No animal is immune to snake bites, but pigs have a thicker layer of skin than most animals. According to Books Upstairs, this is due to the thick layer of adipose tissue that makes it harder for venom to seep into the bloodstream. Science Daily notes that adipose tissue is normally found beneath the skin and around internal organs in mammals.
Since pigs eat just about anything, they also readily devour snakes around them. Pigs also kill snakes out of natural instinct. Because humans have noticed pigs eating and rarely being affected by snake attacks, hogs have garnered a reputation as being immune to snake bites, but this is not entirely true.
A study from Loma Linda University contradicted this myth when testing the hazardous effects of snake venom on human skin. Because pig skin is similar to humans, hogs were used as test subjects. According to the findings, pig skin necrotized at the same rate of human skin when snake venom was injected. With that being said, a pig's reaction to a snake bite largely depends on the pig itself.
Wild pigs in particular have thick hides that are tough to penetrate, which is why many hunters need large caliber bullets to successfully hunt them. The hide of a wild pig is about as thick as armor around their vital organs. A domestic pig could also be a ferocious opponent against a snake, depending on the size and weight of the animal.