2,273. An Animal With Two Spines

Maachalos Assuros 1:5

If a non-kosher animal gives birth to something that resembles a kosher animal, it may not be eaten even if it has split hooves and chews cud, resembling an ox or a sheep in all ways. All this is because things produced by non-kosher animals are non-kosher and those from kosher animals are kosher. This is why a non-kosher fish found in the stomach of a kosher fish is prohibited and a kosher fish found in the stomach of a non-kosher fish is permitted: because they didn’t produce these fish, they just swallowed them.

Maachalos Assuros 1:6

If a kosher animal gives birth to something that has two backs and two spines, or if an animal is found to be this way, it may not be eaten. This is what is meant by the word sh’suah, which is prohibited by the Torah in Deuteronomy 14:7: “These may not be eaten of those that chew cud and have split hooves: the sh’suah...,” meaning an animal that was born divided into two animals.