Pit Viper Bite Poisoning in Dogs

Veronica Higgs, DVM
Published: January 3, 2023
Pit Viper Bite Poisoning in Dogs

What Is Pit Viper Bite Poisoning in Dogs?

Pit vipers are the largest group of venomous snakes in the United States. They are responsible for 99% of all venomous snake bites in the U.S. and about 150,000 bites a year in dogs and cats. Pit vipers are found in every state except Maine, Alaska, and Hawaii.

Pit vipers use their long, hinged, and hollow fangs to inject venom into its prey. The venom composition varies depending on the species, but typically it damages tissues and blood cells preventing normal clotting. 

All snakebites are considered an emergency. If you see or suspect your dog was bitten by any snake, including a pit viper, take it immediately to the local veterinary emergency hospital. 

Why Are Pit Viper Bites Poisonous to Dogs?

The level of poison in a pit viper’s bite varies depending on the species and age of the snake, and if it recently fed. About 25% of the time, snakebites are “dry bites,” meaning venom was not injected. Since it is impossible to tell at the time of the bite, treat any snake bite in your dog as a medical emergency and contact a veterinarian immediately.

Pit viper venom is composed of enzymes and toxins that cause damage to cells in the body. The venom causes swelling, redness, pain, and tissue death (necrosis) around the site of the bite. In some cases, this may progress to a whole-body reaction that includes an inability of the blood to clot and damage to the nervous system, kidneys, heart, and lungs. 

Symptoms of Pit Viper Bite Poisoning in Dogs

Symptoms of pit viper bite usually develop in your dog within 30 minutes of being bitten but the reaction can be delayed up to six hours. Symptoms at the bite site may include:

  • Puncture wounds that may or may not be visible due to swelling

  • Swelling

  • Pain

  • Bruising

  • Redness

  • Bleeding from wound

  • Tissue death–necrosis (often looks like black, leathery skin)

This may progress to more dangerous systemic signs of envenomation:

  • Vomiting/drooling

  • Diarrhea

  • Generalized weakness

  • Muscle twitches/tremors

  • Bleeding from the nose, gums, and bloody urine

  • Trouble breathing

  • Shock

My Dog Was Bitten by a Pit Viper, Now What?

If your dog was bitten, it is usually difficult to identify the snake and determine if its bite contained venom. Therefore, all snakebites should be considered medical emergencies and you should take your dog immediately to the veterinarian if you see—or suspect—it was bitten.  

If you happen to see the snake, look for these distinguishing features of a pit viper:        

  • Retractable fangs

  • Heat-sensing pits located between the nostrils and eyes that appear as four nostrils

  • Vertically elliptical pupils

  • Triangular-shaped head

From appearance alone, pit viper bites may be confused with fractures, abscesses, spider bites, allergic reactions to insect bites or stings, or other snakebites. Do not try to capture the snake or you might risk being bitten. If the snake is killed, bring it to the veterinarian along with the dog that was bitten. Since the head of the snake is the primary way to identify it, take care not to damage it. 

A pit viper bite is very painful and may cause your dog to become agitated and aggressive. On your way to the vet, use a muzzle on your dog to avoid being bitten. Also, to reduce the spread of venom in the dog’s body, try to carry it to limit its activity and keep it quiet. 

There are several myths about giving your dog first aid for snake bites including ice pack/cooling, sucking out the venom, incision of the bite, tourniquet, hot pack/heating, or urinating on the wound. These methods are ineffective, potentially harmful, and should never be attempted. Snakebites require immediate medical attention by your veterinarian. 

How Veterinarians Diagnose Pit Viper Bite Poisoning in Dogs

To diagnose pit viper bite poisoning in your dog, your veterinarian collects a thorough history including any eyewitness descriptions of the snake, examining the dead snake brought in, or photos of it if available. If the snakebite is witnessed, it makes diagnosis much easier as there are no diagnostic tests to confirm pit viper bite poisoning.

Your veterinarian will conduct a physical exam to look for puncture wounds, swelling, and breathing difficulty. A skin marker is used to mark the edges of the wound’s bruising and swelling and to monitor it for complications. A complete blood count, serum blood chemistry, and urinalysis are recommended by your vet for a baseline evaluation.

Because symptoms may be delayed, all snakebite cases should be monitored in the hospital for 24 hours before assuming it was a “dry” bite or a bite from a nonvenomous snake.

Anti-venom is the antidote for venomous snakebites. Many veterinarians may not carry anti-venom, so call your vet to ask if they carry it, or if you should go directly to a local 24-hour emergency veterinary hospital. The earlier anti-venom is administered, the more effective it is. 

Your vet will administer IV fluids to your dog to help maintain blood pressure, and pain medications to keep them comfortable. Other therapies may include blood transfusions, anti-nausea medications, and oxygen therapy.

Your veterinarian will determine the most appropriate course of therapy based on your dog’s case. 

Recovery and Management of Pit Viper Bite Poisoning in Dogs

Early and aggressive care is crucial for successful treatment of pit viper snakebites. The prognosis varies based on the level of venom, location of the bite site, time from the bite to when treatment started, and the individual pet’s response to therapy.

Anti-venom should be given as soon as possible and repeated if necessary. Most dogs with venomous bites remain hospitalized for two to four days for continued supportive care and medication.

At least 70% of dogs with pit viper bite poisoning survive. Most go on to live normal lives with minimal long-term side effects. Symptoms may recur, however, and dogs need to be monitored as outpatients for several weeks after the snakebite. 

Prevention of Pit Viper Bite Poisoning in Dogs

Snakes generally avoid humans and pets. A dog is very curious by nature, and it may want to investigate when encountering a snake.  

About 90% of poisonous snakebites happen between April and October. Snakebites frequently occur on the dog’s face and front legs.

If you are hiking with your dog, go during the day when snakes are resting (most pit vipers are nocturnal). Keep your furry friend on a leash so they do not startle a sleeping snake. Also avoid common snake resting places such as holes, logs, rocks, and heavy brush or ground cover.

References

Carter D, Allen-Durrance A. Today’s Veterinary Practice. Pit Viper Envenomation in a Dog. 2022.

Gwaltney-Brant SM. Merck Veterinary Manual. Snakebites in Animals. 2022.

Hovda L, et al. Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Toxicology. 2nd ed. Wiley-Blackwell; 2016.

Talcott PA, Peterson ME. Small Animal Toxicology. 3rd ed. Elsevier Saunders; 2013.

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