Mojave toxin-type ascending flaccid paralysis after an envenomation by a Southern Pacific Rattlesnake in a dog


  • Sarah R. Hoggan DVM,

    Corresponding author
    • Emergency Department of California Veterinary Specialists, Murrieta, CA
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  • Amy Carr DVM, DACVECC,

  • Karen A. Sausman MS

  • Authors declare no conflict of interest.

Address correspondence and reprint requests to

Dr. Sarah R Hoggan, California Veterinary Specialists, 25100 Hancock Ave, Suite 116, Murrieta, CA 92562, USA.




To describe the clinical presentation and case management of a dog that developed ascending flaccid paralysis after being envenomated by a Southern Pacific rattlesnake.

Case Summary

A dog was presented after it was bitten by a Southern Pacific rattlesnake. Only mild local edema and a minor coagulapathy developed, which is atypical for the Southern Pacific envenomation where hemotoxic effects are more commonly observed. Instead, a severe, rapidly progressing, ascending flaccid paralysis leading to acute respiratory failure, consistent with Mojave toxin, was seen. The patient was treated with repeated doses of antivenin and supported with mechanical ventilation. Despite clinical improvement of the paralysis over subsequent 3 days and successful weaning off the ventilator, the dog decompensated and succumbed to acute respiratory distress syndrome.

New or Unique Information Provided

The geographic region where this envenomation occurred has a documented population of Southern Pacific rattlesnakes with Mojave toxin in their venom. To the knowledge of the authors, this is the first reported case in the veterinary literature of an ascending flaccid paralysis, consistent with Mojave toxin, developing after an envenomation by a Southern Pacific rattlesnake.