Praise be to Allah.
It is proven that the Prophet (peace and blessings of Allaah be upon him) said: “Whoever keeps a dog, except a dog for hunting, farming or herding livestock, one qiraat will be deducted from his reward every day.” Narrated by the two Shaykhs (al-Bukhaari and Muslim) in their Saheehs. And he (peace and blessings of Allaah be upon him) said: “Whoever keeps a dog that is not for farming or herding livestock, one qiraat will be deducted from his reward every day." Saheeh – agreed upon. From these texts and others it is known that what some Muslims do, keeping a dog for none of the three reasons mentioned by the Prophet (peace and blessings of Allaah be upon him), and only doing that in imitation of the kuffaar or just for fun, is haraam and cannot be justified under any circumstances.
Giving medical treatment and food to permissible animals should be done only as much as is needed, and spending on them should not go beyond that to the extent of extravagance, because that is the action of the brothers of the devils, as Allaah says (interpretation of the meaning): “Verily, the spendthrifts are brothers of the Shayaateen (devils), and the Shaytaan (Devil‑Satan) is ever ungrateful to his Lord” [al-Isra’ 17:27]. What is mentioned in the question about some people doing surgery on these animals for which there is no need, rather it is more akin to fooling around, is undoubtedly haraam, because it is changing the creation of Allaah or mutilating the animal, and this is the action of the devils, as Allaah says (interpretation of the meaning):
“Allaah cursed him. And he [Shaytaan (Satan)] said: ‘I will take an appointed portion of your slaves.
119. ‘Verily, I will mislead them, and surely, I will arouse in them false desires; and certainly, I will order them to slit the ears of cattle, and indeed I will order them to change the nature created by Allaah’”
[al-Nisa’ 4:118, 119]
And when the Prophet (peace and blessings of Allaah be upon him) passed by a donkey that had been branded on its face, he said: “May Allaah curse the one who branded it.” Narrated by Muslim in his Saheeh.
Moreover these operations are a kind of extravagance and inappropriate spending. What is befitting for the Muslim is to be moderate in his spending and use of permissible things, and this world should not be his main concern or his ultimate hope. Allaah says, describing His righteous slaves (interpretation of the meaning):
“And those who, when they spend, are neither extravagant nor niggardly, but hold a medium (way) between those (extremes)”
This had to do with permissible things, so how about things that are not permissible? Each person will be asked on the Day of Resurrection about every dirham that he acquired: how did he earn it and on what did he spend it?
And Allaah is the Source of strength. May Allaah send blessings and peace upon our Prophet Muhammad and his family and companions. End quote.
Standing Committee for Academic Research and Issuing Fatwas