Venomous animals, including insects, spiders, and snakes, can cause injury and death through injection of toxic venom. Bees and wasps are the most common cause of fatal insect envenomation, while black widow spider bites, though rarely lethal for adults, pose more risk for children. Snake venom contains various toxins that can induce local tissue damage as well as systemic effects like coagulopathy, shock, and multi-organ failure. Proper first aid like immobilization, compression, and antivenom administration are crucial for managing snake bites. Symptoms of envenomation depend on the type, amount, and potency of venom injected.

1. VENOMOUS ANIMALS
INTRODUCTION
 Fatalities: insects 50%, snakes 30%, spiders 13%
 Bees are the MCC of fatal venomous animal injuries
 Black widow is the MCC of spider related death
 Poisonous animal = animal contains toxin, may become toxic by eating
 Venomous animal = animal has a specific gland for producing the toxic venom which is connected
to an apparatus for delivering the venom to another animal
 Toxicity is highly variable even with the same kind of snake: depends on degree of envenomation
 Many snake bites DO NOT result in envenomation (30-50%)
 Toxicity: local pain, burning -------------> DIC, shock, ARDS, MSOF, death
 Anaphylactoid reaction can also occur
SNAKES
INTRODUCTION
 Five families of venomous snakes
 Crotalidae (pit vipers): rattlesnakes, water moccasins, copper heads
 Colubridae: bird snake, boomslang
 Hydrophidae: sea snakes
 Elapidae: cobras, coral snakes, etc
 Viperidae (true vipers): Russell’s viper, puff adder, etc
 Identifiication
 Only experts should handle snakes; dead snakes can still envenomate
 Pit Vipers: pit between eye and nostril on both sides of head which is a heat-
sensitive organ to locate warm-blooded prey; presence of the pit is 100% accurate;
other features include elliptic pupil, triangular shaped head, and presence of fangs
but these are less uniform
 Toxins
 Toxins have variable toxicity
 Hosts have variable responses to the same toxin
 Venoms are neurotoxic and hematotoxic
 Can be classified s protein and non-protein components
 Protein components: enzymes and polypeptides
 Enzymes: coagulation, anticoagulation, cell lysis, hemorrhage, hemolysis,
destruction of nucleic acids
 Polypeptides: neurotoxins, cardiotoxins, etc
 Phospholipase A: enzyme that inhibits the electron transport chain at cytochrome
C, inhibits neurve axons,, leads to destruction of Ach at nerve terminals, causes
hemolysis: this enzyme has been identified in the venom of all venomous snakes
 Venom Delivery
 Two venom glands, hollow or grooved fangs, ducts connecting the fangs to the
venom gland which are evolved from salivary glands
 Venom glands have nerve supply to allow the control of the gland
 The snake can control the amount of venom that is injected

2. RATTLESNAKE BITES
LOCAL TOXICITY
 Immediate burning, pain, erythema, edema
 Petechiae, ecchymosis, hemorrhagic bullae, necrosis
 Severity of local symptoms/signs related to amount of venom injected
 Compartment syndromes from massive edema has occurred
 Local infections are a later concern
 Tetanus, osteomyelitis, cellulitis, gangrene can occur
SYSTEMIC TOXICITY
 Systemic symptoms: weakness, nausea, fever, vomiting, sweating, metallic taste in mouth,
fasiculations, hypotension, SOB, chest pain
 Death results form disruption of coagulation system and increased capillary lead
 ARDS, shock, DIC, ARF, hepatic failure, MSOF
PREHOSPITAL CARE
 Remove patient from environment
 Calm the patient and immobilize the limb: movement increases the spread of venom
 Place a constricting band above the bite: tight enough to stop venous flow only
 Immobilization and Compression technique: wrap the bitten extremity in an elastic
bandage or place in an air splint ----> technique used in Australia
 Monash method: thick pad and bandage over the bite wound and extremity ---->
another technique used in Australia
 Suction the wound if the bite occurred < 15 minutes ago
 Apply ice bag wrapped in a towel: decreases pain but does not decrease spread of venom (do NOT
immerse in ice water or pack the extremity in ice b/c of increased tissue destruction)
 Identify the snake and bring to hospital if possible
 NPO, NO etoh
 Cardiac monitor, establish iv access
ED ASSESSMENT
 Important historical features
 Time since bite
 Circumstances around bite
 First aid provided
 Location of bite(s)
 Local and systemic symptoms
 PMHx, tetanus, meds
 ALLERGY: ? horses, ? previous serum injections, hay fever, urticaria (all increase
the risk of reaction to antivenin
 Important physical exam features
 Look for signs of envenomation: edema, petechiae, ecchymosis, bullae
 Check distal neurovasc supply
 Check for signs of compartment syndrome
 General exam

3. ED MANAGEMENT
 General
 First aid maneuvers if not done in field and still applicable
 ECG monitoring, iv access
 Labs: cbc, lytes, creat, coags, liver enzymes, fibrinogen, crossmatch for 2 units, CK
and urine for myogloin
 Tetanus, Ancef prophylaxis, Fasciotomies prn
 Grading of Envenomation
 Grade 0
- No evidence of envenomation
- Fang wound may be present
- Minimal pain
- Minimal edema (< 2cm)
- Minimal erythema
- No systemic symptoms within 12hrs
- No antivenom neccessary
 Grade I
- No envenomation
- Fang wounds preent
- Moderate pain or throbbing
- Edema/erythema 1-10 cm around bite
- No systemic symptoms w/i 12hrs
- No lab changes
- No antivenom necessary
 Grade II
- Moderate envenomation
- More severe pain
- Edema, erythema spreading toward the trunk
- Petechieae and ecchymosis limited to the area of bite
- Systemic symptoms of N/V and mild temp
- 5 vials of antivenom
 Grade III
- Severe envenomation
- May initially look to be grade I or II but progresses rapidly within
the first 12 hours
- Edema spreads to the trunk
- Generarlized petechieae and echhymosis
- Tachycardia, hypotension, hypothermia
- 10 vials of antivenom
 Grade IV
- Very severe envenomation
- Sudden, severe pain with rapid progression of swelling,
ecchymoses, bleb formation, and necrosis
- Systemic symptoms within 15 min of bite: weakness, N/V, vertigo,
numbness of face, fasiculations, cramping, pallor, sweating,
tachycardia, hypotension, seizures, decreasing LOC
- 15 vials of antivenom

4.  Skin Testing
 Must be done regardless of history
 Negative skin test decreases chance of reaction but they are still possible
 Skin test may ppt bad reaction
 0.02 ml o 1:1000 solution
 Positive reactions occur within 5-30min: edema around the wheal
 Dosing and precautions
 ANTIVENOM is the only proven therapy
 Be ready for anaphylaxis
 Children’s dose is relatively more than adults
 Pregnancy is not a contraindication
 Do not administer near the bite
 Repeat doses q1-2 hours prn
 5-15 vials iv, 1:10 dilution
 Gravol and steroids for serum sickness
 Crofab
 Fewer allergic reactions
 Developed from sheep
 Disposition
 Sick: admit to ICU
 Asymptomatic: observe 4-6hrs
 Local symptoms: observe 12 hours for progression, d/c if no progression
VENOMOUS ARTHROPODS
INTRODUCTION
 Arthropods = animals with segmented bodies and jointed appendages
 Two classes of interest: Insecta and Arachnida
 More deaths than snakes
 Most deaths from allergic response to venom rather than venom itself
 Three mechanisms: stinging, bitting, secreting venom through pores or hairs
HYMENOPTERA
 Bees, ants, wasps, hornets, yellow jackets, ants
 Most sting but some bite and sting
 Bee: ovipositors protrude from adbomen with barbed stinging apparatus; bee dies with sting
 Wasp: unbarbed stinger, stings without hurting the wasp
 Phospholipase A and hyaluronidase are the most common enzymes
 Many antigens exist that account for the induction of allergy and anaphylaxis
 Sting to the lip, mouth, or tongue has high risk of airway obstruction
 Honeybee venom causes much more histamine release than other hymenoptera venom
 There is little antigenic overlap b/w species thus variability in reaction to stings
 Local effects: immediate pain, swelling, redness, ithcing
 Allergic symptoms: SOB, urticaria, wheezing, throat swelling, cough, resp arrrest
 Killer Bees
 Aggressive bee from Africa and Brazil
 Attach humans or cattle in clouds of bees

5.  Fire Ants
 Small, light - reddish born to dark brown ant
 Venom is unique in that it is 90% alkaloid
 Toxic venoum
 Sting produced by a bite
 Sterile pustule develops at site of bite
 Local symptoms common
 Allergic reaction in 10%
 Managment
 Ice bag to sting to relieve pain
 Anaphylaxis: iv fluids, benadryl, epi, steroids, ventolin, atrovent, nebulized epi,
ranitidine
 NO specific antivenom for hymenoptera stings
 Benadryl q6hr X 24hrs
 Uritcarial rash only: subQ epi + gravol + ranitidine and observe to r/o progression
 Allergic reactions: prescribe EPIPEN and refer to allergist for testing and/or
desensitization
BLACK WIDOW SPIDERS (Latrodectus mactans)
 General
 Found throughout southern Canada
 Female is twice the size of the male
 Only the female is venomous
 Glossy black, bright - red marking on abdomen (“black and red widow”)
 Red marking may look like an hour glass or only two dots
 Spider is about 3cm long
 Found in protected spaces: under rocks, woodpiles, etc
 Female can be aggressive when guarding eggs
 Adults: symptomatic for days, usually not lethal
 Children: higher risk of death!
 Complex venom with protein and nonprotein compounds
 Venom normally used to paralyze prey and liquefy tissues for digestion
 NEUROTOXIN
- is the most toxic component of the venom
- more toxic than pit viper venom
- destabilizes neuronal membranes by opening ion channels, causing
depletion of Ach from presynaptic nerve terminals and increasing
the frequency of spontaneous end plate potentials at the NMJ
- MASSIVE release of Ach and norepinephrine
 Clinical Features
 Initial pinprick sensation followed by minimal swelling, edema, redness
 Two small fang marks may be visible
 The bit may not initially be felt
 15-60min: dull cramping pain in the area of the bite that spreads over the body
 Hypertonic Myopathic Syndrome
- Muscle cramps typically present 13-60 min after bite
- Initially muscle cramps occur at the site of the bite

6. - Progresses to the chest with UE bites and abdomen with LE bites
- Abdomen may become rigid: may mimic an acute abdomen in
rigidity but usually is not that tender
 Faces Latrodectismia
- Sweating, contorted, grimaced face associated with blepharitis,
conjunctivits, rhinitis, cheilitis, trismus of the masseters
 General
- N/V, headache, SOB, pruritis, sweating, weakness, restless,
difficulty speaking, ptosis, dizziness, diffuse cramping
- Hypertension
- ECG changes SIMILAR TO DIG TOXICITY
 Life-Threatening Complications
- Hypertensive crisis: 30% (due to norepi release)
- Respiratory arrest secondary to respiratory muscle paralysis
- Seizures secondary to neuronal activation
 Management
 Ice pack to area for pain relief
 Bring spider if possible!
 Clean wound with soap and water
 Administer tetanus booster prn
 Opiods and benzodiazepines for pain control
 Asymptomatic and NOT a black widow: d/c home, RTED instructions
 Nitroprusside for hypertensive crisis
 Symptomatic: admit to hospital
 Draw cbc, lytes, coages, calcium
 Calcium Gluconate
- 10 ml of 10% solution iv over 20 min
- Repeat dose prn q2-4 hrs
- Cardiac monitoring, follow Ca+ levels
- Traditionally used to decrease cramping
- Mechanism of action unknown to decrease cramping
- Some evidence that it makes things WORSE
- NOT recommended by Goldfranks
 Lorazepam/Morphine
- Treatment of choice for pain control from muscle spasms
 Lacrodectus Antivenom
- <12yo or > 65yo or pregnant are at highest risk of mortality and
may benefit from antivenom
- Can be used in other ages depending on systemic toxicity
- Any patient with severe envenomation should be considered
- One vial diluted n 50 ml of normal saline over 15 min
- TEST for sensitivity as per snake venom testing
- Venom is derived inn horses

7. BLACK WIDOW BOX
Found in Southern Canada
Black spider with Red abdomen
Neurotoxin: Ach and NE release
Severe muscle cramping
Resp arrest, seizures
Hypertensive crisis
Local Mx: clean wound, td
Mx: opiods and bzd for pain control
CALCIUM CONTROVERSIAL
Antivenom for young, old, pregnant, sick
BROWN-RECLUSE SPIDER
 General
 Several deaths have occured
 Many different species
 Identifying feature is the violin-shaped darker area found on the cephalothorax
 No aggressive, mostly in southern US
 Sphingomyelinase D is the primary component of the venom
 Clinical Features
 Local: pain, swelling etc w/i a few hours, bleb forms in the center of an
erythematous ring -------> resembles a BULL’S EYE
 The BLEB darkens as tissue necrosis occurs and continues to spread to skin and
subcutaneous fat
 Systemic
 Management
 Wash wound
 Tetanus prophylaxis
 Do NOT excise the lesion
 Monitor vitals, cardiac monitor
 Send labs, lytes, coags
 Observe for envenomation: d/c after 6hrs if well
 Dapsone
- 50-200 mg/day
- Helpful in preventing the local effects of the venom
- Risk of methemoglobinemia and hemolysis with G6PD def
 Other
- HBOT to decrease tissue toxicity has been used
- Dialysis has been needed for ARF
- Antivenom not readily available
SCORPIONS
 Toxicity varies greatly between species
 Less dangersous produce more local symptoms
 More dangerous produce more sytemic symptoms
 Hemolytic enzymes and proteins in venom
 Severe immediate pain at site of sting

8.  Systemic symptoms: SOB, CP, sweating, muscle spasms, syncope, N/V, HTN
 Cardiac arrythmias or respiratory arrest
 Children are at higher risk of death
 Management
 Ice bag to area
 Transport to ED
 ANTIVENOM for all severe envenomations
 Benzos for myoclonus and muscle spasms
OTHER ARTHROPODS
 Ticks: wood tick and dog ticks can also have a toxin that leads to ascending paralysis = TICK
PARALYSIS
 Beetles and caterpillares: irritating substances which can cause local symptoms, was area with soap
and wate, ice to area