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Heloderma suspectum
General Details, Taxonomy and Biology, Toxins, Clinical Effects, Treatment, First Aid , Antivenoms
Heloderma suspectum ( Gila Monster )  [ Original photo copyright © Dr Julian White ]
Family: Helodermatidae
Genus: Heloderma
Species: suspectum
Subspecies: suspectum , cinctum
Common Names
Gila Monster , Reticulate Gila Monster ( H. s. suspectum ) , Banded Gila Monster ( H. s. cinctum )
Local Names
North America + Central America
Mexico, United States of America
Taxonomy and Biology
Adult Length: 0.35 m
Physique : Large ( but smaller than H. horridum ), stout, robust lizard that usually reaches a maximum adult size of about 0.35 metres although rare specimens have exceeded 0.5 metres in length. The tail may measure up to half the body length. Head is large with a blunt, rounded snout and bulging lower lips ( heavy mandibular muscles ). Eyes are relatively small, protuberant and covered by moveable eyelids. The tongue is thick and bifid distally. Tail is usually thick when the food source is plentiful, but may be very slender in emaciated specimens. The 4th toe barely exceeds the length of the 3rd and all digits have long, strong, sharp recurved claws.

Head Scales : Usually 2 postrostrals ( sometimes 3 ), 2 internasals ( sometimes 3 ), 3 canthals ( rarely 1, 2, or 4 ), 3 superciliaries ( sometimes 4, rarely 5 ), usually 6 to 8 dorsals between posterior superciliaries, usually 12 or 13 ( 11 to 15 ) scales between internasals and occiput, 2 to 4 loreals ( rarely 5 ), 4 to 9 lorilabials, 2 preoculars ( sometimes 1, rarely 3 ), usually 12 supralabials ( 10 to 14 ), usually 14 infralabials ( 12 to 16 ), 3 ( sometimes 4 ) pairs of chinshields along the mental groove.

Body Scales : Scales are non imbricate. Dorsal scales on the head, body and tail, gular region and legs are rounded and convex. The venter is covered with rows of somewhat rectangular shaped scales. Head dorsum scales, vertebral and lateral body scales and scales on the legs and preanal region are underlain with small bony osteoderms ( beads ). There are 56 to 62 scales around midbody, 62 to 72 scales between gular fold and vent, 48 to 59 scales between axilla and groin, 26 to 31 scales around proximal portion of tail, 48 to 62 scales from vent to tail tip and usually 11 ( 18 to 14 ) subdigital lamellae on 4th toe.
Mainly found in rocky foothill locations in desert and mesquite grassland terrain, but also inhabits tropical deciduous forest, thorn forest and pine-oak forest. Tends to avoid open flat regions.
Most active during the cooler periods of the day, late afternoons, dusk, at night or early mornings or anytime on cooler or overcast days. Usually slow moving, diurnal ( mainly nocturnal in hottest months ), and inoffensive disposition if left alone. Although terrestrial, it often climbs into trees during the rainy season and usually takes shelter wherever available to escape the heat during the day. Forages for food at ground level ( strong digger ), in trees and seldom ventures too far from its underground burrow.
Feeds on a wide variety of smaller animals , particularly nestling rodents, lizards and bird and reptile eggs.
Species Map
Small (Approx 20k) version
Average Quantity
17 mg ( dry weight ), Russell and Bogert (1981) ( Ref : R000961 ).
General: Neurotoxins
Present but not clinically significant
General: Myotoxins
Not present
General: Procoagulants
Not present
General: Anticoagulants
Not present
General: Haemorrhagins
Not present
General: Nephrotoxins
Not present
General: Cardiotoxins
Not present
General: Necrotoxins
Not present
General: Other Toxins
Kallikrein-like hypotensive toxin, hypothermia-inducing toxin
Clinical Effects
General: Dangerousness
Moderate envenoming possible but unlikely to prove lethal
General: Rate of Envenoming: 60-80%
General: Untreated Lethality Rate: Unlikely to prove lethal
General: Local Effects
Local pain & swelling
General: Local Necrosis
Does not occur, based on current clinical evidence
General: General Systemic Effects
General systemic effects include vomiting, diarrhoea, "weakness', dizziness, hypotension, rarely shock.
General: Myotoxicity
Does not occur, based on current clinical evidence
General: Coagulopathy & Haemorrhages
Rare, then usually minor coagulopathy only
General: Renal Damage
Rare, usually secondary effect
General: Cardiotoxicity
Rare, usually secondary
General: Other
Shock secondary to fluid shifts due to local tissue injury is possible in severe cases
First Aid
Description: First aid for Helodermatidae Lizard Bites (Gila monster, beaded lizard)
1. Gila monsters frequently hang on when they bite. They should be immediately removed using one of the following methods:
a). A strong stick, bar, pliers, screwdriver or crowbar may be put into the mouth behind the bitten part to open the jaws.
b). The use of a flame under the lizard's jaw, being careful not to burn the bite victim.
c). Submerge the lizard in cold water, which also serves to subdue the reptile (found to be effective by many herpetologists).
d). Another useful tool is a handheld cast spreader used to manually disengage the mandible in the unlikely event that a patient arrives in the emergency department with the lizard attached.
Caution: Pulling the animal away usually results in breaking of the teeth and laceration of the wound.
2. After ensuring the patient and onlookers have moved out of range of further bites by the lizard, the bitten person should be reassured and persuaded to lie down and remain still. Many will be terrified, fearing sudden death and, in this mood, they may behave irrationally or even hysterically. The basis for reassurance is the fact that gila monster bites do not result in lethal envenoming, though they frequently cause intense pain, and recovery is to be expected.
3. Allow the wound to bleed freely for several minutes, if possible assisted by irrigation with clean fresh water.
4. Except for the above, bite wound should not be tampered with in any way. Wiping it once with a damp cloth to remove surface venom is unlikely to do much harm (or good) but the wound must not be massaged.
5. All rings or other jewellery on the bitten limb, especially on fingers, should be removed, as they may act as tourniquets if oedema develops.
6. The bitten limb should be immobilised as effectively as possible using an extemporised splint or sling; if available, crepe bandaging of the splinted limb is an effective form of immobilisation.
7. If there is any impairment of vital functions, such as problems with respiration, airway, circulation, heart function, these must be supported as a priority. In particular, both airway and respiration may be impaired, requiring urgent and prolonged treatment, which may include the mouth to mask (mouth to mouth) technique of expired air transfer. Seek urgent medical attention.
8. Do not use Tourniquets, cut, suck or scarify the wound or apply chemicals or electric shock.
9. Avoid peroral intake except for clear fluids, absolutely no alcohol. No sedatives outside hospital. If there will be considerable delay before reaching medical aid, measured in several hours to days, then give clear fluids by mouth to prevent dehydration.
10. If the offending lizard has been killed it should be brought with the patient for identification.
11. The bite victim should be transported as quickly and as passively as possible to the nearest place where they can be seen by a medically-trained person (health station, dispensary, clinic or hospital). The bitten limb must not be exercised as muscular contraction will promote systemic absorption of venom. If no motor vehicle or boat is available, the patient can be carried on a stretcher or hurdle, on the pillion or crossbar of a bicycle or on someone's back.
12. Most traditional, and many of the more recently fashionable, first aid measures are useless and potentially dangerous. These include local cauterization, incision, excision, amputation, suction by mouth, vacuum pump or syringe, combined incision and suction ("venom-ex" apparatus), injection or instillation of compounds such as potassium permanganate, phenol (carbolic soap) and trypsin, application of electric shocks or ice (cryotherapy), use of traditional herbal, folk and other remedies including the ingestion of emetic plant products and parts of the snake, multiple incisions, tattooing and so on.
Treatment Summary
There is no specific treatment available. Treartment is therefore symptomatic, directed towards pain management, local wound care, control of secondary infection, if present.
Key Diagnostic Features
Local pain, swelling, vomiting, hypotension.
General Approach to Management
All cases should be assessed and observed for at least 6 hrs or longer if symptomatic. The first challenge may occasionally be removal of the lizard. This may require mechanical opening of the jaws, but try cold water immersion first. The use of local flame, often recommended, is potentially dangerous and should be avoided. Blood pressure should be monitored, because occasionally severe hypotension can occur. Similarly, there should be ECG monitoring. There is no clear therapy for persistent vomiting, beyond standard antiemetics.
Antivenom Therapy
No antivenom available
No Antivenoms
Heloderma suspectum ( Gila Monster ) [ Original photo copyright © Dr Julian White ]
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