Farmed land animals are usually slaughtered at a different place to the farm where they were raised, in a facility called a slaughterhouse, also known as an abattoir.

The slaughter process, by its very nature, can cause the animal to suffer not only intense physical pain, but also physiological and psychological stress, not to mention negative emotions such as fear.

To try to reduce the physical suffering of animals during slaughter, it is common practice in many countries that animals should be stunned before slaughter, so that they are unconscious when they are killed.

However, stunning is not required in every country. Even in countries where it is the norm, there may be exceptions on religious grounds. For example, the Jewish method of slaughter called shechita does not allow any pre-slaughter stunning at all. The acceptability of stunning methods for preparing Halal-slaughtered meat has been extensively debated. Over the last few decades, reversible stunning methods have become more acceptable for Halal slaughtering due to an increasing majority of Muslim countries issuing Fatwas (religious rulings) that approve of stunning methods for the Halal slaughtering of food animals.

Several European countries, including Denmark, Belgium, Norway, Iceland, Slovenia, Sweden have banned all slaughter of farmed animals without pre-stunning. There is no exception to this rule on religious grounds. This is also the case in New Zealand.

In the case of Southeast Asia, pre-slaughter stunning is generally mentioned and recommended in the laws relating to animal welfare for most (though not all) countries. However, there are many documented cases in Southeast Asian countries of animals not being adequately stunned before the slaughter process, and this means that the animals will have suffered greatly by being conscious while their arteries and jugular veins were severed with a knife.

Slaughterhouses typically handle many animals per day, and slaughterhouse workers may be paid for how many animals they slaughter. Consequently, stunning may be rushed or overlooked to save time, resulting in animals being fully conscious when they are killed. Working at speed may also result in the killing process being rushed, meaning that it may not be carried out in the most effective way and animals may take longer to die (and therefore suffer for a longer time) than if the slaughter process was completed properly.

It is important to note that even if animals are stunned effectively prior to slaughter and rendered unconscious, it is still highly probable that they suffered extreme fear and stress prior to slaughter.

Another point to note is that in countries where chickens and ducks are displayed live at wet markets and slaughtered on the spot after they have been purchased, there is often little or no regulation in the slaughter process. The animals may not be stunned, equipment may be basic, and unskilled individuals may perform the task. Animals often witness fellow animals being slaughtered, which for these sentient beings, who appear to empathise with each other, is probably highly stressful and also is likely to cause feelings of fear and panic.