Coralsnake envenomation is an uncommon but very dangerous occurrence throughout the southern United States. Coralsnakes are in the family Elapidae with other snakes such as cobras, kraits, and sea snakes; they are the only elapids native to North America. As with pit vipers, envenomations can range from mild to severe. However, unlike most pit vipers, coralsnake venom contains potent neurotoxins that can lead to paralysis and death. This PowerPage will focus on the identification, diagnostics, and management of coralsnake bites and will also discuss some common misconceptions and contraindications.
Key points
- The most common clinical signs of envenomation by a coralsnake include vomiting, ptyalism, tachypnea, paresis, paralysis, pigmenturia, and if left untreated, death.
- The only way to treat an envenomation and prevent progression of clinical signs is with administration of antivenom. Unfortunately, coralsnake antivenom is not readily available. All coralsnake antivenoms are human products. Antivenom is available at certain veterinary institutions or potentially a human antivenom bank.
- As with pit viper envenomations, steroids, Benadryl, and antibiotics are not indicated. NSAIDs are contraindicated.
- There is no single test to confirm whether a patient has been envenomated.
Pathophysiology
- The two main components of coralsnake venom are Phospholipase A2 and alpha neurotoxin. Phosolipase A2 and alpha neurotoxin bind to postsynaptic nicotinic acetylcholine receptors, which prevents motor function and eventually leads to respiratory paralysis, ventilatory failure, and death. Phospholipase A2 also causes hemolysis of red blood cells ranging from mild to severe.
- Puncture wounds are extremely small and often impossible to find. There is no swelling, redness, or bleeding with a coralsnake bite.
- Moderate to severe cases will require mechanical ventilation, typically for a few days until the venom dissipates.
- Severe envenomations may also cause massive hemolysis, possibly even requiring blood transfusions. Filtration of hemoglobin and myoglobin by the kidneys can lead to pigmenturia and acute kidney injury (AKI).
Clinical signs
- Vomiting, ptyalism, tachypnea, paresis, paralysis, pigmenturia, orthopnea/air hunger.
Diagnostics
- PCV/TS to monitor for anemia and evidence of hemolysis.
- Venous or arterial blood gas to monitor CO2 and O2 levels.
- Chemistry if possible, to monitor for signs of organ injury, +/- creatine kinase (CK).
- Blood film to check for echinocytosis, which is common in snake envenomations. This may be especially helpful if a snakebite was not observed or if it is not immediately apparent that an envenomation has occurred.
Treatment
- Antivenom is the only thing that can neutralize circulating venom. It will not reverse current signs but will prevent progression of paralysis and hemolysis.
- Average doses range from 1-4 vials of antivenom.
- Treat with exposure – if a dog or cat has had a coralsnake in its mouth or is found playing with one, treatment with antivenom is recommended.
- Even with antivenom therapy, some patients will still become paretic; the goal is to keep them off the ventilator.
- Fluid therapy will help to maintain renal perfusion. Pigmenturia is common after hemolysis and rhabdomyolysis.
- Pain medications and sedatives are NOT recommended unless you need to mechanically ventilate. These will interfere with the patient’s clinical signs.
- Oxygen therapy if dyspnea/hypoxemia is present.
- Patients will often be paretic for days to a few weeks, therefore recumbency care is very important. This includes but is not limited to frequent rotation of patient, passive range of motion, urinary catheterization, etc.
- In severe cases, mechanical ventilation with a critical care ventilator is needed.
- Additional treatments in severe cases include packed red blood cell transfusions and hemodialysis if severe AKI occurs.
- Hypersensitivity reactions can happen, but are rare. Monitor closely for signs of collapse, vomiting, dyspnea, and acute hypotension during antivenom administration. Treat with epinephrine and diphenhydramine if this occurs.
Additional important information
- Coralsnake antivenom is different than pit viper antivenom, and they cannot be used interchangeably.
- Referral to a critical care hospital is recommended for all coralsnake bites in case mechanical ventilation is needed.
- NSAIDs can lead to worsening coagulopathies as they are platelet inhibitors. NSAIDs can also lead to acute kidney injury in cases of hypotension or severe hemolysis or rhabdomyolysis. They should be avoided as well to prevent GI ulceration.
- Multiple studies show that glucocorticoids are of no benefit. In some snake bites, they may worsen the outcome and potentiate venom effects as well as immunosuppress. Additional considerations are that steroids can lead to GI ulceration.
- Diphenhydramine (Benadryl) is of no benefit. It may also lead to altered mentation, which could be dangerous in patients who are already showing signs of coralsnake envenomation.
- Antibiotics are not indicated in coralsnake envenomations.
