Russell’s viper envenomation in a 9-month pregnant mare saved with high-dose antivenom: a first-in-world case report.

Research Overview

• This article reports the first known case of a 9-month pregnant mare surviving a severe Russell’s viper snakebite using high-dose antivenom treatment.
• The case highlights challenges in managing snakebite and envenomation effects in pregnant large animals, demonstrating successful maternal and foetal outcomes despite complications.

Background and Significance

• Snakebite during pregnancy is rare but can cause serious health risks to both mother and unborn offspring, especially due to the severity of venom effects.
• While snakebite in pregnant women has been documented with known obstetrical complications, snakebites in pregnant animals, particularly horses, are extremely rare with no prior documented cases involving pregnant mares.
• Russell’s viper (Daboia russelii) is a venomous snake prevalent in South Asia, known for causing significant morbidity and mortality.

Case Description

• The subject was a 5.5-year-old Marwari mare in the 9th month of pregnancy.
• The mare received confirmed double bites to the muzzle area from a Russell’s viper.
• Following the bites, the mare developed rapidly progressing craniofacial edema (swelling of the head and face) and respiratory difficulties.
• She also experienced severe venom-induced consumption coagulopathy—a condition where the venom causes blood clotting abnormalities leading to bleeding risks—with recurrent episodes of worsening clotting problems (rebound coagulopathy).

Clinical Management and Treatment

• Management included intensive monitoring of clinical signs and blood coagulation status to guide treatment decisions.
• An unusually high total dose of 60 vials of equine polyvalent antivenom was administered to neutralize the venom effectively.
• The high dose and prolonged treatment were necessary due to several factors:
  • The large burden of venom injected by the two bites.
  • Increased bleeding risk related to pregnancy-associated physiological changes.
  • Delayed redistribution of venom from facial tissues, possibly acting as a reservoir prolonging venom effects.

Outcomes and Implications

• The mare achieved complete clinical recovery, and notably, the foetus remained viable throughout the treatment and recovery period.
• This outcome suggests that aggressive, carefully monitored antivenom therapy can be effective even under complex conditions involving pregnancy and severe envenomation.
• The case sheds light on specific challenges in managing snakebite in pregnant large animals, such as:
  • Venom depot effect in local tissues causing prolonged toxicity.
  • Recurrent coagulopathy requiring repeated or high-dose antivenom administration.
  • Preservation of foetal health during intensive treatment.
• This report fills a gap in veterinary and medical literature by documenting the first-ever case of Russell’s viper envenomation in a pregnant horse and its successful management.

Conclusions

• Close monitoring of coagulation parameters and readiness to administer high doses of antivenom are vital in managing severe envenomation in pregnant mares.
• This case provides a valuable reference for veterinarians handling similar emergencies, highlighting the possibility of favorable mother and foetus outcomes despite high venom challenges.
• Further research and case reporting are encouraged to advance understanding and treatment protocols for snakebite in pregnant large animals.