Effectiveness of glyceryl trinitrate for enhancing digital submural perfusion in horses.
OBJECTIVE
To evaluate the clinical efficacy of topically administered glyceryl trinitrate (GTN) for inducing digital submural vasodilation in clinically normal horses.


METHODS
7 adult horses without foot abnormalities.


METHODS
A concurrent-control crossover design was used to determine whether topical application of GTN ointment for prevention or treatment of laminitis would result in a detectable increase in digital perfusion. Heat-acclimated horses instumented for detection of wall surface temperature (HWST), mean systemic pressure, and heart rate were used. Horses were exposed to cold to induce digital vasoconstriction and treated with GTN in an attempt to induce digital vasodilation.


RESULTS
Application of GTN failed to induce an increase in digital submural perfusion but did induce a mild decrease in mean systemic pressure.


CONCLUSIONS
Topical application of 60 mg of GTN as a 2% ointment on the skin over the major vasculature in the region of the proximal interphalangeal joint (pastern) of horses was not effective in significantly increasing digital perfusion. A decrease in mean systemic pressure following treatment was observed, implying that the drug was absorbed. Use of GTN may result in a decrease in digital submural perfusion secondary to induction of peripheral constriction or a decrease in digital perfusion pressure.
Hoff
Tracy K
TK
Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Texas A&M University, College Station 77842-4466, USA.
Hood
David M
DM
Wagner
Ilka P
IP
D000287:Administration, Topical; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature; D003080:Cold Temperature; D005260:Female; D005534:Foot Diseases / Q000188:drug therapy / Q000517:prevention & control / Q000662:veterinary*; D006339:Heart Rate / Q000187:drug effects; D006724:Hoof and Claw / Q000098:blood supply*; D006734:Horse Diseases / Q000188:drug therapy* / Q000517:prevention & control; D006736:Horses; D007794:Lameness, Animal / Q000188:drug therapy / Q000517:prevention & control; D008297:Male; D005996:Nitroglycerin / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use
D014665:Vasodilator Agents; D005996:Nitroglycerin