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Animal bites and stings

Last updated: January 14, 2022

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A wide variety of animals, both wild and domestic, will bite or sting to ward off enemies or kill prey, posing a common cause for visits to the emergency department. Arthropod, reptile, fish, jellyfish, and mollusk stings and bites generally cause little mechanical trauma to humans, but they can cause potentially severe local and/or systemic damage if they deliver venom. Clinically significant venomous animals include various species of spiders (e.g., black widow and recluse spiders), scorpions (e.g., Arizona bark scorpion), hymenoptera (esp. bees and wasps), snakes (e.g., rattlesnakes), fish (e.g., scorpionfish, stonefish), mollusks (e.g., blue-ringed octopus, cone snails), and jellyfish (box jellyfish). While venomous mammals exist (e.g., shrews, slow lorises, platypuses), attacks on humans are rare. Mammal bites are instead clinically relevant for the mechanical trauma they cause (esp. with larger mammals, such as dogs) and the risk of infection (e.g., rabies, rat-bite fever). Diagnosis involves wound assessment, ruling out hypersensitivity reactions, and identifying the animal responsible to determine the risk of infection and/or envenomation. Symptoms of envenomation depend on the species of animal and may involve local pain, swelling, and paresthesia; hypersensitivity reactions up to anaphylaxis; nonspecific symptoms (e.g., nausea and vomiting); and, in severe cases, neurotoxicity, autonomic dysfunction, and shock. Treatment depends on the severity of the bite or sting and the animal responsible, potentially involving trauma care up to surgery, hypersensitivity management up to epinephrine, care with antibiotics, and the administration of antivenom.

For the general management of animal bites, see ”Bite wounds.” and “Rabies risk assessment.”

  • Epidemiology
    • Account for 1% of injury-related emergency department visits in the United States [1]
    • Account for 60–90% of animal bites [2]
    • Children are more likely to be attacked and their injuries will be more severe than in adults [3]
  • Clinical features
    • Erythema, swelling, and possibly pus in the case of infection
    • Depending on the size of the dog, injuries include puncture wounds, superficial abrasions, lacerations, and/or crush injuries.
    • In adults, the extremities are most commonly affected, and in children < 5 years of age, head and neck injuries are more common.
  • Diagnostics
    • Wound exploration for tendon or bone involvement and foreign bodies (e.g., broken off tooth)
    • Radiography in the case of bone involvement
  • Treatment [3]
    • Clean wound and irrigate with water, normal saline, or dilute povidone-iodine solution
    • Dog bite wounds should generally be left open to prevent infection, if feasible.
      • Wounds with a low risk of infection may be closed after cleaning if the patient wishes (e.g., for cosmetic reasons).
      • Wounds with a high risk of infection (e.g., hand wounds, delayed presentation, puncture wounds) should always be left open.
    • Antibiotic treatment and prophylaxis
      • Should be used for high-risk bite wounds (e.g., wounds to the hand, delayed presentation, puncture wounds) and for wounds requiring closure
      • First-line therapy is amoxicillin/clavulanate
    • Prophylactic vaccination
  • Complications [4]
  • Prevention [3]

References:[5]

  • Epidemiology [6]
  • Clinical features
    • “Dry bites” (bites without envenomation): minor local symptoms
    • Envenomation leads to varying degrees of local and systemic symptoms that depend on the amount and toxicity of the venom (see table below).
Common snakebites [7][8]

Rattlesnakes

Coral snakes

Black mamba snake
Distinguishing features
  • Subtle earth-tone colored skin with rattle tail, triangular head, and vertical pupils
  • Alternating red, yellow, and black color bands
  • Long, slender, cylindrical snake with a coffin-shaped head
Distribution
  • All US states except Maine, Hawaii, and Alaska
  • Southern US and northern Mexico
  • Sub-Saharan Africa

Venom

  • Cytohemoneurotoxic
  • Increases permeability of the cell membrane
  • Fibrinolytic and protein C-activation effect
  • Neurotoxin
  • Causes competitive inhibition of presynaptic and postsynaptic muscarinic AChR
Clinical features of envenomation Local
  • Bite painless or mildly painful
  • Swelling and paresthesia
  • Multiple bite sites
  • No local swelling and minimal tingling sensation
Systemic
  • Diagnostics: usually based on history (description of possible identifying features of the snake) and clinical features
Grading scale for snakebite severity [9][10]
Degree of severity Clinical features
Asymptomatic
  • Asymptomatic
  • Punctures or abrasions
  • Minimal edema and/or erythema
Mild
Moderate
Severe
Life-threatening
  • Management [7]
    • Antivenom administration
      • Can slow or halt the progression of toxicity and is most effective when administered within 4–6 hours of the snakebite [9]
      • Should only be given to patients with clear symptoms of envenomation and in whom the benefits are likely to exceed the risks of adverse reaction to antivenom
      • For pit viper bites: crotalidae polyvalent immune fab
      • Adverse effects: hypersensitivity, serum sickness
    • Pressure immobilization and/or tourniquets are not recommended as part of routine management in the US. [11]
    • Patients must be monitored closely for signs of cardiovascular instability and respiratory compromise.

  • General treatment includes cleaning of the wound, cooling, and analgesia.
  • They rarely require specific medical treatment.
Common spider bites
Brown recluse spider Widow spider
Distinguishing features
  • Violin-shaped marking on its cephalothorax
  • Black body with varying red marks
  • North American species: characteristic red hourglass mark on the ventral portion of the body
Distribution
  • South and North America
  • In the US, it is endemic to the Southeast and Midwest.
  • Found in many regions worldwide
  • In the US: Southwest
Venom
  • Necrotoxin
  • Causes local destruction of tissue integrity, leading to tissue necrosis
Clinical features Local
  • Initially painless bite that develops into an erythematous, painful blister within several hours.
  • Bluish-black skin discoloration usually seen within 24 hours
  • Formation of a dark black eschar by the end of the first week
  • Painful bite that turns into a circular red macule and then a target-like lesion
Systemic
  • Muscle pain and rigidity of the extremities, abdomen, and back
  • Autonomic neurologic symptoms can occur.
Specific treatment

Bark scorpion sting

  • Distribution: Box jellyfish are most commonly found in Hawaii, Northern Australia, and the tropical Atlantic.
  • Pathophysiology: Jellyfish have tentacles with specialized capsules (nematocysts) that attach to the skin and release venom. The toxicity of the venom depends on the species.
  • Clinical features
  • Diagnostics: based on history and clinical features
  • Treatment: Routine management depends on the jellyfish species and the geographic location. [12]
    • Apply topical vinegar: recommended only for some jellyfish species (e.g., box jellyfish)
    • Remove attached tentacles and rinse the sting site with seawater.
    • Immerse in hot water for pain relief.
    • Administer antivenom in the case of severe stings (e.g., stings affecting large areas, systemic symptoms).

  • Examples: bees, wasps, yellow jackets, hornets, fire ants
  • Distribution: worldwide
  • Pathophysiology: Insects from the Hymenoptera order release venom into tissue when stinging, triggering a local skin reaction and potentially life-threatening systemic reactions.
  • Clinical features
    • Local skin reaction at the site of the sting
      • Initial pain
      • Swelling and redness appear within minutes of the sting event.
      • Usually resolves within hours
      • Large local reactions (LLR): gradually extending area of swelling and redness (typically > 10 cm) that lasts for days [13]
    • Systemic allergic reactions, anaphylaxis are possible
  • Diagnostics: primarily a clinical diagnosis
  • Treatment

References:[14]

  1. Maniscalco K, Edens MA. Animal Bites. StatPearls. 2021 .
  2. Ramgopal S, Brungo LB, Bykowski MR, Pitetti RD, Hickey RW. Dog bites in a U.S. county: age, body part and breed in paediatric dog bites.. Acta Paediatr. 2018; 107 (5): p.893-899. doi: 10.1111/apa.14218 . | Open in Read by QxMD
  3. Savu AN, Schoenbrunner AR, Politi R, Janis JE. Practical Review of the Management of Animal Bites.. Plastic and reconstructive surgery. Global open. 2021; 9 (9): p.e3778. doi: 10.1097/GOX.0000000000003778 . | Open in Read by QxMD
  4. Ruha A-M, Kleinschmidt KC, et al. The Epidemiology, Clinical Course, and Management of Snakebites in the North American Snakebite Registry. J Med Toxicol. 2017; 13 (4): p.309-320. doi: 10.1007/s13181-017-0633-5 . | Open in Read by QxMD
  5. Lavonas EJ, Ruha A-M, Banner W, et al. Unified treatment algorithm for the management of crotaline snakebite in the United States: results of an evidence-informed consensus workshop. BMC Emerg Med. 2011; 11 (1). doi: 10.1186/1471-227x-11-2 . | Open in Read by QxMD
  6. Kanaan NC, Ray J, Stewart M, et al. Wilderness Medical Society Practice Guidelines for the Treatment of Pitviper Envenomations in the United States and Canada. Wilderness Environ Med. 2015; 26 (4): p.472-487. doi: 10.1016/j.wem.2015.05.007 . | Open in Read by QxMD
  7. Venomous Snakebites in the United States: Management Review and Update. https://www.aafp.org/afp/2002/0401/p1367.html. Updated: April 1, 2002. Accessed: December 29, 2021.
  8. Buchanan JT, Thurman J. Crotalidae Envenomation. StatPearls. 2021 .
  9. American College of Medical Toxicology, American Academy of Clinical Toxicology, et al. Pressure immobilization after North American Crotalinae snake envenomation. Clin Toxicol. 2011; 49 (10): p.881-882. doi: 10.3109/15563650.2011.610802 . | Open in Read by QxMD
  10. Treatment of Jellyfish Envenomation. https://www.aafp.org/afp/2014/0515/od1.html. Updated: May 15, 2014. Accessed: December 13, 2020.
  11. Bilò MB, Martini M, Pravettoni V, et al. Large local reactions to Hymenoptera stings: Outcome of re‐stings in real life. Allergy. 2019; 74 (10): p.1969-1976. doi: 10.1111/all.13863 . | Open in Read by QxMD
  12. Haftel A, Sharman T. Vibrio Vulnificus. StatPearls. 2020 .
  13. Rothe K, Tsokos M, Handrick W. Animal and Human Bite Wounds.. Deutsches Arzteblatt international. 2015; 112 (25): p.433-42; quiz 443. doi: 10.3238/arztebl.2015.0433 . | Open in Read by QxMD
  14. Holmquist L, Elixhauser A. Emergency Department Visits and Inpatient Stays Involving Dog Bites, 2008: Statistical Brief #101. Healthcare Cost and Utilization Project (HCUP) Statistical Briefs. 2006 .