Sterilizing Animals

Is it halachically permissible to Sterilize ones pets?

Shalom!

Thank you for your question!

As a general rule, sterilizing animals is a Torah prohibition derived form the fact that only animals that are able to reproduce may be offered as sacrifices. Even fish are included in the ban. It is interesting to note, however, that there is some discussion whether sterilizing female animals is a biblical transgression or a rabbinical one. This is because females are not truly required to reproduce.   

One who ignored this halacha and sterilized his animals is required to sell the animal as a penalty.

There are different views on whether the ban on sterilizing animals also applies to non-Jews with most authorities ruling that they are not included in the ban. Le'halacha due to the doubt, a Jew should not instruct a non-Jewish veterinarian to sterilize a male animal but one may have a non-Jew sterilize a female one.

It should be noted that halacha differentiates between two different forms of sterilization: active sterilization and passive sterilization. Active sterilization is when the sterilization is performed directly upon the reproductive organs and this is almost always forbidden, certainly for a Jew. Passive sterilization is more indirect, such as causing the sterilization by taking medication, which is often permitted. Indeed, a woman may use the birth control pill when birth control is permitted. There are further leniencies when the sterilization is reversible.

As one can see, this is a very serious halachic issue, and the best thing to do is to avoid the issue altogether by not acquiring a pet that requires sterilization or by acquiring one that was already sterilized by a non-Jew.

Shabbat 110b; Chagiga 14b; EH 5:11,14 with commentaries; Chatam Sofer , EH 20