Epidemiologic study of ocular/adnexal squamous cell carcinoma in horses.

The study examines the rate of ocular/adnexal squamous cell carcinoma (SCC) in horses, finding that increased longitude, altitude, or solar radiation, and decreased latitude, result in a higher prevalence of the disease. The research also identifies that age, some breeds, neutered males, and certain hair colors are associated with higher prevalence of SCC.

Objective and Methodology

• The primary objective of this study was to investigate the proportional hospital admission ratios for equine ocular/adnexal squamous cell carcinoma (SCC) in 14 veterinary colleges in the Veterinary Medical Data Program, with data collected from 1978 to 1986.
• The research used the geographic and physical data to identify patterns of SCC. The data point comparison included altitude, longitude, latitude, and mean annual solar radiation.
• Further examination of individual horses records diagnosed with SCC from 1978 to 1988 at Colorado State University Veterinary Teaching Hospital was conducted, focusing on diagnosis, age, breed, gender, hair color, and the date and year of admission.

Results

• The study found a strong correlation between an increase in longitude, altitude, or mean annual solar radiation and an increased prevalence of SCC in horses. Similarly, it found a direct correlation with decreased latitude.
• Of the 147 horses at Colorado University diagnosed with ocular/adnexal SCC, the prevalence was notably high with increasing age. Hence, older horses have a higher chance of developing SCC.
• Certain breeds like draft breeds (Belgian, Clydesdale, and Shire) and Appaloosas had a higher occurrence of SCC than Quarter Horses.
• Neutered males or geldings were found to have a higher risk of developing this type of cancer in comparison to sexually intact males and females.
• Additionally, horses with any hair color other than black, brown, or bay were found to have a significantly higher chance of developing SCC.

Significance and Conclusions

• The research is significant as it may contribute to the prevention and early detection of ocular/adnexal squamous cell carcinoma in horses.
• The findings may prompt more detailed investigations into specific risk factors, such as how environmental factors such as altitude and solar radiation contribute to the development of SCC and why certain breeds and hair colors are more susceptible.
• The risk factor identification in this study could aid in creating targeted preventative strategies or treatment protocols for the relevant breeds and age groups, potentially maximizing healthcare and improving the lifespan of affected horses.