Researchers found that 86% of 49 horses that received antivenom survived. | Photo Credit: Anne M. Eberhardt/The Horse

The research team’s recent study was the first in which scientists looked at the clinical signs of elapid snake envenomation in a large population of horses. The team also evaluated laboratory findings, treatments, and outcomes from 52 elapid snake envenomation cases from several universities and private veterinary practices from 2006 to 2016.

Snakebite wounds aren’t always apparent, but affected horses often exhibit signs of envenomation. The researchers found that 94% of cases developed signs of neurotoxicity, typically characterized by neuromuscular weakness. Other associated neurologic signs included unsteady movement, muscle tremors, the inability to stand, pupil dilation (mydriasis), eyelid drooping (ptosis), and partial tongue paralysis. In addition, 50% and 19% of horses developed rhabdomyolysis (muscle damage) and hemolysis (red blood cell damage), respectively.

These clinical signs are quite different from those reported for crotalid (pit vipers, including rattlesnakes) snakebites, the team noted. Those signs can include, but aren’t limited to, pain and swelling at the bite site, tissue sloughing near the bite, coagulopathy and hemorrhage, respiratory distress, shock, collapse, and death