As the weather begins to warm, snakebites are a common cause for visits to the veterinary emergency room. Here is some helpful information to prepare you and your pets for snake season.
Snakes in the Wild:
Most of the snake species native to North Carolina are non-venomous and are not harmful to you and your pets. In general, even venomous snakes are not aggressive and will not attack unless provoked. Pets are usually bitten because of curiosity – sniffing dogs or prodding cats may become injured if a snake becomes startled and bites out of self-defense. Non-venomous species may bite, but only the venomous snakes have the potential to cause serious harm. There are many online and in-print resources for identifying these snakes.
Five of the six venomous species native to North Carolina are in the family Viperidae. These species – copperheads, diamondback rattlesnakes, pygmy rattlesnakes, water moccasins (cottonmouths), and timber rattlesnakes (canebrake rattlesnakes) – are known as pit vipers. Pit vipers get their name from a “pit” that is on each side of the face between the eye and the nostril. They all have triangular-shaped heads, retractable hinged fangs, and cat-like eyes (pupils look like vertical slits).
The sixth venomous species is the coral snake, which is in the family Elapidae. Coral snakes have bright colored bands of red, yellow/white, and black. These snakes are frequently confused with scarlet king snakes, which have very similar color patterns, but are nonvenomous. To determine which snake you may be seeing, remember the classic saying: red next to black is a friend of Jack (scarlet king snake); red next to yellow will kill a fellow (coral snake).
Venom and the Toxins Within:
Pit vipers have long fangs which are very similar to a needle. Venom is secreted from poison glands into their fangs and then injected into the prey or threat. The size or age of the venomous snake does not dictate the amount of venom injected into the bite – in fact, juvenile snakes can’t control their venom production as effectively as adult snakes, and they may have very potent bites. Also, snakes which are agitated (for instance, if a dog is barking at them or a person is poking at them) will increase the amount of venom in their bites. However, about 10 to 25% of bites are “dry bites,” which means that no venom was injected. This most often occurs on the first bite.
Pit vipers’ venom contains three types of toxins: anticoagulant toxins, which disrupt the victim’s ability to clot their blood, causing them to bleed; hemotoxins, which destroy red blood cells and thus affect the victim’s ability to carry oxygen to their tissues; and cytotoxins, which cause the surrounding soft tissue to die and become necrotic. Some pit vipers (e.g. diamondback rattlesnakes and water moccasins) also have neurotoxins, which affect the nervous system and can cause muscle weakness, respiratory difficulty, etc.
Coral snakes have small fangs, so the physical wounds inflicted are generally mild. However, their venom mainly contains neurotoxins which affect motor function (victim’s ability to walk or move) and may paralyze the respiratory system, resulting in death. These bites are less common but more severe than pit viper bites.
Try to make your living environment unsuitable for snakes. Snakes like the protection of tall grass, so keep your lawn cut. Keep timber piles away from the house and neatly stacked, and cover your compost piles to cut down on rodent populations, which can attract snakes. Snakes will seek warm places and are often seen sunning themselves during the day. At night, they will tend to find warm places like rocks, your driveway, the street, etc. Because of this, you should wear shoes when walking in the evening, and always carry a flashlight and cell phone. Keep your dogs on a leash so that you can pull them away from trouble.
Snakebites in Pets:
Dogs usually try to sniff at snakes, and therefore are most often bitten in the face, muzzle, neck, ear, or sometimes the tongue. Cats are usually bitten in the paws or forelimbs because they tend to swat at the snakes rather than sniffing. Dramatic swelling can occur at the site, usually within 1 to 24 hours. Sometimes you can see the two puncture wounds, which often will ooze bloody fluid. Mouth and tongue wounds will often cause hypersalivation (excessive drooling). The swollen areas are extremely painful, and your animal may attempt to bite you if you touch the site.
What To Do:
If you suspect that your pet has been bitten, remain calm. Be careful when comforting your pet, and do not put your face close to theirs as they may bite out of pain. Do not place ice packs, bandages or tourniquets on the wound, and do not cut the wound or attempt to squeeze the venom out. These techniques are outdated and will exacerbate the bite wound, causing more damage to the tissue and potentially worsening the effects of the venom.
Identification of the snake is very helpful to knowing what clinical signs to expect, if any. Try to take a photo of the snake or make a mental note of its appearance. Do not attempt to catch it or kill it, as you will risk getting bitten yourself. Believe it or not, a decapitated snake head can still bite a person reflexively for up to an hour after the head is removed from the body!
If your pet is bitten, it is critical that you consult your veterinarian or a local emergency hospital immediately. Fast treatment will help to minimize the damage that is caused by the toxins in the venom. Any pet, especially cats and small dogs, can have life-threatening complications regardless of where they are bitten.
What to Expect at the Veterinarian:
In addition to having swelling around the bite wound, snakebite victims may be vomiting, drooling, weak, or very painful. Severe envenomations can result in paralysis, seizures, and even death. Although most animals will show signs of the bite within 24 hours, it can take 2 to 3 days for signs of the venom toxicity to develop, so ideally they should still be hospitalized even if everything seems normal. Unfortunately, there is no test to show whether venom has been injected or not.
In severe cases of pit viper bites, the tissue around the bite wound can get dark, bruised, and necrotic, and require extensive wound care. Animals with blood loss due to the anticoagulant toxins in the venom may need a blood transfusion. In the case of severe coral snake bites, tissue damage is generally less, but victims can have paralysis of the respiratory system. Severely affected animals may have to be put on a ventilator.
Antivenom formulas do exist, but they are expensive and may not be available at all hospitals. However, survival has been shown to be improved when these are used early in the course of treatment.
Prognosis is highly variable and depends on the dose of venom, the size of your pet, the location of the bite, and your pet’s particular reaction to the toxins and the treatment. In this area, most snakebites are not fatal if treated. Some bites require only simple monitoring and basic treatment for pain and swelling. However, there is a very real possibility of severe complications, and some animals pass away despite very vigorous and aggressive therapy.
The Bottom Line:
Snakes are a normal part of the North Carolina landscape, and most are completely harmless. However, as we approach the warmer months, bites by venomous snakes can and will occur, and you should be prepared in case your pet is one of the unlucky victims. Take precautions to avoid snakes by making your yard less snake-friendly and by being vigilant when walking your dog. If your dog or cat is bitten, they should see a veterinarian immediately for evaluation and supportive care as needed.
Here’s to a fun, healthy, and