Snake envenomation is a critical and time-sensitive emergency that all veterinarians must be well-prepared to handle. Understanding the effects of snake venom, recognising clinical signs, and administering appropriate treatment can mean the difference between life and death for your patients.
Following our recent webinar on snake envenomation, we were inundated with questions from veterinary professionals keen to refine their approach to treating snakebite cases. We reached out to our ECC Specialists to shed further light on key clinical considerations and best practices. We hope these insights can help guide your decision-making in the field.
1. Is pre-treatment with antihistamines or steroids recommended before administering antivenom?
A common concern in snakebite treatment is whether to pre-treat with antihistamines and/or steroids before administering antivenom. While these medications may help mitigate allergic reactions, their routine use before antivenom administration is not universally recommended. The primary concern is that steroids do not provide immediate benefit in neutralizing venom effects, and antihistamines may not significantly reduce the risk of anaphylaxis. However, their use may be considered on a case-by-case basis, particularly in patients with a history of hypersensitivity.
2. Should you use one or two vials of antivenom?
When we discuss using one or two vials of antivenom, we are generally referring to the combined tiger/brown snake antivenom. The choice between one or two vials depends on the severity of envenomation, clinical signs, and the response to initial treatment. A single vial may be sufficient for mild to moderate cases, while severe envenomation cases may require additional doses to fully neutralize the venom.
3. Should you dilute antivenom and what’s the administration protocol?
Yes, antivenom is typically diluted—often in 100mL of crystalloid fluids—and administered intravenously over 15 minutes. This controlled administration helps minimize adverse reactions while ensuring effective distribution throughout the circulatory system.
4. Should you use Mannitol in snakebite management?
Mannitol has been suggested as a means to “open the tubules” to prevent toxic necrosis from haemoglobin breakdown products, rather than to address oliguria or anuria. There is some debate regarding its routine use, as it is not considered standard of care. However, if used, it may be beneficial for patients with pigmenturia secondary to venom-induced haemolysis. This could be relevant in cases involving both red-bellied black snakes (RBBS) and brown snakes where pigmenturia is present.
5. Is pigmenturia a common symptom of Brown Snake envenomation?
Pigmenturia is more commonly associated with Red-bellied Black Snakes due to their hemolytic venom properties. However, some clinicians have noted an increasing incidence of pigmenturia in Brown Snake envenomation cases. This may be due to variations in venom composition or improved diagnostic recognition. Further investigation and case studies may help clarify this observation.
6. What biochemical changes should you expect to see in cats following snakebite?
Cats can exhibit different biochemical responses to snake envenomation compared to dogs. For brown snake envenomation, we typically expect elevated coagulation times. In Red-bellied Black Snake envenomation, haemolysis is a more prominent feature. Given these variations, a thorough diagnostic workup—including coagulation profiles and hematology—is essential when managing feline snakebite cases.
7. Are there additional ventilation needs for brachycephalic dogs?
This is a particularly interesting and complex topic. Some clinicians have observed that brachycephalic dogs may have a higher likelihood of requiring ventilation following snake envenomation. This could be due to multiple factors, including the physiological stress of envenomation, airway conformation challenges, and potential secondary complications such as pulmonary dysfunction. More data is needed to determine whether brachycephalic breeds are inherently at higher risk, but this observation certainly warrants further discussion and study.
8. Are dilated pupils a clinical sign of envenomation, and if so, how many ‘points’ is it worth in a clinical scoring system?
While pupillary dilation can occur, it is not always a definitive sign of envenomation. Its diagnostic significance likely depends on other accompanying clinical signs and should be interpreted in the broader context of the patient’s condition.
9. What pain relief medications are recommended and commonly used by Specialists?
Pain management is a crucial aspect of snakebite treatment. While opioid analgesics (such as methadone or fentanyl) are frequently used for their effective pain control, adjunctive therapies like NSAIDs may also be considered when appropriate. The selection of analgesia should be tailored to the severity of the envenomation and the individual patient’s needs.
10. Is there any benefit in giving additional vials of antivenom 24-48+ hours after the initial envenomation if the patient is not improving clinically?
While most of the venom is neutralized with early administration, delayed antivenom dosing may be considered in cases where ongoing venom effects are suspected. This decision should be guided by clinical signs, laboratory results, and the patient’s overall response to initial treatment.
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Expert commentary provided by Dr Rob Webster BVSc (Hons) FANZCVS (Emergency & Critical Care) & Dr Ellie Leister BVSc (Hons) FANZCVS (Emergency & Critical Care)