Cutaneous neoplastic lesions of equids in the central United States and Canada: 3,351 biopsy specimens from 3,272 equids (2000-2010).

The study aims to identify trends in skin cancer in horses in central North America, comparing these trends with previously reported ones. The study examined 3351 skin biopsy specimens from 3272 horses diagnosed with cancer, finding melanoma, squamous cell carcinoma, and sarcoid to be the most common types of tumor.

Research Methodology

• The researchers used a retrospective case series method where they reviewed diagnostic reports of biopsy specimens from two diagnostic laboratories – Colorado State University and Prairie Diagnostic Services Inc.
• They collected a range of data for each case. Variables included age, sex, breed, geographic location, date of diagnosis, location of neoplasm on the body and the presence or absence of ulceration. This allowed them to assess various epidemiological trends associated with equine cutaneous neoplasms.

Research Findings

• Sarcoid, squamous cell carcinoma (SCC), and melanoma were identified as the three most common tumors diagnosed in horses.
• The researchers discovered a link between exposure to ultraviolet (UV) radiation and certain types of cancer. These tumors were 2.3 times as common in samples sent to Colorado State University than those sent to the Prairie Diagnostic Services Inc.
• The study identified certain breeds of horses that were more likely to develop certain types of tumors. For example, Appaloosa and American Paint horses were significantly more likely to have tumors associated with UV radiation. Other breeds, such as thoroughbreds and Arabians, were more likely to develop cutaneous lymphoma and melanomas respectively. Draft and pony breeds were more likely to develop benign soft tissue tumors. Basal cell tumors were more common in Morgans and pony breeds.
• The location of the tumor on the horse’s body also correlated with the type of cancer. Tumors in the perianal region were more likely to be melanoma or SCC, and tumors on the limbs were more likely to be giant cell tumor of soft parts.

Conclusions

• The researchers concluded that the data such as the horse’s breed, the location of the mass, and the horse’s geographic location can be used by vets to help determine potential diagnoses for skin masses.
• The study also highlighted the need for further research to better understand the biological basis behind the development of many equine skin neoplasms.