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.
de Brot S, Junge H, Hilbe M.Two horses were presented with non-specific clinical signs of several weeks' duration and were humanely destroyed due to a poor prognosis. At necropsy examination, both horses had multiple small, white nodules replacing pancreatic tissue and involving the serosal surface of the abdominal cavity, the liver and the lung. Microscopically, neoplastic cells were organized in acini and contained abundant (case 1) or sparse (horse 2) intracytoplasmic zymogen granules. Immunohistochemically, both tumours expressed amylase and pan-cytokeratin, but not insulin or neuron-specific enolase. In case 2, a lo...
Pérez-Écija A, Estepa JC, Barranco I, Rodríguez-Gómez IM, Mendoza FJ, Gómez-Laguna J.Verrucous hemangiomas are a rare specific variant of equine skin tumors not well described in the literature. An 8-year-old gelding presented a unilateral lesion on the pastern. Macroscopically, the mass showed a warty and verrucous surface with focal ulcerations. The histology showed a dermal proliferation of endothelial-layered capillaries and venules separated by a delicate stroma of scant fibroblasts and collagen deposition, with pseudoepitheliomatous hyperplasia (exuberant reactive irregular epithelial hyperplasia with tongue-like projections extending into the dermis, mimicking downgrowt...
Laus F, Rossi G, Paggi E, Bordicchia M, Fratini M, Tesei B.Tumors involving the oral cavity of the horse are uncommon. No cases of equine adenocarcinoma on the dorsum of the tongue have been reported in the literature. We report a case of adenocarcinoma located on the dorsum of the posterior one-third of the tongue in a 29-year-old gelding with severe dysphagia. Endoscopy revealed an epiglottis involvement, and histology was consistent with adenocarcinoma arising from minor salivary glands, which was associated with a severe fungal colonization of affected tissues. The goals of this report are to present an uncommon case of dorsum of the tongue-associ...
Bergvall KE.Sarcoids are the most common skin tumors seen in horses worldwide. The pathogenesis of sarcoids is multifactorial, including an association with bovine papillomavirus types 1 and 2 and a genetic susceptibility to tumor development. Clinical manifestations vary and include occult, verrucous, nodular, fibroblastic, mixed, and malignant (malevolent) types. The tumor is nonmetastasizing but can become very aggressive locally. Multiple tumors are common. All clinical types can be present in the same horse. No treatment protocol is universally effective. The tumor has a high risk of recurrence. Recu...
Dixon PM, Loh N, Barakzai SZ.Disorders of the horizontal ramus (body) of the equine mandible are well reported, but there is minimal documentation of disorders of the angle of mandible. A retrospective examination of the records of Edinburgh University Equine Hospital (1997-2011) showed that 32 horses were referred due to swellings of the angle of the mandible. The aetiology of these swellings was identified in just 13/32 cases (41%) including fractures (n=2), traumatic, localised periosteal/cortical lesions (n=4), traumatic soft tissue lesions (n=2), neoplasia (n=3), and inflammation of the adjacent salivary gland (n=1) ...
Rizk A, Mosbah E, Karrouf G, Abou Alsoud M.Penile and preputial neoplasia in horses occurs infrequently and represents diagnostic and therapeutic challenges. The present study was carried out on a total number of 21 equids (14 stallions and 7 donkeys) suffered from different penile and preputial neoplasia. Diagnosis of neoplasms was based up on history of the case, clinical examination as well as histopathological evaluation. Animals with penile and preputial neoplasms were underwent local excision and partial phallectomy with a slightly modified version of the techniques described by William's. The diagnosed neoplasms were penile and ...
Halse S, Pizzirani S, Parry NM, Burgess KE.A 3-year-old Marwari mare was presented for evaluation of an irregular, reddish mass protruding from behind the right third eyelid. The mass appeared to arise at the ventral limbal area, involved the perilimbal bulbar conjunctiva and widely extended into corneal tissue. No other ocular or systemic abnormalities were detected at the time of presentation. The mass was surgically removed by lamellar keratectomy, with defocused CO(2) laser used as adjunctive therapy to treat the surgical exposed area and its surroundings. Histopathologic evaluation showed sheets of densely packed, well-differentia...
Herbach N, Nagel L, Zwick T, Hermanns W.Pancreatic neuroendocrine tumors of glucagon-producing cells are extremely rare in domestic animals. In this report, we describe for the first time, to our knowledge, the incidental finding of multiple glucagon-producing neuroendocrine tumors of the pancreas of a horse. The animal was euthanized due to severe local infection after tooth extraction. On postmortem examination, multiple white nodules of up to 4 cm in diameter were observed in the pancreas. Histologically, pancreatic nodules had the appearance of neuroendocrine neoplasms with positive immunoreactivity for glucagon, synaptophysin, ...
Hildebrandt L, Jäger K, Snyder A, Sobiraj A.The case report describes a narrowing of the spinal canal in the lumbar and sacroiliac regions with entailing acute recumbency in a nearterm 17-year-old Welsh B Pony mare. The reason for recumbency was metastases of a malignant melanoma in the spinal canal of the lumbo-sacral region, where the tumour had invaded the dura mater and applied severe pression on the spinal cord over a length of 10 cm. Clinical findings, laboratory diagnostics, pathological-anatomical and histopathological findings are presented.
Shon W, Folpe AL.Cartilaginous tumors of soft tissue are uncommon, with benign chondromas of soft parts greatly outnumbering rare soft-tissue chondrosarcomas. Over the past several years, we have seen in consultation a distinctive, benign-appearing chondroid soft-tissue lesion of the plantar foot that differs in a number of respects from chondroma of soft parts. Herein we report our experience with this distinctive lesion. A retrospective review of all cases from the foot in our soft-tissue consultation and institutional surgical pathology archives identified 9 similar cases, most often previously coded as 'fi...
Lunardi M, de Alcântara BK, Otonel RA, Rodrigues WB, Alfieri AF, Alfieri AA.Equine sarcoids are locally aggressive fibroblastic neoplasms considered to be the most common skin tumors of horses worldwide. Bovine papillomavirus types 1 and 2 have typically been associated with sarcoids in equids. Investigations aiming to identify papillomavirus strains, aside from bovine papillomaviruses 1 and 2, which might be associated with sarcoid lesions, have been lacking. The aim of this article is to report the identification of a third bovine papillomavirus type, bovine papillomavirus 13, associated with equine sarcoids. Six sarcoid lesions were collected from diverse anatomica...
Ramos-Vara JA, Frank CB, DuSold D, Miller MA.The immunoreactivity of PNL2, Melan A, and protein gene product (PGP) 9.5 was compared with that of S100 protein in 50 formalin-fixed, paraffin-embedded equine melanocytic neoplasms. PNL2, PGP 9.5, and S100 protein were detected in all 50 neoplasms; none expressed Melan A. PNL2 was not expressed in 62 nonmelanocytic tumors (equine sarcoids, schwannomas, carcinomas, sarcomas, endocrine tumors, sex-cord stromal tumors, germ cell tumors, and leukocytic tumors) or in normal tissues other than epidermis. In summary, antibody PNL2 is a sensitive marker of equine melanocytic neoplasms and is more spe...
Schaffer PA, Wobeser B, Martin LE, Dennis MM, Duncan CG.To identify epidemiological trends in cutaneous neoplasms affecting equids in central North America and compare them with previously reported trends. Methods: Retrospective case series. Methods: 3,351 cutaneous biopsy specimens from 3,272 equids with a neoplastic diagnosis. Methods: Diagnostic reports from 2 diagnostic laboratories (Colorado State University and Prairie Diagnostic Services Inc) were reviewed for frequency of specific lesions and epidemiological trends. Variables included in analyses (if known) were age, sex, breed, geographic location, date of diagnosis, location of neoplasm o...
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...
Tesena P, Kingkaw A, Phaonakrop N, Roytrakul S, Limudomporn P, Vongsangnak W, Kovitvadhi A.Equine melanocytic neoplasm (EMN) is a common disease in older grey horses. The purpose of this study was to examine the potential proteins throughout EMN stages from faecal proteomic outlining using functional analysis. Faecal samples were collected from the rectum of 25 grey horses divided into three groups; normal group without EMN ( = 10), mild EMN ( = 6) and severe EMN ( = 9). Based on the results, 5910 annotated proteins out of 8509 total proteins were assessed from proteomic profiling. We observed differentially expressed proteins (DEPs) between the normal group and the EMN group, and 1...
Bogaert L, Woodham AW, Da Silva DM, Martens A, Meyer E, Kast WM.Equine sarcoids are highly recurrent bovine papillomavirus (BPV)-induced fibroblastic neoplasms that are the most common skin tumours in horses. In order to facilitate the study of potential equine sarcoid prophylactics or therapeutics, which can be a slow and costly process in equines, a murine model for BPV-1 protein-expressing equine sarcoid-like tumours was developed in mice through stable transfection of BPV-1 E5 and E6 in a murine fibroblast tumour cell line (K-BALB). Like equine sarcoids, these murine tumour cells (BPV-KB) were of fibroblast origin, were tumorigenic and expressed BPV-1 ...
McMullen RJ, Clode AB, Pandiri AK, Malarkey DE, Michau TM, Gilger BC.A case of epibulbar melanoma in a 6-month-old, gelded, chestnut Hanoverian foal is reported. The location and clinical appearance upon initial presentation led to the tentative diagnosis of staphyloma or a congenital mass of unknown origin. An attempt was made to surgically excise the mass under general anesthesia, but due to its infiltrative nature and intraoperative appearance, most, but not all was removed without compromising the integrity of the globe. Histopathological evaluation revealed a multinodular to packeted, poorly demarcated, unencapsulated, infiltrative exophytic melanocytic ne...
Tennant B, Keirn DR, White KK, Bentinck-Smith J, King JM.Six cases of squamous cell carcinoma of the stomach in horses seen at the New York State College of Veterinary Medicine are compared with 15 similar cases reported previously. Clinical signs included anorexia in all cases, emaciation, fever, anaemia and/or palpable abdominal masses in 3, colic in 2 and dysphagia in one case. Haematological studies revealed normochromic, normocytic anaemia in 3 and absolute neutrophilia in 5 cases. Peritoneal fluid analysis was performed in 4 cases and revealed slightly to moderately elevated total protein concentrations in 3 and a markedly elevated number of w...
Bistner S, Campbell RJ, Shaw D, Leininger JR, Ghobrial HK.A nine-year-old horse was presented with severe exophthalmos of the right eye and a large mass in the vitreal cavity. The affected globe was enucleated and two months following surgery the horse was euthanized because of spread of the tumor into the calvarium producing compression of the brain stem and neurologic signs. Examination of tumor tissue by light and electron microscopic examination showed a mixed neoplasm of primitive neuroepithelium.
Kelton DR, Holbrook TC, Gilliam LL, Rizzi TE, Brosnahan MM, Confer AW.A 14-year-old spayed American Paint mare was evaluated for mild colic, anorexia, pyrexia, and pancytopenia. Physical examination revealed mild tachycardia, tachypnea, and pale mucous membranes. Serial laboratory analyses revealed progressive pancytopenia, hyperfibrinogenemia, and hyperglobulinemia. A few large atypical cells were observed in peripheral blood smears. Results of tests for equine infectious anemia and antipenicillin antibody were negative. Serum protein electrophoresis indicated a polyclonal gammopathy. Smears of bone marrow aspirates contained hypercellular particles, but cell l...
Martano M, Altamura G, Power K, Liguori P, Restucci B, Borzacchiello G, Maiolino P.It is well known that δ-bovine papillomaviruses (BPV-1, BPV-2 and BPV-13) are one of the major causative agents of equine sarcoids, the most common equine skin tumors. Different viruses, including papillomaviruses, evolved ingenious strategies to modulate autophagy, a complex process involved in degradation and recycling of old and damaged material. Methods: The aim of this study was to evaluate, by immunohistochemistry (IHC) and Western blot (WB) analysis, the expression of the main related autophagy proteins (Beclin 1, protein light chain 3 (LC3) and P62), in 35 BPV1/2 positive equine sarco...
Ragle CA, Southwood LL, Hopper SA, Buote PL.Two mares were admitted for ovariectomy of unilateral granulosa cell tumors. Both mares were ovariectomized (1 unilateral and 1 bilateral) by use of a ventral abdominal laparoscopic technique. This approach required tilting the operative table 30 degrees to elevate the pelvis and to allow observation of the ovaries. Using a single laparoscopic portal and 3 to 4 instrument portals, a triangulation technique was used. The ovarian pedicles were isolated and secured via loop ligation. The ovaries then were divided from the ligated pedicle and placed within specimen bags for extraction. The specime...
Rassnick KM, Njaa BL.Squamous-cell carcinoma (SCC) is the second most common tumor in horses, and 40%-50% may occur in ocular and adnexal structures. Cyclooxygenase (COX)-2 is an inducible enzyme responsible for the production of prostaglandins that control cell growth and the development and progression of cancer. Mechanisms responsible for the initial upregulation of COX-2 in neoplasia are unclear; prolonged sunlight exposure and mutations in the p53 gene may be possibilities. Because the etiopathogenesis of ocular SCC in horses may involve ultraviolet sunlight and p53 mutations, the purpose of this study was to...
Clark TL.The rarity of equine ovarian neoplasms is attested to by the lack of reports in the literature. However, sixteen cases have been diagnosed at the Iowa State University Veterinary Hospital in the last 3 years and, of these, the granulosa-cell tumour was the most common. A study of the clinical and subsequent histories of these and other mares reveals some common findings as to age, breed, reproductive status, clinical signs, and post-surgical reproductive capability.
Roxon C, Slack J, Bender S, Burns H, Turner R.A 12-year-old Standardbred stallion presented with a 5-month history of a growing mass in the left testis as well as an overall decrease in left testicular size. Palpation and ultrasonography of the left testis revealed a firm, hypoechoic, clearly delineated soft tissue mass in the craniolateral portion of the testis that measured 2.5 × 2.3 × 1.9 cm. Two smaller, hypoechoic regions also were visible ultrasonographically in the left testis, suggesting the presence of multifocal/multicentric neoplasia. The affected testis was very small (testicular volume of 40.3 cm). The right testis was ...
Walker MA, Schumacher J, Schmitz DG, McMullen WC, Ruoff WW, Crabill MR, Hawkins JF, Hogan PM, McClure SR, Vacek JR, Edwards JF, Helman RG, Frelier PF.Three adult horses underwent aggressive treatment of squamous cell carcinoma of the nasal cavity and paranasal sinuses, using course-fractionated cobalt 60 radiotherapy. Squamous cell carcinoma of the nasal cavity and paranasal sinuses is not commonly diagnosed in horses. Historically, horses with this type of neoplasm have not been treated or have undergone some form of surgery. The prognosis for long-term survival or cure has been poor. Long-term results of cobalt 60 radiotherapy were good to excellent and exceeded those usually reported for horses treated surgically. On the basis of these r...
Szymanski CM.Enlargement of the left eye, corneal opacification, and blindness were clinical signs of a teratoid medulloepithelioma in a 5-year-old Standardbred mare. Diagnosis was made on histologic examination of the enucleated eye. Medulloepitheliomas are congenital intraocular tumors arising from primitive ciliary body epithelium. Their development is rare in domestic animals.
Henson KL, Alleman AR, Kelley LC, Mahaffey EA.Immunohistochemical techniques were used to examine 29 cases of equine lymphoma for estrogen receptor (ER) and progesterone receptor (PR) expression. The lymphomas examined included T-cell-rich large B-cell lymphomas, B-cell neoplasms, and T-cell lymphomas. The individual cases were also classified according to the anatomic location of the tumors. One normal equine lymph node was also examined for ER and PR expression. All of the cases of equine lymphoma and the normal lymph node were negative for Er. A total of 16/29 (55%) PR-positive lymphomas were identified. Seven of the 12 (58%) T-cell-ri...
Baker JL, Aleman M, Madigan J.Clinically apparent hypoglycemia is rare in adult horses. Hypoglycemia is a well-recognized paraneoplastic syndrome in humans and dogs with non-insulin-secreting tumors and may occur in horses as well. Hypoglycemia associated with non-insulin-secreting tumors is believed to result from production of an abnormal form of insulin-like growth factor II. Neoplasia should be considered in the differential diagnosis for adult horses with hypoglycemia.
Loynachan AT, Bolin DC, Hong CB, Poonacha KB.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...
Green SL, Specht TE, Dowling SC, Nixon AJ, Wilson JH, Carrick JB.A neonatal foal was examined because of apparent abdominal pain and distention, anemia, and hemoperitoneum. Exploratory laparotomy was performed, and a large spherical mass, which had ruptured, was found in the area of the left ovary. Left salpingo-oophorectomy was performed. The mass was determined to be a juvenile granulosa cell tumor.
Conley AJ, Scholtz EL, Dujovne G, Cotterman RF, Legacki EL, Uliani RC, Alvarenga MA, Ball BA, Kalra B, Savjani GV, Kumar A.Studies in mares have examined serum inhibin concentrations using immuno-assays unable to distinguish dimeric inhibin-A from inhibin-B isoforms. Inhibin-A and inhibin-B immuno-assays were used to investigate concentrations in cyclic mares, young and old (6 vs 19 years old, respectively) mares following hemi-ovariectomy, mares during pregnancy and in mares with confirmed granulosa cell tumors (GCTs). Mares with inter-ovulatory intervals of 26 days had ovulatory peaks of inhibin-A averaging 80 pg/mL with a mid-cycle nadir of 5 pg/mL. Inhibin-A and inhibin-B concentrations were highly correlate...
Herraez P, Berridge B, Marsh P, Weeks B, Ramiro-Ibañez F.A 12-year-old Appaloosa gelding was referred to the Texas Veterinary Medical Center with a history of chronic diarrhea and weight loss. At necropsy, numerous oval, craterlike ulcers were observed throughout the small intestine. Histologically, these lesions were composed of a neoplastic proliferation of round cells with intracytoplasmic phosphotungstic acid-hematoxylin-positive granules. The tumor cells stained positively for the CD3 antigen and negatively for a B-cell marker. A diagnosis of large granular lymphoma was based on the morphologic and immunohistochemical characteristics of the neo...
Matiasek K, Cronau M, Schmahl W, Gerhards H.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...
Moore BR, Weisbrode SE, Biller DS, Williams J.A 19-year-old Appaloosa gelding was reluctant to move. Radiography revealed diffuse, permeative lysis of the cortex and subchondral bone of the phalanges, third metacarpal bones, proximal sesamoid bones, radius, carpal bones, tibia, mandible, and nasal bones of the skull. A comminuted fracture of the distal aspect of the left third metacarpal bone was identified on a lateral to medial radiographic view of the left metacarpophalangeal joint. Histologic examination of the first phalanx, third metacarpal bone, and sternum revealed multifocal infiltrates of nodular lymphosarcoma in cortical and su...
Sugiyama A, Takeuchi T, Morita T, Matsuu A, Kanda T, Shimada A, Amaya T, Hikasa Y.A 15-year-old, neutered-male pony presented with a history of weight loss during 4 months. Clinical evaluation revealed severe bradycardia and complete atrioventricular block. At necropsy, a lobulated mass in the anterior mediastinum and moderate enlargement of the superficial cervical lymph nodes were observed. The vagus nerve and the brachiocephalic trunk were embedded in this anterior mediastinal tumor. Histologically, the mass was composed of sheets of neoplastic lymphoid cells expressing CD3, with a low mitotic rate. To the best of our knowledge, this is the first reported case of mediast...
Ross MW, Lowe JE, Cooper BJ, Reimers TJ, Froscher BA.A 12-year-old, 195 kg Shetland pony broodmare had eight seizures between May 29 and August 7, 1979. Plasma glucose levels during three of these seizures were markedly depressed (16, 18 and 19 mg/100 ml). Serum insulin levels were elevated during two of the seizures (86.0 and 97.7 microU/ml). Although a fasting hypoglycemia was not demonstrated, plasma glucose values during a normal day were abnormal; a plasma glucose level of 42 mg/100 ml was noted eight hours post-feeding. Serum insulin values obtained during an oral glucose tolerance test and intravenous glucagon tolerance test were consiste...
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...
Dechant JE, Nieto JE, Le Jeune SS.To evaluate clinical findings, underlying causes, and short-term outcome associated with hemoperitoneum in horses. Methods: Retrospective case series. Methods: 67 horses with hemoperitoneum. Methods: Medical records of horses with hemo-peritoneum (excluding postoperative abdominal hemorrhage) from 1989 through 2004 were analyzed. Information obtained included history, signalment, physical examination findings, diagnostic test results, and short-term outcome. Results: Breed distribution was 28 Thoroughbreds, 13 Arabians, 10 Quarter Horses, 5 Warmbloods, 3 Appaloosas, and 1 each of 8 other breed...
Anderson WI, Scott DW, Crameri FM.Two rare equine cutaneous neoplasms, an apocrine gland adenocarcinoma and a carcinosarcoma were diagnosed in a 17-year-old pony and a 14-year-old mare, respectively. The apocrine gland adenocarcinoma was present on the prepuce. Histologically, papillary projections of low cuboidal to columnar epithelial cells were generally well differentiated, and surrounded dilated acini. Stromal invasion was present, but vascular and lymphatic invasion was not seen. The carcinosarcoma was present in the right flank of the mare. Two discrete cell populations were characterized histologically. One portion of ...
Catone G, Marino G, Mancuso R, Zanghì A.The present study describes the clinicopathological features of a mature cystic ovarian teratoma occurred in a 4 year old, cyclic, nulliparous Andalusian mare. The mass was discovered in the left ovary during a breeding soundness examination, and was hard in consistency and variously echogenic. Laparoscopy was performed to confirm the neoplastic change, followed by a unilateral laparotomic ovariectomy in the standing animal. On the cut surface the teratomatous ovary showed a large cyst filled with hair and sebaceous material and three small cysts containing mucous fluid, surrounded by solid ar...
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...
Ueki H, Kowatari Y, Oyamada T, Oikawa M, Yoshikawa H.Thyroid tumours occur in older horses, and most such tumours have been considered to be of follicular epithelial origin. However, their immunohistochemical characterization has not been investigated. The purpose of this study was to confirm a suspicion that most of these tumours are in fact parafollicular cell (C cell)-derived adenomas, and to evaluate their pathogenesis and functional state. Thyroid glands from 38 horses aged 10-29 years were evaluated, all tissue samples being examined histologically, immunohistochemically and ultrastructurally. Nodular tumour masses were found in the thyroi...
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...
