Viper Bites in Cats

Vipera palaestinae, the most common venomous snake in Israel, causes the most snake bites in humans and animals in that country. Viper venom contains many compounds (eg, hemorrhagins, thrombins, cytolysin) that can cause local effects at the site of the bite as well as systemic effects and severe complications. 

It has been hypothesized that cats are more resistant than other species (eg, dogs) to venomous snake bites. This retrospective study analyzed the clinical signs, treatments, complications, and outcomes in 18 cats envenomed by V palaestinae in Israel. The authors found that all envenomations occurred during the hot, dry season (ie, May to October). The most common clinical signs were tachypnea, lameness, depression, fang-penetration marks, hypothermia, hematoma at the bite site, tachycardia, and bradycardia. Bloodwork often showed thrombocytopenia, hemoconcentration, leukocytosis, prolonged coagulation times, elevated serum creatine kinase activity, and hyperglycemia. Factors associated with death were lower body weight, lower initial rectal temperature, lower hematocrit, and lower total plasma protein. The mortality rate was 22%; this indicates that cats may not have an increased resistance to venom from snake bites.

V palaestinae is found in the Middle East, but other vipers are found worldwide. The specific insight is that cats experience equal or higher mortality following Vipera spp envenomations as dogs, in contrast to claims that cats demonstrate resistance to the venom. This may be because of cats’ small size in relation to the venom dose or cats being more likely to be bitten while unsupervised, which can cause a delay in receiving veterinary attention. Because of the small numbers of cats in this study, no inference can be made on treatment efficacy, but it is likely that cats should be treated in a similar way to dogs. Cats in areas frequented by snakes should be kept indoors if possible.—Elizabeth A. Rozanski, DVM, DACVIM, DACVECC