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Family: Viperidae
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Subfamily: Crotalinae
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Genus: Crotalus
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Species: cerastes
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Subspecies: cerastes
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Common Names
( subsp. cerastes ) Mohave Desert Sidewinder
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Local Names
Vibora de Cascabel , Vibora Cornuda
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Region
North America
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Countries
United States of America
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Taxonomy and Biology
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Adult Length: 0.40 m
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General Shape
Small in length, moderately stout bodied rattlesnake with a short tail and a horn-like segmented rattle. Can grow to a maximum of about 0.62 metres with females larger than males. Head is large, broad, flat and very distinct from narrow neck with supraoculars distinctly raised into horn like projections. Eyes are medium to moderately small in size with vertically elliptical pupils. Spinal ridge is evident and dorsal scales are strongly keeled and tuberculate.
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Habitat
Desert ( fine windblown sand to hard rocky terrain ) with scattered vegetation.
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Habits
Terrestrial and diurnal snake ( nocturnal tendencies during the hottest months ). Sit and wait predator, often found coiled on hard ground or partially buried in sand waiting to ambush prey.
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Prey
Feeds mainly on small mammals, rodents and lizards and occasionally snakes.
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Venom
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General: Venom Neurotoxins
Unknown
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General: Venom Myotoxins
Unknown
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General: Venom Procoagulants
Unknown
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General: Venom Anticoagulants
Unknown
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General: Venom Haemorrhagins
Unknown
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General: Venom Nephrotoxins
Unknown
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General: Venom Cardiotoxins
Unknown
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General: Venom Necrotoxins
Unknown
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General: Venom Other
Unknown
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Clinical Effects
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General: Dangerousness
Unknown, but potentially lethal envenoming, though unlikely, cannot be excluded.
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General: Rate of Envenoming: <10%
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General: Untreated Lethality Rate: Unlikely to prove lethal
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General: Local Effects
Local pain & swelling
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General: Local Necrosis
Not likely to occur
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General: General Systemic Effects
General systemic effects unlikely
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General: Neurotoxic Paralysis
Unlikely to occur
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General: Myotoxicity
Not likely to occur
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General: Coagulopathy & Haemorrhages
Unlikely to occur
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General: Renal Damage
Unlikely to occur
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General: Cardiotoxicity
Unlikely to occur
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General: Other
Insufficient clinical reports to know
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First Aid
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Description: First aid for bites by Viperid snakes likely to cause significant local injury at the bite site (see listing in Comments section).
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Details
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.
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Treatment
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Treatment Summary
Rattlesnake bites can cause major, even fatal envenoming. All cases require urgent assessment and management. For larger species, about 20% will have an ineffective bite, with no local or systemic envenoming, so will not require antivenom and may not require prolonged observation. This figure will be higher for the smaller species, which are generally unlikely to cause a severe bite. All other cases, with any degree of local or systemic effects, require extended observation and may require IV antivenom (Crofab), the amount partly dictated by the severity grading. Beware fluid shifts causing shock, coagulopathy and bleeding, kidney damage and necrosis of the bitten area.
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Key Diagnostic Features
Variable severity local pain, swelling, blistering, ± necrosis. Systemic effects may include coagulopathy, bleeding, renal failure, rarely myolysis &/or mild paralysis
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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.
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Antivenom Therapy
Antivenom is the key treatment for systemic envenoming. Multiple doses may be required.
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1. Antivenom Code: SAmPRO01
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Antivenom Name: Polyvalent crotalid antivenom ( CroFab ), Ovine, Fab
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Manufacturer: Protherics Inc. (US)
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Phone: ++1-615-327-1027
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Address: 5214 Maryland Way Suite 405 Brentwood Tennessee 37027 USA
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Country: U.S.A.
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2. Antivenom Code: SAmIBM06
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Antivenom Name: Antivipmyn
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Manufacturer: Instituto Bioclon
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Phone: ++56-65-41-11
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Address: Calzada de Tlalpan No. 4687 Toriello Guerra C.P. 14050 Mexico, D.F.,
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Country: Mexico
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