I have a pet Hognose snake (Heterodon nasicus), and I just read somewhere that they are venomous. Should I be worried about getting bit?
Yes, Hognoses are venomous, but you shouldn't be worried.
Let's explore venom a bit.
Use of venom
For many snakes, venom has an obvious purpose. Killing prey. But this is not the only purpose. As venom becomes more potent, larger and larger animals can be affected by its effects. Eventually, those animals will learn to respect the snake. This turns it into an efficient defensive tool as well.
But another potentially understated purpose for venom lies in its origins. Venom evolved from saliva. Saliva is used generally for digestion. Chewing food mixes saliva with the food particles, so it can properly digest starches. Snakes can't do this, as they don't chew their food in the regular sense. This is where venom comes in play. Many venoms (venom has different composition between species) also have components that help with digestion.
Within venomous snakes, there are various different ways of injecting the venom:
- Proteroglyphous, fixed fangs in the front of the jaws. This is generally used by the Elaphidae, like Cobras and Mambas.
- Solenoglyphous, folding fangs in the front of the mouth. When the mouth is closed, these fangs are folded in; when the mouth opens, they swing out. This means they can be significantly longer compared to fixed fangs. Used by vipers and rattlesnakes.
- Opisthoglyphous, fixed fangs in the rear of the mouth. These fangs are further back in the mouth. This means that generally the venom is injected while chewing. Venom used by these is generally more geared towards digestion. This also means that for a single bite, the chance of being envenomated is lower. There are dangerous species that have these though, like the Boomslang. Hognoses also have these fangs.
- And of course there is aglyphous, our non-venomous friends.
So our Hognoses are rearfanged. Their fangs are used to subdue prey they have already caught, like frogs. These frogs have a pesky defense-mechanism: they inflate their bodies, making it harder to swallow them. This is where the fangs also serve a purpose. They help by puncturing the frogs like a balloon.
Because they are rearfanged, a bite is pretty unlikely to actually envenomate.
This is enhanced by the fact that Hognoses are huge dramaqueens, but not very aggressive. When they feel threatened, they will posture, even flatten their neck like a cobra (or at least try to), but when they strike, most of the time this will be with their mouth closed. Basically they are just bashing you with their head.
So what about their venom?
Their venom is largely harmless. So much so that the WCH rates them as non-venomous.
The only clinical effect they list as something other than "does not occur" and "not likely to occur" is:
General: Local Effects
Mild local effects possible
Bites by this species are not expected to cause medically significant effects and the only risk, probably small, is local secondary infection. Patients presenting with bites by these snakes do not require medical attention, other than to check for infection and ensure tetanus immune status. Patients should be advised to return if local symptoms develop, suggesting secondary infection.
That is less than what they list for a wasp.
Most humans won't notice any effects from a bite, but reportedly, there is a 1/5 chance to be intolerant to the venom, which may cause similar effects to a wasp-sting.
While yes, they do have venom, this is mostly geared towards animals their own size and will cause at very worst some itching and swelling. And that is if envenomation happens, which is very unlikely.
Images taken from Wikipedia