Animal 

Identifying Features

Type of Envenomation

Clinical Features

Treatment

Widow Spiders

Yellow/red hourglass on belly

Neurotoxic- venom releases acetylcholine and norepinephrine

Rash- target lesion with a blanched center and surrounding erythema with localized diaphoresis

Severe muscle cramping and spasms involving large muscle groups (can mimic acute abdomen) and CNS excitation

Supportive (Benzodiazepines and opioids) and antivenin (Latrodectus antivenin) for severe symptoms

Brown Recluse 

Brown fiddle on cephalothorax

Cytotoxin- venom is thought to release hyaluronidase and sphingomyelinase D

Rash- Initially, a painless bite followed by hemorrhagic bleb formation in the center surrounded by erythema a few hours later

Severe envenomation can cause hemolysis, thrombocytopenia, and renal failure usually 24-72 hrs after the bite

Local wound care

No Antivenin

Coral Snake 

(Elapidae)

Red next to Yellow, Kill a fellow

Post-synaptically Neurotoxic- competitive inhibition of the muscarinic acetylcholine receptors

Rash- local edema and rash that is mild

Initial Sxs- nausea, vomiting, abdominal pain, dizziness

12 hrs later- neurotoxic which can present as descending muscle weakness, bulbar paralysis (ptosis, opthalmoplegia, dysarthria, and dysphagia)

Supportive Care and respiratory support

Antivenom should be administered to everyone

Pit Vipers

(Viperidae)

Characteristic pit midway between the eyes and nostrils.

Some will have triangular shaped head, elliptical pupils and fangs

Red on Black, Venom Lack

Coagulopathic and/or hemorrhagic w/ or w/out paralytic features

Rash- fang marks are often undetectable but can cause edema, ecchymosis, and/or hemorrhagic blisters (usually painful and can cause rhabdomyolysis)

Systemic effects: weakness, paresthesias, metallic taste, chest pain, and dyspnea

Hematologic- coagulopathy, thrombocytopenia, bleeding

Antivenin (CroFab)- reserved for moderate to severe envenomations; usually 4-6 vials