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Treatment of Heloderma bites

Treatment of Heloderma bites

Bites by Heloderma may be increasing because, as captive-breeding techniques have improved, more people are keeping these lizards in private collections (chap. 8). The docile nature of Heloderma kept in captivity often lulls their handlers into a dangerous habit of complacency. The vast majority of bites by helodermatid lizards occur on the fingers or hands.

Most of these pass on uneventfully and go unreported (Miller 1995). Although a Heloderma bite is very unlikely to be lethal to a healthy adult, it should nevertheless be considered a serious medical emergency. A common misconception is that only the dentaries in the lower jaw (and to a lesser extent the maxillaries in the upper jaw) can deliver sufficient venom to cause serious effects. This is not the case; significant symptoms can occur by a seemingly minor "slashing" bite from even the premaxillary teeth toward the front of the mouth (Tinkham 1956; Strimple et al. 1997).

When a person is bitten by a Heloderma, the following first aid measures are recommended:
  1. Remove the lizard as quickly as possible.

    The longer the lizard bites, the more venom it is able to deposit into the wound and the more likely the bite is to produce serious symptoms. In mild bites, where only a fold of skin is bitten, it may be possible to simply hold the lizard behind the jaws and carefully pull it away; in cases where the jaws are more firmly attached, it may be necessary to pour water on the lizard or to pry it off with pliers or some other device. A thin, flat lever inserted between the lower jaw and the flesh and turned 90 degrees may work to quickly release the jaws. When Heloderma are forcefully removed from the bite site, as is often required, teeth are usually pulled out and a laceration results (fig. 13). I do not recommend trying to remove the lizard by applying a flame to its chin or by using dangerous solvents such as gasoline (which have been advocated in the past). These measures only add to the possibility that additional injury and pain will result.
  2. Immediately remove any rings, bracelets, or other jewelry (including piercings). These articles may cause complications as edema (swelling) develops.

  3. The bitten part should be immobilized; a light cloth bandage and mild pressure may be applied to control any bleeding.

  4. The victim should be transported (by another person) to medical care as quickly as possible and reassured that they will not die.

  5. DO NOT apply stun guns, heat, or ice to the wound. DO NOT use tourniquets or constriction bands of any kind nor make incisions to suck out venom.

Once the victim has arrived at the hospital, vital signs should be monitored immediately. One of the biggest dangers is shock/hypotensive crisis brought about by a rapid fall in blood pressure. This can be treated in the victim by infusing electrolyte solutions and administering antishock drugs. Pain normally peaks within 1 to 2 hours, but may linger for days (Caravati and Hartsell 1994). It can be difficult to relieve; analgesics and morphine have been used effectively (Strimple et al. 1997). Edema normally peaks within 2 to 4 hours and resolves itself without special meas-ures within 72 hours. Because it is largely subcutaneous, edema has not been reported to cause compartment syndrome or neurological problems. Depending on the severity of the bite, laboratory blood tests should be performed to assess the possibility of electrolyte imbalance, leukocytosis, and coagulopathy, which have been reported previously (see tables 7 and 8). An electrocardiograph should be used to evaluate any heart anomalies; myocardial conduction disturbance (Roller 1977) and myocardial infarction (Bou-Abboud and Kardassakis 1988) have been observed. Antihistamines or corticosteroids are usually unnecessary because allergic reactions are rare, although one case of anaphylaxis has been reported (Piacentine et al. 1986). The wound should be carefully inspected for any broken teeth and thoroughly cleaned with antiseptic. Softtissue radiography is not sufficient to locate broken teeth (Caravati and Hartsell 1994). Antibiotics are routinely given, although tissue necrosis and infections are very rare. Tetanus immunization should be updated if necessary. Most victims of Heloderma envenomation are released from the hospital within 24 hours and recover completely within 2 weeks. More severe cases may require hospitalization up to 48 hours (e.g., Heitschel 1986).

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