Activated charcoal will not help a venomous snakebite. The only effective treatment for envenomation is antivenom.

Per Dr. Brandehoff:

AC (activated charcoal) is only for orally ingested medications that are known to bind AC. Since venom is injected, there is no role for it.

Per Dr. Thomas:

This has been a topic previously on NSS. Activated Charcoal has a lot of uses in medicine. It can absorb any chemical in a liquid form that is positively charged (it is a negatively charged particle). The charcoal, however, must be suspended within the liquid phase of the toxin/chemical to absorb it. When snake venom is injected within tissues it diffuses into the extravascular space and some cellular spaces. In short, the venom's cytotoxic proteins disrupt cell membranes, which is how it devastatingly affects the tissues. Activated charcoal is a large particle, much larger than the molecules of venom. It is not absorbed within tissues and does not enter the extravascular space. So it has no opportunity to absorb any molecule within this space. Ingesting activated charcoal does not distribute it thru the body, it stays within the GI tract. Applying it to a wound, similarly, does not cause absorption into the tissues or extravascular space, where the venom is. It has no positive role in envenomations.

Per Dr. Greene:

Although every medication has the potential to cause an adverse reaction, CroFab has an excellent safety profile. In a large meta-analysis, the incidence of acute adverse reactions to CroFab was estimated at 8% (Schaeffer et al.). A study using data from the North American Snakebite Registry found the incidence of acute adverse reactions to be ~ 2.3% (Kleinschmidt et al.). Authors from the Arizona Poison and Drug Information Center calculated the incidence of acute adverse reactions to be approximately 1.4%, and nobody in this relatively large study required antivenom discontinuation (Khobrani et al.).

There are certain conditions (e.g. latex allergy) that may predispose to an adverse reaction, but there’s no absolute contraindication to antivenom. If somebody’s envenomation warrants treatment, you treat with antivenom. You can always run an epinephrine infusion simultaneously, or at least have it readily available.

The cited articles can be found in our files section, and you can see the abstracts here:

Schaeffer: Incidence of immediate hypersensitivity reaction and serum sickness following administration of Crotalidae polyvalent immune Fab antivenom: a meta-analysis

Kleinschmidt: Acute adverse events associated with the administration of Crotalidae polyvalent immune Fab antivenom within the North American Snakebite Registry

Khobrani: Incidence of allergic reactions to Crotalidae polyvalent immune Fab

If an evenomation requires antivenom, you treat with antivenom. There is no absolute contraindication.

Written by Dr. Spencer Greene and Dr. Nick Brandehoff

Allergies to pineapple, bromelain, papaya, papain, and similar substances, including latex, as well as allergies to sheep or horses, may increase your risk of an adverse reaction to antivenom. The potential risks and benefits must be weighed. There’s no absolute contraindication to antivenom.

Antivenom should not be withheld for an envenomation that warrants treatment. If you are at higher risk of having an adverse reaction, it may be prudent to pre-treat. Allergies and anaphylaxis can be treated. Venom-induced injuries cannot be fixed without antivenom.

If an evenomation requires antivenom, you treat with antivenom. There is no absolute contraindication.

Written by Dr. Spencer Greene

I actually lectured on this for the American College of Medical Toxicology!

All antivenoms have alpha gal to some extent. We have two options when treating an AGS patient with antivenom. We can monitor really carefully and treat if/when signs and symptoms develop, or we can pre-medicate with antihistamines +/- steroids with epinephrine available. You never want to withhold antivenom when it is really necessary. We can treat an allergic reaction.

Per Dr. Greene:

This is not the most comprehensive answer but let me some issues you raised:

Anavip is easier to mix, but most hospital pharmacies exaggerate how difficult it is to prepare CroFab. A study by Quan, et al conducted in Phoenix, where I trained, found that a vial could be reconstituted in a little over one minute. It does not take nearly as long as many pharmacists will tell you.

There are many things that determine the overall price of a vial, and even more that determine the overall cost of treatment. The last I heard, the wholesale price for a vial of Anavip was approximately $1440. The wholesale cost per vial of CroFab is about $3200. But if you look at some of the post marketing data, the median dose used was 6 vials of CroFab versus 17 vials of Anavip, which would suggest that Crofab is cheaper. That said, my colleagues out west tell me that they have found it’s cheaper overall to use Anavip.

As for efficacy, there are some data that suggest Anavip provides better control of late hematologic recurrence. There are others that show no statistically significant difference. On the other hand, there are great data, including a randomized clinical trial, showing that Crofab stops the progression of local findings, which is what we see much more commonly than other manifestations of snake envenomation. There are no clinical data showing that Anavip stops the progression of local findings.

As for safety, most of the data - including the package inserts from both products - suggest that the incidence of adverse reactions is higher in Anavip. Anavip is derived from horses whereas CroFab is derived from sheep, and there’s evidence that horse serum is more immunogenic.

Overall, they’re both good products

Crofab has been used in the US for 21 years and has been used in over 50,000 patients. Anavip was first approved for use in the United States for rattlesnake envenomations in 2018 and got approval for copperhead and cottonmouth envenomations in April 2021.

I’ve only used Crofab in my clinical practice (and Wyeth ACP, before that). I believe Nick Brandehoff has used both, let’s see what he says.

Per Dr. Brandehoff:

I’ve used both and both are solid products.

1) Mixing - the Fab2 products seem to mix much more easily than Fab or IgG products. Anavip reconstitutes in 15 seconds or so. Crofab can reconstitute in a few minutes if done right. I have yet to get down to a minute. The biggest delay is usually pharmacy takes 30 minutes or so to get it all mixed so I typically ask for it to be tubed to me so I can mix it.

2) less costly - remains to be seen. As stated above, Anavip is cheaper wholesale but requires 10 vials vs 4-6 for Crofab at initial dose. The real total cost will be total vials given which still needs to be sorted out via larger studies. I rarely get away with only 6 vials with Crofab in California and Colorado. I’ve had mixed results with Anavip and only giving 10 vials. We just need more data.

3) Anavip does have a longer half live compared to Crofab (~150 vs ~40). What this means clinically is unclear other than maybe decreasing delayed coagulopathy.

4) many hospitals are switching to Anavip. I’m sure there will be a back and forth as different hospitals change their formulations based on what they end up liking.

Extra info:

1) clinically I think they’re similar so far. Again, need more head to head data with both on the market. I think we’ll find one is better in some areas while the other is better in other areas.

2) adverse reactions are probably about the same, maybe a percentage point difference in the long run.

3) proper dosing needs to be used with both antivenoms. So often I hear about improper dosing. We can’t compare efficacy if dosing strategies aren’t followed appropriately.

My two cents.

Per Dr. Greene:

The WHO recommends “antivenom” in English-speaking countries. The Associated Press prefers “antivenin”. Either is fine; just don’t hyphenate the word. That looks silly! Check out this article from Dr. Leslie Boyer for more information.

Antibiotics should not be prescribed routinely following snakebite.

Written by Dr. Spencer Greene and Dr. Cory Woliver

Infection of any type is exceptionally uncommon. In a study from the University of Arizona, infection was observed in fewer than 1% of cases.

In another study Dr. Greene co-authored, the incidence was less than 5% of cases.

Prophylactic antibiotics should not be administered because the side effects outweigh the benefits. Indiscriminate antibiotic use also contributes to antibiotic resistance. And it’s an unnecessary expense.

Finally, there’s in vitro evidence that some antibiotics potentiate certain snake venom components. Antibiotics should only be prescribed when there is clinical evidence of an infection.

The same is true for dog and cat patients, where the incidence of infection is similarly low.

Per Kimberly Wyatt:

NSS supports snake avoidance training for dogs taught by reputable instructors. Not only does learning to detect and avoid snakes decrease your pup’s chances of being bitten, but if your dog alerts to a snake while you are out together, it could potentially keep you from harm. Although avoidance training isn’t 100% foolproof, it is a good option for many dog owners living in areas with venomous snakes.

That said, not all snake avoidance training programs are equal. There are several considerations you should keep in mind before signing your dog up for snake avoidance training. Speak to any potential trainers about the following:

What type of training methods do they employ? Most traditional snake avoidance training programs use a positive punishment (P+) form of conditioning—most commonly with the use of e-collars—but some newer programs use positive reinforcement (R+) methods. Consider your dog’s current training level and temperament when deciding which type of class would work best for your pup(s). A dog MUST have a solid obedience foundation and bulletproof recall to attempt R+ snake avoidance training, whereas P+ methods can be used for dogs whose basic obedience skills aren’t especially strong. I have personally seen (as yet unpublished, but I’m hoping to be able to share in the future) scholarly research demonstrating the efficacy of P+ training. I am unaware of any quality studies on R+ snake avoidance training. That’s not to say it can’t work for some dogs, just that I’ve never seen more than anecdotal “evidence.”

Find out if the program you’re interested in uses captive live snakes (this is strongly recommended). Inquire about the care the program provides for its animals. Do their snakes receive regular veterinary check-ups? Ask how the snakes will be used during classes—what methods do they employ to secure the snakes, and how often are the snakes rotated so they don’t become overly stressed? Muzzling and caging snakes are appropriate restraints for the purpose of these classes, but if a trainer mentions suturing snakes’ mouths shut, defanging, removal of venom glands (these are sometimes called “venomoid” snakes), or any other inhumane treatment of their snakes, RUN AWAY. A program that mistreats its own animals shouldn’t be trusted with your pet(s), and doesn’t deserve to stay in business.

Reputable snake aversion programs will use a number of well-cared for animals, rotating them throughout training sessions so that no single snake is made to “work” for long. A short window during which a snake is safely exposed to dogs (generally 15 min to 1 hr), followed by a week or more off is ideal. Reputable programs will also provide regular veterinary care (and share their vet references if you ask) and good husbandry for their snakes, and will be happy to discuss these details with prospective clients.

A single training session is typical of programs using P+ conditioning methods. Multiple sessions are generally used to train R+. As with any training, periodic refresher courses (ideally annually) are recommended to proof and reinforce concepts.

Snakebites to dogs are costly, often life-threatening emergencies. And all too often, when a dog tangles with a snake, BOTH animals end up injured or worse. Avoidance training with a reputable instructor can provide peace of mind for you as an owner, and safeguard the well-being of both your pup and native wildlife.

There’s absolutely NO BENEFIT from Benadryl following your typical snake envenomation.

Written by Dr. Spencer Greene

Benadryl is an antihistamine. Histamine is not a major component of snake venom, so antagonizing the effects of histamine accomplishes nothing. It does not “buy time” or “reduce inflammation” or anything of the sort. All it does is give people a false sense of security and distracts them from the most important thing: GETTING TO THE HOSPITAL SO THAT SOMEONE CAN DETERMINE THE NEED FOR ANTIVENOM, WHICH IS THE DEFINITIVE TREATMENT FOR SNAKE ENVENOMATION.

The only time Benadryl may be helpful is in the rare case of an allergic reaction to either the venom or the antivenom. And in serious reactions, the drug of choice would be epinephrine, not Benadryl, which helps for hives and itching but not the cardiac or respiratory complications.

Please read this excellent article by Dr. Nick Brandehoff, hosted on the Asclepius Snakebite Foundation's website.

You can also read the most recent anaphylaxis practice guidelines, which address the lack of utility of antihistamine, here.

Do not pop blood blisters following a snakbite. 

Written by Dr. Spencer Greene

We recommend keeping the blisters intact unless they are significantly restricting motion. They serve as a biological shield. If they burst spontaneously, or if you must drain them, do it in sterile fashion and wash the area with warm soapy water several times daily.Item description

If an evenomation requires antivenom, you treat with antivenom.

Per Dr. Brandehoff:

There’s a theoretical increased risk of bleeding. More importantly, your labs will be “off” which may confound the clincial picture of whether to treat or not. At the end of the day though, the treatments are the same.

These are cases where a toxicologist experiences in snakebites should be consulted to guide treatment based on the nuanced clincial presentation.

Do not bring a dead (or alive) snake to the hospital! Snake ID is not required to treat.

Written by Dr. Spencer Greene

You should NOT bring the snake—dead or alive—to the hospital if you have been bitten.

Let’s think about all the possible scenarios:

Bringing a live snake is obviously potentially dangerous to humans as well as the snake.

Bringing a dead snake is also dangerous to humans. People forget that dead snakes can envenomate, typically for about 30–45 minutes after the fatal injury, but the record is approximately 8.5 hours. Don’t believe me? Check these out:

This guy got envenomated by a dead copperhead

This guy almost died after getting bitten by a dead rattlesnake

This guy DID die after getting bitten by a dead prairie rattlesnake

Most importantly, and this may blow some people’s minds, we don’t actually need to know what snake is responsible for the bite! All we have to do is determine whether or not it is a pit viper envenomation, and that’s a clinical diagnosis. A physician who is knowledgeable about snakebites can easily distinguish a bite from a crotalid from a bite from a non-venomous snake. And, in regions where this is relevant, it’s also easy to distinguish a coralsnake bite from a pit viper bite and from a bite from a non-venomous snake.

Once we determine whether or not it’s a pit viper bite, we’re good. Because CroFab & ANAVIP are FDA-approved for all North American pit vipers: copperheads, cottonmouths, rattlesnakes. There is a different antivenom for coralsnake envenomations, when needed. We do not need to know the species in order to treat appropriately.

If you can take a picture of the snake quickly and safely, that’s great. Almost everybody has a camera phone, and it’s nice to know the species for epidemiological purposes. However, we definitely don’t want to delay transport or treatment trying to ID the snake. You treat the patient based on the signs and symptoms.

From Dr. Greene:

Compartment syndrome is exceptionally rare following snakebite. I’ve never seen a confirmed case in more than 800 envenomations. More importantly, the treatment for compartment syndrome secondary to snakebite is more antivenom, not surgery. This is one of the reasons we recommend that snakebites are treated as medical, not surgical, conditions.

1. They need to measure the compartment pressures to determine if you have a compartment syndrome.

2. The initial treatment for compartment syndrome is antivenom. Surgery is reserved for legitimate compartment syndrome that fails to respond to appropriate antivenom. If they skip antivenom and go to surgery, that’s a problem.

Surgical considerations in the management of pit viper snake envenomation

A chance to cut is not always a chance to cure- fasciotomy in the treatment of rattlesnake envenomation: A retrospective poison center study - PubMed

Per Dr. Greene:

Envenomations from the Texas coral snake, Micrurus tener, rarely result in serious systemic toxicity, and there are no deaths from a Texas coral snake bite, ever, in the medical literature. Antivenom is typically withheld unless there is evidence of objective weakness.

Envenomations from the eastern coral snake have greater potential for systemic toxicity, including skeletal and respiratory muscle weakness and paralysis, so most experts have a low threshold to treat with antivenom. There are several antivenom options, including the North American Coral Snake antivenom, which—despite public perception to the contrary—is available. Few hospitals carry coral snake antivenom, so your treating physician may have to obtain coral snake antivenom by contacting poison control or another agency that has access to the antivenom index.

Click here to read more about coral snake envenomations.

Coralsnakes do not have to chew to envenomate.

Written by Dr. Spencer Greene

Coralsnakes have fixed, front fangs. Although they do not deliver venom quite as efficiently as pit vipers, they can bite quickly. They do not have to chew on you in order to envenomate.

If you would like to read more about coral snake envenomations: https://wsed.org/coralsnake-envenomations/

There may not be any swelling or bruising or even signs of pain in cases of coral snake envenomation. It may take 6-8 hours or more for signs of weakness, staggering or paresis/paralysis to develop. Their venom is extremely potent.

Signs of coralsnake envenomation in pets may be delayed 24+ hours. NSS recommends monitoring them in a hospital during that time.

Written by Dr. Cory Woliver

Let’s talk coralsnake envenomations in pets. There are three species of coralsnakes in the United States. Micrurus fulvius (eastern coralsnakes) and Micrurus tener (Texas coralsnakes) both have the potential to cause fatal envenomations in pets. There are no reports of significant injuries or death in pets following an envenomation from Micruroides euryxanthus (Sonoran coralsnakes), but if a pet is bitten it should still be observed by a veterinarian. Coralsnakes have small fangs and are typically very docile. But they will bite if picked up or attacked, which often happens during encounters with pets.

In humans, severe systemic effects are rarely seen following Texas coralsnake bites, but are more common in envenomations from eastern coralsnakes. In pets, we see significant effects, including paralysis and death, following envenomations from Texas coralsnakes as well as easterns.

Both Micrurus species have a neurotoxic and a hemotoxic venom. The main components consist of Phospholipase A2 and alpha neurotoxin. The neurotoxic components cause paresis and paralysis, which if left untreated can cause paralysis of the respiratory muscles, leading to death. The hemotoxic component causes lysis (breakdown) of the red blood cells which can lead to anemia. If enough RBCs break down it can cause injury to the kidneys. Some early signs you may see are weakness, drooling, vomiting, and rapid breathing. Other times you may see what looks like bloody urine.

Antivenom is the only thing that can slow down or stop the effects of the venom. Unfortunately it is very hard to come by and very few places have access to it.

Treatment consists of antivenom where available, fluids, and supportive care. If a coralsnake envenomation progresses far enough to cause respiratory paralysis (which happens often when antivenom is not available), the pet needs to be intubated and placed on a ventilator to breathe for it. One study found the average time on a ventilator to be about 58 hours.

The chance of survival once ventilated is high (the same study showed about a 90% survival rate). However, cost may be a limiting factor, as it is very expensive to ventilate. Even though survival is good on the ventilator, it still comes with risks such as pneumonia and barotrauma. In cases where an envenomation leads to paralysis, recovery to walk again normally takes about 1-2 weeks, sometimes longer. Most pets will recover with ventilation even in the absence of antivenom.

The tricky part of treating these bites is that there is no simple way to tell if a dog or cat has been bitten. Unlike pit viper bites, you almost never see bite marks from coralsnakes. There is no swelling, bleeding, redness, bruising, or significant pain. We will run bloodwork to try and see if we can find evidence to support a bite. We will perform a packed cell volume and total solids (PCV/TS) and look at the color of the serum (fluid part of blood), and if it looks red (indicating hemolysis) that increases our suspicion. We will also look at a blood film under the microscope and look for evidence of echinocytes (when red blood cells look like a sea urchin). If these are present it also is suspicious for an envenomation. If both are present, envenomation is very likely. Unfortunately, these hematologic clues don't happen in every case.

Because antivenom cannot reverse injuries from venom, only slow or stop further damage, it needs to be administered prior to the onset of full respiratory paralysis to prevent the need for ventilation. So the moral of the story is, if a pet is observed with a coralsnake in its mouth or if the pet is seen playing with one, we will administer antivenom prophylactically.

In areas where antivenom is unavailable, it is especially important to try to locate an emergency vet with the resources to provide critical care ventilation which will greatly improve the pets’ chances of survival.

Edited to add: coral snake bites don’t always show immediate signs like a lot of pit vipers do. It can take 24+ hours for signs to show up. We recommend watching them in the hospital for a minimum of 24 hours, sometimes longer to monitor them for signs of envenomation.

Per Dr. Greene:

We never actually need to know the identity of the snake to treat the bite correctly. Pit viper bites look very different from coral snake bites which look very different from bites from non-venomous snakes. A pit viper envenomation is a clinical diagnosis. Anyone who knows how to manage snakebites should be able to make the diagnosis and treat accordingly. If your physician says that he or she cannot treat the patient because the species is unknown, you need to get help elsewhere.

Written by Kimberly Wyatt:

We’ve recently gotten a number of posts from members who have asked their vets about how they treat snakebites (thank you for being proactive—we love to see it!) and have been told things that go against the expert recommendations shared in this group. The following is intended to provide some general info about preparedness for pet owners, as well as tips for having a respectful conversation with your veterinarian about proper snakebite management.

Being prepared…

The best thing you can do for your pet with regard to snakebites is to be proactive and prepare ahead of time for the possibility of a bite. Call around to veterinary hospitals in your area and attempt to locate facilities that have antivenom. In the event of a bite, if a pet is stable, driving a bit further to a facility that has the means to treat appropriately is better than going someplace closer that cannot or will not treat (if a pet is not stable, get to the nearest vet).

Additionally, have a plan to cover treatment. Snakebites are not cheap—it can cost several thousand dollars to treat an envenomation in a pet. Pet insurance (NSS cannot recommend specific plans; make sure you fully understand the costs/payment structure before signing up for any pet insurance) is a great idea. An alternative to pet insurance is a pet emergency fund.

Now, how to politely speak to your vet about proper snakebite management…

First and foremost, BE POLITE AND KIND. Vets are under tremendous stress, and if a vet isn’t snakebite-educated, starting a respectful dialogue is always better than talking down to them.

The next time you have an appointment with your vet, offer to share with them our veterinary algorithm as well as the supplemental information sheets. You can simply say that you’ve taken an interest in learning about snakebite treatment for pets and humans, and found these resources helpful. It’s preferable to have these discussions ahead of an emergency, when possible. Our vet algorithm can be found here, and here is a link to the supplemental info sheets. You can print these and take them with you.

Explain that you’re aware that antivenom is the only thing that can actually neutralize snake venom. Conveniently, both Venom Vet and Rattler, the two available veterinary antivenoms, work for ALL North American pit viper envenomations. Ask if they stock antivenom. If not, why?

If a vet says they don’t carry antivenom due to cost, you may be able to offer to pay up front for the cost of the antivenom on the condition they store it, so they can have it on hand in the event of a bite. If you go this route, speaking to a 24 hour/emergency vet is often the way to go, since regular vets are closed overnight, when many snakebites occur.

If their rationale for not stocking antivenom is because they don’t think it’s necessary, you can explain that research shows that early antivenom administration minimizes overall injury. Even though many pets will survive without it, a majority of snake envenomations would benefit from antivenom. Gently emphasize that you’re interested in preventing unnecessary suffering and reducing the risk of complications that come with allowing an envenomation to run its course. This discussion can also be helpful if a vet says they only give antivenom if a pet has hematologic or systemic toxicity, or that they don’t treat bites from [X] species (this happens frequently with copperheads).

If the vet expresses concern about antivenom safety, you can share this article by Dr. Woliver, which discusses the safety of modern antivenoms and how rare cases of adverse reactions can be safely managed: https://www.snakebitefoundation.org/blog/2023/6/9/a-primer-on-antivenoms-used-by-veterinarians.

Some vets suggest things like Benadryl or steroids in place of antivenom. If this is the case with your vet, politely inquire how these are meant to stop or reverse tissue destruction or edema resulting from damage to lymphatic vessels (answer: they can’t/don’t). Many vets are not ever taught about the pathophysiology of snakebites, and assume snakebite swelling can be treated with the same medications that work great for other types of swelling, but this isn’t true. You can share this excellent article by Dr. Brandehoff, which goes into more detail: https://www.snakebitefoundation.org/blog/2019/7/3/benadryl-is-useless-for-treating-snakebites-dr-nick-brandehoff.

Similarly, if a vet recommends antibiotics in the absence of infection, you can simply explain that you’d prefer to hold off due to the low risk of infection from snakebite and the potential risks from prophylactic antibiotics, but reassure them that you will absolutely agree to antibiotics if they become clinically indicated. This study looked at the incidence of infection in dogs following rattlesnake envenomation: https://pubmed.ncbi.nlm.nih.gov/26112434/. Researchers found that <1% of bites resulted in infection, which is comparable to the rate of infection seen in human snakebite victims (also under 1% in this study: https://pubmed.ncbi.nlm.nih.gov/30392637/). Indiscriminate use of antibiotics contributes to antibiotic resistance. Finally, there’s in vitro evidence that some antibiotics potentiate certain snake venom components: https://www.mdpi.com/2072-6651/12/4/240/htm.

Not all vets will be receptive to this information, but approaching the conversation from a perspective of, “I’ve been learning and I want to share,” versus, “You’re wrong,” can go a long way to opening a dialogue and effecting positive change. If a vet refuses to discuss or reconsider their stance, your best bet will be to seek care elsewhere.

A dry bite means no liquid (venom) was injected into the wound. The injury will be nothing more than the small puncture(s) created by the fangs.

Written by Dr. Spencer Greene

Not all pit viper bites result in envenomation. In about 10% to 15% of bites that present to the emergency department, no venom was delivered. We call this a dry bite. Because no venom is delivered, there will be minimal signs and symptoms. It’s essentially the same as getting pricked by a thumbtack.

IF A PATIENT IS HAVING BRUISING, SWELLING, PAIN, ETC., IT INDICATES THERE HAS BEEN AN ENVENOMATION AND IS THEREFORE NOT A DRY BITE. The absence of lab abnormalities does not mean it’s a dry bite.

Snakebites are a dynamic process. The diagnosis of dry bite cannot be made after 30 minutes of observation. Not even two hours. Not even four hours. Patients who may have been bitten by a venomous snake should be observed for AT LEAST eight hours. If there are no local findings, no systemic toxicity, and no hematologic lab abnormalities, then it is reasonable to make the diagnosis of a dry bite. To call it a dry bite after one hour of observation is a recipe for disaster and has resulted in some pretty expensive lawsuits.

This observation is emphasized in the unified treatment algorithm, which you can read here.

Extraction devices do not work and do cause harm

Written by Dr. Spencer Greene

NSS does not recommend extraction devices. Not only are they a waste of money, they are HARMFUL. A number of us are involved in a public awareness campaign to get them off the market.

Extraction devices are not helpful in snake envenomation. They remove almost no venom following a bite (no more than 2% in one study). Certainly not a clinically significant amount.

Furthermore, there is good evidence that they are harmful. They can cause a negative pressure injury and, by preferentially removing interstitial fluid, these extraction devices could theoretically concentrate the venom.

These kits are good for one thing: profits for the people who manufacture and sell them. But they are certainly not beneficial to a snakebite victim.

Additional Resources

Snakebite suction devices don't remove venom: they just suck

Suction for venomous snakebite: a study of "mock venom" extraction in a human model

Effects of a negative pressure venom extraction device (Extractor) on local tissue injury after artificial rattlesnake envenomation in a porcine model

Do not bring a dead (or alive) snake to the hospital! Snake ID is not required to treat

Written by Dr. Spencer Greene

You should NOT bring the snake—dead or alive—to the hospital if you have been bitten.

Let’s think about all the possible scenarios:

Bringing a live snake is obviously potentially dangerous to humans as well as the snake.

Bringing a dead snake is also dangerous to humans. People forget that dead snakes can envenomate, typically for about 30–45 minutes after the fatal injury, but the record is approximately 8.5 hours. Don’t believe me? Check these out.

This guy got envenomated by a dead copperhead

This guy almost died after getting bitten by a dead rattlesnake

This guy DID die after getting bitten by a dead prairie rattlesnake

Most importantly, and this may blow some people’s minds, we don’t actually need to know what snake is responsible for the bite! All we have to do is determine whether or not it is a pit viper envenomation, and that’s a clinical diagnosis. A physician who is knowledgeable about snakebites can easily distinguish a bite from a crotalid from a bite from a non-venomous snake. And, in regions where this is relevant, it’s also easy to distinguish a coralsnake bite from a pit viper bite and from a bite from a non-venomous snake.

Once we determine whether or not it’s a pit viper bite, we’re good. Because CroFab & ANAVIP are FDA-approved for all North American pit vipers: copperheads, cottonmouths, rattlesnakes. We do not need to know the species in order to treat appropriately.

If you can take a picture of the snake quickly and safely, that’s great. Almost everybody has a camera phone, and it’s nice to know the species for epidemiological purposes. However, we definitely don’t want to delay transport or treatment trying to ID the snake. You treat the patient based on the signs and symptoms.

NSS does not make recommendations for specific pet insurance, as each plan is different. Plans that cover accidents and injuries (especially if they mention animal bites) should cover treatment of snake envenomations, but we recommend confirming before you pick a plan. With a few exceptions, nearly all plans will expect payment at time of service from you, and reimburse costs to you (minus any deductibles/copays) after the fact. Having a plan to pay for treatment at time of an accident is important. There are a number of marketplace-style websites out there where you can compare plans. Google “pet insurance marketplace” or “compare pet insurance plans” to learn more. Consider the monthly cost of insurance, how much they cover (is there a cap per incident/year/etc.), how much you’ll be expected to pay out of pocket, etc. and pick a plan that works best for you and your family. Families with lots of pets may be better served to just make an emergency fund at the bank, or to look into programs that cover households rather than individual animals.

Juvenile snakes CAN meter venom & have less venom volume than adults.

Written by Dr. Spencer Greene

It’s a common misconception that juvenile snakes cannot control how much venom they deliver in a bite and are therefore more dangerous. First, juveniles DO have the ability to regulate how much venom they release. Secondly, even if juveniles did not have that control, their total venom volume is much less than that of an adult snake.

It is true that in some species the ratio of venom components changes as a snake ages, and some toxins may be more potent in juveniles than adults. However, the total volume of venom delivered is a much more important factor in determining the severity of a bite. That is why, on average, a bite from an adult snake is worse than a bite from a juvenile snake.

The most important thing to remember is that every bite is unique, and a bite from any pit viper of any age has the potential to be mild, moderate, or severe.

Please see this excellent article by Dr. Hayes describing the ability of juvenile prairie rattlesnakes to regulate their venom:

Written by Dr. Cory Woliver:

I’ve been seeing a huge increase in cases where pets are receiving NSAIDs lately. These include drugs such as carprofen (Novox, Rimadyl), meloxicam, aspirin, Deramaxx, etc…. These medications are CONTRAINDICATED in a snake envenomation, meaning they should not be given under any circumstances as they can cause harm. They can worsen bleeding caused by the envenomation as well as cause or worsen kidney damage. If your vet recommends an NSAID, you should say no and not allow them to give it. 

Steroids and antibiotics are not indicated but will be less likely to cause harm, although they can depending how/what/when they are used. Steroids don’t work and can delay wound healing and lead to stomach lining injury. Antibiotics used inappropriately (as in too early) will lead to resistance and a harder infection to fight. You can and should tell your vet not to give these medications if they recommend it. If there is an active infection or bad necrosis, antibiotics are recommended at that time and should be prescribed. 

NSAIDs are not recommended immediately following a snakebite.

Written by Dr. Spencer Greene

Historically, snakebite experts have advised against the use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Motrin, Advil) and naproxen (Naprosyn, Aleve) for pain control following pit viper envenomation because of the potential for potential hematologic effects. In the past few years, several studies (of variable quality) have suggested that there is no harm in using NSAIDs when there is no evidence of hematologic toxicity.

We do not recommend using NSAIDs acutely, because snakebites are dynamic, and hematologic toxicity can develop even when the initial labs are normal.

For pain control following hospital discharge, NSAIDs are probably acceptable for copperhead and cottonmouth bites which were never associated with any lab abnormalities. NSAIDs should not be used if there were lab abnormalities, and we advise against their use following rattlesnake envenomation, in which late hematotoxicity is not uncommon.

Acetaminophen (Tylenol) is acceptable, but if you're taking an opioid that is combined with acetaminophen (e.g. Hydrocodone-APAP (APAP is an abbreviation for acetaminophen), make sure you don't exceed the recommended daily dose of acetaminophen.

Kids can receive antivenom, and we DO NOT ADJUST THE DOSE.

Written by Dr. Spencer Greene

You’re not really treating the patient, but rather the venom. In a pediatric snakebite victim, the ratio of venom to body weight is actually higher, so you do not give a smaller antivenom dose than you would use in an adult. Start with the same dose, and give additional antivenom if the child is not improving as expected. In very small children, the antivenom can be prepared in a more concentrated form to prevent volume overload.

Antivenom is the only effective treatment for envenomation.

Per Dr. Brandehoff:

Each envenomation is unique. Any medical condition can increase the risk of complications in a snakebite. With that said, the assessment and treatment is the same.

These are cases where a toxicologist experienced in snakebites should be consulted to guide treatment based on the nuanced clincial presentation.

Please see this informative article written by our very own Kimberly Wyatt, MS

What to Expect When You're Expecting and Snakebitten

Recovery following a venomous snakebite differs as every envenomation is unique.

Written by Dr. Spencer Greene

Recovery after hospitalization, but no antivenom:

Patients with a significant envenomation that goes untreated may take several weeks to months to fully recover, and some people have permanent disability. We recommend that you keep the affected extremity elevated as much as possible, do range of motion exercises as directed, and let your physician - and us - know if you develop worsening pain, joint pain, bleeding, bruising, or any other worrisome signs or symptoms.

Recovery after receiving antivenom:

Every envenomation is unique, but most people who have been treated with antivenom will be back to normal within two weeks. Until then, keep the affected extremity elevated as much as possible, do range of motion exercises as directed, and let your physician - and us - know if you develop worsening pain, joint pain, bleeding, bruising, rash, fever, or any other worrisome signs or symptoms.

Most mild envenomations will recover fully, even without antivenom. However, up to 20% of victims will have prolonged or even permanent disability and/or disfigurement if they are not treated. The percentage increases with the severity of the envenomation. This is why we recommend antivenom for most envenomations; antivenom will accelerate recovery and decrease the likelihood of permanent local damage. For mild envenomations, it is reasonable to engage in shared decision making with your physician. For moderate and severe envenomations, we highly recommend antivenom.

Dog/cat swallowing snake head

Rarely, a pet may consume a venomous snake’s head. Snakes’ bite reflexes normally remain active for a period of time after decapitation. If a snake’s head was swallowed whole and the venom glands and bite reflex pathway were not destroyed (e.g., by chewing), an internal envenomation by a decapitated head would be possible. That said, this has never been documented.

From Dr. Woliver:

It is definitely possible for the snake to envenomate from inside the stomach. That would likely be catastrophic if that happened. If the snake were to retain its bite reflex post mortem, and bit the inside of the esophagus or stomach on the way down, I don’t know that any amount of antivenom would save that patient due to internal necrosis.

If no envenomation occurred inside the esophagus or stomach, the stomach acid would digest the snake head and would not cause any problems. If venom were to leak out, as long as there is no stomach ulcer, the stomach acid should deactivate/digest the venom. Snake venom is denatured around a pH of 5.5, and the pH of the stomach is generally significantly lower than that.

Antivenom is beneficial while there are ongoing venom effects.

Written by Dr. Spencer Greene

Although antivenom is most beneficial when started within the first 6 hours, it can provide benefit even when started several days later. We sometimes dose patients with antivenom even one week after a bite. If there are ongoing venom effects, antivenom should be administered, or at least considered.

Tourniquets and pressure immobilization are NOT appropriate for pit viper envenomations.

Written by Dr. Spencer Greene

When it comes to our native crotalids (copperhead, cottonmouth, rattlesnake), AVOID any technique that attempts to confine the venom in the affected extremity, including a tourniquet, a lymphatic constriction band, and pressure immobilization.

A tourniquet is great when you want to stop life-threatening bleeding, but you don’t want to cut off the arterial blood supply to a bitten extremity. Tourniquets are never appropriate for any snakebite.

Although lymphatic constriction bands and pressure immobilization don’t cut off the blood supply, they do (theoretically) confine the venom to the affected extremity, which, particularly when combined with the increased swelling, causes increased local tissue injury. Because local injury is seen in > 95% of crotalid envenomations, and for most envenomations that’s the only significant manifestation, we need to avoid this. All of the major toxicology organizations produced a position statement condemning the use of pressure immobilization for native crotalid envenomations.

Furthermore, if pressure immobilization is performed incorrectly, it can actually enhance systemic venom absorption while simultaneously causing local injury.

You can read the position statement here.

NSS opinion on viral post referring to stepping on snakes for science

Written by Kimberly Wyatt, MS

Pit vipers use both vision and heat when detecting things in their surroundings, though heat sensing is primarily used for hunting. Pit vipers don’t heavily rely on their thermal pits for predators assessment. Snakes may strike defensively at any object, though a warmed artificial limb is best for replicating human encounters, and will yield the most accurate data.

Additionally, researchers who perform these studies understandably do not want to hurt the snakes, so the amount of pressure applied is significantly lower than what would be applied if you were taking a normal step and accidentally came down on a snake. Taking into consideration these differences, a concern with such studies is that they may give people a false sense of security. It’s true that snakes prefer to bite defensively only as a last resort. But in reality, a snake that gets stepped on (with the full weight of a person’s body behind it, as happens when someone doesn’t see a snake) will be more inclined to try to bite if it cannot escape or is in pain. It’s worth noting that one study found that 81% of bites occur when folks don’t see a snake and get too close (https://pubmed.ncbi.nlm.nih.gov/28975491/), and a more recent, larger data set from the same researchers found the percentage of bites from accidental encounters to be even higher. It is important to watch your step and wear closed-toed shoes when walking outside, and to look before you reach into spaces you cannot see.

It is true that rattlesnakes will not always rattle before striking, but rattles are still a good warning. Listening for a rattle is a good, though not foolproof, way to stay safe. But you should be aware of your surroundings at the same time, in case a snake is silent.

A study published a couple of years ago identified 101 total human deaths in the U.S. from native snakes from 1989-2018, or about 3.4/year (https://pubmed.ncbi.nlm.nih.gov/33046301/). There are somewhere around 8,000 venomous snakebites in the U.S. annually, so the percentage of snakebite victims who die in the United States is actually well under 1% (~0.04%). That said, this is due in large part to widespread access to antivenom. Copperheads and cottonmouths have an untreated mortality rate in the low single digits (1-2% or so), but for some rattlesnake species, your odds of dying if you don’t get treatment are upwards of 30%. That said, it’s important to remember that:

(1) death is possible following bites from ANY medically-significant venomous snake, and

(2) long-term or permanent disability are far more common outcomes than death, especially if someone goes untreated.

A BITE FROM ANY PIT VIPER OR CORALSNAKE IS A MEDICAL EMERGENCY.

Modern estimates actually suggest that fewer than 15% of bites are dry, meaning no venom is delivered (https://emedicine.medscape.com/article/168828-overview). Most people who get bitten will be envenomated. Signs of envenomation often appear quickly, but can be delayed. Never assume a bite was dry; always get to the hospital if bitten.

There are two antivenoms available for all pit viper envenomations in the U.S. The first, CroFab, has been around since the year 2000, while Anavip was first approved to treat rattlesnake bites in 2018. Anavip was subsequently approved to also treat copperhead and cottonmouth envenomations in 2021. So EITHER antivenom can be used for a bite from any North American pit viper. You do not need to see the snake that bit you to receive proper treatment. Coralsnakes are neurotoxic elapids whose venom targets the nervous system. Their bites present entirely differently than pit viper envenomations, and are treated with a different antivenom, when needed.

NSS does not recommend the snakebite vaccine (rattlesnake toxoid) for dogs.

It has not been demonstrated to help, and it may cause harm. Click here to read a detailed article by Kimberly Wyatt, MS with Asclepius Snakebite Foundation.

There is NO published data supporting the efficacy of the vaccine in dogs.

Adverse reactions following vaccination, including anaphylaxis, have been reported.

What if your pet has already received the vaccine?

Per Dr. Woliver:

The chance for anaphylaxis will always exist. Once the body is primed/exposed it always has the possibility of leading to anaphylaxis. The chance may decrease over time but we can’t predict which dogs this may happened to. Overall, it probably won’t happen, the incidence of this happening is rare but will always exist.

Why don't doctors treat with antivenom when they ought to?

Written by Dr. Spencer Greene

There are multiple reasons why a doctor may choose to not treat a patient with antivenom even when it is clearly indicated:

1. He or she may think snakebites are not that serious.

2. He or she may not believe antivenom is effective.

3. He or she may not think antivenom is safe.

4. He or she may think treatment with antivenom is not worth the cost.

5. He or she may not want to bother with treatment because s/he is uncaring and/or lazy.

6. He or she may face pressure from hospital leadership not to treat patients for various reasons, including financial.

We know that bites have the potential to cause serious local and/or systemic toxicity. We also know that antivenom can prevent and treat local, hematologic, and systemic toxicity. We know that CroFab has an excellent safety profile, with an incidence of acute adverse reactions ranging from 1.4 – 8%.

Antivenom is not cheap, but neither is a prolonged or permanent disability. Antivenom accelerates recovery in a clinically significant way. Furthermore, not all bites that go untreated will recover fully, and the incidence of permanent disability or disfigurement increases with the severity of the bite.

Administer antivenom for any of the following:

—Significant or progressive local tissue damage e.g. tenderness, swelling, hemorrhagic bleb

—Hematologic toxicity, e.g. PT > 15 s, fibrinogen < 150 mg/dL, platelets < 150K/µL

—Systemic toxicity, e.g. hypotension, airway swelling, neurological toxicity

Most physicians recognize the need to treat when there is systemic or hematologic toxicity. A common pitfall is to fail to treat the local findings. If the swelling and tenderness are more than minimal and have extended beyond a major joint (e.g. wrist, ankle), antivenom is warranted. If there is significant local tissue injury, e.g. necrosis, antivenom is also indicated, even if the swelling has not progressed across a joint. Antivenom is most effective when given early, and the previous approach of waiting for the damage to cross two joints should be abandoned.

Read the unified treatment algorithm here.

Per Dr. Burns:

Many reasons. One reason might be that small and medium-sized primary care practices often do not even stock antivenom (largely due to cost but also due to inexperience with using it and/or treating snakebites). To get antivenom for a patient often requires a transfer to a regional ER or regional specialty and critical care practice, which are sometimes quite a distance away. So many clients decline transfer. Another reason is cost of antivenom. Many clients may have antivenom mentioned and/or offered but they may have to decline it due to financial constraints. Another reason is many veterinarians are not well-trained or experienced at using antivenom and their experiences with snakebite (particularly copperhead bites) is that most patients live in spite of not getting it. This last statement is also a problem in human medicine--which NSS is working to educate health care providers about.

Per Dr. Crocco-Khan:

A lot of vets are not well versed in correct treatment for snakebites. It happens a lot in human medicine as well. We learn very little about snake envenomations in vet school and unless you go out of your way to read the current research and learn from experts in the field, you don’t perform the correct medicine. [Benadryl and steroids] LITERALLY do nothing for snake envenomations, but it would help with almost any other mechanism of swelling. Unfortunately, a lot of people don’t realize that snake envenomation swelling doesn’t work like other swelling.

Asclepius Snakebite Foundation has a great article on Surviving a Snakebite in the Wilderness.

From Chris Harper, a paramedic with austere medicine training:

Hiking alone has inherent risks. How you react will be dependent on how your body reacts to the bite. Your first priority should be to notify 911 if possible. Secondly, you should begin to move toward your car - if possible. If you're bitten on the hand or calf by a copperhead, chances are you may be able to make your way out. Trying to self rescue, you may not be able to be concerned with elevating an extremity, because you may be trying to walk on it. Your focus is going to be "getting to help". If you're bitten by a rattlesnake species, symptoms may prevent your self-rescue on foot. I have mentioned it before, but I do have an acquaintance that hiked out of the Smokey Mountains for 8 hours after a Timber rattlesnake bite. If you have a Rescue Whistle, start blowing on it. Maybe someone will hear you if you're lucky. If you have a Cell Phone, there are a couple of ways to find your Grid Coordinates and send a Text message to notify someone of your predicament. Cell phones are radios - and voice signals are MUCH more difficult to transmit, so send texts first if possible.

"RATTLESNAKE BITE - JACKS RIVER TRAIL - SEND HELP!!!"

N34 56.005 W84 31.119

Texts also use up less of your battery. (Turn off bluetooth and any apps that aren't necessary to conserve battery) Anyone that receives your text should notify 911. Any 911 system will know how to track you down and get help en route to your location.

I would HIGHLY RECOMMEND using a SPOT GPS device if you hike alone frequently, watch the videos on it and learn how to use it effectively. YouTube has plenty of them.

If you feel like you're being overwhelmed by the venom and you have to lie down, make sure you're on the trail or in a clearing where you can easily be discovered. Put on bright clothing or display something with bright color. Lie down in the recovery position, so that your airway will drain and you won't choke on your own vomit if you pass out.

Here's one way to send GPS coordinates, but there are more. Research it. As a lone hiker, you're taking your life into your own hands. It behooves you to learn everything you can to self-rescue.

https://youtu.be/HgL_PzImfO0