Pit Viper poisoning

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Pit Viper[1]
Acute facial edema associated with pit viper snake bite[2]

Snake-bite poisoning by Pit Vipers is relatively uncommon in dogs, but has been reported in dogs[3].

The Pit Viper (crotaline snakes, pit adders), which includes rattlesnakes, lanceheads and Asian pit vipers, are the largest group of venomous snakes in the United States and Asia and are involved in an estimated 150,000 bites annually of dogs. However, mortalities rates in dogs is relatively low.

Pit Vipers are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head.

Snakebite envenomation by this snake may be identified by fang puncture wounds but primarily as a focal site with a rapid onset of severe swelling, hemorrhage, pain, and potentially necrosis. It is possible for pit vipers' venom to be strictly neurotoxic with virtually no local signs of envenomation. The venom consists of 90% water and has a minimum of 10 enzymes and 3 to 12 nonenzymatic proteins and peptides in any individual snake[4].

The onset of clinical signs after envenomation may be delayed for several hours and the current recommendations for first aid in the field are to keep the victim calm, keep the bite site below heart level if possible, and transport the victim to a veterinary medical facility for primary medical intervention.

The patient should be hospitalized and monitored closely for a minimum of 8 hours for the onset of signs of envenomation.

Crotalid venom causes hematologic abnormalities, local tissue damage, hypotension and occasionally neurological disease.

Blood tests usually show marked thrombocytopenia, hemolytic anemia and various forms of coagulopathy, including defibrination without disseminated intravascular coagulation[5].

The mainstay of treatment includes intravenous crystalloid fluid therapy, antivenom, and analgesic medications.

Currently available antivenom products include a mixed polyvalent Antivenin (Crotalidae) Polyvalent (ACP(a)) and Crotalinae polyvalent immune Fab (Crofab(b))[6].

Glucocorticoids (e.g. prednisolone), nonsteroidal anti-inflammatory drugs (e.g. meloxicam) and antihistamines (e.g. diphenhydramine) are not included in the majority of recommended treatment protocols, although there are some reports that describe their use[7].

Antimicrobial therapy and blood products are used only when clinically indicated.

There is a vaccine available, but at present, it is of unknown efficacy because of a lack of documented scientific information.


  1. Wikipedia.org
  2. Being Stray
  3. Cline CR & Goodnight ME (2013) Pit viper envenomation in a military working dog. US Army Med Dep J Jan-Feb:28-33
  4. Peterson ME (2006) Snake bite: pit vipers. Clin Tech Small Anim Pract 21(4):174-182
  5. Armentano RA & Schaer M (2011) Overview and controversies in the medical management of pit viper envenomation in the dog. J Vet Emerg Crit Care (San Antonio) 21(5):461-470
  6. Woods C & Young D (2011) Clinical safety evaluation of F(ab')₂ antivenom (Crotalus durissus-Bothrops asper) administration in dogs. J Vet Emerg Crit Care (San Antonio) 21(5):565-569
  7. McCown JL et al (2009) Effect of antivenin dose on outcome from crotalid envenomation: 218 dogs (1988-2006). J Vet Emerg Crit Care (San Antonio) 19(6):603-610