title: Cutaneous neoplastic lesions of equids in the central United States and Canada: 3,351 biopsy specimens from 3,272 equids (2000-2010).
abstract: OBJECTIVE
  To identify epidemiological trends in cutaneous neoplasms affecting equids in central North America and compare them with previously reported trends.
  
  
  METHODS
  Retrospective case series.
  
  
  METHODS
  3,351 cutaneous biopsy specimens from 3,272 equids with a neoplastic diagnosis.
  
  
  METHODS
  Diagnostic reports from 2 diagnostic laboratories (Colorado State University and Prairie Diagnostic Services Inc) were reviewed for frequency of specific lesions and epidemiological trends. Variables included in analyses (if known) were age, sex, breed, geographic location, date of diagnosis, location of neoplasm on the body, and presence or absence of ulceration.
  
  
  RESULTS
  Sarcoid, squamous cell carcinoma (SCC), and melanoma were the 3 most common tumors diagnosed. Tumors associated with UV radiation (SCC, SCC in situ, hemangioma, hemangiosarcoma) were 2.3 (95% confidence interval [CI], 1.8 to 3.0) times as common in biopsy specimens received by Colorado State University than in specimens received by Prairie Diagnostic Services Inc. Appaloosa horses and American Paint horses, respectively, were 7.2 (95% CI, 5.6 to 9.2) and 4.4 (95% CI, 3.6 to 5.4) times as likely as other breeds to have tumors associated with UV radiation. Thoroughbreds were predisposed to cutaneous lymphoma, whereas Arabians were more likely to have melanomas. Draft and pony breeds were 3.1 (95% CI, 1.9 to 5.1) times as likely as other breeds to have benign soft tissue tumors. Morgans and pony breeds more commonly had basal cell tumors. Tumors in the perianal region were significantly more likely to be SCC or melanoma while tumors on the limbs were more likely to be giant cell tumor of soft parts.
  
  
  CONCLUSIONS
  Signalment, anatomic location of the mass, and geographic location of the horse can be used to help equine practitioners formulate differential diagnoses for cutaneous masses. Further research is necessary to identify the biological basis for the development of many equine cutaneous neoplasms.
authors.affiliation: Department of Microbiology, Immunology, and Pathology and the Veterinary Diagnostic Lab, College of Veterinary Medicine and Biological Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Paula A
authors.initials: PA
authors.lastname: Schaffer
authors.forename: Bruce
authors.initials: B
authors.lastname: Wobeser
authors.forename: Laura E R
authors.initials: LE
authors.lastname: Martin
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Dennis
authors.forename: Colleen G
authors.initials: CG
authors.lastname: Duncan
mesh_terms: D000818:Animals; D001706:Biopsy; D002170:Canada / Q000453:epidemiology; D006734:Horse Diseases / Q000145:classification / Q000453:epidemiology* / Q000473:pathology; D006736:Horses; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000145:classification / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D014481:United States / Q000453:epidemiology