Gene Glasscock, long distance rider, had reached Texas. He and his two horses, Tennessee Walkers named George and Frank, were making a 20,000 ride to each of the US capitol cities. This particular night they were sleeping under the Texas sky. In the morning Gene noticed a swelling the size of a silver dollar, but didn't think too much of it. But by nightfall he saw the swelling had worsened to the length of a dollar bill and as thick as his hand. George never showed any sign of feeling sick, but the hair sloughed off and the two fang marks were apparent. There was no vet available, so there was nothing Gene could do but go on to the next town. It took about three weeks for the hair to grow back, and then George was good as new. Gene guessed the horse must have rolled over on the snake in the night.

Depending on where you live, once warm weather arrives, so do cold-blooded creatures, including snakes. Of all the snakes in the United States, only a few species are poisonous. They are the copperhead, water moccasin, and several varieties of rattlesnakes and in the extreme southeast, the corral snake. Knowing what to do in case your horse is bitten can mean the difference in a serious or not so serious situation.

It all depends on where you live whether or not your horse is likely to be bitten by a poisonous snake. Rattlesnakes are the most likely species to strike; they are very aggressive. But, for the most part a snake doesn't bite unless you threaten him. When trail riding watch the path ahead of you, and avoid stepping over logs and going through thick brush where you can't see what's ahead of your horse.

Several factors determine the severity of the venom's affect on the horse. The size of the snake and the size of the horse, location of the bite, the health of the horse, and the time it takes to get treatment for your horse all decide how dangerous the bite will be.

As a rule larger snakes have more venom to inject into their victims. Of course the smaller the horse the more harm can be done by the poison, so a foal is more likely to suffer severely than a full-grown horse.

The most dangerous place for a horse to be bitten is on the face. That is because the swelling from the venom can cause suffocation. Unfortunately, that is the most likely place since the horse is apt to put is head down to look at the snake.

If the nostrils swell shut, a piece of garden hose inserted into the nostril could keep your horse's airway open. If you are trail riding and a poisonous snake bites your horse, do not gallop him home for help. Running will only increase the heart rate, speeding up the horse's blood circulation, and sending the poison throughout the body at faster rate. Keep your horse calm and walk him home. On a trail ride, the bite will probably be on the horse's leg, which is not normally fatal. The horse is such a large animal that the venom is reduced by the time it reaches vital organs. You should get veterinary help as soon as possible.

First aid until the vet arrives is to treat the bite like a puncture wound by washing it with soap and water and applying an antibacterial medication. The old advice of cutting a ‘X' and sucking out the blood is no longer recommended for horses or humans that have been bitten by a poisonous snake, because it increases the danger of infection. An antivenin is available, but very expensive. The veterinarian's treatment will include a tetanus shot and antibiotics. She or he might also give drugs to combat inflammation such as steroids. The vet will also look for signs of shock and treat accordingly.

The venom will cause tissue to break down and swell, and like in the case of Frank, the Walking Horse, the skin may slough off. This will require antibacterial dressing to ward off infection until it heals.

To learn to tell the difference between non-poisonous and poisonous snakes you can study pictures of poisonous snakes at trailquest.

 If your horse's whole body starts to swell, or if the horse has trouble breathing because swelling has obstructed its airways call your vet immediately. The vet may advise you give the horse an anti-inflammatory drug such as banamine or  phenylbutazone to reduce the swelling. Keep the horse still and calm. If the air passage is closing pass a short length of garden hose down the nostril as a first aid measure until the vet arrives. This is something you ask your vet to show you how to do before you need the knowledge.

The vet will also prescribe antibiotics and treat the wound as a puncture wound.

Factors that affect the severity of a snake bite to your horse include the amount of venum the snake injects, the size of the horse, the health of the horse (especially its immune system), and the location of the bite.