Imaging diagnosis–Arterial and venous thromboses of the proximal limb in two thoroughbred racehorses.

This research article investigates the diagnosis of certain arterial and venous thromboses, specifically in the cranial tibial vein and brachial, median, and cranial circumflex humeral arteries, in two Thoroughbred racehorses using nuclear scintigraphy and ultrasonography.

Methods and Findings

• The study focuses on two cases of Thoroughbred racehorses exhibiting unilateral lameness. The lameness in each horse was traced back to different causes – thromboses in the cranial tibial vein for Horse 1, and in brachial, median, and cranial circumflex humeral arteries for Horse 2.
• Thrombosis, or blood clotting in the arteries or veins, was identified as the source of the lameness with the help of nuclear scintigraphy. This was initially performed suspecting long bone stress fractures, however, it showed unusual areas of increased radiopharmaceutical uptake in the soft tissues of the affected limbs. This indicated the presence of thrombi instead of fractures.
• Ultrasonography was then used to visualize these regions, which further confirmed the presence of occlusive thrombi, or blood clots blocking the blood vessels, within a 25 cm length of the cranial tibial vein in Horse 1 and varying lengths of affected arteries in Horse 2.

Outcomes and Conclusions

• While the thrombosis issue was successfully identified, the outcomes were different for the two horses. Horse 1 developed consequent infections after the diagnosis and unfortunately had to be euthanized. The bacteria Staphylococcus aureus was isolated from all infection sites, indicating it as the cause of infection.
• In the case of Horse 2, despite the successful diagnosis of the thrombosis, the cause of this issue was not specified in the research paper. Therefore, while the thrombosis may have been treated or managed, it is unclear if preventive measures could be taken in the future due to lack of understanding of the cause.
• This study highlights the significance of imaging diagnostics like nuclear scintigraphy and ultrasonography in identifying atypical causes of lameness like thrombosis in racehorses, which might be mistaken for more common causes like fractures. It also brings to light the risk of subsequent infections associated with these conditions.