In this section we will discuss a few issues the first is why it it is forbidden to castrate or spay a dog or any other animal. For the sake of clarity we will deal directly with dogs.
Castration constitutes a Tora prohibition even when this is being done for the dog’s own good. Shulchan Aruch (Even Ha’Ezer, Chapter 5, Section 11) states that it is likewise forbidden to instruct a non-Jew to castrate a dog. (If one already owns a dog and this is extremely necessary, one should consult a competent Posek, for there are some who allow selling the dog to a non-Jew who will then pass the dog to another non-Jewish veterinarian to neuter the dog. See Otzar Ha’Poskim, page 254.)
Their are Poskim who disagree whether or not one who touches a dog must wash one’s hands afterwards. According to Chacham Zalman, author of the Tanya (Shulchan Aruch Harav, Chapter 97, Section 3), one need not wash one’s hands after touching a dog. On the other hand, the Yafeh La’Lev (Chapter 4, Subsection 24) rules rather stringently on this matter.
It is praiseworthy to act stringently in accordance with the opinion of Yafeh La'Lev view. However, a basic hand-washing is sufficient and Netilat Yadayim is unnecessary.
Interestingly on and during the duration of Pesach and beyond, one may not feed a dog food which is non-kosher.
For these reasons and others, many still abstain from owning or raising a dog.
Summary: If one wishes in spite of the above they must be aware of the laws surrounding owning a dog.
Shabbat Shalom