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.
Ricketts SW, Peace CK.The report describes a case of abdominal neoplasia in a mare diagnosed ante-mortem by the technique of paracentesis abdominis. Histopathological findings suggest that the lesion was a mesothelioma, primarily involving the greater omentum.
Strafuss AC.In a review of neoplasm registry records at Kansas State University (1961 through 1971), 58 squamous cell carcinomas were reported in 10 breeds of horses. Mean age of the affected horses was 12.4 years. The head, eye and ocular adnexa accounted for 43.1%, the external male genitalia, 44.8%, and female perineal region, 12.0% of the squamous cell carcinomas, altogether representing 20.2% of 287 neoplasms recorded.
Hall WC, Nielsen SW, McEntee K.Tumours of the male genital tract, excluding the testes, are relatively rare in the six major domestic animals. The most important tumours are prostate carcinoma and transmissible venereal tumour of the penis in dogs, fibropapilloma of the penis in bulls, squamous papilloma and squamous cell carcinoma in horses, and squamous papilloma in pigs. Four histological types of canine prostate carcinoma exist: alveolar papillary, acinar, organoid, and poorly differentiated. The biological behaviour of prostate carcinomas is similar to that in man, with frequent metastasis to the regional pelvic nodes,...
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.
Baker JR, Leyland A.In a histological survey of 244 tumerous growths from 155 horses, the tumours commonly found were fibromas, squamous cell carcinomas, sarcoids and papillomas, most frequently affecting the skin, external genitalia, eye and orbit. The histological features that differentiate fibroblastic citaneous growths are detailed so that the clinical behaviour of these distinct neoplasms can be studied.
Hayes HM, Priester WA, Pendergrass TW.From 11 North American veterinary university hospitals and clinics, 248 animals were a confirmed diagnosis of nervous-tissue tumor were identified; 7 tumors were found in cattle, 28 in horses, 14 in cats, 199 in dogs, and none in other species. Tumors were divided for analysis into three categories-glial, meningeal, and peripheral nerve. In cattle and horses, all tumors involved peripheral nerves, the risk of which, in horses, reached a plateau at 4-6 years of age and remained constant thereafter. In cats, the tumors were equally distributed among the three tumor categories whereas, in dogs, t...
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...
A 25-year-old pony mare was presented to the clinic with preliminarily reported severe acute colic. The pony during the previous week had shown inappetence, apathy and fever of unknown origin. Clinical examination and placement of a gastric tube were indicative of a secondary gastric dilation. Rectal exploration found moderate caecal meteorism with a tensed and painful medial taenia as well as a dilated and fluid-filled small intestine. In addition, a solid, mobile, non-painful structure of approximately 10 cm diameter was palpated ventrally. A hyperechogenic mass close to the caecum was detec...
Beermann A, Hamza E, Reinhard S, Koch C, Oberhänsli T, Unger L.We investigated microRNAs (miRNAs) as potential prognostic biomarkers for equine sarcoid (ES) disease. In a breed-, age-, and sex-matched case-controlled study involving 45 ES-affected and 15 control horses, we assessed the diagnostic, prognostic, and theragnostic value of 3 miRNAs (eca-miR-127, eca-miR-379, eca-miR-432) in horses treated with European mistletoe () extract versus placebo. Whole-blood miRNA concentrations were measured using reverse-transcription quantitative real-time PCR (RT-qPCR) at 3 different times. We found that eca-miR-432 expression was lower in ES-affected (median =â...
du Preez S, Lynch B, Lindsay S, Simon O, Ferlini Agne G.To describe the case details of an equine corneal squamous cell carcinoma (SCC) arising from the central scar of a previous conjunctival pedicle graft. Methods: An 18-year-old Thoroughbred gelding, showing a progressive increase in diameter, depth, opacity, and pigmentation of a conjunctival pedicle graft scar of the left eye, 34 months after surgery. Methods: Complete ophthalmic examination, standard histologic and immunohistochemical evaluation of an incisional biopsy to formulate a definitive diagnosis. Carbon dioxide (CO) laser photoablation combined with topical mitomycin C treatment. R...
Ostendarp C, Barton AK.Intraocular neoplasia in horses is rare and only few case reports and small case series exist. Intraocular neoplasia has various clinical signs and includes important differential diagnoses in ocular disease. This narrative review of the current literature aims to provide a clinically relevant overview and classification of intraocular tumors in horses and adds a comparative oncological perspective concerning diagnosis, treatment and future considerations. The available clinical and imaging examination techniques allow for a reliable and differentiated investigation of the tumor, even in the s...
Muresu Ibba GM, Poeta A, De Lorenzi G, Pupillo G, D'Annunzio G, Pezzarossi A, Bisceglia I, Mangone L.Melanomas are dermal-epidermal and subcutaneous tumors commonly found in horses, especially those with grey coats. This study aimed to characterize melanomas in slaughtered horses by analyzing their distribution according to sex, age, and nationality, and to describe the veterinary inspection interventions required at slaughterhouses based on lymph node involvement and distant metastases in a province of northern Italy. Between January and December 2024, 182 grey horses were examined, and 28 cases of melanoma were identified (15% of grey horses) with an average age of 14 years: 8 males (mean a...
Alonso FH, Hallum J, Arndt S.We report here a case of lipid-rich abdominal fluid in a 31-y-old Arabian gelding with acute colic. Abdominocentesis yielded opaque, yellow-to-orange peritoneal fluid with an elevated triglyceride concentration (42 g/L, RI: <0.10 g/L; fluid:serum triglyceride ratio 11.4, RI: <1.0). A second abdominocentesis performed 3 d later revealed clear fluid, suggesting transient chyloabdomen. Despite medical management, the horse developed respiratory distress secondary to pharyngeal edema and was euthanized. Autopsy identified a large omental lipoma and severe ulcerative gastritis, but no effusion....
Derar D, Ali A, Al-Sobayil F, Refaai W.Granulosa cell tumors (GCTs) represent the most common ovarian neoplasms in mares, yet data on their epidemiology, risk factors, and clinical outcomes in Arabian horses are limited. Understanding their prevalence and diagnostic features is crucial for improving fertility management in this breed. Unassigned: Clinical records from 807 Arabian mares housed on 35 stud farms in central Saudi Arabia were retrospectively reviewed to determine the prevalence of GCT and potential risk factors, including age, parity, and anabolic steroid use. Twenty-four confirmed cases were further investigated using ...
Sidwell A, Shanklin A, Miller H, Cahoon M, Hole SL, Bianco C, Pereira R.A 3-year-old Connemara X filly was referred to a UK equine hospital for further investigation of unilateral nasal discharge and facial swelling. Diagnostic imaging documented the presence of a heterogenous, soft tissue opacity with areas of focal mineralisation within the right paranasal sinuses, completely obliterating the nasal cavity, in addition to endodontic disease and significant periapical pathology associated with the right permanent fourth premolar (Triadan 108). Subsequent histopathologic examination confirmed the mass as a fibro-inflammatory polyp.
Stoeckle SD, Stage HJ, Gehlen H.Thyroid diseases in horses are rare and pose challenges for veterinarians due to the complexity of clinical and diagnostic approaches. This retrospective case series describes cases of equine thyroid disease in a referral hospital population. Files of horses examined for suspected thyroid disease at an equine university clinic between 2009 and 2024 were reviewed. Data from nine horses examined for suspected thyroid disease, including signalment, clinical presentation, laboratory results, imaging findings, fine needle aspirates, biopsies, diagnoses, and treatments, were summarised. Diagnoses in...
de Chaisemartin C, Belluco S, Nottrott K.Dental masses such as odontogenic masses, heterotopic polydontia, or ectopic supernumerary teeth have been documented in the equine head. This is the first case report of a large maxillary sinus mass with 3 ectopic teeth in an adult horse. A 14-year-old warmblood gelding was presented for evaluation of chronic right-sided nasal discharge. After imaging exploration, surgery was performed on the standing horse with a conchofrontal sinus trephination and a large maxillary bone (MB) sinusotomy. The examinations revealed a sinusal mass in the right maxillary sinus covered by sinusal mucosa and surr...
Morales Yñiguez FJ, Leise BS.Over 25% of all emergencies are classified as wounds, making them the most common health conditions treated by veterinarians. While equine wounds may heal with minimal intervention, many complications associated with wound management can occur, thereby delaying wound healing and leading to chronic non-healing wounds. Wounds should be closed primarily when possible; however, numerous factors influence the risk of complications. Infection and biofilm production are common causes of delayed wound healing. Other causes of non-healing wounds include the presence of foreign material, sequestrum form...
Massardi E, Gaudenzi G, Carra S, Oldani M, Rybinska I, Persani L, Vitale G.Cushing's disease (CD) is a rare neuroendocrine disorder caused by ACTH-secreting pituitary adenomas, presenting significant diagnostic and therapeutic challenges. Given the evolutionary conservation of the hypothalamic-pituitary-adrenal axis, this review explores the translational value of spontaneous CD forms in dogs, horses, cats, small mammals, and rats, as well as of experimental models in mice, rats, and zebrafish. Dogs are the most studied, showing strong molecular and clinical similarities with human CD, making them valuable for preclinical drug and diagnostic research. While equine an...
Hegger A, Köhne M, Gerhauser I, Görgens A.A 19-year-old Oldenburg stallion was presented multiple times over the course of several months with recurrent colic signs. At each examination, an enlargement of the scrotum was noted, which could not be further specified by palpation and ultrasonographic examination. The increase in circumference was noted both on palpation and on inspection and the size remained unchanged throughout. No special findings were noted during the general examination and the special examination of the colic patient. A few months after the first onset of symptoms, a chicken egg-sized mass was palpated on the right...
Pereira EL, Pereira GR, Osório ML, Terra JLA, Gayger JB, Gularte JS, Demoliner M, Pereira VMAG, Filippi M, de Matos QS, Tessman A, Canal CW, Daudt C....Papillomaviruses (PV) are significant agents capable of inducing simple, multiple, and/or proliferative lesions in the dermis and epidermis of animals, known as cutaneous papillomatosis. These lesions can be benign or malignant and have been identified in various hosts, including mammals, birds, reptiles, and fish. PVs are strictly species- and tissue-specific, although some established and unusual cases of cross-infection, such as BPV in equine sarcoids, have been reported. Sarcoids are horses' most common skin tumors, which can be locally aggressive and cause significant clinical signs. It i...
Mau A, Keller SM, Kol A.Basophils are the rarest blood leukocyte in most healthy domestic mammals and the clinical significance of basophilia is poorly understood. Objective: To empirically determine magnitude thresholds for basophilia, identify its hematologic correlates, and identify associations between breeds, specific diseases, disease categories, organ systems, and basophilia in dogs, cats, and horses. Methods: CBCs and clinical information from dogs, cats, and horses were collected from the University of California-Davis School of Veterinary Medicine between 2000 and 2020. Relationships between basophil concen...
Batista LAS, de Alencar Santos Júnior D, Rodrigues AS, Menezes AA, do Nascimento MJR, de Galiza GJN, de Medeiros Dantas AF, Frade MTS.The present study describes the morphological and immunohistochemical characteristics of a case of diffuse seminoma in a 16-year-old male mixed-breed horse. According to the owner, the animal's left testicle had been gradually increasing in size over a period of 2 months. On palpation, the testicle had a firm consistency, with no sensitivity to digital pressure, was adhered to the scrotum and measuring 16 cm × 8 cm. In the ultrasound examination, it presented a heterogeneous texture and areas of hypoechogenic echogenicity without visualization of the mediastinum. Therefore, the bila...
Uchida-Fujii E, Kato Y, Ueno T, Numasawa Y, Yusa S, Haga T.Equus caballus papillomavirus 2 (EcPV2) is known to cause genital neoplasms in horses. However, reports on EcPV2 in Japan and Asia are limited. Herein, we present the histopathological and virological findings of the first reported case of an EcPV2-associated penile mass in Japan. The patient was a 22-year-old stallion with a history of breeding in Japan and abroad. Histopathological examination contained RNA in situ hybridization targeting the E6/E7 region and an immunohistochemical approach, and whole-genome sequencing was conducted within the viral examination. Proliferating epidermal cells...
Cutarelli A, Buonavoglia A, Fusco G, Pellicanò R, Napoletano M, Brandt S, Roperto S.Sarcoids are benign and locally aggressive skin lesions that commonly affect horses and other equid species. Sarcoids are generally considered to be caused by bovine delta-papillomaviruses (δPVs) types 1 and 2 (BPV1 and BPV2, respectively). Moreover, while bovine δPV types 13 and 14 (BPV13 and BPV14, respectively) are also suspected to induce sarcoids, information regarding this possibility and the occurrence of multiple bovine δPV infections in sarcoids is scarce. This study aimed, for the first time, to assess BPV1, BPV2, BPV13, and BPV14 infections and co-infections in equine sarcoid sam...
