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GILA MONSTER (HELODERMA SUSPECTUM)

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Classification   |    Detailed evidence-based information

Substances Included Synonyms

Therapeutic Toxic Class

    A) The Gila Monster is one of only two species of venomous lizards; both are of the family Helodermatidae and both are similar in appearance and habits. Its venomous cousin, the Mexican Beaded Lizard (Heloderma horridum), is slightly larger and darker.

Specific Substances

    1) Gila monsters
    2) Helodermatids
    3) Heloderma suspectum
    4) H. cinctum
    5) H. horridum
    6) HEE-LA MONSTER (PHONETIC PRONUNCIATION)
    7) HELODERMA SUSPECTUM (GILA MONSTER)
    8) HILA MONSTER (MISSPELLING OF GILA MONSTER)

Overview

Life Support

    A) This overview assumes that basic life support measures have been instituted.

Clinical Effects

    0.2.1) SUMMARY OF EXPOSURE
    A) DESCRIPTION: Helodermatids are venomous lizards that live in arid climates. Heloderma suspectum suspectum and Heloderma suspectum cinctum are found in the southwestern US, including Utah, Arizona, New Mexico, Nevada and small areas of southern California and south into Sonora. Heloderma horridum is found from Mexico south to Guatemala and is larger and darker than the US species. These lizards are corpulent, slow-moving, largely nocturnal, and the skin is covered with bead-like scales. Venom glads are in the lower jaw, but they lack musculature to inject venom. The venom is used defensively and introduced by chewing.
    B) EPIDEMIOLOGY: Bites are rare and deaths have not been reported.
    C) TOXICOLOGY: Heloderma venom contains serotonin, amine oxidase, phospholipase, hyaluronidase, protease, salivary kallikrein, and arginine ethyl ester hydrolase, but seems to lack acetylcholinesterase, nucleotidase, amino acid oxidase, and fibrinogenocoagulase activity. The lethal activity is thought to be associated with the proteolytic activity. Venom also contains a neurotoxin (gilatoxin), a toxin that causes inhibition of contractile response to direct stimulation of the isolated mouse hemidiaphragm, and heliothermine, a toxin which depresses body temperature in injected mice.
    D) WITH POISONING/EXPOSURE
    1) MILD TOXICITY: The vast majority of cases will have only local effects.
    2) LOCAL EFFECTS: The bite is usually forceful and tenacious. The small puncture wounds caused by the teeth may number from several to 15, and in some cases the teeth may be difficult to find and remove. Pain is usually present when venom is injected, and is described as burning or intense, reaching its peak in the wound area between 15 to 45 minutes. Some pain may persist for 8 to 24 hours. Edema occurs in most cases. It may be delayed in onset, but has not caused compartment syndrome. The area around the wound is generally quite tender, and both lymphangitis, and lymphadenitis may be present. Local tenderness at the site may last 3 to 4 weeks. The area around the puncture wounds may appear bluish or erythematous and there may be superficial hemorrhage or ecchymosis, but necrosis is rare. Paresthesias may be present at the bite site.
    3) MODERATE TO SEVERE TOXICITY: SYSTEMIC EFFECTS: Weakness, faintness, anxiety, dizziness, and seating are common early manifestations. Systemic manifestations include nausea, vomiting, tinnitus, diaphoresis, muscle fasciculations, headache, tachycardia, and hypotension in more severe envenomations. Transient conduction defects and nonspecific T-wave changes have been described. Myocardial infarction has been reported on rare occasions Anaphylactoid reactions have also been reported.
    0.2.5) CARDIOVASCULAR
    A) Tachycardia is common and hypotension may develop in severe cases. ECG changes and myocardial infarction are rare.

Laboratory Monitoring

    A) Patients without evidence of systemic effects do not require routine lab evaluation.
    B) Patients with systemic effects may require complete blood counts including platelets, coagulation profile (INR or PT, PTT, fibrinogen), serum electrolytes, and ECG in severe envenomations.
    C) Obtain radiographs of the bite site to evaluate for retained teeth or other foreign bodies. Gila monster teeth may not be detected on plain radiographs. Ultrasound may be useful in identifying teeth, but this has not been studied.

Treatment Overview

    0.4.7) BITES/STINGS
    A) MANAGEMENT OF MILD TO MODERATE TOXICITY
    1) WOUND CARE: Do not incise the fang marks or traumatize the wound area. Anesthetize the wound and explore to locate any broken teeth. Cleansing and irrigation of the wound should be performed upon presentation. Wounds should be covered with a sterile dressing. It is important to keep the injured part out of the completely dependent position for at least one week, but the part should be exercised during this period. TETANUS: Tetanus immune status should be updated, if not current. ANTIBIOTICS: There are no studies evaluating the usefulness of prophylactic antibiotics but they are recommended by some authors. Antibiotics should be instituted if evidence of wound infection or cellulitis develops. ANALGESICS: Give analgesics for pain control.
    B) MANAGEMENT OF SEVERE TOXICITY
    1) HYPOTENSION: Infuse 10 to 20 mL/kg isotonic fluids. If hypotension persists, administer dopamine or norepinephrine. Titrate to dose response.
    C) DECONTAMINATION
    1) PREHOSPITAL: The lizard should be disengaged as quickly as possible without breaking teeth off in the wound. This can be done by prying open the jaws with a strong stick, pliers, a screwdriver, or crowbar.
    2) HOSPITAL: Anesthetize, cleanse and irrigate the wound upon admission. A handheld cast spreader may be used to disengage the jaw, if the patient arrives with the reptile attached.
    D) AIRWAY MANAGEMENT
    1) Endotracheal intubation should be performed in patients with significant respiratory distress.
    E) ALLERGIC REACTION
    1) MILD TO MODERATE: Antihistamines with or without inhaled beta agonists, corticosteroids or epinephrine.
    2) SEVERE: Aggressive airway management, oxygen, epinephrine, antihistamines, corticosteroids, ECG monitoring and IV fluids.
    F) BRONCHOSPASM
    1) Administer inhaled beta adrenergic agonists, if bronchospasm develops.
    G) THROMBOCYTOPENIC DISORDER
    1) In the rare case in which platelets have fallen below 100,000, a return to normal usually occurs within 3 days, even without treatment, and clinically significant bleeding is rarely an issue.
    H) PATIENT DISPOSITION
    1) OBSERVATION CRITERIA: Patients should be observed in a medical facility for evidence of systemic effects for a minimum of 6 hours.
    2) ADMISSION CRITERIA: Patients with persistent evidence of systemic effects should be admitted.
    3) CONSULT CRITERIA: Consult a medical toxicologist for assistance for patients with systemic manifestations or any needed help with medical management.

Range Of Toxicity

    A) TOXICITY: The lethal dose of Heloderma venom in an adult has been estimated at 5 to 8 mg, the average yield of venom obtained by milking is 17 mg. Because the lizards do not have an efficient way of delivering venom, it is unlikely that a bite could deliver a lethal dose of venom except in a young child.

Clinical Effects

Summary Of Exposure

    A) DESCRIPTION: Helodermatids are venomous lizards that live in arid climates. Heloderma suspectum suspectum and Heloderma suspectum cinctum are found in the southwestern US, including Utah, Arizona, New Mexico, Nevada and small areas of southern California and south into Sonora. Heloderma horridum is found from Mexico south to Guatemala and is larger and darker than the US species. These lizards are corpulent, slow-moving, largely nocturnal, and the skin is covered with bead-like scales. Venom glads are in the lower jaw, but they lack musculature to inject venom. The venom is used defensively and introduced by chewing.
    B) EPIDEMIOLOGY: Bites are rare and deaths have not been reported.
    C) TOXICOLOGY: Heloderma venom contains serotonin, amine oxidase, phospholipase, hyaluronidase, protease, salivary kallikrein, and arginine ethyl ester hydrolase, but seems to lack acetylcholinesterase, nucleotidase, amino acid oxidase, and fibrinogenocoagulase activity. The lethal activity is thought to be associated with the proteolytic activity. Venom also contains a neurotoxin (gilatoxin), a toxin that causes inhibition of contractile response to direct stimulation of the isolated mouse hemidiaphragm, and heliothermine, a toxin which depresses body temperature in injected mice.
    D) WITH POISONING/EXPOSURE
    1) MILD TOXICITY: The vast majority of cases will have only local effects.
    2) LOCAL EFFECTS: The bite is usually forceful and tenacious. The small puncture wounds caused by the teeth may number from several to 15, and in some cases the teeth may be difficult to find and remove. Pain is usually present when venom is injected, and is described as burning or intense, reaching its peak in the wound area between 15 to 45 minutes. Some pain may persist for 8 to 24 hours. Edema occurs in most cases. It may be delayed in onset, but has not caused compartment syndrome. The area around the wound is generally quite tender, and both lymphangitis, and lymphadenitis may be present. Local tenderness at the site may last 3 to 4 weeks. The area around the puncture wounds may appear bluish or erythematous and there may be superficial hemorrhage or ecchymosis, but necrosis is rare. Paresthesias may be present at the bite site.
    3) MODERATE TO SEVERE TOXICITY: SYSTEMIC EFFECTS: Weakness, faintness, anxiety, dizziness, and seating are common early manifestations. Systemic manifestations include nausea, vomiting, tinnitus, diaphoresis, muscle fasciculations, headache, tachycardia, and hypotension in more severe envenomations. Transient conduction defects and nonspecific T-wave changes have been described. Myocardial infarction has been reported on rare occasions Anaphylactoid reactions have also been reported.

Cardiovascular

    3.5.1) SUMMARY
    A) Tachycardia is common and hypotension may develop in severe cases. ECG changes and myocardial infarction are rare.
    3.5.2) CLINICAL EFFECTS
    A) HYPOTENSIVE EPISODE
    1) WITH POISONING/EXPOSURE
    a) Hypotension may occur with severe envenomation (Hooker & Caravati, 1994).
    b) INCIDENCE: In a series of 4 patients with Gila monster bites, 3 developed hypotension (Hooker & Caravati, 1994). One of these was also intoxicated with ethanol and opiates (Hooker & Caravati, 1994).
    1) Of 13 patients with Gila monster bites reported in US literature, 62% developed hypotension (Hooker & Caravati, 1994).
    c) CASE REPORT: Severe hypotension was reported in a young adult (Bou-Abboud & Kardassakis, 1988; Preston, 1989).
    B) TACHYARRHYTHMIA
    1) WITH POISONING/EXPOSURE
    a) Tachycardia is common (Hooker & Caravati, 1994).
    b) INCIDENCE: Of 13 patients with Gila monster bites reported in US literature, 62% developed tachycardia (Hooker & Caravati, 1994).
    C) ELECTROCARDIOGRAM ABNORMAL
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: Transient conduction defects and nonspecific T-wave changes were described in an otherwise healthy 20 year old man (Roller, 1977).
    D) MYOCARDIAL INFARCTION
    1) WITH POISONING/EXPOSURE
    a) Myocardial infarction has been reported in one patient (Bou-Abboud & Kardassakis, 1988).
    b) CASE REPORT: A 23-year-old healthy man had ECG evidence of an acute anterolateral infarct following a bite by a banded Gila monster. The patient denied chest discomfort or shortness of breath. Creatinine kinase was 4,697 International Unites with a positive MB band (Bou-Abboud & Kardassakis, 1988). The same case was reported by Preston (Preston, 1989).

Respiratory

    3.6.2) CLINICAL EFFECTS
    A) HYPERVENTILATION
    1) WITH POISONING/EXPOSURE
    a) An increase in respiratory rate may be observed.
    b) INCIDENCE: In a series of 4 patients with Gila monster bites, one patient presented with a respiratory rate of 26 (Hooker & Caravati, 1994).

Neurologic

    3.7.2) CLINICAL EFFECTS
    A) FATIGUE
    1) WITH POISONING/EXPOSURE
    a) Weakness and dizziness are common and may be related to hypotension or pain. Most victims have weakness within 15 to 30 minutes which may persist for several days.
    b) INCIDENCE: Of 13 patients with Gila monster bites reported in US literature, 64% developed weakness (Hooker & Caravati, 1994).
    c) CASE REPORT: A 40-year-old man developed dizziness, vomiting, diaphoresis, lethargy, and severe local pain with marked swelling of his hand, lips, and tongue following a bite on his hand by a captive Mexican beaded lizard. Although cyanosis was not noted, his oxygen saturation decreased to 55%. Following supportive care, he was discharged the next day (Cantrell, 2003).
    B) PARESTHESIA
    1) WITH POISONING/EXPOSURE
    a) Paresthesias may develop at the bite site (Hooker & Caravati, 1994).
    C) ANXIETY
    1) WITH POISONING/EXPOSURE
    a) Anxiety may occur in some patients (Cantrell, 2003).

Gastrointestinal

    3.8.2) CLINICAL EFFECTS
    A) NAUSEA AND VOMITING
    1) WITH POISONING/EXPOSURE
    a) INCIDENCE: Of 13 patients with Gila monster bites reported in US literature, 69% developed nausea and/or vomiting (Hooker & Caravati, 1994).
    b) CASE REPORT: A 44-year-old man developed vomiting, diaphoresis, and dizziness within 15 minutes following a bite on his right ring finger from a small Gila monster (Caravati et al, 1999).
    c) CASE REPORT: A 37-year-old herpetologist developed immediate localized swelling of the hand and stinging pain at the bite site followed by throbbing pain radiating throughout the fingers within 2 to 3 minutes of been bitten by a Gila monster. About 15 minutes later the patient complained of nausea, diaphoresis and dizziness. However, at the time of admission (about an hour later), systemic effects had subsided with normal vital signs and laboratory studies. The patient was admitted for pain control and wound care and discharged the following day with decreased pain (Strimple et al, 1997).
    d) CASE REPORT: A 40-year-old man developed dizziness, vomiting, diaphoresis, lethargy, and severe local pain with marked swelling of his hand, lips, and tongue following a bite on his hand by a captive Mexican beaded lizard. Although cyanosis was not noted, his oxygen saturation decreased to 55%. Following supportive care, he was discharged the next day (Cantrell, 2003).

Genitourinary

    3.10.2) CLINICAL EFFECTS
    A) ACUTE RENAL FAILURE SYNDROME
    1) WITH POISONING/EXPOSURE
    a) Acute renal failure resulted from a Gila monster bite secondary to severe hypotension (Bou-Abboud & Kardassakis, 1988).

Hematologic

    3.13.2) CLINICAL EFFECTS
    A) THROMBOCYTOPENIC DISORDER
    1) WITH POISONING/EXPOSURE
    a) There is rarely evidence of coagulation defects. Slight thrombocytopenia is rarely reported in serious bites.
    b) CASE REPORT: Coagulopathy, with elevated PT and PTT and platelet count of 62,000 was reported in one case (Bou-Abboud & Kardassakis, 1988; Preston, 1989).
    B) LEUKOCYTOSIS
    1) WITH POISONING/EXPOSURE
    a) INCIDENCE: Of 13 patients with Gila monster bites reported in US literature, 62% developed leukocytosis (Hooker & Caravati, 1994).
    b) CASE REPORT: A 40-year-old man developed dizziness, vomiting, diaphoresis, lethargy, and severe local pain with marked swelling of his hand, lips, and tongue following a bite on his hand by a captive Mexican beaded lizard. Although cyanosis was not noted, his oxygen saturation decreased to 55%. Laboratory tests revealed WBC of 18,500 k/mm(3) with 80% segmented polymorphonuclear leukocytes. Following supportive care, he was discharged the next day (Cantrell, 2003).

Dermatologic

    3.14.2) CLINICAL EFFECTS
    A) BITE - WOUND
    1) WITH POISONING/EXPOSURE
    a) The bite has been described as forceful and tenacious; while some may only nip, some Gila monsters may hold on for 10 to 15 minutes. A bite does not always result in envenomation. The wounds may be simple punctures, lacerations or may include macerated areas with some crushing, varying from 1 to 15 in number. Teeth may be broken off and imbedded under the skin.
    B) PAIN
    1) WITH POISONING/EXPOSURE
    a) ONSET: With envenomation pain is a consistent symptom, present within 30 seconds to 5 minutes. Pain is usually intense and may spread to involve the entire extremity within 10 minutes. Radiating pain up the arm or leg may be described.
    b) DURATION: In minor bites, pain peaks in 15 to 45 minutes and then subsides. In major bites pain may last 3 to 5 hours and recede slowly. Shooting pain or dull pain in the extremity may persist up to 8 hours. Local tenderness at the site may last 3 to 4 weeks.
    c) INCIDENCE: Of 13 patients with Gila monster bites reported in US literature, 82% developed pain (Hooker & Caravati, 1994).
    d) CASE REPORT: A 37-year-old herpetologist developed immediate localized swelling of the hand and stinging pain at the bite site followed by throbbing pain radiating throughout the fingers within 2 to 3 minutes of been bitten by a Gila monster. About 15 minutes later the patient complained of nausea, diaphoresis and dizziness, and within 40 minutes of the bite swelling had progressed to include the entire dorsum of the hand. Pain persisted and became severe requiring repeated doses of IV morphine. Symptoms improved the following day and the patient was discharged with acetaminophen/hydrocodone and a one week course of prophylactic oral cephalexin (Strimple et al, 1997).
    e) CASE REPORT: A 40-year-old man developed dizziness, vomiting, diaphoresis, lethargy, and severe local pain with marked swelling of his hand, lips, and tongue following a bite on his hand by a captive Mexican beaded lizard. Although cyanosis was not noted, his oxygen saturation decreased to 55%. Following supportive care, he was discharged the next day (Cantrell, 2003).
    C) EDEMA
    1) WITH POISONING/EXPOSURE
    a) PRESENTING SIGN: Edema is an important presenting sign, beginning within 15 minutes and slowly progressing over 4 to 8 hours. Edema and erythema may spread to involve most of the affected limb (Strimple et al, 1997; Cantrell, 2003; Hooker & Caravati, 1994).
    b) INCIDENCE: Of 13 patients with Gila monster bites reported in US literature, 77% developed edema (Hooker & Caravati, 1994).
    D) EXCESSIVE SWEATING
    1) WITH POISONING/EXPOSURE
    a) Increased diaphoresis is common, appearing within 30 minutes and lasting several hours (Strimple et al, 1997; Cantrell, 2003; Hooker & Caravati, 1994).
    b) INCIDENCE: Of 13 patients with Gila monster bites reported in US literature, 46% developed diaphoresis (Hooker & Caravati, 1994).
    c) CASE REPORT: A 40-year-old man developed dizziness, vomiting, diaphoresis, lethargy, and severe local pain with marked swelling of his hand, lips, and tongue following a bite on his hand by a captive Mexican beaded lizard. Although cyanosis was not noted, his oxygen saturation decreased to 55%. Following supportive care, he was discharged the next day (Cantrell, 2003).
    E) PURPURA
    1) WITH POISONING/EXPOSURE
    a) Some bluish discoloration or ecchymosis may be present, usually without tissue breakdown or necrosis.
    F) MUSCLE PAIN
    1) WITH POISONING/EXPOSURE
    a) Generalized myalgias have been reported (Hooker & Caravati, 1994).

Musculoskeletal

    3.15.2) CLINICAL EFFECTS
    A) LYMPHADENOPATHY
    1) WITH POISONING/EXPOSURE
    a) Axillary lymphadenopathy may be common in severe envenomations of the upper extremity, especially when extensive edema is present.
    b) INCIDENCE: Of 13 patients with Gila monster bites reported in US literature, 23% developed lymphangitis (Hooker & Caravati, 1994).

Immunologic

    3.19.2) CLINICAL EFFECTS
    A) ANAPHYLACTOID REACTION
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: A 40-year-old man developed dizziness, vomiting, diaphoresis, lethargy, and severe local pain with marked swelling of his hand, lips, and tongue following a bite on his hand by a captive Mexican beaded lizard. Although cyanosis was not noted, his oxygen saturation decreased to 55%. Following supportive care, he was discharged the next day (Cantrell, 2003).
    b) CASE REPORT: Facial and tongue edema and hypotension have been reported after a bite to the left forearm (Piacentine et al, 1986).
    c) CASE REPORT: Severe anaphylaxis occurred, including facial and tongue edema, hypotension, and inspiratory and expiratory stridor, in a 44-year-old man following a bite on his right ring finger by a small Gila monster. The patient recovered following treatment with steroids, epinephrine, and diphenhydramine (Caravati et al, 1999).
    1) Twenty years earlier, the patient had been given antivenom following a rattlesnake bite. The authors speculate that prior exposure to rattlesnake venom may have increased the patient's risk for development of an acute hypersensitivity reaction due to the antigenic similarities of the venoms.

Laboratory Monitoring

Monitoring Parameters Levels

    4.1.1) SUMMARY
    A) Patients without evidence of systemic effects do not require routine lab evaluation.
    B) Patients with systemic effects may require complete blood counts including platelets, coagulation profile (INR or PT, PTT, fibrinogen), serum electrolytes, and ECG in severe envenomations.
    C) Obtain radiographs of the bite site to evaluate for retained teeth or other foreign bodies. Gila monster teeth may not be detected on plain radiographs. Ultrasound may be useful in identifying teeth, but this has not been studied.
    4.1.2) SERUM/BLOOD
    A) BLOOD/SERUM CHEMISTRY
    1) Patients without evidence of systemic effects do not require routine lab evaluation.
    2) Serum electrolytes, renal function tests and creatine kinase levels may be useful.
    B) HEMATOLOGIC
    1) Obtain complete blood count including platelets in sever envenomations.
    C) COAGULATION STUDIES
    1) Coagulation profile (INR or PT, PTT, fibrinogen) in severe envenomations.
    4.1.3) URINE
    A) URINALYSIS
    1) Monitor urine output and urinalysis.
    4.1.4) OTHER
    A) OTHER
    1) ECG
    a) Obtain ECG in severe envenomations.

Radiographic Studies

    A) OTHER
    1) Obtain radiographs of the bite site to evaluate for retained teeth or other foreign bodies. Retained teeth may not always be visible on x-ray (Hooker & Caravati, 1994).

Treatment

Life Support

    A) Support respiratory and cardiovascular function.

Patient Disposition

    6.3.6) DISPOSITION/BITE-STING EXPOSURE
    6.3.6.1) ADMISSION CRITERIA/BITE-STING
    A) Patients with persistent evidence of systemic effects should be admitted.
    6.3.6.3) CONSULT CRITERIA/BITE-STING
    A) Consult a medical toxicologist for assistance for patients with systemic manifestations or any needed help with medical management.
    6.3.6.5) OBSERVATION CRITERIA/BITE-STING
    A) All patients should be observed for evidence of systemic effects in a health care setting for a minimum of 6 hours (Hooker & Caravati, 1994).

Monitoring

    A) Patients without evidence of systemic effects do not require routine lab evaluation.
    B) Patients with systemic effects may require complete blood counts including platelets, coagulation profile (INR or PT, PTT, fibrinogen), serum electrolytes, and ECG in severe envenomations.
    C) Obtain radiographs of the bite site to evaluate for retained teeth or other foreign bodies. Gila monster teeth may not be detected on plain radiographs. Ultrasound may be useful in identifying teeth, but this has not been studied.

Oral Exposure

    6.5.1) PREVENTION OF ABSORPTION/PREHOSPITAL
    A) LIZARD DISENGAGEMENT
    1) The lizard should be disengaged as quickly as possible without breaking teeth off in the wound. This can often be done by prying open the jaws with a strong stick, pliers, a screwdriver, or crowbar. Immersion in cold water has also been recommended to subdue the reptile (Strimple et al, 1997; Miller, 1995).
    2) A match under the lower jaw will sometimes disengage the lizard, but is generally not recommended (Strimple et al, 1997).
    B) FIRST AID
    1) The patient should be placed at rest, given reassurance, and the injured part lightly immobilized. All constriction bands should be removed, nothing given by mouth, and the patient transported to a medical facility as quickly as possible.

Abstracts

Case Reports

    A) ADULT
    1) ACUTE EFFECTS
    a) A 29-year-old woman with history of chronic alcohol abuse, recent alcohol abuse, and a seizure disorder presumably resulting from alcoholism was bitten on the abdomen by her pet Gila monster. The lizard was dislodged by slashing the neck with a knife. On arrival to the emergency department she complaining of difficulty in breathing and speaking of pain in the area of the bite. She was diaphoretic with an ashen skin color. She developed frequent and profuse vomiting and diarrhea. She was treated with symptomatic and supportive care and was discharged approximately 48 hours after admission (Heitschel, 1986).
    2) A 40-year-old man developed dizziness, vomiting, diaphoresis, lethargy, and severe local pain with marked swelling of his hand, lips, and tongue following a bite on his hand by a captive Mexican beaded lizard. Although cyanosis was not noted, his oxygen saturation decreased to 55%. Following supportive care, he was discharged the next day (Cantrell, 2003).

Range Of Toxicity

Summary

    A) TOXICITY: The lethal dose of Heloderma venom in an adult has been estimated at 5 to 8 mg, the average yield of venom obtained by milking is 17 mg. Because the lizards do not have an efficient way of delivering venom, it is unlikely that a bite could deliver a lethal dose of venom except in a young child.

Minimum Lethal Exposure

    A) ACUTE
    1) The lethal dose of Heloderma venom for man has been estimated at 5 to 8 mg, but this is probably a low figure (Russell & Bogert, 1981). The average yield of venom obtained by milking is 17 mg.

Toxicity Information

    7.7.1) TOXICITY VALUES

Pharmacology Toxicology

Toxicologic Mechanism

    A) VENOM
    1) An adult helodermatid has about 15 to 20 mg dried weight of venom, and its intravenous LD50 in mice is approximately 0.5 to 1.0 mg/kg, as compared with 2.18 for that of the western diamondback rattlesnake. It is unlikely that a fatal dose of venom could be delivered, except perhaps to an infant or child. The venom contains serotonin, amine oxidase, phospholipase, hyaluronidase, protease, salivary kallikrein, and arginine ethyl ester hydrolase, but appears to lack acetylcholinesterase, nucleotidase, amino acid oxidase, and fibrinogenocoagulase activities. The lethal activity is thought to be associated with the proteolytic activity. It appears that the physiopharmacology is very similar to that of rattlesnake venom poisoning (Russell, 1983).
    B) Heloderma horidum horidum venom is know to contain (Mochca-Morales et al, 1990):
    1) Hyaluronidase
    2) Arginine hydrolase, kallikrein-like enzymes
    3) Phospholipase
    4) A pancreatic secretory protein with phospholipase activity
    5) A neurotoxin (gilatoxin) which is an acidic protein
    6) A toxin that causes inhibition of contractile response to direct stimulation of the isolated mouse hemi-diaphram
    7) Helothermine, a toxin which depresses body temperature in injected mice

References

General Bibliography

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    9) Miller MF: Gila monster envenomation (letter). Ann Emerg Med 1995; 25:720.
    10) Mochca-Morales J, Martin BM, & Possani LD: Isolation and characterization of helothermine, a novel toxin from Heloderma horridum horridum (Mexican beaded lizard) venom. Toxicon 1990; 28:299-309.
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    14) Piacentine J, Curry S, & Ryan PT: Life-threatening anaphylaxis following Gila monster bite. Ann Emerg Med 1986; 15:959-961.
    15) Preston CA: Hypotension, myocardial infarction, and coagulopathy following Gila monster bite. J Emerg Med 1989; 7:37-40.
    16) Product Information: diphenhydramine HCl intravenous injection solution, intramuscular injection solution, diphenhydramine HCl intravenous injection solution, intramuscular injection solution. Hospira, Inc. (per DailyMed), Lake Forest, IL, 2013.
    17) Product Information: dopamine hcl, 5% dextrose IV injection, dopamine hcl, 5% dextrose IV injection. Hospira,Inc, Lake Forest, IL, 2004.
    18) Product Information: norepinephrine bitartrate injection, norepinephrine bitartrate injection. Sicor Pharmaceuticals,Inc, Irvine, CA, 2005.
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