A snake in the grass

ANY years ago I was walking in the New Forest when I met a fellow dog walker with a fine pair of English springers. We chatted for a while and he told me how adder bites were a major hazard in the summer when walking his dogs. One of his spaniels had been bitten on several occasions but survived. So can a dog gain immunity from snake bite? I gathered that the local veterinary practices were well used to seeing dogs suffering from snake bites, and that these were rarely fatal.