animal castration – through mediation or chemically

According to the Shulchan Aruch, castration of a male dog entails a Torah prohibition. (E.H. 5:11) The Gemara remains unresolved whether amira l'nochri (instructing a non-Jew), which is prohibited rabbinically on Shabbat, is prohibited also in other areas. The Shulchan Aruch and Rama rule that amira l'nochri applies also to other prohibitions, including castration. (E.H. 5:14; C.M. 338:6)

Thus, castration through a non-Jewish veterinarian is also not allowed. However, in cases of need, the Chasam Sofer (Responsa C.M. #185) allows through "heter mechira," selling to a non-Jew, who will have it castrated, and purchasing back from him. (See also Otzar Haposkim 5:83,85)

Rav Amar is further cited as having allowed amira l'nochri to castrate dangerous dogs on account of hezeka d'rabim (public danger). (See O.C. 334:27)

Castrating a male animal through medical means is also prohibited. (E.H. 5:12) Where the animal is in danger, some permit it even through a Jew and others only through a non-Jew. (Pischei Teshuva 5:12) However, from a veterinary perspective, castration through medication is less preferred.

Meir Orlian