Veterinarians use palmar digital nerve blocks to numb horses’ feet for a variety of reasons, ranging from lameness diagnostics to standing surgical procedures. | Photo: Stephanie L. Church/The Horse

Physicians sometimes add small amounts of epinephrine to local anesthetic solutions to intensify and prolong their analgesic effects. So Ana Velloso Alvarez, LV, a resident at the Auburn University College of Veterinary Medicine, in Alabama, and colleagues sought to test the approach in horses. She presented their results at the 2018 American Association of Equine Practitioners Convention, held Dec. 1-5 in San Francisco, California.

The researchers tested three anesthetic combinations in PDN blocks on lame limbs in six horses:

• 2% lidocaine (a common local anesthetic choice for veterinarians performing nerve blocks);
• 1% lidocaine; and
• 1% lidocaine plus epinephrine.

Then, the team used the Lameness Locator (a tool designed to objectively measure lameness) to evaluate the horses’ gaits every five minutes for the first 30 minutes after PDN administration, and every 15 minutes for another 1.5 hours. They also measured skin sensation between the horses’ heel bulbs using a force gauge