Aslam

Praise be to Allah.Shaykh

Muhammad ibn Saalih al-‘Uthaymeen was asked this question and he said:

If an animal gets sick, if it is an animal

whose meat it is not permissible to eat, and there is no hope that it

will recover, then there is no sin on you if you kill it, because if

it is kept alive it will become a burden on you which may be a waste

of your money, as you will have to spend on it and this spending will

be a waste of your money. Keeping it alive until it dies without giving

it food and drink is haraam, because the Prophet

(peace and blessings of Allaah be upon him) said: “A women went to Hell

because of a cat which she detained. She did not feed it when she detained

it, and she did not let it free to eat of the vermin of the earth.”

But if it is an animal whose meat may be eaten, and it reaches a state

where you cannot benefit from it or give it to someone else who can

benefit from it, then the ruling is the same as that concerning an animal

whose meat is haraam, i.e., it is permissible to kill it, whether you

slaughter it or kill it with bullets. Do whatever is easiest on the

animal, because the Prophet (peace

and blessings of Allaah be upon him) said: “If you kill, kill well,

and if you slaughter, slaughter well. Let each one of you sharpen his

blade and let him spare suffering to the animal he slaughters.”