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Family: Viperidae
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Subfamily: Crotalinae
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Genus: Agkistrodon
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Species: piscivorus
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Subspecies: leucostoma
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Common Names
( subsp. leucostoma ) Western Cottonmouth
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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: 1.00 m
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General Shape
Large in length, stout bodied snake with a moderately short to short, slender tail that terminates with a moderately long caudal spine. Can grow to a maximum of about 1.58 metres. Head is broad, flattened, triangular and distinct from neck. Canthus rostralis is prominent. Eyes are medium in size with vertically elliptical pupils. Dorsal scales are keeled. Caudal spine is not curved downwards ( straight ).
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Habitat
Lowland swamps and marshes, lakes, rivers and streams, canals, irrigated land and frequently found in rice fields.
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Habits
May be seen basking during the day but most active at night. Found in and around water and, unlike most other water snakes, swims with its head well out of water. When disturbed tends to hold its ground and gape, exposing the white ( cotton coloured ) mouth lining.
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Prey
Feeds mainly on frogs and fish, but will eat lizards birds and smaller snakes. Juveniles twitch their yellowish or greenish tipped tail to lure prey.
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Venom
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General: Venom Neurotoxins
Not present
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General: Venom Myotoxins
Systemic myotoxins present
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General: Venom Procoagulants
Fibrinogenases
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General: Venom Anticoagulants
Probably not present
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General: Venom Haemorrhagins
Possibly present
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General: Venom Nephrotoxins
Probably not present
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General: Venom Cardiotoxins
Probably not present
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General: Venom Necrotoxins
Probably not present
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General: Venom Other
Unknown
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Clinical Effects
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General: Dangerousness
Moderate envenoming possible and potentially lethal
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General: Rate of Envenoming: Unknown but likely to be moderate
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General: Untreated Lethality Rate: Unknown but lethal potential cannot be excluded
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General: Local Effects
Local pain, swelling, bruising & blistering
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General: Local Necrosis
Potentially may occur
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General: General Systemic Effects
Insufficient clinical reports to know, but might develop systemic symptoms in severe cases; headache, nausea, vomiting, abdominal pain, collapse
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General: Neurotoxic Paralysis
Does not occur, based on current clinical evidence
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General: Myotoxicity
Does not occur, based on current clinical evidence
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General: Coagulopathy & Haemorrhages
Insufficient clinical reports to know, but coagulopathy & haemorrhage might occur
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General: Renal Damage
Does not occur, based on current clinical evidence
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General: Cardiotoxicity
Does not occur, based on current clinical evidence
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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
Bites by Agkistrodon species vary from only minor local effects to moderate, rarely severe local effects, the latter potentially including hypovolaemic shock. Major systemic effects are likely to be confined to coagulopathy, though systemic myolysis is a theoretical risk, but not paralysis. Cases with major local or systemic envenoming should receive antivenom IV.
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Key Diagnostic Features
Local pain, swelling, ecchymosis ± coagulopathy & haemorrhage
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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
Only antivenoms available are for related species, but should be used for significant envenoming
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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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