The Hanafis said that there is nothing wrong with neutering animals, because that benefits both the animals and humans.
The Maalikis said that it is permissible to neuter animals whose meat may be eaten, and it is not makrooh, because that makes the meat better.
The Shaafa’is made a distinction between animals whose meat is eaten and others. They said that it is permissible to neuter animals when they are small if they are animals whose meat is eaten, but it is haraam in other cases. They also stipulated the condition that this neutering should not cause the animal’s death.
As for the Hanbalis, it is permissible in their view to neuter sheep because that makes the meat better, but it was said that it is makrooh in the case of horses etc.
Imam Ahmad said: I do not like for a man to neuter anything, rather that is makrooh because of the prohibition on causing pain to animals.
See
al-Majmoo’ 6/155;
al-Adab al-Shar’iyyah, 3/144, 145;
al-Fataawa al-Hindiyyah, 5/358)
There is also a comment on neutering cats: “If neutering cats will bring some benefit or ward off some harm, then there is nothing wrong with it, as it says in
al-Kubra.”
(
al-Fawaakih al-Dawaani, 2/346)
Hence we say that if there is some benefit in neutering the cat and if that will not cause its death, then it is permissible.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said:
If there are too many cats and they are a nuisance, and if the operation will not harm them, then there is nothing wrong with it, because this is better than killing them after they have been created. But if the cats are ordinary cats and are not causing a nuisance, perhaps it is better to leave them alone to reproduce.
Fataawa Islamiyyah, 4/448