The ethics of pouring salt on a slug can be a subject of debate. From a strictly biological perspective, pouring salt on a slug can be considered cruel because it causes harm and can lead to the slug's death. Salt draws water out of the slug's cells through osmosis, leading to dehydration and eventually killing the slug.
Slugs are living creatures, and many people advocate for treating all living beings with respect and compassion. Deliberately causing harm to any living creature, even if it is a small and seemingly insignificant one like a slug, raises ethical questions.
From a practical standpoint, some individuals may resort to using salt to control slug populations because slugs can be pests in gardens and can damage plants. However, there are alternative, more humane methods for dealing with slug problems, such as using barriers, traps, or organic slug repellents that do not cause harm to the slugs.
Ultimately, the decision to use salt or any other method to control slugs is a personal one, but it's essential to consider the potential consequences and ethical implications of our actions towards other living beings. Whenever possible, seeking humane and environmentally-friendly solutions is encouraged.