Snake Bites

Original Date: 07/2003 | Supersedes: 06/2017 | Last Review Date: 10/2020
Purpose: To provide guidance on the evaluation and management of snake bites in the Houston area

Contacts

Poison Control Center 1-800-222-1222 (This is first contact for snakebites to help facilitate anti-venin, especially for coral snakes and exotic snakes)

The herpetologists at the Houston Zoo are available to help in the identification of snakes or procurement of anti-venin for coral/exotic AFTER discussion with poison control.

  1. Herpetology Curator
    Office 713 533-6527 (7am-7pm)
  2. Herpetologist, Stan Mays, 713-483-4583 (after hours)
  3. Houston Zoo Operator Number (afterhours, emergency)
    Operator 713-533-6500
  4. Houston Zoo Rangers 713-203-5695
  5. Spencer Greene, MD, Houston Zoo Toxicologist (602-384-6460)

Antivenin for Rattlesnake, Copperhead and Water Moccasin

Crofab (Protherics; Ovine-derived polyvalent Fab-1 antibody)

Antivenin for Coral Snakes

Coralmyn

Available at Houston Zoo, not approved by FDA

*additional consent for usage must be signed

Antivenin for Exotic Snakes

Not readily available. Contact the poison control center for assistance. They will assist in obtaining antivenin if the snake is not found in the Houston Zoo collection.

*additional consent for usage must be signed

If the victim has a personal supply of antivenin for the type of snake involved, it can be used if it is not visibly turbid or expire/ five or fewer years beyond its expiration date.

Identification of Snakes

There are four classes of poisonous snakes in the Houston area; Rattlesnake, Copperhead, Water Moccasin, and Coral.

  1. Coral snakes are easily identified due to their bright colors. Corral snakes in the United States are poisonous if the color red touches yellow. Red on black are not native poisonous snakes to the U.S. This general principle reliably applies only to coral snakes native to North America.

Rattlesnakes, Copperheads, and Water Moccasins can be difficult to identify. If question is raised to weather the snake is poisonous some principles can be taken to identify poisonous verses non-poisonous. Copperheads and water moccasins require much less aggressive care than rattlesnakes and antivenin if often not needed. (Figure 1)

Exotic snakes: Identification of the snake is of key importance in providing appropriate care as envenomation by some of these snakes requires a specific antivenin. If at all possible, a herpetologist should see the snake or a high-quality photograph of the snake in order to identify the snake as precisely as possible. (See contact information above).

Rattlesnake, Copperhead or Water Moccasin Management

  1. Attend to ABC’s
    1. If concern for compartment syndrome, early consultation with trauma service or pediatric surgery advised
  2. Ensure no tourniquet placed
  3. Obtain the following labs
    1. CBC
    2. BMP
    3. PT/PTT, INR
    4. TEG
    5. D dimer
    6. Fibrinogen
  4. Depending upon the circumstances, consider the following:
    1. Liver profile, UA
    2. EKG – Older adults and those with known heart disease
    3. CPK – Patients with significant local edema
    4. Type and Cross – Those with significant coagulopathy
    5. Consider X-ray of the bite site to rule out a retained fang or fragment thereof and manage accordingly per retained foreign body
  5. Mark and track the spread of erythema/ swelling on the patient’s skin, along with time.
  6. Notify poison control.
  7. Tetanus prophylaxis, if indicated.
  8. Antibiotics – not indicated.
  9. Antivenin- Crofab if evidence of severe envenomation with significant limb swelling, severe coagulopathy, or severe systemic involvement.
    1. Copperhead bites and to a lesser extent Water Moccasin bites require less aggressive care and often do not need antivenin administration.

Rattlesnake, Copperhead and Water Moccasin Antivenin Administration

Categorize the snakebite as severe enough to require antivenom or not and follow the Crofab Algorithm (Figure 2).

Administer the first portion of the antivenin slowly over 10 minutes. If no adverse effects occur, continue administration so that the initial 4-6 vials are administered over 1 hour.

Rattlesnake, Copperhead and Water Moccasin Disposition

If admission is warranted, consult appropriate hospitalist service for admission. Trauma or pediatric surgery should be consulted if concern for compartment syndrome.

  1. The following patients should be placed in the ICU or IMU per discretion of the ED physician and/or hospitalist.
    1. Patients with systemic symptoms even if the symptoms resolved with the administration of antivenin.
    2. Patients with active bleeding and coagulopathy.
    3. Patients with grossly abnormal coagulation indices.
  2. Documented or concern for compartment syndrome should be admitted to Trauma/Pediatric Trauma with Hand subspecialty service consult as needed.
    1. If no concern for compartment syndrome after consultation, patient may be admitted to appropriate hospitalist service with surgical consultant(s).
  3. If mild envenomation, placement in observation under the hospitalist/general pediatrics is appropriate.
    1. If only minimal swelling and no other signs of envenomation, if there is no progression of swelling after 4 hours from time of initial bite, patient could be discharged home with shared decision making, especially for copperhead and water moccasin bites.
  4. If no swelling, ecchymosis, abnormal labs or vitals and the ED attending deems appropriate, patient can be discharged with close follow up primary care.

Coral Snake Management

  1. Attend to ABC’s
  2. Consider elective tracheal intubation if any signs of bulbar paralysis are present.
  3. Consider an EKG – Anecdotal evidence suggests that coral snake envenomation is sometimes associated with cardiac arrhythmias.
  4. Obtain the following labs: CBC, BMP, PT/PTT, INR, TEG, D dimer, fibrinogen
  5. Tetanus prophylaxis, if indicated.
  6. Antibiotics – not needed.
  7. Notify poison control
  8. Systemic effects may be delayed for many hours but can include: Impending respiratory failure, Respiratory distress, Pharyngeal spasm, Hypersalivation, Cyanosis, Trismus, Neurologic dysfunction, Altered mental status, Ptosis, Generalized weakness, Muscle fasciculations, Cardiovascular collapse, Hypotension, and Tachycardia.
  9. If the snake is positively identified, antivenin should be considered in cases of envenomation after consultation with poison control and/or Houston Zoo herpetologist/toxicologist.
  10. Antivenin- Coralmyn.

Coral Snake Antivenin Administration

  1. The only FDA approved coral snake antivenin, Wyeth Micrurus, is no longer being produced and limited stock piles are now expired.
  2. Alternative is antivenin called Coralmyn. It is manufactured in Mexico and is available in the US, however, not approved by the FDA. If needed, it must be obtained from the Houston Zoo with approval from their herpetologist and/or toxicologist. Special consent must be signed if this is used.
  3. Pretreat with diphenhydramine and H2 blocker.
  4. Assure that airway devices, epinephrine, steroids, and other medications and equipment necessary to treat anaphylaxis are at the bedside.
  5. To administer antivenin reconstitute the antivenin as directed on the package and follow instructions.
  6. Begin a slow infusion while observing the patient for symptoms. If no reaction occurs after a few minutes of slow infusion, then the infusion rate may be increased so that the entire initial dose is administered over 1-2 hours.

Coral Snake Disposition

  1. Asymptomatic patients should be observed for 24 hours. Symptoms may be delayed in onset for up to 12 hours or more. Given the potentially lethal nature of coral snake venom, these patients should be admitted for monitoring.
  2. All patients with a good history for envenomation by a coral snake should be admitted to the IMU or ICU (per discretion of ED Attending and Hospitalist) for at least 24 hours of monitoring. Exceptions to this rule include patients who sustained bite many hours prior to arrival and can be efficiently monitored in the ED to complete their 24-hour period.

Exotic Snake Management

Different species of snake and members of the same species from different environments have different qualities of venom. Toxins: Neurotoxin, Cardiotoxin, Nephrotoxin, Coagulotoxins, Myotoxins/Necrotoxins.

  1. Attend to the ABC’s
  2. Be prepared to support ventilation should respiratory distress occur.
  3. Obtain the following labs: CBC, BMP, PT/PTT, INR, TEG, D dimer, fibrinogen
  4. Contact the herpetologist to determine if offending snake is found in the Houston Zoo’s collection. If so, they will have antivenin available.
  5. Contact the poison control center for management advice. They can help to obtain antivenin, if the snake is not found in the Houston Zoo collection. Some types of antivenin are difficult to obtain and must come from other states.
  6. If the victim has a personal supply of antivenin for the type of snake involved, it can be used if:
    1. Is not visibly turbid
    2. It is not expired or is five or fewer years beyond its expiration date

Exotic Snake Disposition

All patients bitten by non-native venomous snakes should be admitted to the appropriate hospitalist for further monitoring.

Live or Dead Snake disposal (if brought to ED by patient, family, or EMS)

Notify ED charge nurse of need for snake disposal. Snake will be placed in a bucket pending safe disposal.

Appendix

Figure 1: US poisonous snake/pit viper identification

US poisonous snake/pit viper identification

Figure 2: Algorithm for Poisonous Snake Bite Management and Disposition

Algorithm for Poisonous Snake Bite Management and Disposition