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Lachesis muta
General Details, Taxonomy and Biology, Venom, Clinical Effects, Treatment, First Aid , Antivenoms
Lachesis muta  ( Bushmaster )  [ Original photo copyright © Dr Jurg Meier ]
Family: Viperidae
Subfamily: Crotalinae
Genus: Lachesis
Species: muta
Subspecies: muta , rhombeata
Common Names
Bushmaster , Mapepire Zannana ( L. m. muta )
Local Names
Abaacua , A'tami , Boba, Bosmeester , Cascabelle , Cascabel Pua , Cascabel Puga , Cofasi , Concha Pina , Couanacouche , Cresta del Gallo , Cuaima , Cuaima Concha de Pina , Cuaima Gallo , Cuanira , Culebra Sapa , Culebra Sibucano , Daya , Diamante , Dueno del Monte, Guacama , Guayma , Ipolipo , Juba-vitu , Kapasisneki , Macagua , Macape , Macaurel , Maitre de la Brousse , Makasneki , Makkaslang , Mapana Rayo , Mapanare , Mapanare Verrugosa , Mapepe , Mapepire Galle , Mapepire Z'ananna , Mapepire Zanana , Mapipi , Martiguaja , Matabuey , Mazacuata , Mikaka , Moi-tata , Monairai , Monare , Montuno , Motolo , Nawii , Pararaipu , Pico de Jaca , Pineapple Mapepire , Poritambe , Pucarara , Pudridora , Rieca , Shuchupe , Shushupe , Sungusero, Surucucu , Surucucu de Fogo , Surucucu Pico de Jaca , Surucucutinga , Surucutinga , Taacabe ,Toboa Real , Urukuku , Verrugosa , Verrugosa del Choco , Yamongsse , Yamontse , Yamunga
South America
Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, Trinidad and Tobago, Venezuela
Taxonomy and Biology
Adult Length: 1.60 m
General Shape
Very large in length, ( world's longest viper ) moderately stout bodied snake with a short tail and laterally compressed tail spine. Can grow to a maximum of over 3.60 metres. Head is somewhat broad and elliptical when viewed from above and distinct from neck. Eyes are moderately small with vertically elliptical pupils. Snout is not elevated. Dorsal scales are broad with rounded apices and lack apical pits. Mid dorsals have prominent knob-like keels, the height of these keels decrease laterally with the first 3 to 5 scale rows being smooth. Distal 13 to 18 subcaudals finely divided into 4 or 5 rows of spine-like scales.
Tropical rainforest and lower montane wet forest and may extend into tropical dry forest near rivers and streams.
Terrestrial and diurnal snake.
Feeds mainly on rodents and small mammals.
Species Map
Small (Approx 20k) version
Average Venom Qty
280 to 450 mg ( dry weight ), U.S. Dept. Navy (1968) ( Ref : R000914 ).

L. m. muta : Para, Brazil : 324 mg ( dry weight ) ( range 168 to 552 ), Sanchez et al (1992) ( Ref : R000690 ).
General: Venom Neurotoxins
Probably not present
General: Venom Myotoxins
Possibly present
General: Venom Procoagulants
Mixture of procoagulants
General: Venom Anticoagulants
Possibly present
General: Venom Haemorrhagins
Zinc metalloproteinase
General: Venom Nephrotoxins
Probably not present
General: Venom Cardiotoxins
Probably not present
General: Venom Necrotoxins
Probably not present
General: Venom Other
Not present or not significant
Clinical Effects
General: Dangerousness
Severe envenoming likely, high lethality potential
General: Rate of Envenoming: Unknown but likely to be high
General: Local Effects
Marked local effects; pain, severe swelling, bruising, blistering, necrosis
General: Local Necrosis
Uncommon but can be moderate to severe
General: General Systemic Effects
Variable non-specific effects which may include headache, nausea, vomiting, abdominal pain, diarrhoea, dizziness, collapse or convulsions
General: Neurotoxic Paralysis
Does not occur, based on current clinical evidence
General: Myotoxicity
Does not occur, based on current clinical evidence
General: Coagulopathy & Haemorrhages
Common, moderate to severe coagulopathy + haemorrhagins causing extensive bleeding
General: Renal Damage
Recognised complication, usually secondary to coagulopathy
General: Cardiotoxicity
Does not occur, based on current clinical evidence
General: Other
Shock secondary to fluid shifts due to local tissue injury is likely in severe cases
First Aid
Description: First aid for bites by Viperid snakes likely to cause significant local injury at the bite site (see listing in Comments section).
1. After ensuring the patient and onlookers have moved out of range of further strikes by the snake, 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 many venomous bites do not result in envenoming, the relatively slow progression to severe envenoming (hours following elapid bites, days following viper bites) and the effectiveness of modern medical treatment.
2. The 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.
3. All rings or other jewellery on the bitten limb, especially on fingers, should be removed, as they may act as tourniquets if oedema develops.
4. 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.
5. 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, for bites causing flaccid paralysis, including respiratory paralysis, 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.
6. Do not use Tourniquets, cut, suck or scarify the wound or apply chemicals or electric shock.
7. Avoid peroral intake, 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.
8. If the offending snake has been killed it should be brought with the patient for identification (only relevant in areas where there are more than one naturally occurring venomous snake species), but be careful to avoid touching the head, as even a dead snake can envenom. No attempt should be made to pursue the snake into the undergrowth as this will risk further bites.
9. The snakebite 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.
10. 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
Bites likely to cause major local & systemic effects, require urgent assessment & treatment. Admit all cases. Antivenom important therapy. IV fluids important, avoid hypovolaemic shock.
Key Diagnostic Features
Local pain, swelling, blistering, necrosis + coagulopathy, bleeding
General Approach to Management
All cases should be treated as urgent & potentially lethal. Rapid assessment & commencement of treatment including appropriate antivenom (if indicated & available) is mandatory. Admit all cases.
Antivenom Therapy
Antivenom is the key treatment for systemic envenoming. Multiple doses may be required.
1. Antivenom Code: SAmIBB03
Antivenom Name: Soro antibotropico-laquetico
Manufacturer: Instituto Butantan
Phone: +55-11-3726-7222
Address: Av. Vital Brasil, 1500 Butanta
Sao Paulo - SP
Country: Brazil
2. Antivenom Code: SAmFED04
Antivenom Name: Soro Antibotropico-laquetico
Manufacturer: Fundacao Ezequiel Dias - FUNED
Phone: ++55-31-3371-9525
Address: Rua Conde Pereira Carneiro, 80 - Gameleria
Belo Horizonte, MG - CEP 30510-010
Country: Brazil
3. Antivenom Code: SAmIBM06
Antivenom Name: Antivipmyn
Manufacturer: Instituto Bioclon
Phone: ++56-65-41-11
Address: Calzada de Tlalpan No. 4687
Toriello Guerra
C.P. 14050
Mexico, D.F.,
Country: Mexico
4. Antivenom Code: SAmLBP01
Antivenom Name: Anti : Bothopicos - Lachesicos - Crotalicos
Manufacturer: Laboratorios Biologicos PROBIOL Ltda.
Phone: +571-6773057, +571-6711023
Address: Sandafe de Bogota
Country: Colombia
Lachesis muta ( Bushmaster ) [ Original photo copyright © Dr Jurg Meier ]
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Lachesis muta ( Bushmaster ) [ Original photo copyright © Dr Wolfgang Wuster ]
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Lachesis muta ( Bushmaster ) [ Original photo copyright © Dr Wolfgang Wuster ]
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Lachesis muta ( Bushmaster ) [ Original photo copyright © Dr Julian White ]
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