Skip to Main Content

+

  • • Distinguishing whether the patient has been bitten and envenomed, bitten but not envenomed, or bitten by a nonvenomous snake is critical prior to starting treatments

    • Treatments may not only cause discomfort but may also produce serious side effects

    • Bite by a venomous snake results in envenomation in only 50-70% of cases

    • Degree of envenomation depends on the size of the snake and the duration of contact

++

Venomous Snakes

+

  • • Indigenous venomous snakes of North America can be placed in 4 groups:

    • 1. Rattlesnake

      2. Copperhead

      3. Cottonmouth

      4. Coral snake

++

Pit Vipers

+

  • • Include rattlesnakes, copperhead, and cottonmouth

    • Can be distinguished from nonvenomous snakes by a round mouth and a pit between the eyes and the nares on each side

    • Have retractable canaliculated fangs that can rapidly spring into biting position and deliver venom

    • The large venom glands also give the head a triangular or diamond shape

    • Have vertically oriented elliptiform irises

    • Most deliver a primarily hemotoxic venom

    • Hemotoxic effects are mediated by proteolytic enzymes, peptides, and metalloproteins that cause local tissue destruction directly and by intimal injury to blood vessels, followed by thrombosis and necrosis

    • Activation of the coagulation cascade can occur at multiple points, resulting in net anticoagulation

++

Coral Snakes

+

  • • Have small mouths, short teeth, and deliver secreted venom into prey through created lacerations

    • Bite lacks the characteristic fang marks of bites by pit vipers, sometimes making it hard to detect

    • Body coloration pattern is red bands immediately adjacent to yellow bands

    • Coral snake venom is primarily neurotoxic

    • Neurotoxic venom can cause dysphagia, dysphonia, diplopia, headache, weakness, and respiratory distress

++

Nonvenomous Snakes

+

  • • Most snakebites in the United States are from nonvenomous snakes

    • Nonpoisonous snakes such as the red milk snake and the scarlet king snake mimic the bright red, yellow, and black coloration of the coral snake

    • -True coral snakes have red bands immediately adjacent to yellow bands

      -The mimics have black bands immediately adjacent to the red bands, thus the mnemonic: "Red on black, venom lack; red on yellow, kill a fellow"

++

Epidemiology

+

  • • About 8000 people are bitten by venomous snakes in the United States each year

    • Death from serious envenomation occurs in 9-15 victims per year in the United States

++

Symptoms and Signs

+

  • • Puncture marks, local ecchymosis and discoloration, vesicles and bullae, and rapid appearance of swelling and edema at the injured area

    • Pain of the bite can be quite severe

    • Additional signs of hypotension, diaphoresis, nausea, weakness, and faintness are common

    • Perioral or peripheral paresthesias, taste changes, and fasciculations

    • Signs suggestive of neurotoxic envenomation include dysphagia, dysphonia, diplopia, headache, weakness, and respiratory distress

++

Laboratory Findings

+

  • • ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.

Ok

About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Subscription Options

AccessSurgery Full Site: One-Year Subscription

Connect to the full suite of AccessSurgery content and resources including more than 160 instructional videos, 16,000+ high-quality images, interactive board review, 20+ textbooks, and more.

$995 USD
Buy Now

Pay Per View: Timed Access to all of AccessSurgery

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.