Equis ISSN 2398-2977

Skin: neoplasia - melanoma

Synonym(s): Gray's disease

Contributor(s): Cody Coyne, Reginald Pascoe, Sue Paterson, Vetstream Ltd, Anna Hollis

Introduction

  • A common tumor of the melanotic tissue, seen most often in gray horses over 6 years old.
  • Cause: unknown.
  • Signs: hyperpigmented, firm nodular lesions.
  • Diagnosis: pathology.
  • Treatment: depends upon extent and site of lesion.
  • Prognosis: variable, often benign and cause no problems (especially in gray horses); may be malignant and metastasize. As lesions enlarge they may cause problems due to obstruction of the rectum or urethra, and secondary complications such as ulceration, abscessation and maggot infestation are also seen.
Print off the Owner factsheets on Melanoma - skin tumourCancer in horses and Lumps and bumps to give to your client.

Pathogenesis

Predisposing factors

General

  • Some mare families are predisposed to tumor.

Pathophysiology

  • Melanosarcoma found in the same locations as melanoma, but more aggressively invasive.
  • Tumors of varying malignancy arising from the melanocytes or melanoblasts of the equine skin.
  • Benign or malignant, or may suddenly become malignant and metastasize widely.

Timecourse

  • Variable.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Valentine B A, Calderwood Mays M B & Cheramie H S (2014) Anaplastic malignant melanoma of the tail in non-grey horses. Equine Vet Educ 26 (3), 156-158 VetMedResource.
  • Moore J S et al (2013) Melanoma in horses: Current perspectives. Equine Vet Educ 25 (3), 144-151 VetMedResource.
  • Barrelet A, Foote A & Littlewood J D (2010) Common equine skin tumours. UK Vet 15(6), 9-17 VetMedResource.
  • Finocchiaro L M E, Riveros M D & Gilkin G C (2009) Cytokine-enhanced vaccine and suicide gene therapy as adjuvant treatments of metastatic melanoma in a horse. Vet Rec 164 (9), 278-279 PubMed.
  • Pilsworth R C & Knottenbelt D (2006) Melanoma. Equine Vet Educ 18 (5), 228-230 VetMedResource.
  • Henson F M D & Dobson J M (2004) Use of radiation therapy in the treatment of equine neoplasia. Equine Vet Educ 16 (6), 315-318 VetMedResource.
  • Quinn C (2003) Skin tumours in the horse: clinical presentation and management. In Pract 25 (8), 476-483 VetMedResource.
  • Fleury C et al (2000) The study of cutaneous melanomas in Camargue-type gray-skinned horses (2) - epidemiological survey. Pigment Cell Res 13 (1), 47-51 PubMed.

Other sources of information

  • Knottenbelt D C, Patterson-Kane J C & Snalune K L (2015) Clinical Equine Oncology. Elsevier, UK.
  • Phillips J (1997) Melanoma. In: Current Therapy in Equine Medicine. 7th edn. Eds: Robinson N E & Sprayberry K A. Elsevier-Saunders, USA. pp 524-527.


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