Transitional cell carcinoma of the urinary bladder in a Thoroughbred, with intra-abdominal dissemination.

This study presents the case of a 14-year-old Thoroughbred gelding horse diagnosed with transitional cell carcinoma, a type of bladder cancer, which had spread into the abdominal area. The diagnosis was made posthumously and through the examination of various tumor markers.

Disease Presentation and Necropsy Findings

• The 14-year-old Thoroughbred gelding was presented for post-death examination (necropsy) after having a history of sudden onset of blood in urine (hematuria).
• Upon necropsy, the horse was diagnosed with a type of bladder cancer called transitional cell carcinoma.
• The disease had spread (disseminated) to the horse’s abdomen.
• Tumor masses were found on the spleen’s outer covering (splenic capsule) and surrounding the large artery in the lower part of the abdomen (distal abdominal aorta).

Tumor Cell Analysis

• Investigation into the nature of the tumor cells revealed a widespread presence of protein filament (cytokeratin) within the cell cytoplasm. This is a common finding in many types of cancer and indicates the cells’ epithelial origin, typical for transitional cell carcinoma.
• The researchers tested for several tumor markers, such as the epithelial membrane antigen, carcinoembryonic antigen, tumor-associated glycoprotein 72, and another protein filament, vimentin. Here, the tumor cells proved negative. This result can help eliminate other types of cancers from consideration.

Significance of the Study

• Cases like this contribute to understanding bladder cancer in non-human subjects, adding value to veterinary medicine. It demonstrates the importance of early detection and intervention, as the disease was found to spread to the abdomen at the time of the examination.
• These findings also underscore the utility of specific tumor markers in making an accurate, posthumous cancer diagnosis and gaining insight into the tumor’s cell properties.