Effects of topical nitroglycerine patches and ointment on digital venous plasma nitric oxide concentrations and digital blood flow in healthy conscious horses.

The research paper is a study on the effects of topical nitroglycerine patches and ointment on the blood flow in horses, concluding that these treatments do not significantly alter digital blood flow in healthy horses.

Introduction and methodology

• This experimental study involved healthy adult horses. The goal was to measure and compare the flow of blood in the arteries and veins of the lower part of the horses’ legs (known as ‘digital blood flow’) and nitric oxide (NO) concentrations after applying topical nitroglycerine (NTG).
• Measurement of digital blood flow was achieved by surgical implantation of an ultrasonic Doppler flow probe around the medial palmar digital artery, an artery located on the inside of the horse’s foot.
• Blood was collected from a catheter placed in the medial palmar digital vein to quantify NO levels.
• NTG patches and ointment were applied over the palmar digital vessels at the level of the fetlock as well as control patches. In a pilot study, an NTG solution was also infused directly into the artery of two horses.

Results

• The results showed no significant changes in digital arterial blood flow or NO concentrations in the veins after application of NTG patches, ointment or control patches.
• However, in the pilot study with the direct infusion of NTG into the artery, an increase in digital arterial blood flow and venous NO concentrations was observed.

Conclusion

• The research concluded that applying NTG patches or ointment proved ineffective in altering digital blood flow or NO concentrations in healthy horses.
• In the context of treating laminitic horses – a painful condition affecting the hooves – these findings suggest that NTG treatments are unlikely to have an impact on the digital vasculature. Nonetheless, more research is needed to fully understand the implications of these results on horses with laminitis.