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.
Hill FW, Moulton JE, Schiff PH.A fifteen-year-old thoroughbred gelding with exophthalmos of the left eye, was found at necropsy to have an adenocarcinoma of the left frontal sinus. The tumour extended caudally through the cribriform plate into the orbit, displacing the eyeball anteriorly.
Madewell BR, Munn RJ.Abnormal irregularly branched and anastomosing tubules within cisternae of endoplasmic reticulum were observed by transmission electron microscopy in tumour cells comprising connective tissue neoplasms (sarcoids) from three horses and a mule. These tubuloreticular inclusions were also observed in cultured tumour cells from one of these horses examined, but were not detected in fibroblasts (fibrocytes), epidermis, or vascular endothelial cells in skin biopsy specimens from five clinically healthy horses, nor in one additional equine connective tissue neoplasm.
Hamir AN.During a routine necropsy examination of a 4-year-old standardbred mare, a well-demarcated dermal mass was seen near the right elbow. Grossly, the mass consisted of multifocal variably sized areas of dark brown, firm material that was separated by thin white septa. Histologically, within the individual compartments, there were numerous multinucleated giant cells, macrophages, and free erythrocytes. A diagnosis of giant cell tumor of soft tissues was made.
Allen D, Swayne D, Belknap JK.The clinical signs, medical and surgical management, and pathological findings are described for a ganglioneuroma, an atypical intestinal tumor, that caused colic because of small intestinal obturation.
Wilson DA, Foreman JH, Boero MJ, Didier PJ, Lerner DJ.A large granulosa cell tumor was believed to be responsible for causing obstruction and subsequent rupture of the small colon in a 10-year-old Quarter Horse mare. Two months earlier, a mass, tentatively diagnosed as granulosa cell tumor of the left ovary, had been identified by means of rectal palpation and ultrasonography. The mare was evaluated for clinical signs of acute, severe, abdominal pain, increased heart rate, cyanotic mucous membranes, clinical dehydration, with high PCV, leukopenia, and extreme abdominal distension. A large soft tissue mass and taut band that constricted the lumen ...
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.
Morse CC, Saik JE, Richardson DW, Fetter AW.Benign proliferative fibro-osseous lesions of the rostral mandible in six young horses are classified as equine juvenile mandibular ossifying fibroma. Histologically there is a characteristic abrupt transition from subgingival fibroblastic stroma to a zone of proliferating osteoblasts that form irregular spicules of osteoid. The layer of proliferating osteoblasts blends with a deeper zone of bony trabeculae rimmed by osteoblasts and separated by intertrabecular spaces of moderate cellular density. Incomplete surgical excision resulted in local recurrence, while rostral mandibulectomies resulte...
Broström H, Fahlbrink E, Dubath ML, Lazary S.The distribution of equine leucocyte antigens (ELA) in Swedish Halfbreds affected by sarcoid tumors was determined and compared with that of control horses of the same breed. ELA-haplotype A3W13 appeared more frequently in affected horses, resulting in a chi 2 value of 4.45 (P = 0.034) for A3 and 9.05 (P = 0.0026) for W13, respectively. The relative risk factor (RR) could be estimated to 2.13 and 3.00 for A3 and W13, respectively. The etiology fraction (EF) was calculated to 28% and 37% for A3 and W13, respectively. Thus, in the population of Swedish Halfbreds approximately 40% (at least) of t...
Adams R, Calderwood-Mays MB, Peyton LC.A highly successful surgical technique for removing cutaneous tumors in humans was used in seven horses with cutaneous squamous cell carcinoma (n = 3) or sarcoid (n = 4). In humans, the complete underside of the tumor is evaluated histologically by processing horizontal sections from the tumor base, and orientation between the wound surface and the undersurface of the excised tumor is maintained by mapping both surfaces. The technique ensures that small foci of residual tumor can be located accurately and removed. Based on our experience, three modifications of the human technique are suggeste...
Millington WR, Dybdal NO, Dawson R, Manzini C, Mueller GP.Equine Cushing's disease is caused by an adenomatous hyperplasia of the intermediate pituitary which secretes high levels of beta-endorphin, ACTH, and other peptide derivatives of POMC. In the present study we found that plasma and cerebrospinal fluid immunoreactive beta-endorphin (i beta-endorphin) levels were 60- and 120-fold higher than control values in horses with Cushing's disease. There were no significant differences in intermediate lobe i beta-endorphin concentrations, although anterior lobe i beta-endorphin was significantly reduced in Cushing's horses, presumably because high levels...
Whiteley HE, Sundberg JP.A group of spontaneously occurring animal papillomas which were negative or positive for papillomavirus group-specific antigen were examined with a battery of biotinylated lectins including Con A, WGA, succinylated-WGA, PNA and UEA-I. Canine papillomas, equine papillomas, white-tailed deer fibromas, mule deer fibromas, and bovine fibropapillomas were examined. Each lectin had a specific staining pattern. No obvious differences in staining patterns between normal skin, viral antigen-positive and -negative neoplasms were identified. This may be due to the well-differentiated and organized nature...
Doran R, Allen D, Gordon B.Ovarian granulosa theca cell tumours were removed surgically in 10 mares. Stapling instruments were used to facilitate haemostasis of the ovarian pedicle in five out of 10 cases and as a sole method of haemostasis in the remaining five cases. Postoperative haemorrhage from the ovarian pedicle was suspected in only one case. All cases survived long term follow-up from six months to four years. Results from this series of cases indicate that stapling instruments provide a rapid, easy and efficient means of ligating ovarian pedicles when performing ovariectomy in the mare.
Angelos J, Oppenheim Y, Rebhun W, Mohammed H, Antczak DF.The relationship between breed and the risk of developing sarcoid tumours or uveitis of unknown etiology was evaluated in a retrospective study of 16242 equine cases admitted between 1975 and 1987 to the New York State College of Veterinary Medicine Large Animal Hospital, and 3198 equine tissue samples sent to the New York State Veterinary Diagnostic Laboratory between 1977 and 1987. Of 120 sarcoid cases from the Large Animal Hospital, sarcoids were twice as likely to develop in Quarter Horses (odds ratio, OR = 1.8, P less than 0.05) relative to Thoroughbreds and less than half as likely to de...
Romagnoli SE, Momont HW, Hilbert BJ, Metz A.Two yearling, paternal half-sibling Appaloosa fillies were ovariohysterectomized for treatment of multiple uterocervical leiomyomas. The tumors recurred in both fillies, originating from cervical tissue that could not be removed at surgery. Previously reported cases of uterine leiomyoma in the mare have been of solitary tumors in older mares that were treated successfully by surgical removal.
Moll HD, Slone DE, Juzwiak JS, Garrett PD.A diagonal paramedian approach to the abdomen was used for unilateral ovariectomy in 15 mares. In each case, surgery was performed for removal of a granulosa cell tumor. All horses recovered from surgery with minimal complications. Surgical exposure of the affected ovary was adequate to allow exteriorization and ligation. Other advantages of this approach were ease of closure and lack of postsurgical complications.
Clem MF, DeBowes RM, Leipold HW.A mass originating from the dorsal rectal wall of a 4-year-old mare was diagnosed as a leiomyosarcoma. General anesthesia and meticulous surgical dissection were required to effect removal. In spite of incomplete excision, as indicated by histologic sections, the mass has not recurred in the 18 months since removal.
Munson L.A 17-year-old Quarter Horse mare developed rapidly progressive, bilateral, firm enlargements of both mammary glands, ventral abdominal edema, dyspnea, and neurologic signs. The horse was euthanatized, and a carcinoma of the mammary gland was diagnosed at necropsy. Microscopically, normal glandular parenchyma was replaced by neoplastic nodules, and the tumor had metastasized to most visceral organs and throughout the musculoskeletal and central nervous systems. The tumor had a solid pattern, with microglandular differentiation, and numerous syncytial sheets.
The Journal of heredityMay 1, 1987
Volume 78, Issue 3 171-177 doi: 10.1093/oxfordjournals.jhered.a110351
Leone NC, Shupe JL, Gardner EJ, Millar EA, Olson AE, Phillips EC.Hereditary multiple exostosis (HME), a bone tumor first described by Virchow, has been studied over a period of 15 years on a comparative basis. The horse, an excellent biomedical model for this physically deforming multiple bone tumor in man, has been utilized in this study. The etiology, hereditary pattern, potential for malignancy and other aspects of this strange affliction need additional clarification. This in-depth study of 261 individuals from 144 families was compared with that of 55 horses bearing the HME trait, selectively bred and studied over the same period. Important information...
Johnstone AC.Congenital vascular tumours in the skin of the legs of two horses showed histological features at biopsy which were consistent with capillary haemangioma but, at necropsy, one tumour had invaded the superficial digital flexor tendon and was therefore classified as a haemangiosarcoma.
Gelberg HB, McEntee K.Interstitial cell tumors from nine stallions were described. In all but one horse the tumors were found in undescended testes. Five animals had bilateral tumors. Two animals showed increased aggression. Tumors contained two cell types. The first type were large distinctly bordered eosinophilic cells interpreted to be hyperplastic and hypertrophic interstitial cells. They blended with pleomorphic often spindloid neoplastic cells which had fibrillar, vacuolated cytoplasm and indistinct cell borders. This latter cell population was arranged in nodules or broad sheets as endocrine-like packets or ...
Hultgren BD, Zack PM, Pearson EG, Kaneps AJ.A juvenile granulosa cell tumour is described in a 3-month-old Arabian filly. The 32 X 27 X 27 cm tumour had replaced the right ovary. The neoplasm was composed of multiple nodules of neoplastic granulosa cells which formed microfollicles, macrofillicles and cysts, as well as solid nests and trabeculae. The supporting stroma contained theca cells. Mixing of the neoplastic granulosa cells and theca cells in disorderly fashion was noted. The diagnosis was based on age of occurrence and histological appearance.
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.
Fatemi-Nainie S, Anderson LW, Cheevers WP.MC-1 is an equine sarcoid-derived cell line which spontaneously releases a retrovirus possessing genomic sequence homology with an inducible endogenous retrovirus of normal equine cells. A complete characterization of MC-1 tumor cells was undertaken, including morphology, growth kinetics, and saturation density, selective growth in semisolid media, uptake of 2-deoxyglucose, and tumorigenicity in athymic nude mice. MC-1 cells, in contrast to normal equine dermal fibroblasts, exhibit all of the characteristics of malignantly transformed cells.
Gulevsky AK, Grischenko VI, Tereschenko OS, Shchenyavcky IJ.The experimental data presented in the work testify to the cytostatic activity of 1-10 kD polypeptide fractions from brains of the hibernating ground squirrel and the Yakut horse towards Ehrlich ascitic carcinoma (EAC) cells. The experiments on the investigation of the inhibiting influence of 1-10 kD fractions from tissues of the hibernating and cold-adapted animals on protein-synthesizing system of EAC cells allow us to conclude that the cytostatic effect of the fractions is effected at the genetic level in the tumor cells.
Flores AR, Azinhaga A, Pais E, Faria F, Nunes F, Gartner F, Amorim I.This report describes an ocular mast cell tumor in a 13-year-old female sport horse. Clinical examination revealed a solitary firm mass located in the ocular mucosa, protruding from behind the left lower eyelid. The lesion was surgically removed and submitted to histopathology. Microscopically, the mass was composed of sheets of well-differentiated neoplastic round cells circumscribed by delicate connective tissue. Positive Giemsa and Toluidine Blue staining confirmed the presence of cytoplasmic granules. Neoplastic cells showed strong membranous and mild diffuse cytoplasmic immunoreactivity f...
McCoy DJ, Beasley R.Hypercalcemia associated with malignancy was diagnosed in a 2-year-old Thoroughbred filly admitted because of weight loss and reduced exercise tolerance of approximately 2 months' duration. Laboratory findings included hypercalcemia, hypophosphatemia, anemia, marked neutrophilia with lymphopenia and eosinopenia, and normal immunoreactive parathyroid hormone concentration. At necropsy, a 53.6-kg tumor was located in the cranioventral aspect of the abdominal cavity. Gross renal lesions were not noticed. Bone tissue appeared to be normal on gross and histologic examinations. The parathyroid gland...
von Zallinger C, Tempel K.A review of the latest literature concerning the present level of radiation therapy in veterinary medicine is given. In a general section physico-technical as well as biological fundamentals are discussed. In the special part of the paper indications for a radiation therapy of dogs, cats and horses are stated. In this respect the basis for a decision is the TNM-classification into different clinical stages according to the directions of the WHO. Tumors of the hemolymphatic system are very responsive to radiation therapy. While epithelial tumors are sensitive, tumors arising from the mesenchyma...
Sutton RH, Coleman GT.Abstract Extract A 15-year-old pony mare developed firm irregular bony swellings on all four legs. These were most severe around the carpal and fetlock joints of the forelegs, restricting both flexion and extension. Over about 6 months the horse had periodic bouts of coughing. She showed moderate weight loss and a depressed demeanour.
Hendrix DV, Newkirk KM.To determine whether epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) are expressed in periocular squamous cell carcinomas (SCCs) of horses. Methods: Biopsy specimens of SCCs from 46 horses. Methods: Pathology records were searched retrospectively for biopsy specimens of periocular SCCs obtained from horses. Slides of the specimens were reviewed histologically to confirm the SCC diagnosis and stained for EGFR and HER2 by immunohistochemical methods. For both EGFR and HER2, the immunohistochemical staining intensity and percentage of stain-positive cel...
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...
Ensink JM, Voermans M, Bartels JH, Passon-Vastenburgen MH, Loeb E.A 14-year-old Haflinger mare was presented with a wound on the right metatarsus which it had sustained 3 years earlier. The wound had never completely healed but had only recently become a problem. Over a period of several months, the wound became larger, produced a lot of exudate, and the horse became lame on the affected limb. Clinical examination and radiographs failed to reveal the cause of the deterioration. Histological evaluation of tissue removed during debridement of the wound revealed squamous cell carcinoma. Because the tumour had already invaded the bone, the prognosis was unfavour...
Paradis MR.Neoplasia of the central nervous system (CNS) can be divided into two main categories: nonpituitary CNS neoplasia and pituitary adenomas. Nonpituitary CNS neoplasias are generally compressive in nature, although some are also invasive. The majority of reported CNS tumors are secondary with only a few originating from nervous tissue. Pituitary adenomas predominantly occur in the pars intermedia of the older horse. Clinical signs, diagnostic testing, and possible treatments are discussed.
Saroglu M, Aktas M, Olgun D, Arun SS.A tumor-like tissue mass of lateral-limbal site in the right eye of a 12-year-old Cob Pony mare was presented for surgical removal. The mass, covering the lateral limbus, bulbar conjunctiva and part of the cornea, was surgically removed, and the corneal defect repaired with a pedicle bulbar conjunctival graft. The mass was inflammatory in nature containing mononuclear cells. No recurrence or complication occurred at 6- and 12-month follow-up examination.
Johnstone AC.Congenital vascular tumours in the skin of the legs of two horses showed histological features at biopsy which were consistent with capillary haemangioma but, at necropsy, one tumour had invaded the superficial digital flexor tendon and was therefore classified as a haemangiosarcoma.
Lubczyk B, Nothelfer HB.A case of generalized equine leucosis is presented. The most important clinical signs were cachexia, loss of condition, fever, tachycardia, subcutaneous tumors and severe lameness accompanied by edema of the right thoracic limb. Hematology showed anemia and neutrophilia; clinical biochemistry indicated hypalbuminemia, hyperphosphatemia and hyperfibrinogenemia. Necropsy revealed multiple tumors throughout the body which mainly originated from lymph nodes. Histopathologically the tumors consisted of two cell-types: a. uniform lymphocytoid cells with a highly infiltrative growth pattern; b. heter...
Ochi A, Nishioka T, Kurimoto S, Kishi D, Ueno T, Nukada T.A 2-year-old male Thoroughbred horse presented with a mass in the maxilla. The focally ulcerated mass, approximately 8 cm in diameter, covered the upper left intermediate and corner incisor teeth (nos. 602 and 603 according to the modified Triadan system) and radiographic examination revealed displacement and lysis of the incisors. Histologically, the tumour was composed of a dense proliferation of spindle-shaped cells and neoplastic odontogenic epithelial cells arranged in island, follicular, plexiform or sheetlike patterns. The spindle-shaped cells were immunopositive for cytokeratins AE1/A...
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...
De Paolis L, Armando F, Montemurro V, Petrizzi L, Straticò P, Mecocci S, Guarnieri C, Pezzolato M, Fruscione F, Passeri B, Marruchella G, Razzuoli E.Vulvar squamous cell carcinoma (VSCC) has been recently associated with Equus caballus papillomavirus type 2 (EcPV2) infection. Still, few reports concerning this disease are present in the literature. Objective: To describe a case of naturally occurring EcPV2-induced VSCC, by investigating tumour ability in undergoing the epithelial-to-mesenchymal transition (EMT). Methods: Case report. Methods: A 13-year-old Haflinger mare was referred for a rapidly growing vulvar mass. After surgical excision, the mass was submitted to histopathology and molecular analysis. Histopathological diagnosis was c...
McCowan C, Stanley RG.Abstract A heavily pigmented tumor was removed from the lateral, perilimbal, bulbar conjunctiva of a bay Thoroughbred horse. Excision was incomplete and the base of the tumor was lasered on the assumption that the tumor was a melanoma. No other ophthalmic lesions were seen. Histology showed the mass to be a pigmented squamous cell carcinoma (SCC). The prognosis and recommended treatment protocols are different for SCC and melanoma. This is, to the best of our knowledge, the first report of an ocular, pigmented SCC in the veterinary literature.
Whiteley HE, Sundberg JP.A group of spontaneously occurring animal papillomas which were negative or positive for papillomavirus group-specific antigen were examined with a battery of biotinylated lectins including Con A, WGA, succinylated-WGA, PNA and UEA-I. Canine papillomas, equine papillomas, white-tailed deer fibromas, mule deer fibromas, and bovine fibropapillomas were examined. Each lectin had a specific staining pattern. No obvious differences in staining patterns between normal skin, viral antigen-positive and -negative neoplasms were identified. This may be due to the well-differentiated and organized nature...
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...
Loynachan AT, Bryant UK, Williams NM.A 35-year-old horse was submitted to the necropsy service at the University of Kentucky Livestock Disease Diagnostic Center. At necropsy, multiple 1-4-cm-diameter cystic structures were incidentally identified unilaterally in the right renal medulla and the cortex. On histologic examination, the cystic structures compressed the normal renal architecture, were lined by tall columnar epithelium that formed occasional papillary projections, and contained large amounts of mucicarmine and periodic acid-Schiff-positive mucinous material. The masses were diagnosed as renal mucus-gland cystadenomas. T...
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...
Nickels FA, Brown CM, Breeze RG.A unilateral pulmonary granular cell tumor occurred in a Thoroughbred mare with longstanding respiratory disease wrongly attributed to chronic obstructive pulmonary disease. The clinical features, radiology and endoscopic appearance permitted an accurate diagnosis, which was supported by subsequent necropsy and histologic examination. Obstructive pulmonary disease was ruled out after measurement of arterial blood gases and maximum intrathoracic pressure changes, and after microscopic examination of the lung.
Stutsel M, Gimeno M, Young A, Bell JW, Horadagoda N.A 2-year-old Standardbred gelding was referred for a mass on the palmaromedial right front pastern which was accompanied by progressively worsening lameness. The mass was firm to palpation and covered by normal skin. Ultrasonographically, a smooth encapsulated mass was present, medial to the flexor tendons and palmar to the neurovascular bundle. Because of a poor prognosis for future athletic performance without surgical or chemotherapeutic intervention and economic constraints preventing further diagnostics and treatment, the horse was euthanised. Post-mortem magnetic resonance imaging, histo...
Nasir L, Reid SW.An evolutionary conserved 1.3 kb fragment corresponding to the horse p53 tumour suppressor gene was PCR amplified, cloned and the nucleotide sequence determined. The p53 fragment encoded exons 5 to 9 and the intervening introns. The nucleotide sequence and the predicted aminoacid sequence showed a high level of homology with human and donkey p53 sequences.
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.
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.
Broome TA, Allen D, Baxter GM, Pugh DG, Mahaffey E.A 2-year-old Arabian filly was referred for evaluation of a serosanguineous vaginal discharge. Palpation per rectum revealed a large, fluid-filled uterus and a uterine mass. The filly developed septic metritis and secondary laminitis as a result of torsion and necrosis of a pedunculated uterine mass. Ovariohysterectomy was performed. The entire cervix was removed with the uterus. Gross examination of the excised uterus revealed 3 intraluminal masses. Histologic evaluation identified the tumors as fibroleiomyoma. The filly recovered completely, and there was no recurrence of the tumor.
Fidel JL.Although the diagnosis of cancer is relatively uncommon in horses, tumors do occur in this species. Surgery, radiation, and chemotherapy are traditional cancer treatments in all species. In equine patients, surgery has often been the only treatment offered; however, not all tumors can be controlled with surgery alone. In small animal oncology, newer and better therapies are in demand and available. Radiation therapy is often used to control or palliate tumors locally, especially to satisfy clients who demand sophisticated treatments. The large size of equine patients can make radiation therapy...
Gebhart W, Niebauer GW.The morphological substrates of pigmented and depigmented skin as well as the structural characteristics of spontaneously developing melanomas were revealed by clinical, light- and electron microscopic methods in gray horses (Lipizzaner breed) from the Vienna Spanish Riding School. On clinical investigations in a group of 31 older horses (more than 10 years old) 20 exhibited melanomas, whereas 23 younger animals (less than 10 years of age) had no evidence for visuable melanotic tumors. Concomitantly with the progressive graying of the hair a depigmentation of the skin was frequently observed. ...
Tanimoto T, Yamasaki S, Ohtsuki Y.A well-demarcated solitary splenic mass (20 x 20 x 15 cm in size) containing hemorrhagic and necrotic foci was observed in a 4-year-old Thoroughbred stallion. Histologically, the mass consisted of lymphoma cells of the diffuse large non-cleaved type, with a high mitotic index and scattered macrophages that formed a starry sky pattern. The lymphoma cells revealed diffuse positivity for acid phosphatase and alpha naphthyl butyrate esterase, and were also positive for intracytoplasmic IgM on occasion, and mostly for proliferating cell nuclear antigen. Ultrastructural examination revealed moderate...
