Steroid diffusion into the navicular bursa occurs in horses affected by palmar foot pain.

This research study investigated whether steroids administered into a horse’s joint could diffuse to other parts of the foot, particularly the navicular bursa, a small sac that cushions and protects a ligament in the foot. The results suggest that the diffusion does occur, especially in cases where the foot pain is less severe.

Research Methodology

• The study involved nine horses suffering from palmar foot pain. Both forelimb distal interphalangeal joints (DIPJs, a specific type of joint in a horse’s foot) of these horses were injected with 10mg of triamcinolone acetonide (TA), a type of steroid.
• After six hours, samples were taken from the navicular bursa, a sac filled with synovial fluid protecting tendons in the horse’s foot, in both the forelimbs and one hind limb (serving as a systemic control).
• The samples were then analysed for the presence of TA using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS), a reliable and precise analytical technique for chemical substance detection.

Results and Findings

• Forelimb navicular bursa samples showed significantly higher concentrations of TA than the systemic control samples. This provides evidence that the steroid had effectively diffused from the DIPJ into the navicular bursa.
• The horses’ foot radiographs were graded based on the severity of changes observed. Horses with a higher grade of changes (more than 2) were four times more likely to have lower TA concentrations than those with a lower radiographic grade, indicating the decrease in steroid diffusion with the increase in severity of the condition.

Conclusions

• The study concludes that in horses affected by palmar foot pain, TA is capable of diffusing locally from the DIPJ into the navicular bursa, a finding that can inform treatment plans for horses suffering from this condition.
• The findings also suggest that the severity of the foot condition could affect the level of TA diffusion, with more severely affected horses showing lower steroid concentrations. This points to a possible need for adjusting dosage or treatment strategies in horses with more severe symptoms.