Overview and controversies in the medical management of pit viper envenomation in the dog

Abstract

Mortality from North American crotalid envenomation is generally rare and is influenced by several variables, including the amount of venom injected, the size and species of snake, the size of the victim, the location of the bite, time elapsed until treatment, and the therapy initiated. Mortality rates range from 1% to 30%.

Retrospective analysis of clinical findings and outcome of cats with suspected rattlesnake envenomation inSouthernCalifornia: 18 cases (2007–2010)

“…Proteolytic enzymes in the venom cause coagulopathy and necrosis . Fibrinolytics can lead to increased clotting times and a disseminated intravascular coagulation (DIC)‐like disorder in which spontaneous bleeding is rarely seen . This disorder is called “venom induced coagulopathy” and results in pure defibrination.…”

“…The clinical signs of envenomation with a neurotoxin can include weakness and paralysis secondary to noncompetitive calcium channel blockade . The clinical signs are usually seen by 8–19 hours post envenomation and usually within 30 minutes . The rate of absorption from the site of envenomation may account for the delayed clinical signs …”

“…Phospholipase A is a component of snake venom common to all species of Crotalinae . The phospholipase A has an effect on the lecithin contained within the RBC membrane causing echinocytosis in a dose‐dependent manner . It can progress to a hemolytic anemia at higher doses .…”

“…It can progress to a hemolytic anemia at higher doses . Echinocytosis is transient and is only found in 89–92% of dogs with known envenomation but not in all cases . The transformation usually resolves by 48 hours .…”

Comparison of the protective effect of a commercially available western diamondback rattlesnake toxoid vaccine for dogs against envenomation of mice with western diamondback rattlesnake (Crotalus atrox), northern Pacific rattlesnake (Crotalus oreganus oreganus), and southern Pacific rattlesnake (Crotalus oreganus helleri) venom

“…6,7 The authors are not aware of any data on evaluation of the effectiveness of the CAT vaccine in scientific journals. 8 Manufacturer data and advertisements suggest this CAT vaccine is efficacious against bites from WD rattlesnakes and also provides cross-protection against envenomation from other rattlesnake species. 9,a However, analysis of snake venom reveals it to be a complex milieu of peptides and proteins, and venom from related species and subspecies of rattlesnakes can differ markedly in composition.…”