Pit vipers (rattlesnakes, copperheads, cottonmouths) cause the majority of venomous snake bites in North American dogs. Envenomation can cause local swelling, coagulopathy, and systemic effects. Antivenom given within 4-6 hours improves outcomes. Use the Triage/Emergency Specialist for assessment and the Drug Formulary for dosing.
Signs: puncture wounds (may be single or multiple), rapid swelling at bite site, pain, bruising, ptyalism, vomiting. Severe envenomation: coagulopathy (prolonged PT/PTT, thrombocytopenia), hypotension, tachycardia, hemorrhage.
Snake bite severity score (0-3) guides treatment. Grade 0: dry bite, no envenomation. Grade 1: local swelling only. Grade 2: moderate swelling, systemic signs. Grade 3: severe swelling, coagulopathy, shock.
Warning: Do not use tourniquets, ice, or incision/suction. These can worsen tissue damage. Keep the dog calm and transport immediately. Do not attempt to capture or kill the snake—identification is rarely necessary for pit vipers.
Crotalidae Polyvalent Immune Fab (CroFab) or F(ab')2 antivenom (Anavip) neutralizes venom. Dose: 1-2 vials IV initially; repeat based on clinical progression. Antivenom is most effective when given early.
Supportive care: IV fluids, pain management (opioids preferred; avoid NSAIDs with coagulopathy), antibiotics if tissue necrosis, plasma if coagulopathy. Monitor coagulation, platelet count, and swelling progression.
Coral snake envenomation (elapid) is less common but causes neurotoxicity. Antivenom exists but may be difficult to obtain. Supportive care and mechanical ventilation if needed.
- Pit viper bites: swelling, pain, possible coagulopathy—seek emergency care.
- Antivenom within 4-6 hours; 1-2 vials initially, repeat as needed.
- No tourniquets, ice, or incision—transport calmly.
- Monitor coagulation, platelets; opioids for pain.
- Prevention: avoid snake habitat, leash control, rattlesnake vaccine (adjunct only).