"I like go on a trail ride with my horse to California's Mojave Desert for a change of scenery and the wide open spaces. While on the trail ride, I sometimes come across rattlesnakes. So first, what should I do to avoid my horse getting bitten on the trail? Second, what should I do if he does get a bite? I'm especially worried about a bite on the nose that would restrict his breathing. Third, what exactly happens to a horse when he gets bitten? And finally, I've heard of snakebite kits - should I carry one?"
-Olivia de Luca
Diamond Bar, California
Olivia, your question is a very good one, as well as timely. Now that I'm a full-time resident of South Dakota, I don't see dangerous snakes as I did when I spent eight months a year in New Mexico. In the Southwest, poisonous snakes can be aggressive, but they usually let you know they're around. The sound of an upset rattlesnake is one you'll never forget.
Avoidance is best. Keep your eyes and ears open, and let your horse do the same, so that both of you can do your best to avoid an encounter with a potentially dangerous snake. If you see or hear a rattler, head the other way.
Snakebite is rare in horses, but due to their strong curiosity, they can be bitten. Their curiosity predisposes them to bites on the nose, which can be serious (as I'll explain). However, they usually quickly learn from the experience and don't repeat the mistake.
Here, I'll describe what happens when a horse suffers a snakebite, and the steps to take should your horse get bitten, despite your best efforts to avoid it.
Snakebite Science
Pit vipers (rattlesnakes, copperhead, and cotton mouths) are by far the most common offenders in human snakebites and, according to the available literature, are almost the only source of snakebites in horses.
Snake venom is injected into the prey to speed digestion after swallowing; it's also used as a defense mechanism. Venom is made up of about 25 ingredients, some of which have yet to be identified. Enzymes in the venom cause tissue destruction, the primary result of a snakebite in a horse.
The snake controls the amount of venom injected, depending upon the size of the prey or degree of defensiveness. The snake might not even inject venom at all; rattlesnakes fail to inject venom about 20 percent of the time. Snakebites also vary in severity according to species. The venom of a Mojave green rattlesnake and a diamondback is more poisonous than a copperhead's.
Clinical signs are mostly contained in the bite area. To be lethal to a horse, it'd take much more venom than most snakes could produce. Swelling and skin discoloration are almost always present. The degree of swelling in the head/muzzle can pose a life-threatening situation by blocking airflow. Dead tissue is common and can be extensive. Dead tissue often becomes infected.
