Did you know that each year in the United States, over one million animal-bite wounds are reported? Dogs and cats inflict the vast majority. On occasion the tables get turned on our canine friends though, and without warning they are recoiling from the pain inflicted by sharp, venom-injecting fangs. Caught off guard, it is a moment you will never forget if you and your dog encounter a venomous snake while simply taking a pleasant walk in the outdoors.
Snakebites are a fact of life for dogs and humans in a wide area of North America. Venomous snakes bite about 8,000 people annually in the United States, but according to most estimates, no more than 12 of these bites are fatal each year.
You won’t find details on the numbers of dogs bitten, or killed, by venomous snakes, though. I don't believe we there is a valid source of information on the actual numbers of dogs bitten or killed by snakes annually in the United States. Although there surely are isolated areas of the United States where venomous snakes are not plentiful, their range spreads all across the country with only Alaska and Hawaii reporting no species of the venomous kind. Many cases of snakebite occur in dogs that are "just visiting" a part of the country where venomous snakes are plentiful. It has happened that dog owners who reside in an area devoid of venomous snakes are shocked into reality when visiting an area where venomous snakes reside!
May see one, two, or several small puncture wounds, bleeding, bruising, immediate and extremely painful swelling at the site of the bite, and tissue necrosis. The more severe systemic signs may take up to several hours to appear and include hypotension and shock, lethargy and weakness, muscle tremors, nausea, vomiting, and neurological signs including depressed respiration.
Identify the snake if possible. Restrict movement of the pet. Loosely immobilize the limb in a functional position if bitten on an extremity. DO NOT incise the bite wound to aspirate the venom and DO NOT apply a tourniquet without veterinary assistance. DO NOT apply ice to the area. Seek veterinary attention.
General treatment: The animal will be kept quiet and the bitten area immobilized if possible to decrease the spread of the venom. The area around the wound will be clipped and cleaned.
Supportive treatment: Antihistamines may be administered and IV fluids given to help prevent low blood pressure. Oxygen is given if needed. Antibiotics are used to prevent secondary infections. Pain medication is provided as necessary. Laboratory tests to check for bleeding problems and organ damage will be performed repeatedly. Blood transfusions may be necessary in cases of severe coagulopathies. The area above and below the bite wounds may be measured every 15 minutes to monitor the edema. Nonsteroidal anti-inflammatory drugs (NSAIDs) are contraindicated in the early phase (first 24 hours) of treatment because of the different types of venom and the anticoagulant effects of NSAIDs. The use of corticosteroids may be contraindicated also, as some research shows they increase the severity of the bite.
Specific treatment: Antivenin may be administered. The use of antivenin is controversial and is used at the discretion of the attending veterinarian. To be most effective, antivenin should be given within 4 hours of the bite. It becomes less effective as more time passes.
All snake bite victims should be observed for a minimum of 12 hours, even when there are no clinical signs. If clinical signs are present, the length of observation is increased to 48-72 hours, as damage to organs may not appear immediately.
A study of animals bitten by pit vipers showed that those treated with antivenin, intravenous fluids, and antibiotics had a mortality rate less than 1% and local tissue damage was rare. The mortality rate in untreated patients depended on the species of snake involved. For example, in patients bitten by the Northern Pacific Rattlesnakes, the mortality rate was about 10%. In the much more dangerous Mojave rattlesnake, it could be as high as 35%.