What Every Dog Owner Should Know About Snakebites

By Cory Woliver DVM, Nicklaus Brandehoff MD, Wayne Zuvers DVM and Krista Halling DVM CCRP DACVS

Snakes weave a tale of intrigue and, for our canine companions, potential danger. With over 2,500 species of snakes – found on all continents except Antarctica – several of which are able to inject life-threatening doses of venom through their bite, it is crucial for dog owners to understand the nuances of snakebites and how to safeguard their canine companions. Let’s explore the types of venomous snakes, the action of venom, and, most importantly, how to protect and care for our four-legged friends.

Snakebites rarely result from a snake launching an offensive attack on a dog, but rather from a snake defending itself against a dog approaching too close.

What is the difference between a poison, a toxin and a venom?

While they all can cause harm or death, the difference between a poison, a toxin and a venom lies in the origin or method of delivery:

• Poison (n): a chemical substance capable of causing harm to a living organism, when delivered by inhalation, ingestion, or absorption
• Toxin (n):  a chemical substance produced by a living organism (such as bacteria, fungus, plant or animal), capable of causing harm to another organism. A toxin is thus a poison that is produced by a living organism
• Venom (n): a toxin that enters an organism by injection, typically from a bite or a sting.
• Envenomation (n): the act of an organism injecting venom into another organism

Taxonomy of venomous snakes

Most snake species either do not produce any venom or do not produce enough venom to be of concern. However, five groups of snakes stand out as being medically significant. Their bite can result in hospitalization, permanent injury or death to both humans and domestic animals: 

• Rattlesnakes, copperheads, water moccasins are all pit vipers, belonging to Crotalinae. This group is responsible for most of the snakebites in North America.
• Cobras, mambas and coral snakes belong to Elapidae. This group is very concerning due to their highly toxic venom and thus elevated risk of fatality from a bite.
• Adders and vipers belong to Viperidae
• Boomslangs are members of Colubridae
• Sea snakes belong to Hydrophiidae

Why do snakes attack dogs?

Snakes are habitually shy creatures and dogs are not their normal prey. Dogs, on the other hand, are curious creatures. It’s therefore important to highlight that snakebites rarely result from a snake launching an offensive attack on a dog, but rather from a snake defending itself against a dog approaching too close. In this article we will describe ways to prevent these unwanted encounters.

Understanding the bite

All snakes have teeth, but not all snakes have fangs. Fangs are highly specialized teeth designed to deliver venom. Some fangs are long and hinged, located in the front of the snake’s mouth and capable of being flicked forward to inject venom deep into tissue; while other fangs are shorter and rigid.

Dogs are most commonly bitten on their face and muzzle.

Snake venom affects its victim by several life-threatening or deadly means:

• Hemotoxic: toxins which cause the breakdown of blood cells and induce hemorrhage
• Cytotoxic: destroying proteins and cells walls, resulting in tissue and cell death
• Neurotoxic: leading to paralysis of the body and respiratory system

In North America, most of the reported dog envenomations are attributed to the family Crotalinae: the majority being from rattlesnakes and copperheads. Crotaline venom is primarily hemotoxic and cytotoxic; however, occasionally neurotoxins are present.

Following a bite, venom can persist in a dog’s blood stream for more than 24 hours, and the onset of clinical signs (see below) ranges from a few minutes to hours post-bite. Notably, not all snakebites are venomous and not all venomous snakebites result in venom being injected. In some cases the venomous snake bites a victim but does not inject its venom. This is called a ‘dry’ bite, occurring only 15-30% of the time, depending on the species of snake. And since there is no way of initially knowing whether venom was injected, it is important to seek immediate veterinary care for any potentially venomous snakebites.

Where on their body are dogs most commonly bitten?

• The muzzle and face are the most common snakebite sites in dogs
• Sometimes the forelimbs are bitten
• Occasionally on the hind limbs
• The trunk of the body is rarely bitten

How likely is a dog to develop severe signs from envenomation?

Signs can range from mild to severe, depending on both the volume of venom injected, the dog’s body size, the venom-to-body-mass ratio, the depth and number of bites, the bite location, post-bite activity and the time elapsed until treatment. 

All snake bites should be treated as an emergency. The prognosis is good if the dog receives prompt treatment and antivenom.

Small dogs, due to their reduced mass, are at greater risk (than are larger dogs) of developing severe signs from a given volume of venom. Additionally, being physically active following a snakebite may increase the spread of venom through a dog’s circulation.

What are the signs of envenomation in dogs?

• Your dog may or may not yelp when bitten
• Localized swelling, pain and bleeding from fang marks are the most common signs. Usually this involves the face/muzzle.
• Fang marks are not always identified at the bite site; and sometimes abrasions or lacerations are present
• Other signs such as vomiting, paralysis, and systemic shock may develop

A young dog with a swollen face receiving veterinary care following a venomous snakebite. Photo: Wayne Zuvers DVM

What to do if you think your dog has been bitten by a snake (venomous or not)?

• Seek emergency veterinary care. It is a good idea to call ahead and check whether the veterinary clinic has antivenom. They may redirect you to somewhere that does
• Keep your dog calm. To help reduce the spread of venom, it may be best to carry him/her back to the car
• Use a muzzle if needed, to prevent yourself from getting bitten by your dog. Snakebites are very painful and your dog may exhibit atypical behaviour if in pain
• DO NOT place a tourniquet on the affected body part
• DO NOT try to suck out the venom
• DO NOT try to catch or kill the snake. This only puts you at risk of being bitten as well; and snake species identification is usually not necessary for treatment intervention

What is the current veterinary standard of care for snakebite envenomations in dogs?

• Timing of treatment is critical to a dog’s medical outcome: all snakebites should be treated as an emergency
• Antivenom: this is the cornerstone of snakebite therapy and is recommended even if uncertain whether envenomation occurred 
• IV fluids
• Pain medications
• Monitoring for at least 24 hours
• Contrary to previous belief, antibiotics, diphenhydramine (ex: Benadryl) and glucocorticoids (i.e. steroids) are generally not indicated for snakebites in dogs. 
• Non-steroidal anti-inflammatory drugs (NSAIDs) are considered contra-indicated due to the possible concurrent presence of low blood pressure, myoglobin release from damage muscle, and the potential for a venom-induced bleeding disorder. 

In North America, venomous snakebites in dogs carry a reported death rate of 1-30%. Fortunately, the prognosis for survival from a venomous snakebite is good, if your dog is treated promptly, with antivenom therapy playing the most important role. 

Antivenom is the cornerstone of snakebite therapy in dogs.

What is snake antivenom? 

Antivenom is a commercially-available product comprised of immunoglobulins (i.e. antibodies) obtained from horses who have been repeatedly injected with small doses of snake venom from targeted species of snakes. The horses respond by mounting an immune response to the venom, and their anti-venom antibodies are then harvested to produce the antivenom.

Can a dog just use its own antibodies to neutralize the snake venom?

No. For antibodies to be produced by one’s immune system, both time and exposure to the specific offending substance (in this case snake venom) are required. A dog, when bitten by a snake, would not have sufficient time to produce its own antibodies against the venom. This is why they are made in advance using horses, who are large enough to produce a sufficient amount of antibodies for widescale use.

When the commercial antivenom is injected into a dog, the horse’s antibodies bind to and neutralize the snake venom in the dog’s circulation. An allergic reaction (i.e. type I hypersensitivity) by the dog to the foreign antivenom can occur, but it is an uncommon event.

In North America, the snakebite antivenom covers endemic venomous species, therefore for the antivenom treatment to be effective, it is not necessary to identify the species of snake that bit your dog.

I have heard of a rattlesnake vaccine for dogs. Will this vaccine prevent my dog from requiring veterinary care if bitten by a snake?

No. Antivenom therapy and emergency veterinary care is still recommended. While the canine rattlesnake vaccine claims to reduce the severity of illness in dogs bitten by certain North American species of venomous snakes, a protective effect of the vaccine has not yet been scientifically shown.

Guidelines for keeping your dog safe in snake country 

The good news is that snakes do not want to encounter your dog any more that you want your dog to encounter the snake. In regions where venomous snakes are known to inhabit, practice safe and respectful snake etiquette:

• Keep your dog on a leash
• Stay on designated trails/paths
• Avoid walking through tall grass
• Be on the lookout for snakes sunning themselves on trails and logs, and give them respect and wide berth if you encounter one 
• Note the contact information of the closest veterinary clinic which stocks snake antivenom; an emergency veterinary clinic may be necessary if after-hours
• Remember that your dog is not likely to learn from a bite that snakes are dangerous, so always consider the above guidelines
• Seek immediate veterinary care if a snakebite is known or suspected in your dog

Enjoy embracing the great outdoors with your four-legged companion, just be mindful and respectful of the serpentine residents sharing our natural world. By staying informed and following the tips shared, you can enjoy dogpacking adventures with the wildlife around us.

Additional resources for dog owners and veterinarians

• The Asclepius Snakebite Foundation
• National Snakebite Support
• Venomous snakes by region
• VenomMaps
• North American Pit Viper Algorithm for Veterinarians

About the authors

Cory Woliver is a Clinical Lecturer in Emergency and Critical Care at the University of Florida College of Veterinary Medicine and a veterinary advisor to The Asclepius Snakebite Foundation.

Nicklaus Brandehoff is board-certified in emergency medicine, medical toxicology and addiction medicine, as well as Co-Founder and Executive Director of The Asclepius Snakebite Foundation. Follow on Instagram: @snakebite_foundation

Wayne Zuvers is an emergency medicine and critical care veterinarian with expertise in snakebites, at the Veterinary Care and Specialty Group, Chattanooga, TN.

Krista Halling is a board-certified small animal surgeon and canine rehabilitation practitioner and Co-founder of Dogpacking.com.

References

Woods JP, Rosenstein P (2017) Snakebites (Envenomation). In Mathews KA (ed) Veterinary Emergency and Critical Care Manual 3rd Ed: 471-480

Woliver C, Schaer M (2023) Neurologic and hematologic sequelae following a timber rattlesnake (Crotalidae horridus) envenomation in a dachshund. Toxicon X Apr 18;18:100156

Brandehoff N, Wilson B. (2023) Snakes 101: Bites, Myths and Antivenom. In: Backpacker Radio podcast episode 223: October 16

McGee JL, Bree’s C, Cruikshank A. (2014) Effects of the canine rattlesnake vaccine in moderate to severe cases of canine crotalid envenomation. Vet Med (Auckl) Oct 31:5:153-158

Bassett TE, Schaer M (2023). A review of 95 pit viper envenomations in Northcentral Florida (2018-2020). Toxicon: June 15

Witsil AJ, Wells RJ, Woods, C, Rao S (2015) 272 cases of rattlesnake envenomation in dogs: Demographics and treatment including safety of F(ab’)2 antivenom use in 236 patients. Toxicon Oct:105:19-26

Armenians RA, Schaer M (2011) Overview and controversies in the medical management of pit viper envenomation in the dog. J Vet Emerg Critical Care (San Antonio) 21(5):461-470

Buchanan JT, Thurman J (2022) Crotalidae envenomation. In: StatPearls (Internet). Treasure Island, FL. Available from www.ncbi.nlm.nih.gov/books 

Rautsaw, R.M., Jiménez-Velázquez, G., Hofmann, E.P. et al. (2022) VenomMaps: Updated species distribution maps and models for New World pitvipers (Viperidae: Crotalinae). Sci Data 9, 232 

Hardy MC, Cochrane J, Allavena RE. (2014) Venomous and poisonous Australian animals of veterinary importance: a rich source of novel therapeutics. Biomed Res Int. 671041