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.
Porter BF, Storts RW, Payne HR, Edwards JF.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...
Brown HM, Cuttino E, LeRoy BE.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...
Cole R, Chesen AB, Pool R, Watkins J.Equine mast cell tumors are typically benign solitary growths of the head, neck, trunk, or limbs. When involving the limbs, these masses tend to be adjacent to joints without involving them. In radiographs there is often a well-circumscribed soft tissue mass with granular mineralization. The Arabian breed appears to be over represented. Surgical removal is usually curative. In this report, we describe the diagnosis, clinical features, and management of mast cell tumors in the rear limb of a horse.
Plummer CE, Smith S, Andrew SE, Lassaline ME, Gelatt KN, Brooks DE, Kallberg ME, Ollivier FJ.The purpose of this study was to evaluate the effectiveness of postoperative beta-irradiation with strontium-90 as an adjunctive treatment to superficial keratectomy and permanent bulbar conjunctival graft for removal of equine corneolimbal squamous cell carcinoma (SCC), in decreasing recurrence rate. Methods: The retrospective case study included 38 horses diagnosed and treated for SCC of the eye that involved the limbus and/or cornea. The patients were treated between 1990 and 2002, with strontium-90 irradiation immediately after corneal and conjunctival graft surgery. Recurrence was defined...
Elce YA, Orsini JA, Blikslager AT.To assess expression of cyclooxygenase (COX)-1 and -2 in naturally occurring squamous cell carcinomas (SCCs) and the analogous normal tissues in horses. Methods: Tissue samples collected from 3 conjunctival, 2 vulvar, 4 preputial, and 5 penile SCCs during surgical excision in 14 horses and from corresponding body regions (conjunctiva [n = 5 horses], vulva [2], prepuce [3], and penis [3]) in 5 horses euthanized for reasons unrelated to neoplasia. Methods: Tissue samples were snap frozen in liquid nitrogen and stored at -80 degrees C until analysis. Protein was extracted from the frozen tissues,...
de Bruijn CM, Veenman JN, Rutten VP, Teske E, van Nieuwstadt RA, van den Ingh TS.This study documents the clinical, histopathological, immunohistochemical and flow-cytometric findings in five horses with cutaneous non-epidermotropic malignant lymphoma (ML). The median survival time after discovery of the first subcutaneous nodules was 3.8 years (range 2-5 years: n=4). Histologically, the cutaneous ML had a pleiomorphic structure and contained a mixture of large reticulo-endothelial cells, medium-large sized lymphoid cells with a rounded nucleus and small nucleoli, many medium sized lymphoid cells with irregular nuclei, and some small lymphoid cells. Immunohistochemically (...
Yuan Z, Gallagher A, Gault EA, Campo MS, Nasir L.Bovine papillomavirus (BPV) type 2 is involved in carcinogenesis of the urinary bladder in cattle, while BPV-1 is commonly associated with equine sarcoid tumours. In both cases the early viral proteins are expressed, but virion is not produced. Given the similarities in BPV biology between the tumours in cattle and horses, bovine bladder cancers and equine sarcoids were compared with respect to physical status, load of viral DNA and variability of the E5 open reading frame (ORF). Rolling circle amplification demonstrated that BPV-1 and BPV-2 genomes exist as double stranded, episomal, circular...
McCue PM, Roser JF, Munro CJ, Liu IK, Lasley BL.The granulosa cell tumor is the most common ovarian tumor in mares. A clinical diagnosis can be made based on the presence ofa unilaterally enlarged ovary and a small inactive contralateral ovary. Endocrine testing may be beneficial to confirm a diagnosis. Surgical removal of the tumor eliminates the adverse effect on pituitary function and results in resumption of follicular development and ovulation in the opposite ovary over time.
Hewes CA, Sullins KE.To determine outcome for equids with cutaneous neoplasms treated with cisplatin-containing biodegradable beads, alone or in conjunction with debulking. Methods: Retrospective case series. Methods: 56 horses, 1 zebra, 1 donkey, and 1 mule. Methods: Medical records were reviewed. Follow-up information was obtained through telephone conversations with owners and trainers of the animals. Results: 22 tumors were sarcoids, 6 were fibrosarcomas, 1 was a fibroma, 2 were peripheral nerve sheath tumors, 11 were squamous cell carcinomas, 14 were melanomas (13 gray horses and 1 bay horse), 1 was a lymphos...
Meyer J, Delay J, Bienzle D.Clinical, laboratory and tissue findings from 37 horses with lymphoma were investigated. Horses ranged in age from 0.3 to 20.5 years (median 5.0 years) and included 18 females and 19 males. Weight loss (n = 25) and ventral edema (n = 21) were the most common historical and physical abnormalities. The most common laboratory abnormalities were hyperfibrinogenemia (n = 26), hypoalbuminemia (n = 19), anemia (n = 19), leukemia (n = 14), hyperglobulinemia (n = 13), and thrombocytopenia (n = 13). Thirty-four tumors involved multiple lymphoid tissues and abdominal or thoracic organs, and 3 tumors were...
Ollivier FJ, Kallberg ME, Plummer CE, Barrie KP, O'Reilly S, Taylor DP, Gelatt KN, Brooks DE.The purpose of this study was to evaluate the usefulness and effectiveness of permanent amniotic membrane transplantation as an adjunctive treatment to superficial keratectomy alone or combined with strontium-90 irradiation for treatment of equine corneolimbal squamous cell carcinoma (SCC) to decrease corneal scarring and recurrence rate. Methods: The retrospective case study included 11 horses (n = 12 eyes) diagnosed and treated for ocular SCC that involved the limbus and cornea. Nine of those horses (n = 9 eyes) were treated between 2002 and 2006, with superficial lamellar keratectomy alone ...
Nunes J, Mackie JT, Kiupel M.A 3.5-year-old Thoroughbred mare presented at necropsy with a large mass at the root of the mesentery and multiple smaller mesenteric masses. The mucosa of the small intestine contained numerous raised nodules. Histologic examination revealed severe granulomatous mesenteric lymphadenitis and enteritis. Epithelioid macrophages and multinucleated giant cells frequently contained numerous intracytoplasmic yeast organisms, which were strongly positive on immunohistochemical staining when using a polyclonal antibody against Histoplasma spp. A diagnosis of abdominal histoplasmosis was made based on ...
Serena A, Joiner KS, Schumacher J.Hemangiopericytoma (HP) is a well-recognized neoplasm arising from vascular pericytes that has been reported only in the dog and man. In this study, we describe a 14-year-old female Arabian horse that was presented for surgical excision of a 2-cm-diameter expansile subcuticular mass in the right lower eyelid. Histologically, the mass consisted of loosely arranged interlacing streams and storiform bundles of spindle cells that often formed distinct whorls around a central capillary and bundles of collagen (Antoni A-like pattern). Immunohistochemical analysis revealed strong diffuse cytoplasmic ...
Nogueira SA, Torres SM, Malone ED, Diaz SF, Jessen C, Gilbert S.Imiquimod is an immune response modifier with potent antiviral and antitumour activity. The objective of this pilot study was to evaluate the efficacy of an imiquimod 5% cream (Aldaratrade mark: 3M, Saint Paul, MN, USA) as a topical treatment for equine sarcoids. Fifteen horses with a total of 19 tumours were enrolled, including mixed (7), fibroblastic (5), flat (3), verrucous (2), and nodular (2) types. Baseline data included history, physical examination, tumour location, measurement and digital photography. Imiquimod was applied by the owners three times a week until complete resolution of ...
Kasperowicz B, Rotkiewicz T, Otrocka-Domagała I.The purpose of the study was a pathomorphological and immunohistochemical analysis of tumour cells and connective tissue in equine sarcoids. Investigations were performed using histopathological, ultrastructural, immunohistochemical (PCNA, p53, cytokeratin, vimentin) and histochemical (Ag-NORs) methods. The study was conducted on 50 sarcoids originating from 36 horses and classified as occult, verrucous, fibroblastic and a mixed type of sarcoid based on their clinical appearance. Most of the tumours were located on the girth (30%), neck (24%), head (12%), and legs (12%). The average age of the...
Yamate J, Izawa T, Ogata K, Kobayashi O, Okajima R, Kuwamura M, Kotani T, Aoki M.An 11-year-old thoroughbred gelding was euthanatized because of right nasal cavity tumor. The tumor consisted of round to oval cells with a scanty cytoplasm and hyperchromatic nuclei. Homer-Wright rosettes and pseudorosettes, as well as microcysts were seen. Neoplastic cells were immunoreactive to vimentin, S-100 protein, and neuron-specific enolase, glial fibrillary acidic protein and microtube-associated protein in varying degrees, indicating neurogenic nature. Based on these findings, this tumor was diagnosed as an olfactory neuroblastoma. Since this type is an uncommon tumor showing histol...
Lykkjen S, Strand E, Haga HA, Lie KI.To report treatment and wound healing after radical surgical mass excision in the equine buccal region. Methods: Clinical case reports. Methods: An 11-year-old Warmblood gelding and a 9-year-old Norwegian Trotter gelding. Methods: Large tumoral masses were removed from the buccal region by radical electrosurgery, creating large defects into the oral cavity. Wound ultimately healed by second intention. Results: Buccal defects in both horses healed well by second intention without tumor recurrence. Conclusions: Locally invasive tumors involving the cheek region of the horse can be successfully t...
Hubert JD, Burba DJ, Moore RM.To describe a laparoscopic technique for granulosa cell tumor removal using a vessel sealing device (LigaSuretrade mark) in standing mares. Methods: Retrospective study. Methods: Eight mares (8-24 years old; weighing, 406-525 kg). Methods: Before surgery, ovarian size and adjacent body wall thickness was determined by ultrasonography. Mares were sedated and after local anesthesia (inverted L and local infiltration), laparoscopic cannulation was performed without insufflation. The mesovarium was anesthetized and the LigaSure instrument applied to the mesovarium for hemostasis and resection to r...
Zelli R, Sylla L, Monaci M, Stradaioli G, Sibley LE, Roser JF, Munro C, Liu IK.Granulosa-theca cell tumors (GTCTs) are able to secrete variable amounts of sex steroids and immunoreactive inhibin (ir-INH). Although the pituitary appears to be affected by the presence of a GTCT, pituitary responsiveness to exogenous GnRH has not been examined. The aims of the present study were to: (i) assess the plasma hormone concentrations of ir-INH, gonadotropins and sex steroids in eight mares with GTCT and (ii) assess the responsiveness of pituitary gonadotroph cells to exogenous GnRH stimulus both before and after tumor removal. In seven mares, the contralateral ovary was firm, smal...
Bogaert L, Van Poucke M, De Baere C, Peelman L, Gasthuys F, Martens A.Real-time quantitative PCR can be a very powerful and accurate technique to examine gene transcription patterns in different biological conditions. One of the critical steps in comparing transcription profiles is accurate normalisation. In most of the studies published on real-time PCR in horses, normalisation occurred against only one reference gene, usually GAPDH or ACTB, without validation of its expression stability. This might result in unreliable conclusions, because it has been demonstrated that the expression levels of so called "housekeeping genes" may vary considerably in different t...
Saifzadeh S, Derakhshanfar A, Shokouhi F, Hashemi M, Mazaheri R.We report a 5-year-old gelding with a rare benign tumour of 2-month duration in the subcutis of the hind limb that presented with lameness. Physical examination revealed normal vital signs. Laboratory findings were within normal ranges. No bone abnormalities were detected on radiographic examination of the affected area. Bloody fluid was obtained by aspiration. Through an I-shape skin incision the tumour was excised en-block. Microscopic study showed a vascular hamartoma characterized by cavernous haemangiomatous tissue and proliferation of multiple vessels of variable diameter. This report hi...
Story MR, Gaughan EM, Andrews GA, Balch S.A 14-month-old male Quarter horse was presented for evaluation of a grade 3 out of 5 (grade 0 = sound; grade 5 = non-weight bearing) right rear lameness. A firm, 8 x 16 cm mass was palpable at the caudal medial aspect of the distal tibia and proximal tarsal region of the right hind limb. A percutaneous needle aspirate contained mesenchymal cells that were moderate to large in size with single, oblong nuclei. Differential diagnoses included fibrous hyperplasia, fibroma, or well-differentiated fibrosarcoma. Excisional biopsy for both definitive diagnosis and treatment was offered and selected by...
Valentine BA.A retrospective study examined data regarding equine cutaneous and mucocutaneous neoplasms submitted to the Veterinary Diagnostic Laboratory at Oregon State University in a 3.5-year period. A total of 536 neoplasms were identified, accounting for 30% of the total equine pathology submissions. Sarcoid, squamous cell carcinoma, melanocytic tumors, papillomas, and mast cell tumors were the most common neoplasms, constituting 87.5% of all cutaneous neoplasms. Sarcoids represented 51.4% of all neoplasms and 15.18% of total equine accessions. Sarcoid was most common in paints, quarter horses, and Ar...
Stewart AA, Rush B, Davis E.To document the efficacy of intratumoural injections of 5-fluorouracil for the treatment of equine sarcoids. Methods: A prospective study that included 13 horses and one donkey. Methods: Sarcoids were confirmed by histological examination and treated with intratumoural 5-fluorouracil every 2 weeks. If the sarcoids did not resolve after seven treatments, treatment was considered a failure. All cases were re-examined 6 months after treatment commenced and owners were telephoned 3 years after commencement of treatment to report on tumour recurrence. Outcome comparisons were performed to determine...
Lefebvre R, Theoret C, Doré M, Girard C, Laverty S, Vaillancourt D.An 8-year-old Arabian mare was admitted for a large ovarian anovulatory follicle. A clinical diagnosis of ovarian tumor and endometritis was established. Histological examinations revealed an ovarian teratoma and a grade II endometritis. Three months after unilateral ovariectomy, the mare was confirmed pregnant and eventually gave birth uneventfully. Une jument Arabe de 8 ans fut présentée pour un gros ovaire. Un diagnostic de tumeur ovarienne et d’endométrite fut posé. L’examen histologique confirma un tératoma ovarien et une endométrite grade II. Trois mois après une ovariectomie...
Ishigami N, Horiba K.A 41-year-old woman presented with symptoms of cardiac tamponade. Diagnosis of a primary malignant tumor in the right atrium without distant metastasis was made by echocardiography, computed tomography and coronary angiography. Aggressive surgery consisting of resection of the tumor including the right atrial wall together with the right coronary artery and sinus node was performed. This was followed by coronary artery bypass grafting with myocardial electrode implantation for reconstruction of the right atrial wall using an equine pericardium. Final diagnosis was of angiosarcoma by pathologic...
Boerboom D, Paquet M, Hsieh M, Liu J, Jamin SP, Behringer RR, Sirois J, Taketo MM, Richards JS.Misregulation of the Wnt/beta-catenin signaling pathway is a hallmark of several forms of cancer. Components of the Wnt/beta-catenin pathway are expressed in ovarian granulosa cells; nevertheless, its potential involvement in granulosa cell tumorigenesis has not been examined. To this end, human (n = 6) and equine (n = 18) granulosa cell tumors (GCT) were analyzed for beta-catenin expression by immunohistochemistry. Unlike granulosa cells of normal ovaries, most (15 of 24) GCT samples showed nuclear localization of beta-catenin, suggesting that activation of the Wnt/beta-catenin pathway plays ...
Scarratt WK, Crisman MV.Tumors of the equine respiratory tract occur infrequently. An accurate diagnosis of neoplasia of the respiratory tract is critical because the prognosis is usually grave. The clinical signs and diagnostic procedures are discussed for tumors of the nasal and paranasal sinuses, nasopharynx/larynx, guttural pouch and thorax including lung, pleura, and thymus.
Arenas-Gamboa AM, Mansell J.Haemangiosarcomas (HSAs) are malignant tumours of endothelial cell origin. Epithelioid HSA is a variant of the histologically conventional HSA that has little or no morphological evidence of a vascular origin and has been reported rarely in domestic animals. The following report documents six cases of equine epithelioid HSA occurring in the ocular tissues of horses with a mean age of 19.8 years at the time of diagnosis. Microscopically, all of the lesions consisted of solid sheets or cords of epithelioid cells with rare narrow clefts or small spaces containing erythrocytes that were often the ...
Zanghì A, Catone G, Marino G, De Vico G, Nicòtina PA.A 30-year-old Standardbred stallion was examined for unilateral scrotal swelling. Physical and ultrasound examinations revealed a painless enlarged left testis with a non-homogeneous echogenicity, when compared with the controlateral testis. The stallion underwent left unilateral orchiectomy. Grossly, the excised testis was irregularly enlarged (12 x 9 x 9 cm; weight: 530 g) and firm. The sections showed that testicular parenchyma was replaced by a lobulated, greyish-white mass, which involved the epididymal head. At microscopy, a dual Leydig and Sertoli cell tumour component could be seen. Ne...
Garma-Aviña A, Valli VE, Lumsden JH.Four cases of equine congenital cutaneous papillomatosis were found during a review of 555 cutaneous tumours received at the pathology department, Ontario Veterinary College, during a 10-year period. A fifth case received after that period was also included. Two of the tumours were found in Thoroughbreds, one in a Standardbred, one in an Arabian and in one case the breed was not specified. The anatomical locations were the rib cage, head, hind leg and 2 on the forehead.
Santschi EM, Slone DE.Infertility was associated with a uterine mass in 2 Thoroughbred mares. Both mares had produced live foals, but had been barren for 2 years, despite repeated breedings. Each mass was removed through a right ventral paramedian incision. Histologic examination of the masses revealed a leiomyoma and an ovarian abscess. In 1 mare, approximately 30% of 1 uterine horn was removed because of tumor attachment; in the other mare, approximately 50% of 1 uterine horn was removed because of adhesions to the ovarian abscess. Pregnancy information was available for both mares for the 3 years after surgery; ...
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 ...
Richardson DW, Evans LH, Tulleners EP.Rostral mandibulectomy with primary gingival closure was performed in 5 horses with rapidly growing or bleeding mandibular tumors. The technique involved preservation of the most caudal portion of the mandibular symphysis to maintain stability. There were no surgical complications or recurrences, and the cosmetic and functional results were good. The histopathologic diagnosis of all the tumors was ossifying fibroma. Rostral mandibulectomy affords a simple and effective technique of treating tumors of the rostral portion of the mandible in horses.
Basher AW, Severin GA, Chavkin MJ, Frank AA.Three horses were examined because of exophthalmos and others signs indicative of a space-occupying orbital mass. In 2 horses, exenteration was used to remove the orbital mass. In a third horse, an orbital tumor and lung metastases were found at necropsy. Routine histologic and Grimelius' histochemical staining were used on fixed tissues; immunohistochemical staining for chromogranin and electron microscopy also were performed. Masses were orbital neuroendocrine tumors. Horses that underwent exenteration were alive 19 and 24 months after surgery. Hypotension was encountered at surgery in both ...
Moore JN, Kintner LD.Squamous cell carcinoma involving the pars esophagea of the stomach caused recurrent esophageal obstruction in an 11 year old Pinto gelding. The tumor encircled the esophagus and was attached to the diaphragm, spleen, aorta, left adrenal gland and kidney. Definitive diagnosis was provided by biopsy of the mass via standing left flank laparotomy.
Hatai H, Hatazoe T, Seo H, Tozaki T, Ishikawa S, Miyoshi N, Misumi K, Hobo S.A 27-y-old Anglo-Arabian gelding with bay coat color was presented with a swelling of the left maxillary region. Fenestration on the left maxilla revealed that the left maxillary sinus was filled with black-red tissue. A portion of the tissue was excised and diagnosed histologically as malignant melanoma. Genotyping of the STX17 gene for gray coat color revealed that the horse did not have the "gray" factor. The horse was euthanized ~3 mo after first presentation. During autopsy, a black-to-gray mass extended from the left nasal cavity to the surrounding paranasal sinus and invaded the hard ...
van der Zaag EJ, Rijkenhuizen AB, Kalsbeek HC, Peperkamp NH.An 11-year-old Arabian mare had sudden signs of colic 10 days post partum. Rectal examination revealed a large mass in the abdomen. The mare was successfully operated on for a granulosa cell tumour of 31.5 kg. The large abdominal wound healed by primary intention.
Pazzi KA, Kraegel SA, Griffey SM, Theon AP, Madewell BR.Wild type equine p53 was amplified between exons 2 and 9 by the polymerase chain reaction using primers designed from conserved regions in other species. An 828 base pair region, corresponding to codons 25-313 of human p53, was sequenced in both directions. Human and equine amino acid sequences were 87% homologous in this region and 96% homologous in conserved domains II-V. Of eight equine cutaneous or mucocutaneous squamous cell carcinomas directly sequenced from exons 5-8, two had p53 point mutations resulting in single amino acid substitutions.
Chen W, Zhang Y, Li X, Chen H, Sun J, Feng F.We took advantage of gasotransmitter HS as a chemical reaction-based trigger for controlled release of doxorubicin which is precoordinated by copper ions and enclosed in horse spleen apoferritin. The nanocomposite is stable at physiological pH and temperature before HS activation. The drug release process avoids disassembly of protein shells and is controllable by the strong affinity of sulfide with copper ions. The in vitro cytotoxicity assay indicates the antitumor effect of doxorubicin toward tumor cells could be achievable by HS activation.
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.
Roberts MC, Groenendyk S, Kelly WR.A 4 month old foal with right sided maxillary enlargement and considerable upper airway obstruction had an ameloblastic odontoma in the right maxillary sinus. This odontogenic tumour, probably congenital in nature, had extensively distorted the structure and contours of the sinus, and displaced the adjacent turbinates and nasal septum.
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 ...
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.
Strohmayer C, Klang A, Kneissl S.Squamous cell carcinoma (SCC) is the most common equine sinonasal and feline oral tumour. This study aimed to describe the computed tomographic and histopathological characteristics of equine and feline SCC. Thirteen horses and 10 cats that had been histopathologically diagnosed with oral or sinonasal SCC and had undergone computed tomography (CT) of the head were retrospectively included in the study. CT characteristics of the mass and involved structures were noted. Histological examinations were evaluated according to a human malignancy grading system for oral SCC, which considered four gra...
Axon JE, Russell CM, Begg AP, Adkins AR.A 10-month-old Thoroughbred filly was presented with a 2-month history of recurrent fever and pleural effusion. Major clinical findings were pyrexia and congested mucous membranes. Clinical pathology tests revealed an erythrocytosis, hyperfibrinogenaemia and hyperglobulinaemia. Pleural fluid was seen on ultrasonographic examination of the thorax and analysis of a thoracocentesis sample indicated a lymphocytic, modified transudate. A transtracheal aspirate was normal. The erythrocytosis persisted despite IV fluid therapy. Arterial blood gas analysis and bone marrow aspirate were normal. These f...
Mair TS, Taylor FG, Brown PJ.Two horses affected by chronic, intermittent colic were found, at post-mortem examination, to have localized annular thickening of a segment of the duodenum. Histological examination of the lesion in both cases revealed a tumour composed of bundles of oval or spindle-shaped cells that stained as muscle with van Gieson stain. The histological diagnosis was leiomyosarcoma. The tumour had caused partial bowel obstruction in both horses.
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...
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...
Saifzadeh S, Derakhshanfar A, Shokouhi F, Hashemi M, Mazaheri R.We report a 5-year-old gelding with a rare benign tumour of 2-month duration in the subcutis of the hind limb that presented with lameness. Physical examination revealed normal vital signs. Laboratory findings were within normal ranges. No bone abnormalities were detected on radiographic examination of the affected area. Bloody fluid was obtained by aspiration. Through an I-shape skin incision the tumour was excised en-block. Microscopic study showed a vascular hamartoma characterized by cavernous haemangiomatous tissue and proliferation of multiple vessels of variable diameter. This report hi...
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...
De Cock HE, Labelle P, Magdesian KG.The clinical, gross morphological, histological and immunohistochemical characteristics of an ameloblastic carcinoma in a 30-year-old Quarter Horse mare are reported. This tumour was fast growing, locally invasive and destructive. Histologically, it showed an infiltrative pattern of large islands, broad sheets and, at the periphery, small cords of moderately pleomorphic round, oval to spindle-shaped cells. Immunohistochemical evaluation revealed positive labelling for vimentin, cytokeratin 5/6 and cytokeratin 14. In the oral cavity of human beings, this immunolabelling pattern is unique for th...
Meyerholz DK, Caston SS, Haynes JS.An Appaloosa filly was born with a ventral midline, approximately 8 x 12 x 15 cm subcutaneous cervical mass. The nonencapsulated mass was composed of interlacing and haphazard bundles of spindle cells on moderate to abundant loose myxomatous stroma. A moderate number of cells showed cross striations with minor nuclear variation and a low mitotic rate. Immunohistochemical staining for myoglobin, desmin, actin, vimentin, and S-100 was positive and negative for glial fibrillar antigen and keratin. Rhabdomyomas are rare benign tumors of striated muscle. Rhabdomyomas described previously in the vet...
Méndez A, Martín de las Mulas J, Bautista MJ, Chacón F, Millán Y, Fondevila D, Pumarola M.The presence and distribution of S100 protein (alpha and beta subunits), cytokeratin polypeptides, glial fibrillary acidic protein, neurofilaments, vimentin, neuron specific enolase, synaptophysin, HLA class II DR antigen, and pituitary hormones (prolactin, adrenocorticotropic hormone and human chorionic gonadotrophin) in stellate cells were studied immunohistochemically in four normal canine pituitary glands, five canine pituitary adenomas, two canine pituitary carcinomas and two equine pituitary adenomas (with surrounding normal glandular tissue). Stellate cells of the pars distalis and pars...
Turk JR, Gallina AM, Liu IM, Nickels F, Grossman B.A 6-month-old Morgan colt was examined because of preputial edema and multiple nodular masses in the left inguinal region. A tentative diagnosis of lymphatic hamartoma was made on the basis of initial biopsy findings. The prognosis for surgical excision was poor due to the progressive expansile growth of the tumor. Secondary infectious complications developed, and the colt was euthanatized at the owner's request. An abdominal and retroperitoneal mass was seen at postmortem examination. The mass was adherent to the left lumbar musculature, the craniodorsal aspect of the pelvic inlet, the midjej...
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.
