A dry bite from a snake occurs when there are no clinical signs of envenomation present. Snakes don’t always inject venom when they bite you, and this can happen for several good reasons.
Snakes won’t inject venom if they’ve run out. For example, if the snake has used up its venom to kill prey or fight off another predator. Snakes realize that venom is a precious resource and will use it sparingly. A snake could also issue a dry bite as a warning to stay away.
You’re more likely to get a dry bite from an adult than a baby snake. Babies haven’t learned to control the release of venom yet, but will do in time. They’re also immediately left to fend for themselves, so they can’t afford to take any chances in a potentially dangerous situation.
What Is a Dry Bite?
You’re bitten by a non-venomous snake. These snakes can never use venom because they lack venom glands and the fangs to deliver any venom. By definition, every non-venomous snake’s bite is a dry bite.
It’s also possible for a venomous snake to dry bite. That’s because snakes can choose to use their venom, or not, for many reasons. Depending on the species, some snakes will almost never use their venom.
Why Do Snakes Dry Bite?
A snake’s venom is its only weapon against large, predatorial animals that threaten it. So if you’re bitten by a snake, what possible reason could the snake have not to use venom?
Most people think that snakes would try to envenomate everyone they bite, but that’s quite some way from the truth.
1) Snake Venom is a Scarce Substance
Snakes can only produce a limited supply of venom, often only as much as a teaspoon. And when they do make venom, they use up the precious energy they get from their food.
That means that even when food is scarce, they have to be able to make venom, which can lead to them losing fat and muscle reserves. They, therefore, have to avoid using up this resource. Not only that, but it takes several days to replenish their reserves of venom.
Dry biting is the ideal way to avoid using venom. Instead of using up their venom reserves, a snake that dry bites will be sending out a painful warning shot to ‘stay away’ instead.
Bear in mind that a snake bite can still be exceptionally painful, even without venom, so any predator that’s coming for a snake will still be deterred, even by a non-venomous dry bite.
2) Snakes Can Dry Bite by Mistake
There’s also the chance that the snake never intended to dry bite. There’s a chance that it tried to bite, but never sunk its teeth in.
Scratches like these can still be envenomated to an extent, but not as much as if the snake managed to sink its fangs far enough to hit a blood vessel.
3) Snakes Can Run Out of Venom
Venom is a limited resource. It’s possible that a snake could run out of venom entirely. It’s possible that the snake recently hunted or had to fight off a predator. These sorts of events happen all the time in the wild.
Perhaps the snake has a problem with its venom glands or ducts that connect the glands to the fangs. In that situation, it can’t envenomate.
What Percentage of Snake Bites are Dry?
The rate of dry bites varies by species. One species will use dry bites the majority of the time, whereas another will almost always inject venom.
Australian eastern brown snakes dry bite an incredible 80% of the time, but inland taipans use venom 95% of the time.
Unfortunately, there aren’t many researchers that have examined this question. The obvious dangers involved precluding scientific study.
How Many Rattlesnake Bites are Dry?
Rattlesnakes frequently dry bite, at least one-third of the time. Again, the idea is that they’re trying to give you a warning shot.
Rattlesnakes are all about trying to scare you. They use their rattle to warn you away before getting ready to strike. It’s, therefore, no surprise that sometimes they’ll give you a warning bite, too.
If you’re bitten by a rattlesnake, you’ll notice within the first ten minutes. You’ll feel nauseous, in pain and disoriented.
Do Baby Snakes Use Venom When They Bite?
Hatchling and juvenile snakes can use venom from the very moment they emerge from their eggs. This is for their safety in the wild.
Few snake species look after the eggs once they’re laid, let alone after they hatch, so the moment they do the hatchlings have to fend for themselves.
While it hasn’t been studied scientifically, anecdotal evidence suggests that juvenile snakes use venom more frequently than their adult counterparts. It seems that a baby copperhead is more likely to use venom than not.
How Are Dry Bites Diagnosed?
A doctor can diagnose a dry bite after treatment. According to Toxicon, doctors assess the following factors to determine if a bite was venomous:
- Presence of fang marks at the bite site
- The absence of local or systemic signs and symptoms, even after 12 to 24 hours post-bite
- No laboratory evidence of envenomation
- The absence of venom antigens in bodily fluids or tissue
If somebody is bitten by a highly venomous snake, and antivenom is available, then a medical professional will administer it whether or not they’re confident that venom was used.
If you’re ever bitten by a snake, even if you think that it’s a dry bite, you should always see a medical professional without delay.