Got 5 dogs that have lived through rattlesnake, cotton-mouth and copper head bites on a regular basis and they were all born with no dew claws. And believe me, I let em swell and if they make it they make it.
I use no drugs for snake bite... natural selection only. Hadn't lost a dog in 12 bites and going strong.

ALL dogs are born with FRONT dew claws.
The rear dew claws are a genetic trait of certain breeds of dogs.
The old timers I grew up around always said that a snake bite wouldn't hurt dogs that had rear dew claws . .