The effect of oral isoxsuprine and pentoxifylline on digital and laminar blood flow in healthy horses.

The research study conducted and examined the impact of oral isoxsuprine and pentoxifylline on blood flow within the lower legs of healthy horses. The study however concluded that neither of the two medications significantly enhanced blood flow to the digit or dorsal laminae, which are sections of the horse’s hoof.

Methodology

• The study focused on 6 healthy horses. Each horse needed to have at least one nonpigmented forelimb hoof wall and to be free from laminitis, a severe inflammation of a horse’s foot.
• Every horse was equipped with a flow probe on one palmar digital artery and a laser doppler flow probe inside a perforation in the dorsal hoof wall. These instruments were used for measuring digital blood flow and laminar perfusion.
• Before and between treatments, baseline readings of palmar digital blood flow and laminar perfusion were taken.
• Then horses were randomly grouped and were treated with oral isoxsuprine (1.2 mg/kg, twice daily for 10 days) or pentoxifylline (4.4 mg/kg, every 8 hours for 10 days) in a cross-over design.
• The measurements of digital blood flow (DBF) and laminar perfusion (LP) were taken on 2nd, 5th, 7th and 10th days of treatment.
• In the washout period, horses were also administered acetylpromazine as a positive control, and similar measurements were conducted every 15 minutes until they returned to baseline.
• The collected data were then analyzed using repeated measures ANOVA.

Findings

• Digital Blood Flow (DBF) and Laminar Perfusion (LP) differed between horses, with the DBF ranging from 11.2 to 97.7 mL/min and LP from 1.0 to 11.1 capillary perfusion units.
• The 10-day treatment with either isoxsuprine or pentoxifylline caused no statistically significant increases in DBF or LP.
• Blood flow to the digit significantly increased with acetylpromazine, beginning 15 minutes after treatment and lasted for about 75 minutes.
• An insignificant but mild increase in laminar perfusion was noticed after acetylpromazine treatment.

Conclusion

• Oral isoxsuprine and pentoxifylline treatments failed to increase blood flow to the digit or dorsal laminae in healthy horses.
• In contrast, acetylpromazine led to an improved blood flow to the digit.
• The research concludes that acetylpromazine could potentially have a greater positive influence on horse’s digit blood flow than oral isoxsuprine or pentoxifylline, thus playing a potential role in managing ischemic conditions of the foot in horses.