Effects of topical nitroglycerine patches and ointment on digital venous plasma nitric oxide concentrations and digital blood flow in healthy conscious horses.
OBJECTIVE
To measure and compare palmar digital venous plasma nitric oxide (NO) concentrations and digital arterial blood flow after application of topical nitroglycerine (NTG).


METHODS
Experimental study.


METHODS
Healthy adult horses (n=8).


METHODS
Digital blood flow was measured by an ultrasonic Doppler flow probe surgically implanted around the medial palmar digital artery. Blood was collected from a catheter placed in the medial palmar digital vein for quantification of NO. NTG patches, NTG ointment or control patches were placed over the palmar digital vessels at the level of the fetlock. Two horses had an intra-arterial infusion of an NTG solution into the medial palmar digital artery in a pilot study.


RESULTS
Digital arterial blood flow did not change significantly with application of the NTG patches, NTG ointment, or control patches. There were no statistically significant or biologically important changes in digital venous NO concentrations across time or between treated and control horses. In the pilot study, digital arterial blood flow and palmar digital venous NO concentrations increased with intra-arterial infusion of NTG.


CONCLUSIONS
In clinically healthy horses, digital arterial blood flow and digital venous plasma NO concentrations did not change significantly with application of the NTG patches/ointment. These treatments are unlikely to have an effect on the digital vasculature of laminitic horses, however, further investigation is warranted.


CONCLUSIONS
Although NTG patches have been used as a method of decreasing vasomotor tone and improving digital blood flow in horses with laminitis, this study provides evidence in healthy conscious horses that this treatment is not effective in altering digital blood flow.
Gilhooly
Meaghan H
MH
Equine Health Studies Program, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 708033, USA.
Eades
Susan C
SC
Stokes
Ashley M
AM
Moore
Rustin M
RM
D000287:Administration, Topical; D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects / Q000662:veterinary; D005534:Foot Diseases / Q000097:blood / Q000188:drug therapy / Q000662:veterinary; D006724:Hoof and Claw / Q000098:blood supply* / Q000187:drug effects; D006734:Horse Diseases / Q000097:blood / Q000188:drug therapy; D006736:Horses; D007794:Lameness, Animal / Q000097:blood / Q000188:drug therapy; D009569:Nitric Oxide / Q000097:blood*; D005996:Nitroglycerin / Q000494:pharmacology* / Q000627:therapeutic use; D009824:Ointments / Q000494:pharmacology; D011897:Random Allocation; D012039:Regional Blood Flow / Q000187:drug effects; D018608:Ultrasonography, Doppler / Q000662:veterinary; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology* / Q000627:therapeutic use
D009824:Ointments; D014665:Vasodilator Agents; D009569:Nitric Oxide; D005996:Nitroglycerin