However, in a puzzling discovery, their blood actually exaggerated the destructiveness of venom from the Western diamondback, common to the arid Southwest. Other squirrel populations also showed varying degrees of resistance to prairie and Western diamondback rattlesnake venom. However, their protection was weaker for the nonnative rattlers than for the northern Pacific rattlesnake. Such differences, the researchers say, could provide clues for developing safer, more effective antivenin for people bitten by rattlesnakes. A UC Davis study published in 1987 found that squirrel blood serum could protect mice from rattler venom.
Mice have no natural resistance to rattlesnake bites.
A rattlesnake's venom is a complex mixture that can both paralyze its prey and begin digestion from the inside out. Antivenin currently used to treat people bitten by rattlesnakes typically comes from horses made immune by injecting them with increasing doses of venom. However, Biardi and Coss said the horse develops an immune response to all the components in venom, not just the toxins. Humans treated with the antivenin develop antibodies to the horse serum itself, creating the risk of a potentially lethal reaction if another round of treatment is needed, Coss said. Antivenin developed from ground squirrel blood serum would have far fewer foreign proteins, reducing the chances of anaphylactic shock from a second treatment, he said.