Melanoma in horses is a type of skin tumor commonly observed in gray horses, although it can occur in horses of any color. These tumors are typically found in areas such as the under-tail region, perineum, and around the lips and eyes. While many melanomas remain benign, some can become malignant and metastasize to other parts of the body. The underlying causes of melanoma in horses are not fully understood, but genetic factors and coat color are known to influence their development. Diagnosis often involves clinical examination and, in some cases, biopsy or imaging techniques. This page compiles peer-reviewed research studies and scholarly articles that explore the prevalence, diagnosis, progression, and management of melanoma in equine populations.
Pielberg G, Mikko S, Sandberg K, Andersson L.Grey horses are born coloured, turn progressively grey and often develop melanomas late in life. Grey shows an autosomal dominant inheritance and the locus has previously been mapped to horse chromosome 25 (ECA25), around the TXN gene. We have now developed eight new single nucleotide polymorphisms (SNPs) associated with genes on ECA25 using information on the linear order of genes on human chromosome 9q, as well as the human and mouse coding sequences. These SNPs were mapped in relation to the Grey locus using more than 300 progeny from matings between two Swedish Warmblood grey stallions and...
LeRoy BE, Knight MC, Eggleston R, Torres-Velez F, Harmon BG.A 14-year-old bay Thoroughbred gelding was presented for evaluation of a mass at the base of the tail. The mass had been present for 1 year, and recently had begun to increase in size. Additional masses were found around the eye and shoulder. A fine-needle aspirate of the tail-base mass revealed highly anaplastic round to polyhedral cells containing dark green to black cytoplasmic granules interpreted to be melanin. Histologically, the mass was composed of pleomorphic, poorly pigmented, round to polyhedral cells interpreted to be neoplastic melanocytes. With immunohistochemistry, the cells wer...
Labelle P, De Cock HE.Although metastases to the adrenals are common in humans, they have not been thoroughly studied in animals. The purpose of this retrospective study was to document the types of malignant tumors that metastasize to canine, feline, equine, and bovine adrenals, and the rate at which they do so. The average rate of adrenal involvement in metastatic cancer was 112/534 (21.0%) in dogs, 12/81 (14.8%) in cats, 18/67 (26.9%) in horses, and 5/16 (31.3%) in cattle. In dogs, 26 different tumor types metastasized to the adrenals. Pulmonary, mammary, prostatic, gastric, and pancreatic carcinomas, and melano...
Seltenhammer MH, Heere-Ress E, Brandt S, Druml T, Jansen B, Pehamberger H, Niebauer GW.Equine melanoma shows striking features particularly with regard to clinical development in grey horses: in contrast to malignant melanoma in humans and in solid coloured horses that are characterized by early onset of metastasis, pigment cell tumours display almost benign clinical features in ageing grey horses. Through evolution, grey horses appear to be in a favourable position in regard to the biological behaviour of melanomas. Yet unknown factors inhibiting or retarding early melanoma metastasis may be responsible for this phenomenon. In this study, immunostaining profiles and histopathol...
Rowe EL, Sullins KE.To determine whether excision was an acceptable treatment for dermal melanomatosis in horses. Methods: Retrospective study. Methods: 11 horses with dermal melanomatosis involving the perineal, perianal, or perirectal region or ventral surface of the tail in which treatment consisted of tumor excision. Methods: Medical records were reviewed. Follow-up information was obtained from owners through telephone interviews. Results: 9 of the 11 horses were alive at the time of follow-up interviews. None of the horses had regrowth at the surgery site where the primary tumor was removed. There were no c...
Elsinghorst TA.In this fourth article of a series of papers listing first case reports of animal diseases published since 2000, the following six cases of horse diseases are discussed: Disseminated metastatic intramedullary melanoma. Lipoma of the extensor tendon sheaths. Meningoencephalomyelitis in a neonatal foal due to Salmonella agona infection. Neuronal ceroid lipofuscinosis. Placentitis due to Rhodococcus equi infection. Right atrial diverticulum in a foal. After a short introduction, the bibliographical data, the abstract of the author(s), and some additional information derived from the article are g...
de Blaauw JA, Rijkenhuizen AB, van Nieuwstadt RA, Grinwis GC, Back W.Two grey mares, a 12-year-old Arabian and a 13-year-old Lippizaner cross, were referred for chronic pelvic limb lameness and abduction of the limb during the non supporting phase of the stride. The clinical examination revealed melanomas under the tail and on the perineum, and oedema of the proximal lame limb. A mass in the pelvic area was detected on rectal palpation. Laparoscopy was performed and the provisional diagnosis of malignant melanoma was made. Histological examination of the biopsy taken under laparoscopic control from the mass in the pelvis confirmed the diagnosis of malignant mel...
Seltenhammer MH, Simhofer H, Scherzer S, Zechner R, Curik I, Sölkner J, Brandt SM, Jansen B, Pehamberger H, Eisenmenger E.Equine melanomas occur most commonly in grey horses at age 5 years or more. Generally, benign and malignant melanomas are distinguished by microscopy, but a more distinct classification would be helpful. Objective: The objectives of this study were to gain further evidence concerning the occurrence of melanotic tumours, and to evaluate the impact of heredity on melanoma development. Methods: A clinical study was conducted on a defined population of 296 grey horses of Lipizzaner breed. Individuals were classified according to their stage of disease using a 0-5 scale. Heritability was estimated ...
MacGillivray KC, Sweeney RW, Del Piero F.The clinical and pathologic findings are reviewed for 14 horses with metastatic melanoma. All were older gray horses, with an average age of 16 years. The most common sites of primary tumors were the ventral tail, perineum, and parotid salivary gland. Metastases were found in multiple locations and caused a variety of clinical syndromes. The most common sites for metastases were the lymph nodes, liver, spleen, skeletal muscle, lungs, and surrounding or within blood vessels throughout the body. Many of the horses had dermal melanomas for years (range 1-6 years) before succumbing to metastatic d...
McCauley CT, Hawkins JF, Adams SB, Fessler JF.To determine outcome of horses in which cutaneous masses were removed with a carbon dioxide laser. Methods: Retrospective study. Methods: 32 horses. Methods: Medical records of horses with 1 or more cutaneous masses treated with a carbon dioxide laser were examined. Follow-up information was obtained through telephone interviews with owners and referring veterinarians. Results: Cutaneous masses were classified as sarcoids (15 horses), neoplastic masses other than sarcoids (squamous cell carcinoma [91; fibroma [1]; and melanoma [1]), and nonneoplastic masses (6). Minimum follow-up time was 6 mo...
Patterson-Kane JC, Sanchez LC, Uhl EW, Edens LM.A 12-year-old grey Warmblood stallion presented with fever of unknown origin, and anaemia. Five days later it had developed ataxia and become recumbent, and was humanely killed. At necropsy, malignant melanomas were identified in the perineal subcutis, spleen, and thoracic vertebral canal (T10-11). Populations of malignant melanoma cells were scattered throughout medullary cavities of the axial and appendicular skeleton, and were identified grossly as irregular areas of black to grey discoloration. To the authors' knowledge, this is the first report of disseminated intramedullary melanoma in a...
Requena L, de la Cruz A, Moreno C, Sangüeza O, Requena C.Animal type melanoma is a rare histopathologic variant of melanoma characterized by sheets and nodules of heavily pigmented epithelioid melanocytes that involve the entire thickness of the dermis. This human neoplasm mimics melanocytic neoplasms seen in gray horses and laboratory animals; thus, is termed animal type melanoma. It is quite rare and, with only a few reported cases, its biological behavior is not well understood. We report an example of animal type melanoma on the back of a 27-year-old man. The lesion showed areas of melanoma in situ, which ruled out the possibility of metastatic ...
Heinzerling LM, Feige K, Rieder S, Akens MK, Dummer R, Stranzinger G, Moelling K.Preclinical studies investigating new therapeutic principles against melanoma are presently being carried out in mouse models; however, these are not optimal. Here we describe a novel animal model using gray horses. These animals spontaneously develop metastatic melanoma that resembles human disease and is thus highly relevant for preclinical studies testing new immunotherapy protocols. We found that injection of plasmid DNA coding for the human cytokine interleukin 12 into established metastases induced significant regression in all 12 treated lesions in a total of 7 horses. Complete disappea...
Roels S, Tilmant K, Van Daele A, Van Marck E, Ducatelle R.Melanocytic tumours are a well-known clinical and pathological entity in horses, but further phenotypic characterization of these tumours is lacking. Six melanocytic tumours from five horses (two metastatic and four benign) were examined by Ki67, PCNA and p53 immunostaining, DNA nick end labelling (Tunel) and Feulgen staining. The stainings were evaluated using quantitative image analysis. The resulting parameters of growth fraction (Ki67), S-phase index (PCNA), p53 index, apoptotic index, DNA index, nuclear diameter, ploidy balance, proliferation index (Feulgen) and hyperploidy were analysed....
Fleury C, Bérard F, Balme B, Thomas L.The clinical and pathological characteristics of cutaneous melanomas occurring in Camargue-type gray-skinned horses are reported. Examination of 83 tumor-bearing horses revealed that the tumors occurred most frequently underneath the tail (93.9%) and at high rates in the peri-anal region (43.0%), the lips (33.0%), and the eyelids (24.0%), but rarely in the vulva (3.8%). Tumorous lesions were characterized by the presence of either hemispheric nodules or large infiltrated plaques, or their combinations. Microscopic examination indicated that tumorous lesions were composed mostly of melanocytes ...
McCue PM.Granulosa cell tumors of the ovary and SCC and melanoma of the external genitalia are the most common neoplasms in the mare. Tumors of the tubular reproductive tract and the mammary gland are rare.
Johnson PJ.Cutaneous neoplasia represents a clinical problem with which veterinarians are commonly challenged. This article addresses equine cutaneous squamous cell carcinoma, squamous cell papilloma, melanoma, mastocytosis, and lymphosarcoma. Current concepts regarding the origin, pathogenesis, diagnosis and treatment of each neoplasm is emphasized.
Murray MJ, Cavey DM, Feldman BF, Trostle SS, White NA.Sympathetic denervation in a 20-year-old, gray, Thoroughbred-Percheron gelding was manifested by cutaneous hyperthermia and sweating over the right side of the body, demarcated by a line from the withers to the elbow and extending cranially. There was cutaneous hyperthermia over the right side of the head, but other signs of Horner's syndrome (sweating, ptosis, miosis, enophthalmos) were not present. The pattern of cutaneous hyperthermia and sweating was consistent with sympathetic denervation localized to the cervicothoracic ganglion, and thoracic radiographs revealed increased density in the...
Valentine BA.A study of 57 cutaneous melanocytic tumors from 53 horses revealed 4 distinct clinical syndromes: melanocytic nevus, dermal melanoma, dermal melanomatosis, and anaplastic malignant melanoma. Melanocytic nevus and anaplastic melanoma each had histopathologic features that distinguished them from dermal melanoma and dermal melanomatosis. Dermal melanoma and dermal melanomatosis were histologically similar but could be differentiated by their clinical features. Melanocytic nevi were diagnosed in 29 horses with an average age of 5 years; they were solitary, superficial masses that occurred in both...
Ohmuro K, Okada K, Satoh A, Murakami K, Satake S, Asahina M, Numakunai S, Ohshima K.A thoroughbred horse, gelding, gray color, aged 19 years old had cutaneous melanomas from the root to the middle of the tail, and throughout the connective tissues of the whole body. Histologically, the tumors were diagnosed as mature melanotic melanomas characteristically deposited with abundant melanin pigment. Examined with an electron microscope, melanosomes were electron opaque without internal structure (stage IV), or as mature granular and lamellar types. Most of them were fused with each other, and formed compound melanosomes, which was similar to internal melanin aggregates in shape. ...
Mair TS, Brown PJ.Thirty-eight horses with confirmed thoracic neoplasia included 28 (37.7%) with lymphosarcoma, 4 (10.5%) with metastatic renal cell carcinoma, 2 (5.3%) with primary lung carcinoma, 2 (5.3%) with secondary squamous cell carcinoma from the stomach, 1 (2.6%) with pleural mesothelioma, and 1 (2.6%) with malignant melanoma. The major clinical features included weight loss, inappetence, dyspnoea and coughing, but in cases of lung metastases, they related more to the primary site of tumour formation. Haematological and serum biochemical abnormalities were non-specific. Specific pre-mortem diagnosis wa...
Blanchard TL, Schumacher J, Edwards JF, Varner DD, Lewis RD, Everett K, Joyce JR.A Thoroughbred stallion developed priapism that was unresponsive to medical treatment and lavage of the corpus cavernosum penis with heparinized 0.9% NaCl solution. Three weeks after onset of priapism, the penis was firm and noncompliant, and penile pain sensation and ability to retract the penis were lost. Ultrasonography confirmed thrombosis of the corpus cavernosum penis. The stallion was euthanatized because of poor prognosis for return to breeding soundness. Necropsy revealed enlargement of numerous lymph nodes. The dorsal penile nerves were demyelinated distal to the crura of the penis. ...
Honnas CM, Liskey CC, Meagher DM, Brown D, Luck EE.A 24-year-old horse had a malignant melanoma of the right forefoot. Because surgical excision of the melanoma was incomplete, as determined by histologic examination of the excised tissue margins, the tumor margins were injected with a matrix therapeutic implant containing cis-diamminedichloroplatinum, epinephrine, and purified bovine collagen matrix. The foot healed and the horse remained clinically free of disease for 26 months before recurrence of malignant melanoma. Surgical exploration of the digit revealed extensive involvement of the foot, and the horse was euthanatized.
Schott HC, Major MD, Grant BD, Bayly WM.Spinal cord compression by melanomas at C7-T1 is described in 2 horses. Despite similar location of the lesions, the onset of neurologic signs and clinical progression varied. Both horses were gray, but few cutaneous melanomas were found. Internal dissemination, however, was extensive in both horses. Antemortem diagnosis was made in one horse, and surgical decompression of the spinal cord was performed. Neoplasms of the vertebral canal and spinal cord are uncommon in horses. Melanoma in the spinal canal should be included in the differential diagnosis of neurologic disease, especially in matur...
Goetz TE, Ogilvie GK, Keegan KG, Johnson PJ.Cimetidine, an H2 histamine antagonist, was used in the clinical management of progressive, multifocal melanomatosis in 3 adult gray horses. Prior to treatment, the tumors had increased rapidly in size and number in 2 horses (duration of 6 and 27 months, respectively) and slowly in the third horse (duration of 48 months). All 3 horses were treated with cimetidine (2.5 mg/kg of body weight, PO, q 8 h) for 2 months to 1 year. During treatment, the number and size of the melanomas decreased substantially (50 to 90%). The progression of the disease was halted in 2 horses and controlled in the thir...
Patterson-Kane JC, Sanchez LC, Uhl EW, Edens LM.A 12-year-old grey Warmblood stallion presented with fever of unknown origin, and anaemia. Five days later it had developed ataxia and become recumbent, and was humanely killed. At necropsy, malignant melanomas were identified in the perineal subcutis, spleen, and thoracic vertebral canal (T10-11). Populations of malignant melanoma cells were scattered throughout medullary cavities of the axial and appendicular skeleton, and were identified grossly as irregular areas of black to grey discoloration. To the authors' knowledge, this is the first report of disseminated intramedullary melanoma in a...
Seltenhammer MH, Simhofer H, Scherzer S, Zechner R, Curik I, Sölkner J, Brandt SM, Jansen B, Pehamberger H, Eisenmenger E.Equine melanomas occur most commonly in grey horses at age 5 years or more. Generally, benign and malignant melanomas are distinguished by microscopy, but a more distinct classification would be helpful. Objective: The objectives of this study were to gain further evidence concerning the occurrence of melanotic tumours, and to evaluate the impact of heredity on melanoma development. Methods: A clinical study was conducted on a defined population of 296 grey horses of Lipizzaner breed. Individuals were classified according to their stage of disease using a 0-5 scale. Heritability was estimated ...
Steinmetz A, Gittel C, Böttcher D, Lapko L, Offhaus J.A melanoma of the upper eyelid was resected in a gray warmblood gelding. A full functional eyelid could be obtained by completion a sliding skin graft with a free labial mucocutaneous graft transplantation to restore the mucocutaneous junction and to decrease the risk of postoperative trichiasis.
Chapman SW, Metzger N, Grest P, Feige K, von Rechenberg B, Auer JA, Hottiger MO.Gray horses spontaneously develop metastatic melanomas that resemble human disease, and this is often accompanied with metastasis to other organs. Unlike in other species, the establishment of primary equine melanoma cultures that could be used to develop new therapeutic approaches has remained a major challenge. The purpose of the study was to develop a protocol for routine isolation and cultivation of primary equine melanocytes. Melanoma tissues were excised from 13 horses under local anesthesia, mainly from the perianal area. The melanoma cells were isolated from the melanoma tissue by seri...
Honnas CM, Liskey CC, Meagher DM, Brown D, Luck EE.A 24-year-old horse had a malignant melanoma of the right forefoot. Because surgical excision of the melanoma was incomplete, as determined by histologic examination of the excised tissue margins, the tumor margins were injected with a matrix therapeutic implant containing cis-diamminedichloroplatinum, epinephrine, and purified bovine collagen matrix. The foot healed and the horse remained clinically free of disease for 26 months before recurrence of malignant melanoma. Surgical exploration of the digit revealed extensive involvement of the foot, and the horse was euthanatized.
MacKay RJ.All gray horses inherited a single gene mutation, STX17G, that unbalances melanocyte behavior to cause graying and propensities to develop vitiligo and melanoma. The coat color genes ASIPa and MC1RE add risk such that relative likelihood of melanoma based on pregraying coat color is black > bay > chestnut. Melanomas begin at about 4 years. Locoregional control of melanoma masses depends on surgical removal and/or intralesional chemotherapy (possibly with adjunctive hyperthermia or electroporation). Systemic treatment is not evidence based but immunomodulators (cimetidine, levamisole) and ...
Dixon J, Smith K, Perkins J, Sherlock C, Mair T, Weller R.Melanomas are one of the most common neoplasms in the horse and are frequently found in the head region. There is a genetic predisposition in horses with a gray hair coat. Computed tomography (CT) is frequently used in referral practice to evaluate the equine head but there are few reports describing the CT appearance of melanomas in this location. The aim of this retrospective, case series study was to describe characteristics in a group of horses with confirmed disease. Case records from two referral hospitals were reviewed, and 13 horses were identified that had undergone CT of the head, wi...
Hattori K, Matsuda N, Murakami T, Ito E, Ugawa Y.A 62-year-old man with acute paraplegia was transferred to our hospital. He had flaccid paraplegia and multiple cranial nerve palsies, such as mydriasis of the left pupil, abduction palsy of the left eye, hoarseness and dysphagia, but no meningeal irritation signs. MRI of the spinal canal showed swellings of the conus medullaris and the cauda equine, and also contrast enhancement of the spinal meninges. The cerebrospinal fluid (CSF) showed pleocytosis and protein increment. The lymph node was swollen in his right axilla. The biopsy specimen from the right axillary lymph node revealed metastasi...
Biegel U, Mevissen M, Schuller S, Ruess K, Christen O, Ayrle H, Koch C, Walkenhorst M.Cancer is a common disease in humans and in companion animals and treatment is challenging. The aim of this systematic review was to identify and assess the potential use of Viscum album L. extracts (VAE) for treatment of neoplastic diseases in companion animals. Peer-reviewed animal, in vivo and in vitro studies were included, considering the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and A Measurement Tool to Assess Systematic Reviews (AMSTAR). Overall, 6,148 references were identified. Following a predefined protocol, 114 full-text references were ...
Labelle P, De Cock HE.Although metastases to the adrenals are common in humans, they have not been thoroughly studied in animals. The purpose of this retrospective study was to document the types of malignant tumors that metastasize to canine, feline, equine, and bovine adrenals, and the rate at which they do so. The average rate of adrenal involvement in metastatic cancer was 112/534 (21.0%) in dogs, 12/81 (14.8%) in cats, 18/67 (26.9%) in horses, and 5/16 (31.3%) in cattle. In dogs, 26 different tumor types metastasized to the adrenals. Pulmonary, mammary, prostatic, gastric, and pancreatic carcinomas, and melano...
Baba AI, Gaboreanu M, Rotaru O, Kwieczinsky R.Malignant melanomas in 5 horses, 1 calf, 1 cow and 2 pigs were described. The disease, in white or gray horses, was tegumentally located and generalized in the organs of the abdominal cavity. Microscopically, dendritic and fusiform pigment cells and multinucleated cells were identified. In the hypophysis there microcysts and in one case a hypophyseal adenoma were encountered. Electronmicroscopically, differentiated melanophores and melanophages were also found. The mature melanosomes were intensely black and the elementary granules concentrically and lamellarly arranged. In cattle, the general...
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...
Druml T, Brem G, Horna M, Ricard A, Grilz-Seger G.Melanoma prevalence in gray horses reaches up to 50% and more. Several studies have documented a genetic melanoma predisposition which is referred to the 4.6 kb duplication in intron 6 of STX17 and its surrounding haplotype. However, the genetic background and mechanisms responsible for differences in etiopathogenesis of equine dermal melanomatosis still remain unknown. In the current study, we performed a genome wide association analysis in 141 Lipizzan horses and subsequently identified one candidate gene on chromosome 24 putatively involved in melanoma pathogenesis in gray horses. The assoc...
Valentine BA.A study of 57 cutaneous melanocytic tumors from 53 horses revealed 4 distinct clinical syndromes: melanocytic nevus, dermal melanoma, dermal melanomatosis, and anaplastic malignant melanoma. Melanocytic nevus and anaplastic melanoma each had histopathologic features that distinguished them from dermal melanoma and dermal melanomatosis. Dermal melanoma and dermal melanomatosis were histologically similar but could be differentiated by their clinical features. Melanocytic nevi were diagnosed in 29 horses with an average age of 5 years; they were solitary, superficial masses that occurred in both...
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. ...
Thamm DH, Ehrhart EJ, Charles JB, Elce YA.The enzyme cyclooxygenase-2 (COX-2) is expressed in some tumor and stromal tissues, and catalyzes production of prostaglandins with growth stimulatory, antiapoptotic, proangiogenic, and immunosuppressive properties. Pharmacologic inhibition of COX-2 is associated with antitumor activity in various human and canine malignancies. The purpose of this study was to assess COX-2 expression in a series of equine sarcoids, melanomas, and squamous-cell carcinomas (SCC). COX-2 expression was assessed in formalin-fixed paraffin-embedded tissues from 14 sarcoids, 11 melanomas, and 37 SCC that represent va...
Redding WR, O'Grady SE.This article addresses nonseptic diseases associated with the hoof complex, namely keratoma, white line disease, canker, and neoplasia. Keratoma is an uncommon cause of lameness, which may be surgically removed. White line disease, a keratolytic process on the solar surface of the hoof, is treated with therapeutic farriery and resection of the hoof wall when appropriate. Equine canker is an infectious process that results in development of a chronic hypertrophy of the horn-producing tissues. Neoplasia involving the equine foot is rare, and melanoma is the most common type of neoplasm reported....
Jiang L, Campagne C, Sundström E, Sousa P, Imran S, Seltenhammer M, Pielberg G, Olsson MJ, Egidy G, Andersson L, Golovko A.Constitutive activation of the ERK pathway, occurring in the vast majority of melanocytic neoplasms, has a pivotal role in melanoma development. Different mechanisms underlie this activation in different tumour settings. The Grey phenotype in horses, caused by a 4.6 kb duplication in intron 6 of Syntaxin 17 (STX17), is associated with a very high incidence of cutaneous melanoma, but the molecular mechanism behind the melanomagenesis remains unknown. Here, we investigated the involvement of the ERK pathway in melanoma development in Grey horses. Methods: Grey horse melanoma tumours, cell lines ...
Pielberg G, Mikko S, Sandberg K, Andersson L.Grey horses are born coloured, turn progressively grey and often develop melanomas late in life. Grey shows an autosomal dominant inheritance and the locus has previously been mapped to horse chromosome 25 (ECA25), around the TXN gene. We have now developed eight new single nucleotide polymorphisms (SNPs) associated with genes on ECA25 using information on the linear order of genes on human chromosome 9q, as well as the human and mouse coding sequences. These SNPs were mapped in relation to the Grey locus using more than 300 progeny from matings between two Swedish Warmblood grey stallions and...
Rosengren Pielberg G, Golovko A, Sundström E, Curik I, Lennartsson J, Seltenhammer MH, Druml T, Binns M, Fitzsimmons C, Lindgren G, Sandberg K....In horses, graying with age is an autosomal dominant trait associated with a high incidence of melanoma and vitiligo-like depigmentation. Here we show that the Gray phenotype is caused by a 4.6-kb duplication in intron 6 of STX17 (syntaxin-17) that constitutes a cis-acting regulatory mutation. Both STX17 and the neighboring NR4A3 gene are overexpressed in melanomas from Gray horses. Gray horses carrying a loss-of-function mutation in ASIP (agouti signaling protein) had a higher incidence of melanoma, implying that increased melanocortin-1 receptor signaling promotes melanoma development in Gra...
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.
Teixeira RB, Rendahl AK, Anderson SM, Mickelson JR, Sigler D, Buchanan BR, Coleman RJ, McCue ME.Both graying and melanoma formation in horses have recently been linked to a duplication in the STX17 gene. This duplication, as well as a mutation in the ASIP gene that increases MC1R pathway signaling, affects melanoma risk and severity in gray horses. Objective: To determine if melanoma susceptibility in gray Quarter Horses (QH) is lower than gray horses from other breeds because of decreased MC1R signaling resulting from a high incidence of the MC1R chestnut coat color allele in the QH population. Methods: A total of 335 gray QH with and without dermal melanomas. Methods: Blood or hair roo...
Campagne C, Julé S, Bernex F, Estrada M, Aubin-Houzelstein G, Panthier JJ, Egidy G.Melanocytic proliferations are common in horses but the diagnosis of malignancy is not always straightforward. To improve diagnosis and prognosis, markers of malignancy are needed. Receptor for activated C kinase 1 (RACK1) protein may be such a marker. RACK1 was originally found to characterize malignant melanocytic lesions in the Melanoblastoma-bearing Libechov minipig (MeLiM) and, later, in human patients. Our purpose was to investigate the value of RACK1 in the classification of cutaneous melanocytic proliferations in horses. Results: Using immunofluorescence, we report here that both MITF ...
Nowacka-Woszuk J, Mackowski M, Stefaniuk-Szmukier M, Cieslak J.The equine graying with age causative mutation in the syntaxin-17 gene (STX17) has been known for over a decade, but proper genotyping of this variant remains challenging due to its molecular character (4.6-kb tandem duplication). Precise information on gray mutation status is important for horse breeders and veterinarians, since gray homozygous horses are more prone to developing aggressive melanoma tumors than heterozygotes. Since recent studies have confirmed that droplet digital PCR is a valuable technique for copy number analysis, we decided to investigate whether this method can be used ...
Pimenta J, Prada J, Cotovio M.Adult grey horses have a high incidence of melanocytic tumors. This article narratively reviews the role of some genetic features related to melanoma formation in horses, such as STX17 mutation, ASIP or MITF alterations, and the link between the graying process and the development of these tumors. A clear system of clinical and pathological classification of melanocytic tumors in naevus, dermal melanoma, dermal melanomatosis and anaplastic malignant melanoma is provided. Clinical and laboratorial methods of diagnosing are listed, with fine needle aspiration and histopathology being the most re...
Ohmuro K, Okada K, Satoh A, Murakami K, Satake S, Asahina M, Numakunai S, Ohshima K.A thoroughbred horse, gelding, gray color, aged 19 years old had cutaneous melanomas from the root to the middle of the tail, and throughout the connective tissues of the whole body. Histologically, the tumors were diagnosed as mature melanotic melanomas characteristically deposited with abundant melanin pigment. Examined with an electron microscope, melanosomes were electron opaque without internal structure (stage IV), or as mature granular and lamellar types. Most of them were fused with each other, and formed compound melanosomes, which was similar to internal melanin aggregates in shape. ...
Fleury C, Bérard F, Balme B, Thomas L.The clinical and pathological characteristics of cutaneous melanomas occurring in Camargue-type gray-skinned horses are reported. Examination of 83 tumor-bearing horses revealed that the tumors occurred most frequently underneath the tail (93.9%) and at high rates in the peri-anal region (43.0%), the lips (33.0%), and the eyelids (24.0%), but rarely in the vulva (3.8%). Tumorous lesions were characterized by the presence of either hemispheric nodules or large infiltrated plaques, or their combinations. Microscopic examination indicated that tumorous lesions were composed mostly of melanocytes ...
Seltenhammer MH, Heere-Ress E, Brandt S, Druml T, Jansen B, Pehamberger H, Niebauer GW.Equine melanoma shows striking features particularly with regard to clinical development in grey horses: in contrast to malignant melanoma in humans and in solid coloured horses that are characterized by early onset of metastasis, pigment cell tumours display almost benign clinical features in ageing grey horses. Through evolution, grey horses appear to be in a favourable position in regard to the biological behaviour of melanomas. Yet unknown factors inhibiting or retarding early melanoma metastasis may be responsible for this phenomenon. In this study, immunostaining profiles and histopathol...
Pigoli C, Gibelli LR, Caniatti M, Moretti L, Sironi G, Giudice C.In fluorescence microscopy, light radiation can be used to bleach fluorescent molecules in formalin-fixed and paraffin-embedded (FFPE) samples, in order to increase the ratio between signal of interest and background autofluorescence. We tested if the same principle can be exploited in bright field microscopy to bleach pigmented melanoma FFPE sections together with cell morphology maintenance. After dewaxing and rehydration, serial FFPE sections of a feline diffuse iris melanoma, a canine dermal melanoma, a gray horse dermal melanoma and a swine cutaneous melanoma were irradiated with visible ...
