×

Please Remove Adblock
Adverts are the main source of Revenue for DoveMed. Please remove adblock to help us create the best medical content found on the Internet.

Northern Pacific Rattlesnake Bite

Last updated March 18, 2019

Approved by: Krish Tangella MD, MBA, FCAP

Ken-ichi Ueda

The Northern Pacific rattlesnake (Crotalus oreganus oreganus) is a highly venomous snake that averages about 3 feet in size; although, some are small at about 15 inches, while others can grow to be even 5 feet in length.


What are the other Names for this Condition? (Also known as/Synonyms)

  • Crotalus Oreganus Oreganus Snake Bite

What is Northern Pacific Rattlesnake Bite? (Definition/Background Information)

  • The Northern Pacific rattlesnake (Crotalus oreganus oreganus) is a highly venomous snake that averages about 3 feet in size; although, some are small at about 15 inches, while others can grow to be even 5 feet in length. The rattlesnake is a subspecies of the western rattlesnake (Crotalus oreganus), a pit viper, belonging to the family Viperidae
  • The Northern Pacific rattlesnake is a sturdy species of rattlesnake that is observed in the state of California, Washington, and Idaho (in the USA) and British Columbia (Canada). The snake is observed to inhabit rocky grasslands, rocky hillsides, mountain woods, and mountain streams; in many cases, the snake is seen hiding inside rocky crevices
  • The snake is mostly nocturnal; but, it can be active during the day, while avoiding the hottest part of the day. The Northern Pacific rattlesnake is an ambush predator that preys on rodents (rats and ground squirrels), rabbits, lizards, frogs, and even birds
  • The snake is noted to have varying body color that includes gray, pale green, yellow, brown, or even red-brown; the underbelly is lighter with odd-shaped patches. Darker blotches are observed along the length of the body with black borders, which form bands towards the tail region. Juvenile snakes have bright tails that are usually yellow in color
  • The head is large and triangular-shaped with a narrowed neck, a rather heavy body, and a rattle tail. Like many other rattlesnakes, the Northern Pacific rattlesnake may coil, make hissing sounds, and shake/rattle its tail as a warning sign and announce its presence to any intruder
  • Northern Pacific Rattlesnake Bites involving humans are not uncommon; even though, the snake generally avoids humans and other larger predators through thermal detection and vibration awareness. Intruders, who approach the snake, may be warned by its continuous rattling, raised head and body posture, and striking actions
  • Nevertheless, a bite from a fully-grown Northern Pacific rattlesnake can result in severe envenomation (venom injection) and death, in the absence of adequate treatment. The snake venom is a potent mix of lethal neurotoxins, hemotoxins, and myotoxins
  • The signs and symptoms of Northern Pacific Rattlesnake Bite may include intense pain, swelling, blistering, along with nausea and vomiting. The venom can also impair blood coagulation and breakdown the red blood cells, leading to severe systemic symptoms including shock and multiple organ damage
  • Early administration of suitable antivenom (or antivenin) is the mainstay of treatment. Apart from this, symptomatic treatment is necessary, which may include the use of pain medication, platelet (blood) transfusion, and peritoneal dialysis. The prognosis of Northern Pacific Rattlesnake Bite with prompt and effective therapy is usually good

Who gets Northern Pacific Rattlesnake Bite? (Age and Sex Distribution)

  • Northern Pacific Rattlesnake Bite may occur to any individual exposed to the snake, particularly in its natural habitat
  • Individuals of any age and gender are prone to snake bites
  • The snake is found in the following geographical regions:
    • Canada: Southern parts of  British Columbia, along the Rocky Mountains
    • USA: Northwestern part of California, west and north of Washington, and west-central Idaho

What are the Risk Factors for Northern Pacific Rattlesnake Bite? (Predisposing Factors)

The risk factors for Northern Pacific Rattlesnake Bite include the following factors:

  • Camping, hiking, and trekking in the endemic regions
  • Mountain climbing in unknown terrain in areas where the snake is observed, especially using one’s bare hands
  • Living or residing in the endemic areas
  • Wildlife enthusiasts and scientific study groups, who explore the region
  • Walking unprotected through bushes, woods, and grasslands
  • Venturing outdoors during the night without adequate protection
  • Keeping them as pets
  • Handling dead or live snakes; intentionally or accidentally picking up the snake
  • Drug addicts and alcoholics who come into contact with the snake have a greater risk for being bitten
  • Children, elderly adults, and individuals with weak immune system have a higher risk for severe symptoms

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Northern Pacific Rattlesnake Bite? (Etiology)

Northern Pacific Rattlesnake Bite can take place when one comes into contact with the venomous snake, usually unintentionally or inadvertently.

  • The snake is observed to inhabit grassy plains, woodlands, and rocky outcrops within the endemic zones, including coastal areas. Most rattlesnakes bite only if threatened or in self defense, when they are provoked to a point of retaliation. Before it strikes, the snake displays sufficient warning and aggression signs, to be left alone
  • The venom of western rattlesnakes (to which the Northern Pacific rattlesnake belongs) are mostly neurotoxic and myotoxic affecting both the neurological system and hematological (blood) systems

What are the Signs and Symptoms of Northern Pacific Rattlesnake Bite?

The signs and symptoms of Northern Pacific Rattlesnake Bite can vary from one individual to another. The signs and symptoms depend on the age (whether child or adult), weight, and overall health status of the individual (whether having an underlying condition or illness). Also, the signs and symptoms vary according to the potency and amount of venom injected.

The signs and symptoms may develop within a period of few hours and may include:

  • Burning pain at the bite site; presence of noticeable fang marks, which may be single or double set of marks
  • In a majority of cases, snake bites occur on the feet and ankles followed by the hands
  • Skin discoloration; the skin color may change to blue and black
  • Blistering of skin
  • Swelling at the bite site that slowly involves a wider region; the severity of poisoning can be ascertained from the speed at which the swelling progresses up the arm or leg
  • Bleeding from the wound; the oozing blood is thin
  • Sensation of metallic taste in the mouth; salivation
  • Twitching of eye and mouth
  • Paresthesia or tingling sensation and numbness
  • Chills and sweating
  • Anxiety
  • Breathing difficulties
  • Nausea and vomiting
  • Abdominal pain
  • Blurred vision and droopy eyelids
  • In some cases, death of tissue (or necrosis) around the affected region or limb, observed within a few days
  • Low blood pressure
  • Tachycardia, or heart rate that is above normal
  • Feeling faint or dizzy
  • Weakness and malaise

Some of the systemic signs and symptoms may include:

  • Bleeding disorder due to: (usually mild to moderate)
    • Decreased blood platelets or thrombocytopenia
    • Destruction of red blood cells or hemolysis
  • Internal hemorrhaging including:
    • Blood in urine
    • Bleeding from recent wounds
    • Mucosal bleeding - from nose, ears, eye, gastrointestinal tract, etc.
    • Anemia due to spontaneous bleeding
  • Acute kidney injury or kidney failure
  • Neurological symptoms

Note: 

  • In some cases, the fang marks may not be pronounced or even visible. Sometimes only small scratch marks or lacerations may be observed. Thus, any contact with a rattlesnake merits immediate medical attention
  • Severe anxiety may also result in some misleading symptoms of snakebites, such as sweating, fatigue, and shock, even when no bite has taken place (the individual may be imagining), or when it is a dry bite. Nevertheless, even in suspect cases, the presence of any such symptoms requires the attention of a qualified medical professional
  • Also, if the individual has been treated using alternative/native medicines, it may present additional confusing symptoms. Thus, it is important to always consult a qualified healthcare provider promptly

How is Northern Pacific Rattlesnake Bite Diagnosed?

Northern Pacific Rattlesnake Bite may be diagnosed using the following tests and exams:

  • Complete physical examination with comprehensive evaluation of medical history; a physical examination of the affected site by the physician may be normally sufficient to diagnose a snake bite
  • The individual may be asked to provide an account (history) of the events that occurred (what took place and how), if possible
  • Assessment of the signs and symptoms exhibited by the individual may be carefully observed
  • Blood tests that may include: (many of these tests are repeated over the course of treatment)
    • Complete blood count (CBC) with differential and platelet count
    • White blood cell count
    • Hematocrit blood test: Hematocrit is the proportion of blood that is made up of red blood cells
    • Prothrombin time (PT) and partial thromboplastin time (PTT) tests
    • Fibrinogen blood test
    • Lactate dehydrogenase (LDH) test
    • Serum electrolytes including blood urea nitrogen (BUN) and creatinine levels
    • Arterial blood gas
  • Urine test or urinalysis to test for free protein, myoglobin, and hemoglobin levels
  • Continuous urine output monitoring is helpful to determine damage to the kidneys, if any
  • Electrocardiogram or ECG, to check for arrhythmias (or irregular heartbeat) and hyperkalemia (increased blood potassium)
  • Kidney function test
  • Liver function test
  • Nerve conduction studies and neurological evaluation

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Northern Pacific Rattlesnake Bite?

The complications of Northern Pacific Rattlesnake Bite may include:

  • Multiple bites, causing injection of a large quantity of venom
  • Hyperkalemic cardiotoxicity due to muscle breakdown
  • Blood clotting defects resulting in severe internal bleeding
  • Deep tissue and muscle damage of the affected leg or hand, which can result in superimposed infections and gangrene formation
  • Rarely, increased pressure causing compartment syndrome, which is an urgent medical condition
  • Loss of limb function
  • The snake toxin can damage the muscle resulting in muscle breakdown known as rhabdomyolysis. Extensive muscle breakdown can lead to a variety of complications including kidney failure
  • Flaccid paralysis that is severe; in some, the onset of paralysis may occur within a few hours following the snake bite
  • Severe shock
  • Seizures and coma
  • Multiple organ failure

Presence of misleading symptoms due to fear and anxiety, which may be also aggravated by those around the individual, such as one’s family members, can sometimes result in inappropriate or over-treatment.

Antivenom reactions:

  • Some individuals may develop an allergic reaction, such as anaphylaxis, to the antivenom that may be serious. This may develop within 10 minutes or even after 6 hours, typically starting with itchiness over the scalp and other skin areas
  • Life-threatening anaphylactic reactions that require immediate medical treatment may include:
    • Low blood pressure or hypotension
    • Bronchospasm causing narrowing of the airways (bronchi) resulting in breathing difficulties
    • Angioedema: Swelling of skin tissue layers at various locations including the throat, causing speaking and breathing difficulties
  • Serum sickness may develop as a complication of antivenom therapy causing fever, nausea, itchy skin, muscle and joint pain, etc. It may develop after 4 days or even 2 weeks (average 7 days) following the administration of antivenom serum

How is Northern Pacific Rattlesnake Bite Treated?

All snake bites should be considered as medical emergencies and evaluated by trained medical professionals, as soon as possible; the first 6-8 hours are particularly vital for preventing life-threatening symptoms. Failure to obtain early assessment and management from the highest level of care (available within the community) may potentially result in severe complications and death.

The following measures may be considered in the treatment of Northern Pacific Rattlesnake Bite, based on the medical evaluation of a trained healthcare professional:

  • Administration of intravenous fluids to keep the patient well-hydrated; pain medication
  • Administration of anti-snake venom (ASV) to neutralize the venom through slow intravenous injection or infusion method, especially when neurological symptoms, such as altered mental status, and cardiac abnormalities are noted
  • Address any signs or early allergic reaction: A close observation of the patient is necessary for a minimum of 60 minutes immediately following antivenom administration, to detect early allergic reactions, if any
  • Periodic blood and urine tests are undertaken for 12-24 hours or more
  • Tetanus vaccination is usually required, if it is not up to date
  • The patient is generally admitted and placed in an ICU setting and monitored for at least a day following the abatement of symptoms; the patient has to be rested and kept warm
  • If necessary, blood and plasma transfusions for severe cases
  • Intubation and respiratory support
  • Providing life support, such as ventilation assistance and treatment for shock, for those with severe symptoms leading to potential organ failure
  • Medications to control blood pressure
  • Peritoneal dialysis for acute kidney failure
  • Pressure management (using appropriate pressure devices) of affected limb for compartment syndrome
  • Removal or necrotic tissue through surgical debridement
  • Rehabilitation of the affected limb through physical therapy

Note:

  • For envenomation involving rattlesnake bites, the use of prophylactic antibiotic therapy is medically not advised
  • Consultation with a medical toxicologist is recommended for all cases requiring the administration of anti-snake venom
  • Even though antivenom therapy is the key treatment for systemic envenomation; on its own, it may never be adequate enough to completely resolve the condition. Other supportive and symptomatic measures are always necessary to save the patient
  • The dose of antivenom does not vary for a child, adult, or even for a pregnant woman, since the snake typically injects the same quantity of venom into an individual
  • Gynecological evaluation may be necessary for pregnant women bitten by snakes to evaluate the health of the fetus
  • In many instances, the type of venomous snake involved in the bite is unknown; hence, all vital organs and systems should be closely monitored and treated appropriately, as necessary

How can Northern Pacific Rattlesnake Bite be Prevented?

Northern Pacific Rattlesnake Bite may be avoided by:

  • Learning to recognize rattlesnakes using the following tips:
    • The specific coloration and shapes/patterns on the body
    • The snake stays perfectly still and tries to blend more into the surrounding, until approached very closely or disturbed
    • Rattlesnakes provide clear warning signs by slightly expanding their body and raising their head and body when approached
    • The unmistakable back and forth shaking of tail producing a rattle sound
    • Before striking, the snake continuously coils in a serpentine manner
  • If you spot a rattlesnake, step back slowly and keep a safe distance of at least 10 feet or more (between yourself and the snake)

Outdoors:

  • Being alert, if you are in snake-infested regions, particularly containing dangerous species of snakes
  • Be on the lookout for snakes and other animals while trekking or hiking; also, if you are with a pet, do not allow the pet to wander away
  • Always allow snakes crossing your path the right of way
  • Always stay on established paths and clearings, while walking in the woods, grasslands, or through thick undergrowths
  • Avoid picking up firewood sticks, stones, or rocks without checking the area for any concealed creatures
  • Always step on top of large rocks and fallen trunks; never place one’s foot by the side of big rocks and rotting tree stumps. Some snake species are known to take shelter or warm themselves on the sides, during the day
  • Always check before sitting on dead tree logs, stumps, or a pile of rocks; use a stick to stir or probe around the area
  • Do not reach out to move or hold bushes or tree branches without properly examining them for any camouflaged creatures such as snakes
  • Watch where you place your hands while climbing a ledge, trees, rocky slopes, or mountains
  • Avoiding being outdoors at night in forested areas; be careful while camping outdoors
  • Avoid tall grassy areas or thick bushes; if you plan to explore the area, use heavy boots and thick pants
  • While walking through areas with thick undergrowth, pay attention to the sound of birds that may warn of potential dangers such as snakes
  • While walking outdoors at night, use a flashlight or lamp and make constant noise (singing or talking to others) or large stomping sounds that may alert the snake to move away from the region
  • While walking through tall grass or undergrowth, try to walk one behind the other in a single file
  • Avoid snake-infested regions or even walking on cleared forest paths and roads during nights, immediately after heavy rains that may flush snakes out to the open, due to flooding of their burrows and holes
  • Wildlife explorers, amateur adventurers, and others are requested to carry first aid kit, especially when traveling through areas containing highly venomous snake species

Residential settlements:

  • Keep homes and surrounding areas clean and clear of rubbish or leafy piles, termite mounds, even building materials (like bricks and large stones)
  • Cut tall and unkempt grass or low-lying shrubs and bushes around dwelling areas that provides hiding places for snakes and other rodents
  • In regions where snakes are regular home visitors, always switch on the lights before entering one’s shed or garages (and try to stand clear of exits that may serve as possible escape routes for the snakes)
  • Natural disasters, such as floods and forest fires, are known to drive out snakes and other creatures into homes seeking shelter. Hence, always remain vigilant when returning home following such situations
  • Never intentionally run over snakes on the road while on a vehicle (cycle, other 2-wheeler, or 4-wheeler); the injured snake lying on the road may strike other pedestrians, or get entangled in the vehicle and be carried to the parking lot or even inside one’s garage

Other points to consider:

  • Exercise vigilance while working in farms, particularly during the harvest season or after flooding
  • Avoid playing with or teasing snakes such as by touching their tails
  • Do not pick up dead snakes - they may be poisonous and still bite through a reflex action
  • Do not reach into dark nooks/corners/recesses with your bare hands/foot
  • Teach and educate children about the dangers and importance of snakes
  • Take steps to educate the members of a community to identify venomous snakes, recognize bite symptoms, and how to avoid encounter with snakes
  • Completely avoid any form of native or traditional treatment for snake bites

Both large and small snakes have the potential for severe envenomation; hence, all snake bites should be treated promptly and appropriately.

What is the Prognosis of Northern Pacific Rattlesnake Bite? (Outcomes/Resolutions)

  • The prognosis of Northern Pacific Rattlesnake Bite is dependent on the size of the snake, site of bite, overall health of the individual, promptness of medical response, and continued observance and treatment of complications following admission of the patient. In many cases, the prognosis is good with immediate treatment and administration of antivenom
  • Without treatment or access to proper healthcare, deaths from severe complications, such as respiratory distress, severe paralysis, and organ failure, have been reported

Additional and Relevant Useful Information for Northern Pacific Rattlesnake Bite:

  • It has to be noted that snakes of the same species may vary in their physical and biological characteristics, including in their habitat and prey, from one geographical region to another. Due to this, it is always recommended to consult your local (zoological) expert to understand or evaluate the nature of the snake, including whether it is venomous or non-venomous
  • In some cases, the snake bite may be a ‘dry bite’, meaning that even though there is a bite mark, no venom injection occurs. However, even for dry bites, the patient must be placed under observation and monitored closely for a period ranging anywhere from 12-24 hours, prior to discharge

Depending on the geographical region, either monovalent antivenom or polyvalent antivenom may be administered for systemic envenomation. Monovalent antivenom neutralizes venom of a single snake species only, whereas polyvalent antivenom can neutralize the venom of several snake species.

The snake venom is a highly complex mix of several proteins, enzymes, amino acids, peptide chains, fats, and even certain metals. The bite causing venom injection into the body may be categorized as:

  • Intramuscular injection: Long-fanged snakes have a potential for injecting venom directly into the muscles (this is highly infrequent though)
  • Intraperitoneal injection: When the snake bite involves the stomach or abdomen region
  • Intravenous injection: In very rare cases, the snake fangs may inject venom directly into a blood vessel, releasing venom directly into blood (posing an even greater danger than normal snake bites)
  • Subcutaneous injection: A majority of snake bites involve the subcutaneous skin layers (venom is injected just below the skin surface)

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: March 18, 2019
Last updated: March 18, 2019