Snakebite in Dogs

Laurie Anne Walden, DVM

Juvenile southern copperhead. Photo by James Gathany, CDC.

It’s snake season in North Carolina. Snakes are most active in the early spring through fall, and dogs that accidentally disturb snakes sometimes get bitten. Although a bite from a venomous snake is a medical emergency, try not to panic if it happens to your dog.
 

North Carolina snakes
North Carolina is home to about 37 snake species. Most are nonvenomous. Don’t run for the hoe if you see a snake in your yard; chances are it’s a nonvenomous snake that’s helping control the rodent population.

Six venomous snake species live in North Carolina: copperheads, cottonmouths, 3 rattlesnake species, and coral snakes. Copperheads are by far the most common. In our state, venomous snakebites are usually from copperheads. Rattlesnakes and possibly cottonmouths can also be found in the Piedmont. Coral snakes are rare and live in the southeastern part of the state.

See photos of NC snakes here: http://herpsofnc.org/snakes/.
 
Symptoms of snakebite
Nonvenomous bites: Nonvenomous snakes may bite if they are provoked. These bites may look like small abrasions or punctures in the shape of a horseshoe (if they’re visible at all). Venomous snakes sometimes bite without injecting any venom. Nonvenomous bites typically don’t require medical attention unless they become infected.

Venomous bites: Venomous bites are easy to diagnose if you see a snake bite your dog. Diagnosis is a little trickier if the bite isn’t witnessed. Fractures, abscesses, and insect bites can cause symptoms similar to those of snakebite.

Copperheads, rattlesnakes, and cottonmouths are all pit vipers belonging to the family Crotalidae. These snakes inject venom through 2 long fangs. The puncture wounds might or might not be visible through a dog’s fur.

Crotalid venom causes significant tissue damage at the bite site. Copperhead venom is typically less toxic than rattlesnake and cottonmouth venom. The severity of symptoms depends on the size of the dog, the amount of venom delivered, and the location of the bite (for example, bites to the face or neck can cause swelling that obstructs breathing). Symptoms that usually appear right away include the following:

• Intense pain
• Swelling
• Darkening or reddening of skin around the bite site
• Drainage of blood-tinged fluid from puncture wounds

Crotalid venom can also interfere with blood clotting. The venom of some rattlesnake species (not native to North Carolina) damages the nervous system.

Coral snakes are in the family Elapidae, like cobras and mambas. Elapid venom targets the nervous system and can paralyze the muscles of breathing. Bites from coral snakes are serious medical emergencies but luckily are very rare.
 
If your dog is bitten by a snake
Stay as calm as possible; this will help your dog stay calm too. Limit your dog’s movement by carrying him to your car (if possible) instead of having him walk. Snakebites can be extremely painful, so you may need to muzzle your dog before handling him to prevent him from biting in response to pain. Take your dog to a veterinary hospital without delay. Treatment of crotalid bites depends on the severity of symptoms, and your dog will probably need to be hospitalized. Copperhead bites do not necessarily require antivenin. The decision to use antivenin depends on the individual case and the severity of symptoms.

Do not try first aid techniques that you might have read about. These can worsen the tissue damage caused by crotalid venom and delay transport to a veterinarian.

• Do not apply a tourniquet.
• Do not apply ice.
• Do not cut the skin over the bite.
• Do not attempt to suck out the venom.

Don’t try to kill or capture the snake. You risk being bitten yourself if you do. Snake identification is not necessary for treatment. Nearly all venomous snakebites in Mecklenburg County are from copperheads, but the treatment is similar for all pit viper bites. Crotalid antivenin is polyvalent, meaning the same antivenin treats copperhead, rattlesnake, and cottonmouth bites.
 
Preventing snakebites
The best way to avoid being bitten is to leave snakes alone. Copperheads are not aggressive and do not typically bite except in defense. Dogs may stumble upon snakes by accident, though, so take the following measures to reduce the risk:

• When hiking, stay on paths and keep your dog out of tall grass and shrubbery.
• Limit rodent and snake habitat around your house: keep grass mown, locate woodpiles away from the house, keep shrubbery trimmed, and reduce the depth of mulch in shrub beds.

 
For more information, check out the Snakes of North Carolina section of the NC Cooperative Extension website and the Carolinas Poison Center website.

Image credit: CDC/James Gathany

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