Animal bites and stings: Wounds or punctures of the skin made by any animal or insect.

• There are different causes of bites and stings caused by the following:

o Animal bites

Human bites

Dog, foxes and cat bites

Snake bites

Crocodile bites

o Stings

Bee

Scorpion

Spider

Centipede

• Snake bites and stings result in injection of venoms.

• Type of venom depends on the causative agent of the bite or sting.

Types of Toxins/Venom

• Cytotoxins cause local tissue damage.

• Haematotoxins cause internal bleeding.

• Neurotoxins affect the nervous system.

• Cardiotoxins act directly on the heart muscles.

• Myotoxins act directly on skeletal muscles.

Bites

• Human bite

o The wound is usually contaminated by mixed organisms.

• Dogs, fox bites and cat bite

o There is danger of transmission of bacterial infection and rabies.

o One should suspect rabies from animal bites.

• Snake bites

o Extremities usually are the sites of the bite.

o Venom is a mixture of enzymes and non-enzyme compounds.

o Most snake bites are not poisonous.

o Many bites from poisonous snakes do not result in poisoning (about 25%).

o Bites by non-venomous snakes can cause infection and allergic reactions.

o Bites by venomous snakes result in a wide range of effects, from simple puncture

wounds to life-threatening illness and death.

o The findings following a venomous snakebite can be misleading.

o A victim can have no initial significant symptoms, and then suddenly develop

breathing difficulty and shock.

Clinical Presentation of Animal Bites and Stings

Signs and Symptoms of Snake Toxins/Venom

• Local effects

o Pain and tenderness

o Swelling

o Blisters

o Wounds

o Numbness

o Necrotic tissue around the site of the bite

o Bleeding from bite site and internal organs (unchecked bleeding can cause shock or

even death)

• Nervous system effects

o Cobra and black mamba snakes produce neurotoxic venom that can act particularly

quickly by stopping the breathing muscles, resulting in death without treatment.

o Initially, victims may have vision problems, speaking and breathing trouble, and

numbness.

• Muscle death

o Venom from Russell's Vipers, sea snakes, spitting cobras, and some Australian

Elapids contain myotoxins that can directly cause muscle death in multiple areas of

the body.

o The debris from dead muscle cells can clog the kidneys, which try to filter out the

proteins. This can lead to kidney failure.

• Eyes

o Spitting cobras and Ringhals (cobra like snakes from Africa) can actually eject their

venom quite accurately into the eyes of their victims, resulting in direct eye pain and

damage.

• Heamorrhage

o Boomslang snakes produce a heamotoxin that causes poor blood coagulation leading

to bleeding in internal organs, under the skin and at the bite site.

Signs and Symptoms of Stings

• Most of the signs and symptoms are caused by bees, scorpions, spiders and centipedes

which may result in local effects, systemic effects, or both.

• Local effects include:

o Pain and tenderness

o Swelling

o Blister and erythematous rash

o Wounds

o Numbness

o Ischaemic local lesion

o Local necrosis

• Systemic effects include:

o Nervous system effects (transient fever, headache, vomiting, coma)

o Cardiovascular system effects (anaphylactic reaction)

o Respiratory system effects (pulmonary oedema, airway obstruction)

Management of Animal Bites and Stings

Primary Survey Assessment

• Remember ‘A-B-C’:

o Airway: Ensure patent airway and beware of excess secretions

o Breathing: Look out for dyspnea (difficulty breathing)

o Circulation: Look out for bleeding and hypotension

• Reassure patient to reduce anxiety

• Patient should not walk to avoid spread of venom

• No tourniquet or constriction bands

Secondary Assessment

• Look for systemic signs

• Assess affected limb and site of bite

• General treatment

o Reassure patient

o IV line/fluids

o Antibiotics

o Tetanus Toxoid prophylaxis

o Analgesic

Specific Treatment

• Neurotoxicity – may require oxygen and ventilation

o Neostigmine and atropine may prevent the use of ventilation

• Systemic poisoning – antivenom (beware of anaphylaxis)

o Give prophylactic antihistamine and steroids before antivenom

o Adrenaline is helpful for severe cases of anaphylaxis

• Titrate dose according to clinical response

• Extreme swelling – may need fasciotomy

• Monitor vital signs.

• Mammalian, dog and fox bite

o Elevate extremity with sling if edema is present

o Examine the wound for possible nerve or tendon damage, or bone injury

o Clean the wound with water and antiseptics solution and remove any damaged tissue

o Perform surgical debridement and wound should be left open

o Prescribe an antibiotic and Tetanus toxoid

o Give human rabies immunoglobulin

o Give rabies vaccine on days 0, 3, 7, 21, and 28

• Snakebite treatment

o Treat the breathing problems and shock

o Wash the wound with large amounts of soap and water.

o Inspect the wound for foreign bodies (e.g. broken teeth or dirt)

o Even a bite from a non venomous snake requires excellent wound care

o The victim needs a tetanus booster if he or she has not had one within five years

o The victim is monitored for worsening signs at the wound site, or worsening systemic

symptoms in the breathing or cardiovascular systems

o Do not cut and suck.

o Cutting into the bite site can damage underlying organs, increase the risk of infection

and bleeding, and does not result in venom removal

o Do not use ice.

o Ice does not deactivate the venom

o Do not use alcohol.

o Alcohol may deaden the pain, but it also makes the local blood vessels bigger, which

can increase venom absorption

o Do not use tourniquets or constriction bands.

o These have not been proven effective and may cause increased tissue damage

• The specific treatment of snake bite

o Give by very slow intravenous (IV) injection 20 - 30 mls of snake polyvalent antisera

diluted in 3 volumes of normal saline: 100 -150 mls may be given in severe

invenomination with symptoms of neurotoxicity and heamotoxicity.

o This therapy can be life-saving.

o Antivenom can cause allergic reactions, even anaphylactic shock, a life-threatening

type of shock requiring immediate medical treatment with hydrocortisone 200- 500

mg IV, or Adrenaline 1:1000 subcutaneous (S.C.) or IV 1-2 mg stat.

• Stings treatment

o Treatment will depend on the severity of the condition.

o It is important to note that no specific antivenom is available to counteract the poison

injected by the insect.

o Allergic reaction to the sting causes the majority of problems requiring medical

treatment.

o In case of a single sting with no allergic symptoms, remove any stings remaining in

the skin (most likely from bees).

o Application of ice to the sting site may provide some mild pain relief.

o Give an antihistamine such as diphenhydramine (Benadryl) for itching.

o Give non-steroid antinflamatory for pain relief as needed.

o Wash the sting site with soap and water.

o In severe allergic reaction (such as low blood pressure, swelling blocking air getting

into the lungs, and/or other serious breathing problems), treatment may include

intubation, antihistamines, steroids, epinephrine and IV fluids.

 

References

• Bewes P. (1984). A Manual for Rural Health Workers. Nairobi: African Medical and

Research Foundation.

• Burkitt G. & Quick C. (2002). Essential Surgery, Problems, Diagnosis and Management.

(3rd ed.), Churchill Livingstone.

• Russell R.C.G., Norman S.W. & Bulstrode C.J.K. (2004). Bailey and Love’s Short

Practice of Surgery (24th ed.). London: Edward Arnold.

• Steadman T.L. (1999). Steadman’s Medical Dictionary (27th ed.). USA: Lippincott

Williams & Willkins.