Praise be to Allaah.
If their harm cannot be
warded off except by means of what is mentioned of poisoning them, then that
is permissible. The Standing Committee for Issuing Fatwas was asked about
the permissibility of killing with poison or other means, especially if they
are harmful or causing the transmission of some diseases.
They replied:
There is nothing wrong with
killing cats if they are harmful or carry harmful diseases, if it is not
possible to get rid of them by means other than killing.
End quote. Fataawa
al-Lajnah al-Daa’imah (16/190).
They were also asked about
the ruling on poisoning cats that are found in large quantities in some
hospitals, because they harm the patients.
They replied:
If the situation is as
described, that the cats pose a danger and it is not possible to protect the
patients from their harm or ward off their evil, and getting rid of their
harm can only be done by killing them, then it is permissible to kill them
by the easiest means of disposing of them, whether it is by poison, shooting
them with bullets, and so on.
Fataawa al-Lajnah al-Daa’imah (26/190).