Sharī’ah is silent on the issue of mercy killings regarding pet animals. In
this regard, consequently, the matter seems to rest on human intellect. Both
ways can be adopted depending upon the circumstances. If a person thinks that
he should put an end to a poor animal's misery, he can do so and if he is of
the view that he can soothe its ailment by some sort of treatment, he can
continue to look after the creature in whatever way he is able to.