Scintigraphic evaluation of digital circulation during the developmental and acute phases of equine laminitis.

The study investigates the impact of acute laminitis, a disease in horses, on the digit (foot) blood circulation, using scintigraphy, a diagnostic test involving radioactive substances. Findings suggest total blood flow to the lamellae (interlocking tissues connecting the hoof to the foot) do not decrease during laminitis, contrary to previous theories hinting at lowered blood flow being the primary trigger.

Introduction

• The research examined the blood circulation within the foot of horses suffering from acute laminitis, a condition instigated by feed overload, often with high-starch content, causing severe inflammation and pain in the horses’ hooves.
• The authors used a method known as scintigraphy, a diagnostic procedure where radioactive materials (in this case, technetium-99m) are used to create images and analyse the circulatory condition.

Methodology

• The experiment involved two sets of horses, one control group containing 11 healthy horses, and a test group of nine horses affected with acute laminitis.
• The researchers injected technetium-99m macroaggregated albumin in the main artery servicing the head and forelimbs (brachiocephalic trunk) and captured static images of the right front foot.
• In addition, dynamic radionuclide angiograms and static blood pool images were collected after injecting technetium-99m diethylenetriamine pentaacetic acid in the horses’ jugular vein.
• All these procedures were performed on standing horses with little or no tranquillisation required.

Results

• The captured images were analysed for parameters representing blood circulation in the entire foot, including specific regions within the foot.
• There was no evidence of decreased total blood flow to the lamellae during the development or acute phases of laminitis.
• In fact, the data showed total blood flow increased, particularly in the peripheral regions of the foot, with statistically significant elevations recorded consistently within the lamellae.

Conclusion

• The increased total blood flow to the lamellae could be due to a rise in capillary flow or arteriovenous shunt flow.
• The findings challenge previous beliefs suggesting that ischemia (reduced blood supply) in the lamellae was the primary cause of acute equine laminitis.