Are My Sheep Immune to Snake Venom?

If you own livestock, you already know that one of the biggest threats any of your animals can face is a close encounter with a venomous snake. Although most animals instinctively retreat from snakes, so much of the time they won’t know it is there until it is too late.

A bite from any venomous reptile can sometimes lead to maiming if it doesn’t cause death outright, and in the end your animal may even need to be euthanized. On the other hand, depending on the size and location of the bite, som sheep recover just fine…

This is probably why some folks say that sheep do not need to fear venomous snakes because they are, supposedly, naturally immune. So what’s the deal? Are your they actually immune to snake venom?

No. Sheep, categorically, are not immune to snake venom. But, evidence suggests that some sheep may be somewhat resistant to snake venom. Another reason this is confusing is because sheep have long been used in laboratory settings for the production of antivenin – hence the confusion!

The immunity thing is one of those things that sounds true – it’s so outrageous it must be, right? – but it’s an urban legend. Don’t be ashamed if you believed it. I believed it for a lot of years, and for a long time many publications stated as much!

Here’s the important thing: even if your sheep have shown resistance to a snake bite in the past, be they rattlesnakes or some other snake, any bite from a venomous snake can still prove to be a significant medical emergency next time for the poor critter. You must take it seriously and act every single time.

There’s a lot more to know. Keep reading and I will tell you a lot more about this fascinating topic.

Bottom Line Up Front: Never Assume Your Sheep Are Resistant to Snake Bites!

Despite some evidence of resistance in these animals, the reality is that that a bite from a venomous snake is quite likely to kill or severely sicken sheep. There are so many factors going into the equation that you cannot hope to know before the fateful day. Assuming otherwise might doom your animal.

Accordingly it is always important to take preventative measures and be prepared for potential snake bites among your sheep the same way you would with any other livestock.

How Can Sheep Possibly Resist Snake Venom?

It’s a matter of physical makeup and some special facets of their blood. Again, this is a tenuous subject, and should not be taken as any assertion of immunity in sheep. 

For starters, Sara Fleenor, Agriculture and Natural Resources Educator at the University of Wyoming Extension, cites sheep blood as having a degree of natural resistance against venom owing to their unique antibody response – making sheep great candidates for the production of anti-venom.

The Institute for Environmental Research and Education (IERE) has weighed in on the matter, also, noting sheep are less likely to suffer serious snakebites (read:envenomation) generally owing to their blood coagulation system that helps to minimize tissue damage…

The IERE and other sources also cite the presence of Mannheimia haemolytica , a bacteria present in the respiratory tract of sheep that has long been alleged – but not proven – to offer some mechanism of defense against snake venom.

I must point out that while these resistance mechanisms can help, they do not, and have not, provided any kind of real natural immunity to domestic or wild sheep, and furthermore are not foolproof. Once again, your sheep should still be monitored carefully for signs of snake bites and treated promptly if they are bitten.

The Different Types of Venom

It is important to point out that venomous snakes and their venoms are not interchangeable. They don’t share some universal, generic recipe. Hardly!

There’s vast and deadly variety of deadly cocktails produced by these terrifying reptiles. Among snakes, there are two common types of venom, each distinguished by the dreadful effects it has on the unfortunate recipient of the snake’s wrath: neurotoxins and hemotoxins.

Neurotoxins affect the nervous system, while hemotoxins affect the circulatory system. Both can be more or less lethal depending on the specific enzyme composition, but all are terrible.

It is thought that most pit vipers, using hemotoxic venom, are what sheep tend to have some resistance against, and this is what most of the research into antivenin production is based on. Regardless, any members of your flock will be in serious trouble if bitten by any snake and injected with venom.

Know What Kinds of Snakes You Have Around

It’s so important for all shepherds to learn the types of snakes in your area, and very especially to become familiar with ones you have actually caught on your property. This info is critical if your sheep get envenomated because antivenins are species, or at least venom type, specific.

Can Sheep Survive a Bad Snake Bite?

Sometimes. The odds of survival of sheep that have been bitten by a snake will depend on several factors, including the type of snake, the amount of venom injected, the bite location, and the size and overall health of the animal. In all cases, if a bite where envenomation occurs is untreated, the chances of survival decrease.

Mass and bite location are also huge factors. Bigger sheep breeds with more mass fare better; smaller sheep fare worse. Likewise, a relatively minor bite on the face, jaw or neck might still cause death due to airway restriction.

Some venomous snakes may also “dry bite”, or bite defensively without injecting any venom at all. Hard to believe, but true: venom is a huge investment for these snakes to make, so they tend not to waste it! Be aware that the puncture can still affect the animal, so it still needs to see a vet.

I should also point out that even if a sheep survives a snake bite, there may be long-term consequences, such as tissue damage bite site or other health issues. See the next section for more.

What are the Consequences of a Snake Bite for Sheep?

Any venomous snake bite is basically a medical emergency for a sheep. Depending on the type of snake and the amount of venom injected, a bite can cause localized or systemic damage to tissues or the nervous system, cause respiratory distress, and even death outright.

You should learn how to identify a snake bite. Inspect the sheep for swelling at the site of the bite (with one or more bloody puncture wounds at the center), progression of swelling up the leg or body, and negative changes in behavior. In severe cases, the sheep may collapse and become totally unresponsive.

Many Snakebites Don’t Seem Too Bad At First

Once it gets inside a n animal, snake venom is quick to act. The toxins are spreading and doing their diabolical work, and will start doing irreversible damage…

Even in the case of a minor or dry bite, the bite wound itself could kill days after the imminent danger has seemingly passed if it becomes infected. This doesn’t happen very often but it can happen. Snakes’ mouths are rife with nasty bacteria, and infection is a possibility. Other major illnesses are common, including really horrible things like tissue necrosis, hemolysis, and more.

What To Do if Your Sheep Is Bitten by a Snake

If your sheep is bitten, you need to act fast! The first step is to cautiously investigate the area to make sure the snake is gone or dead. Then, if you need to, remove the animal from the area to a more comfortable place. If you can, seek veterinary care at once.

Keep the sheep as calm and quiet as possible, as increased activity can cause the venom to spread more quickly, and get them to a vet, or get a vet to come to you, as quickly as possibly.

Does Sheep Blood Make Antivenin?

Yes, in a manner of speaking. Sheep have long been used to produce antivenin, an ovine-derived antivenom called CroFab, for snake bites in humans.

This is because the immune system of sheep is ideal for producing the necessary precursors and antibodies that are then used to produce antivenin. This is done by slowly building up massive immunity to the snake’s venom through controlled dosing in a controlled setting. The resulting end product is capable of neutralizing snake venom directly, but not the sheep’s blood by itself. Don’t make that mistake!

In the end, these antibodies are harvested from the sheep’s blood as serum and then purified to create antivenin. It is this bit of scientific trivia that probably gave rise to the long-accepted folk “wisdom” that sheep are immune to snake venom. But now you know the truth!