Answer
Wa `alaykum as-salamu wa rahmatullahi wa barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
If your cat is too sick to recover and there is no hope of it ever being able to lead a normal life, or you do not have the means and resources to get adequate treatment for it, then you must hand it over to the humane society. It is up to them to decide what to do with the cat.
In his response to the question you raised, Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states,
Message of Mercy
Islam is a mercy not only for all humans but for all creatures as well. Almighty Allah says, “We sent you not save as a mercy for the beings.” (Al-Anbiyaa’ 21:107)
Being a mercy for all creatures, Prophet Muhammad (peace be upon him) showed us through his commandments and teachings how to tend to and care for these creatures.
Prophet Muhammad explained Allah’s anger and punishment for those who burden animals or treat them mercilessly. For example, he once said, “A woman was deemed to enter the Fire because of a cat. She imprisoned it and neither fed it nor set it free to eat the rodents of the earth.” (Al-Bukhari)
Mercy Killing
If your cat is sick and it can be treated, you must do so if it is within your means and ability to do so. Simply allowing mercy killing because the cat is sick is not allowed in Islam.
Should you do so, you will be responsible before Allah for causing undue suffering to an animal.
If, however, your cat is too sick to recover and there is no hope of it ever being able to lead a normal life, or you do not have the means and resources to get adequate treatment for it, then you must hand it over to the humane society. It is up to them to decide what to do with the cat.
If they decide the process of mercy killing because of not finding a home, or because of their decision that such an animal cannot be cared for or let free, mercy killing is permitted according to the principles of the Shari`ah.
It is generally agreed by scholars that if leaving certain animals free becomes a cause of genuine concern for the safety of human habitat and society, it is permitted in Shari`ah to ‘to put them down’ as a lesser of the two evils.
Allah Almighty knows best.
Editor’s note: This fatwa is from Ask the Scholar’s archive and was originally published at an earlier date.