Sarli G, Brunetti B, Muscatello LV, Girone C, Bacci B.Sarcoids are the most common cutaneous tumor of equids and are caused by bovine papillomavirus (BPV). Different clinical subtypes of sarcoids are well characterized clinically but not histologically, and it is not known whether viral activity influences the clinical or histological appearance of the tumors. The aim of this study was to verify whether the development of different clinical types of sarcoids or the presence of certain histological features were associated with BPV distribution within the tumor. The presence of BPV was assessed by polymerase chain reaction (PCR) and visualized in ...
Honnas CM, Snyder JR, Olander HJ, Wheat JD.A 21-year-old mare was evaluated for intermittent episodes of apparent abdominal pain of 6 month's duration. Abdominal palpation per rectum revealed distended small intestine in the caudal portion of the abdomen. Ventral midline celiotomy revealed a mass in the midjejunal region. The mass was resected, and a side-to-side anastomosis performed. The histologic diagnosis was tubular adenocarcinoma of the small intestine. The mare was still alive 13 months after surgery.
Sheahan BJ, Atkins GJ, Russell RJ, O'Connor JP.Two aged mares with histiolymphocytic lymphosarcoma had multiple rapidly proliferating tumours in the subcutis. Consistent haematological changes were absent. One mare had lymph node involvement but no neoplastic lesions in the viscera. Microbiological examination of tumour tissue showed coryneform bacteria; there was no evidence of C-type or lytic viruses or of reverse transcriptase. Prominent intramitochondrial crystalline inclusions were in histiocytic tumour cells.
Orsini JA, Nunamaker DM, Jones CJ, Acland HM.A large oral squamous cell carcinoma in a 27-year-old Arabian stallion was removed by partial excision of the incisive bone. There was no gross evidence of recurrence or metastasis 5 months later.
Rosol TJ, Nagode LA, Robertson JT, Leeth BD, Steinmeyer CL, Allen CM.Humoral hypercalcemia of malignancy was evident in a horse that had a locally invasive ameloblastoma of the left hemimandible. Surgical removal of the neoplasm resulted in prompt return of serum calcium and parathyroid hormone concentrations to within reference limits. The tumor contained parathyroid hormone-related protein, as demonstrated by immunohistochemistry and western blot analysis. It is likely that production of this protein by the neoplasm was important in the pathogenesis of the hypercalcemia. The case represented a sporadic form of humoral hypercalcemia of malignancy attributable ...
Thompson R, Armién AG, Rasmussen JM, Wolf TM.A 25-yr-old, nulliparous, female Przewalski's wild horse (Equus ferus przewalskii) with a history of pituitary pars intermedia dysfunction and recent onset of serosanguinous vaginal discharge was euthanized after a period of lethargy and inappetance. Postmortem examination confirmed an infiltrative uterine adenocarcinoma, which is an uncommon neoplasia in equids. Reproductive disease is significant in this species as they are considered endangered by IUCN. Reproductive soundness and success are paramount to conservation efforts.
Rangel-Sánchez IY, Salas-Treviño D, Soto-Domínguez A, Garza-Rodríguez OI, Saucedo-Cárdenas O, Zapata-Benavides P, Zarate-Ramos JJ....The Wilms' tumour gene (WT1) has previously been described as an oncogene in several neoplasms of humans, including melanoma, and its expression increases cancer cell proliferation. Recent reports associate the expression of the PPARβ/δ gene (peroxisome proliferator-activated receptor beta/delta) with the downregulation of WT1 in human melanoma and murine melanoma cell lines. The aim of this work was to analyse the expression of WT1 and its association with PPARβ/δ in samples of healthy and melanoma-affected skin of horses by immunohistochemistry. WT1 protein expression was detected in hea...
Ricketts SW, Peace CK.The report describes a case of abdominal neoplasia in a mare diagnosed ante-mortem by the technique of paracentesis abdominis. Histopathological findings suggest that the lesion was a mesothelioma, primarily involving the greater omentum.
Mills JH, Fretz PB, Clark EG, Ganjam VK.An ovarian neoplasm measuring 10 by 8 by 6 cm was surgically removed from a 14-year-old Appaloosa mare. For 2 years prior to surgery, the mare had manifested marked behavioral changes, becoming aggressive toward other broodmares. Histologically, the tumor was found to be an arrhenoblastoma. Preoperative endocrinologic findings (high serum testosterone and low serum estradiol concentrations) supported the diagnosis.
Hacker DV, Moore PF, Buyukmihci NC.In 4 horses with ocular angiosarcomas, the common characteristics were that all horses were aged, and the neoplasms developed initially on conjunctival surfaces, grew slowly, and metastasized despite excision and radiation treatment. Histopathologically, the neoplasms were of 2 types: a capillary pattern of scant stroma and endothelial-lined vascular channels, and a solid pattern composed of sheets of pleomorphic cells with hyperchromatic nuclei and poorly defined cytoplasmic borders. Definitive diagnosis was made by use of factor VIII:RAg, which stained the tissues intensely.
Hance SR, Bertone AL.Equine tumors are rather uncommon; however, of the body regions, the head is a relatively common location for neoplasia, including sarcoids and squamous cell carcinomas of the skin, tumors of the sinus/nasal cavity, and bony tumors of the head. Tumors discussed in the article include odontogenic and bony tumors; sarcoids; tumors of the guttural pouch and pharyngeal and oral mucosa; tumors of the larynx; and tumors of the paranasal sinuses and nasal passages. In general, tumors involving deeper structures of the head carry a poor prognosis; however, some tumors such as sarcoids, ossifying fibro...
Rebhun WC.This article reviews options in dealing with tumors of the cornea and conjunctiva, nictitating membrane neoplasms, and eyelid neoplasms. Orbital tumors, optic nerve and other intraocular tumors are also discussed.
Ford GH, Empson RN, Plopper CG, Brown PH.Masses removed from the superficial fascia of the jugular groove of a 12-year-old Arabian mare and from the femoral canal of a 7 1/2-year-old female cat appeared to be counterparts of the human malignant giant cell tumor of soft parts, even recapitulating the clinical behavior of the respective subgroups. Histologically, both neoplasms contained the characteristic features of the malignant giant cell tumor of soft parts: large multinucleate giant cells, pleomorphic mononuclear giant cells, histiocytes, fibroblasts and fibrocytes that were sometimes sarcomatous, and foci of hemorrhage and necro...
Gearhart PM, Steficek BA, Peteresen-Jones SM.A 12-year-old Belgian draft horse presented for a right eye third eyelid mass and red-tinged ocular discharge of 3 months' duration. The third eyelid was excised and submitted for histopathology. On histopathologic examination, the mass was composed of both hemangiosarcoma and squamous cell carcinoma. The horse developed thickened eyelids and hemorrhagic ocular discharge from the right eye approximately 16 months following surgery, and was euthanized. Necropsy and histopathology confirmed local recurrence and regional metastasis of the hemangiosarcoma. This was an unusual case because there we...
Dalefield RR, Palmer DN.Thyroid tumours have been described as "moderately common" in horses, but diseases associated with them are rare and the actual incidence has not been reported. A survey of thyroids from 29 horses aged 12 to 32 years revealed gross lesions in 11 animals, all older than 17. Most lesions were microfollicular adenomas. There was no evidence that the horses suffered from long-standing iodine deficiency or diffuse hyperplasia. Adenomas were more common than hyperplastic nodules and it is unlikely that the former arose from the latter. One thyroid adenocarcinoma was discovered. Progression from thyr...
Hübers E, Bauer N, Fey K, Moritz A, Roscher K.The retrospective study aimed to evaluate the prevalence of true thrombocytopenia and ethylenediaminetetraacetic acid (EDTA)-induced pseudothrombocytopenia in horses and ponies and to assess the diagnostic and prognostic utility of true thrombocytopenia. Methods: In 3592 patients (2008-2015) hematological data (ADVIA® 2120, Siemens) were reviewed. Inclusion criteria were platelet counts < 90 x 109/l (EDTA-blood) and/or < 84 x 109/l (citrate blood). Thrombocytopenia was classified as true, EDTA-induced, and questionable. Patients with true thrombocytopenia were assigned to nine groups ac...
Karcher LF, Le Net JL, Turner BF, Reimers TJ, Tennant BC.An 18-year-old Appaloosa mare was examined because of squamous cell carcinoma of the vulva, anorexia with pronounced weight loss, and hypercalcemia. The tumor had developed rapidly over a period of 3 months and externally extended ventrally involving the perineum and the dorsal aspect of the udder. Necropsy examination demonstrated a large primary squamous cell carcinoma of the vulva, perineum, and mammary gland with metastases to the supramammary, sublumbar, deep inguinal, and mediastinal lymph nodes. No gross renal lesions were observed and, histologically, there was only mild vacuolation of...
Pusterla N, Stacy BA, Vernau W, De Cock HE, Magdesian KG.The clinical findings in two horses with secretory multiple myeloma and secondary immunoglobulin A (IgA) monoclonal gammopathy were non-specific and included weight loss, pale mucous membranes, limb oedema and bacterial respiratory tract infection. Consistent laboratory abnormalities included hyperproteinaemia, hyperglobulinaemia, hypoalbuminaemia and hypercalcaemia. The diagnosis was based on the presence of IgA monoclonal gammopathy in serum and urine and bone marrow plasmacytosis (> 10 per cent). One horse was euthanased; it had neoplastic plasma cell infiltrates in its kidneys, spleen, ...
Smith FL, Magdesian KG, Michel AO, Vaughan B, Reilly CM.A new syndrome of hematuria in horses has been documented. Objective: Hemorrhagic cystitis is a novel cause of stranguria and hematuria in horses. This syndrome may be difficult to differentiate from bladder neoplasia because they share several clinical features. Methods: Eleven horses with idiopathic hemorrhagic cystitis and 7 horses with bladder neoplasia. Methods: Retrospective cohort study. Results: Hemorrhagic cystitis was detected on cystoscopy of affected horses, with hemorrhagic and thickened apical bladder mucosa. Clinical signs and endoscopic appearance of the bladder resolved within...
IJzer J, van den Ingh TS.A 15-year-old Dutch Warmblood mare presented with respiratory distress and anorexia. Clinical examination revealed liquothorax and an abdominal mass. At necropsy, an infiltrating tumour was found in the visceral trunk, continuing through the diaphragm into the mediastinum. Histopathology, immunohistochemistry and electronmicroscopy showed empty channels lined by atypical endothelial cells, and neoplastic cells in a disorganized pattern, consistent with the diagnosis of a lymphangiosarcoma.
Knowles S, Blas-Machado U, Butler AM, Gomez-Ibañez SE, Lowder MQ, Fayrer-Hosken RA.An 11-year-old Oldenburg mare presented with a 3-month history of weight loss and swelling of the posterior right mandible. Physical examination and radiographs showed a soft-tissue mass in the right mandible with foci of mineralization, periosteal proliferation, and a retained molar. The tumor increased in size over several weeks, and the mare was euthanized. On necropsy, a 24 cm × 15 cm × 15 cm firm, white mass had obliterated the posterior right mandible. The mass was multinodular with discrete clusters of blood-filled cystic spaces. Histologically, the mass was composed of neoplastic ...
Recknagel S, Nicke M, Schusser GF.To evaluate the diagnostic value of peritoneal fluid (PF) cytology for clinical diagnosis of abdominal neoplasia in horses. Methods: Ten horses with histopathologically confirmed abdominal neoplasia, in which a PF analysis was performed, were included in this retrospective study. PF was analyzed for total protein concentration and a nucleated cell count was performed. Using cytological criteria of malignancy, the PF samples were evaluated regarding their probability of malignancy. Results: Cytologic classification of cells according to criteria of malignancy allowed a positive cytologic diagno...
Ogden NKE, Jukic CC, Zedler ST.To describe a surgical technique for rostral mandibulectomy and reconstruction of the mandibular symphysis. Methods: Case report. Methods: One 5-month-old warmblood cross filly. Methods: A preoperative diagnosis of a juvenile ossifying fibroma was made on the basis of clinical appearance and was later confirmed via histology. The tumor was large, rapidly growing and extending to the caudal aspect of the mandibular symphysis. Computed tomography was performed for surgical planning. The tumor was excised by performing a mandibulectomy caudal to the symphysis. The mandibular symphysis was reconst...
Zehetner V, Cavalleri JV, Klang A, Hofer M, Preining I, Steinborn R, Ramsauer AS.There is strong evidence that equine parvovirus-hepatitis (EqPV-H) is associated with the onset of Theiler's disease, an acute hepatic necrosis, in horses. However, the impact of this virus on other hepatopathies remains unknown. The objective of this retrospective study was to evaluate the prevalence and quantify the viral loads of EqPV-H in formalin-fixed, paraffin-embedded equine and donkey livers with various histopathologic abnormalities. The pathologies included cirrhosis, circulatory disorders of the liver, toxic and metabolic hepatic diseases as well as neoplastic and inflammatory dise...
Johnson JE, Beech J, Saik JE.A 6.5-year-old horse with a history of exercise-induced pulmonary hemorrhage was admitted because of acute onset of epistaxis, dyspnea, high respiratory rate, pale mucous membranes, and dark feces. There was no clinical or laboratory evidence of a bleeding disorder, and the horse's anemia was considered to be secondary to pulmonary hemorrhage. The cause of the hemorrhage was not found on thoracic sonograms or from cytologic examination of transtracheal aspirates. Despite supportive care, the horse's health deteriorated, and it was euthanatized. Necropsy revealed blood in the thoracic and perit...
MacGillivray KC, Graham TD, Parente EJ.A 2-year-old male Thoroughbred was evaluated for multiple firm, raised nodules of the maxilla and mandible that had been present since 6 months of age. The horse was evaluated as a yearling with a final histologic diagnosis of fibrosarcoma. As a 2-year-old, the colt made a loud upper airway sound and was agitated after strenuous exercise. Results of upper airway endoscopy indicated severe narrowing of the nasal passages and pharynx with normal resting function. Radiography revealed multiple circular bony lesions in the mandible, maxilla, multiple long bones, and cervical vertebrae. Biopsy spec...
Sedrish SA, McClure JR, Pinto C, Oliver J, Burba DJ.A 12-year-old Morgan mare was examined because of stallion-like behavior of 45 days' duration. Palpation per rectum and transrectal ultrasonographic examination revealed a large left ovary with multiple cystic areas and crepitus. A granulosa-theca cell tumor was suspected. During hospitalization for further evaluation of the affected ovary, the mare developed signs of abdominal pain. Exploratory surgery revealed a large left ovary, which was black with a necrotic and friable surface, and a 720 degrees clock-wise torsion of the ovarian pedicle. Torsion was corrected, and oophorectomy was perfor...
McEntee MF.Thirty equine cutaneous mastocytomas were examined histologically and two were studied ultrastructurally. Lesions were characterized by distinct sheets of well-differentiated mast cells with variable degrees of eosinophil infiltration, collagen degeneration, necrosis, granulomatous inflammation and fibrosis. Twenty-two of 25 growths did not recur for up to 6 years after surgical excision, two recurred at the surgical site and one spontaneously regressed less than 3 months after obtaining a biopsy sample. Equine cutaneous mastocytoma is a benign proliferative lesion which seldom recurs after ex...
Hall WC, Nielsen SW, McEntee K.Tumours of the male genital tract, excluding the testes, are relatively rare in the six major domestic animals. The most important tumours are prostate carcinoma and transmissible venereal tumour of the penis in dogs, fibropapilloma of the penis in bulls, squamous papilloma and squamous cell carcinoma in horses, and squamous papilloma in pigs. Four histological types of canine prostate carcinoma exist: alveolar papillary, acinar, organoid, and poorly differentiated. The biological behaviour of prostate carcinomas is similar to that in man, with frequent metastasis to the regional pelvic nodes,...
Charles LN.A 3-year-old Quarter Horse mare presented with an approximate 1-month history of progressive weight loss, anorexia and lethargy that abruptly worsened 48 h before death. Post-mortem examination revealed free flocculent fluid and a large mass within the ventral abdomen that dorsally displaced the caecum and large intestine. An ovarian teratocarcinoma with metastasis to regional lymph nodes was diagnosed histologically. Although benign teratomas are the second most common ovarian neoplasm in equids, reports of malignant teratomas in horses are rare. This report documents an unusual presentation...
