There are two primary families of the venomous snake in the United States. They are the Crotalidae and the Elapidae. The Crotalidaes are the most prevalent in the U.S. and include 27 species of rattlesnakes, 3 species of the water moccasins, 5 species of the copperhead, 3 species of the pygmy rattlesnake, and 3 species of the massauga. Water moccasins and copperheads are found in the eastern U.S. and south towards Texas. Rattlesnakes are found throughout the U.S. with the highest concentration in the south and southwest. The Elapidaes are Australian venomous snakes such as cobras, mamba, taipans, kraits, etc. The only species of the elapidae occurring naturally within the U.S. is the coral snake. They are found on the coastal parts of the Southeast of the U.S.
The family Crotalidae are also known as pit vipers. This term refers to the heat sensing facial pits located on each side of the head. These pits serve as extremely sensitive thermo receptive organs which aid the snake in locating their prey. They are also identified by their triangular heads and retractable fangs. For the purpose of general considerations, the venoms belonging to the family of the Crotalidae, with few exceptions can primarily be considered hematoxic, hemolytic and cytolytic. With the Coral snake their venom is primarily neurotoxic, affecting the respiratory system and causing respiratory paralysis. A bite from this snake is almost always fatal to a dog. The site of a bite from this snake may not swell or be painful, but the venom causes paralysis. If treatment is attempted, it is usually to prevent convulsions and inflammation, in hope that the bite had little venom. The effects of their venom are similar to those of most other Elapidae, such as the cobra.
Most snake bites tend to occur on the dog’s neck or head. It is said that bites that are on the trunk of the body usually have a poorer prognosis. Snake bites may affect one or more of the dog’s body systems including the cardiopulmonary, nervous, and/or the coagulation system. Usually if the snake is not poisonous the bite site will have minimal pain, swelling, and bruising. The effects of a poisonous snakebite are best understood in terms of the time frame as it relates to the components of the pit vipers venom. Snake venom is essentially made up of proteins that are designed to kill and “pre-digest” its prey.
- Neurotoxins are responsible for the immediate effects. They enter the circulation system within 10 minutes after the bite and affect the central nervous system. You may see the dog collapse, be nauseated, have blurred vision, have a loss of blood pressure, go into shock, and eventually die.
- Hemotoxins are proteins that kill the blood components and cells. Within the first couple of hours after the bite, massive swelling may appear on the affected limb or area. If the bite is on the neck, the swelling may affect the dog’s breathing. The bite area will be extremely painful and the dog may seem lethargic. After the swelling has peaked, dark red or purple bruising may become visible on the area that was bitten. A reddish black fluid may begin to ooze from the punctured areas on the skin. This is a sign that cell destruction has taken place and the area may begin to slough off the skin and peel like a large scab. As alarming as this sounds, it is just new tissue growing beneath the dead tissue. There is little that can be done to prevent this from happening. Clotting problems may also develop from this type of venom. Be alert for any signs of internal bleeding.
What to Do….
- Attempt to identify the snake without getting bit yourself. If you have to kill the snake to protect yourself and your pet, take it with you for identification. Please be aware that a decapitated snake head can still be venomous for up to 2 hours after death.
- Remain calm and do everything you can to keep your dog calm as well. Activity and excitement can cause the snake venom to circulate more rapidly through the dog’s system. Immobilize the bitten area if possible.
- Call a veterinarian, they may advise you to administer Benedryl. The dosage for Benedryl is 1 mg/pound.
- Put on gloves and clean the wound with an antibacterial solution. Be careful as the affected area may be very painful.
- Loosen or even remove the dog’s collar. If the bite is on the head or neck area, the swelling could cause strangulation from the collar.
- Encourage your dog to drink fluids.
- Keep the dog warm to help prevent shock.
- Transport to the veterinarian or the nearest clinic and monitor their vital signs.
What Not to Do….
- Do not apply ice to the affected area. Even though the ice will help with the swelling, it will also slow the circulation of the body’s chemical defenses to the affected area. Also if it is applied incorrectly, it can further damage the tissue area.
- Do not cut an “x” across the puncture wound and attempt to suck out the venom. While venom is not harmful if digested, it can be absorbed in the membranes in the mouth and can envenommate the person trying to suck the venom from the wound. Cutting the wound can also cause further damage to the injured tissue.
- Do not apply a tourniquet.
Once your dog is at the veterinarian clinic, he will be kept quiet and the bitten area will have the hair clipped around the area and cleaned. Antihistamines and IV fluids may be administered to help prevent low blood pressure. Oxygen may also be given. Antibiotics will be given to prevent infection and pain medication will be provided as needed. Blood work will be done to check for organ and bleeding problems. The blood work will need to be done repeatedly to monitor their blood levels. Blood transfusions may also be necessary. Antivenin may also be administered; the use of it is controversial and will be used at the discretion of the veterinarian. To be the most effective, it needs to be given within 4 hours of the bite. Areas that have a high population of pit vipers may have this product on hand.
All snake bites should be observed for a minimum of 12 hours, even if the dog is not showing any clinical signs. If clinical signs are present, the length of observation will increase, as damage to internal organs may not appear for a few days following the bite.
Read our Imflammation Article for information about the swelling that can occur due to bites, stings and injuries.