Vascular hamartomas of the dorsal carpal region in three young thoroughbred horses.

This study details the clinical and pathological investigations of unusual vascular tumors found in the subcutis of the dorsal carpus in three young Thoroughbred horses. The tumors, eventually diagnosed as hamartomas rather than neoplasms, presented diagnostic challenges due to complications from recurrent hemorrhages and surgical interventions.

Case Overview

• The study focused on three young Thoroughbred horses, all of whom developed peculiar vascular tumors (later discovered to be hamartomas) in their dorsal carpus.
• The uncommon site of origin of these tumors and the diagnostic problems encountered due to repeated bleeding and surgical procedures became the main points of interest.

Case One: Thoroughbred Filly

• The first case involved a three-year-old Thoroughbred filly, whose initial symptoms were a rapidly forming fluid swelling over the right carpus.
• Although the swelling was incised and treated with daily cleaning and bandaging, consistent bleeding from the incision site and the persistence of the swelling lead to a more extensive evaluation.
• Radiographical examination revealed only soft tissue swelling, with debridement and medical treatment undertaken after bacterial cultures of the site identified a mixed bacterial infection.
• Despite changes in antibiotic treatment in response to sensitivity results, the filly’s condition did not improve and the swelling increased in size, with bleeding and new ulcers forming.

Surgical Findings and Histological Examination

• Upon surgical exploration under general anesthesia, the mass was found to be a network of fragile blood vessels in close proximity to the carpal joint capsule. Necrotic areas were discovered beneath the skin erosions.
• Attempts were made to remove the mass surgically, followed by a freeze-thaw cycle using liquid nitrogen on the surgical field.
• However, a histological examination of a sample taken during surgery revealed abnormal blood vessel formation and thrombosis within hemorrhagic granulation tissue, which suggested the possibility of malignancy.
• The medical team investigated potential metastatic spread but found no abnormalities in radiographs of the thorax, cytological examinations of peritoneal fluid, or manual and ultrasonographic examinations of abdominal contents.

In conclusion, the study documents the presentation, investigative procedures, and histological findings of vascular hamartomas in the dorsal carpus of Thoroughbred horses — a rare and diagnostically challenging condition. Additionally, it highlights the need for further research to understand disease pathogenesis and develop more effective treatment protocols.