Primary pulmonary neoplasm in a horse.

The study examines a rare case of primary lung cancer (bronchioalveolar adenocarcinoma) in a 16-year-old Thoroughbred horse, identified through a combination of radiography, cytology, and ultrasonography methods.

Research Subject and Initial Findings

• The subject of the research was a 16-year-old Thoroughbred gelding (castrated male horse) that was initially brought in for respiratory disease evaluation.
• Upon postmortem examination, a primary lung tumor was discovered, which is uncommon in horses.

Diagnostic Methods

• A tentative diagnosis was established while the horse was still alive (antemortem), using a combination of diagnostic methods.
• Radiography was used to image the structure of the horse’s lungs and identify any abnormal growths.
• Cytologic examination of a needle aspirate guided by ultrasonography was also conducted. This involved extracting cells from the horse’s lung tumor by needle (aspiration) and examining them under a microscope. Ultrasonography was used to guide the needle to the precise location of the tumor.

Final Diagnosis and Significance

• The histologic (microscopic tissue structure) examination of the lung tumor confirmed a diagnosis of bronchioalveolar adenocarcinoma, a specific form of lung cancer.
• The presence of this type of primary (originating from the location) lung tumor is particularly rare in horses.
• It is noted that the most frequently-reported pulmonary (lung) tumor in horses is the granular cell tumor, which differs from the adenocarcinoma found in the horse discussed in this study.
• This case is significant as it adds data to the scarce literature on equine primary pulmonary neoplasms. It can form the basis for further investigations into the causes, diagnostics, and potential treatments of lung tumors in horses.