This might help people understand why salt/preservatives are bad for our snakes. Sure, we can eat a can of "kippered snacks" those extremely salty little fish, and our kidneys would simply excrete the excess salt and remove it from our body, discharging it in the urine. This is necessary to retain salt balance. Otherwise the excess salt would dehydrate our cells through osmosis. In other words, the salt would pull the water right out of our cells and we would shrivel up and die if we didn't get rid of it.

http://www.slideshare.net/jayswan/ap-biology-chapter-44

The excess salt (and sodium based preservatives) would kill most snakes by causing renal failure. Why? there is some explanation of reptilian kidney function in this paper.

Read: http://jeb.biologists.org/content/214/13/2140.full.pdf