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Crotalus tigris
General Details, Taxonomy and Biology, Venom, Clinical Effects, Treatment, First Aid , Antivenoms
Crotalus tigris  ( Tiger Rattlesnake  )  [ Original photo copyright © Dr Julian White ]
Family: Viperidae
Subfamily: Crotalinae
Genus: Crotalus
Species: tigris
Common Names
Tiger Rattlesnake
Local Names
Cascabel Tigre , Vibora de Cascabel
North America + Central America
Mexico, United States of America
Taxonomy and Biology
Adult Length: 0.45 m
General Shape
Small in length, medium bodied rattlesnake with a short tail and a moderately long horn-like segmented rattle. Can grow to a maximum of about 0.89 metres. Head is moderately small for genus, broad, flat and very distinct from narrow neck. Eyes are moderately small in size with vertically elliptical pupils. Dorsal scales are keeled.
Elevations up to about 1450 metres ( a single record of 2440 metres ) in mainly desert and mesquite-grassland and extending into fringes of tropical deciduous forest. Usually found in rugged rocky locations.
Terrestrial and mainly diurnal snake.
Feeds mainly on lizards, rodents and small mammals.
Species Map
Small (Approx 20k) version
Average Venom Qty
6.4 mg ( n=2 ), Minton and Weinstein (1984) ( Ref : R000494 ).

10.0 mg, Weinstein and Smith (1990) ( Ref : R000644 ).
General: Venom Neurotoxins
Presynaptic neurotoxins
General: Venom Myotoxins
Systemic myotoxins present
General: Venom Procoagulants
Possibly present
General: Venom Anticoagulants
General: Venom Haemorrhagins
Not present
General: Venom Nephrotoxins
General: Venom Cardiotoxins
General: Venom Necrotoxins
Not present
General: Venom Other
May include; Lectins; Nerve growth factors; Phospholipase inhibitors; Proteinase inhibitors; Complement inactivators; Biogenic amines; Carbohydrates; Lipids; Nucleosides & nucleotides
Clinical Effects
General: Dangerousness
Moderate envenoming possible but unlikely to prove lethal
General: Rate of Envenoming: Unknown but likely to be low
General: Untreated Lethality Rate: Unknown but may cause major envenoming
General: Local Effects
Local pain & swelling
General: Local Necrosis
Does not occur, based on current clinical evidence
General: General Systemic Effects
Variable non-specific effects which may include headache, nausea, vomiting, abdominal pain, diarrhoea, dizziness, collapse or convulsions
General: Neurotoxic Paralysis
Insufficient clinical reports to know
General: Myotoxicity
Insufficient clinical reports to know
General: Coagulopathy & Haemorrhages
Insufficient clinical reports to know
General: Renal Damage
Unlikely to occur
General: Cardiotoxicity
Unlikely to occur
General: Other
Insufficient clinical reports to know
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 by species showing the South American rattlesnake clinical pattern are quite different from North American rattlesnake bites. The bite may cause few if any local effects, but can cause severe, even lethal systemic effects, particularly paralysis & myolysis (coagulopathy also possible). Therefore every case must be admitted at least overnight and closely observed. Should any evidence of paralysis or myolysis develop, antivenom is the principal treatment. Specific antivenoms exist for several major species.
Key Diagnostic Features
Minimal to mild local reaction + flaccid paralysis, myolysis, sometimes 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: SAmPRO01
Antivenom Name: Polyvalent crotalid antivenom ( CroFab ), Ovine, Fab
Manufacturer: Protherics Inc. (US)
Phone: ++1-615-327-1027
Address: 5214 Maryland Way
Suite 405
Tennessee 37027
Country: U.S.A.
2. 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
Crotalus tigris ( Tiger Rattlesnake ) [ Original photo copyright © Dr Julian White ]
Larger version
Crotalus tigris ( Tiger Rattlesnake ) [ Original photo copyright © Dr Julian White ]
Larger version
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