Unclean animals, in some religions, are animals, on whose consumption or handling is labelled a taboo. According to these religions' dogmas, persons who handle such animals may need to purify themselves to get rid of their uncleanness.
The most well known prescriptions concerning clean and unclean animals are probably those found in the Bible. Both the books Leviticus and Deuteronomy contain lists of unclean animals but the idea can also be found in the book of Genesis in the story of Noah and the Ark.
Of clean beasts, and of beasts that are not clean, and of fowls, and of every thing that creepeth upon the earth|||
The Book of Leviticus states:
Nevertheless these shall ye not eat of them that chew the cud, or of them that divide the hoof: as the camel, because he cheweth the cud, but divideth not the hoof; he is unclean unto you.|||Bible_(King_James)/Leviticus#Chapter 11
It should be noted that the translations of some of the aforementioned animals from the Hebrew are a matter of dispute in classical Jewish commentaries. With respect to birds the Torah only specifies ones which may not be eaten and the translations of these are also a matter of contention in traditional Jewish texts so it is common practice to eat only birds with a clear tradition of being kosher, eg. domestic fowl:
Many additional animals are not mentioned specifically by name, but from the characteristics mentioned in the books of Leviticus and Deuteronomy, may also be considered to be unclean. For example, all shellfish are generally considered unclean. Examples of animals often considered to be unclean by their characteristics:
Bible_(King_James)/Leviticus#Chapter_11 permits certain kinds of "winged swarming things" (i.e. insects) while prohibiting others; however, today rabbis are uncertain as to which insects were specifically permitted, so now all insects are prohibited to be on the safe side. An exception to this is a number of Yemenite communities that have retained their own traditions with respect to kosher locusts. As a result these particular locusts are considered kosher for the specific community which has the tradition. Bees' honey is, however, considered kosher because the honey is not made by bees, but is rather collected Nectar and concentrated by bees. There are no exceptions to the rule that any product of a non-kosher animal is also non-kosher, for example gelatin (but see the controversy on shellac). Within the past twenty years "kosher gelatin" has begun appearing. Some of this is derived from cows or from fish and made in a manner keeping with kosher traditions; others are derived from a plant or seaweed base using agar or pectin.
In order to eat an animal or bird it must be slaughtered according to Jewish law (Shechita). This involves cutting the animal's trachea and esophagus, the carotid artery and jugular vein are also severed in this operation – as are most arteries and veins leading to and from the brain – with a sharp knife that has been thoroughly checked for imperfections beforehand. The cut must be swift and without pause, to avoid tearing, and must be performed by an expert. Fish must also be killed before being eaten, but no particular method is specified in Jewish law.
The animal must then be determined to be free of treifot – which are 70 different categories of injuries, diseases and abnormalities – whose presence renders the animal non-kosher.
Not all parts of the animal may be eaten; certain fats, known as Chelev, may not be eaten. As much blood as possible must be removed from the meat, either by soaking, salting and rinsing or by broiling over a fire. In addition the sciatic nerve in each leg and the fat surrounding the nerve must be removed.
It is forbidden to cook, eat, or derive any benefit from mixtures of milk and meat (and their by-products). It is also forbidden to cook or eat dairy products together with poultry as a rabbinic injunction against mixing milk and meat.
The Qur'an states:
"Forbidden to you are: dead meat, blood, the flesh of swine, and that on which hath been invoked the name of other than Allah. that which hath been killed by strangling, or by a violent blow, or by a headlong fall, or by being gore#Etymology 2d to death; that which hath been eaten by a wild animal; unless ye are able to slaughter it; that which is sacrificed on stone [Altar?]; [forbidden] also is the division by raffling with arrows: that is impiety..." Qur'an (English translation)#Al-Maidah - The Table Spread
According to Muslims the most important condition is that bismillah (pronouncing the name of Allah) be performed at the time of slaughter. Also important is that the meat of those animals were ended by Zabiha (Sharia slaughter) of which tasmiyah is a condition. If not those animals are considered Maytah (carrion) and are expressly forbidden. The meat of animals slaughtered by a Kafir (unbeliever) or Mushrik (polytheist) is also forbidden.
Dogs are mentioned in the holy book of Islam the Quran several times e.g. in the main story of sura 18 where a dog is a companion of the dwellers of the Cave. The Quran also tells that it is permissible to eat what trained dogs catch (5:4). Nevertheless, many Islamic teachers state dogs should be considered unclean and that Muslims licked by them must perform purification. According to a Sunni Islam Hadith, anything a dog touches must be washed seven times .
Trading dogs for money has been discouraged by Islam. According to the majority of Sunni Muslims, dogs can be owned by farmers, hunters, and shepherds, for the purpose of hunting and guarding only.
"For it seemed good to the Holy Ghost, and to us, to lay upon you no greater burden than these necessary things; that ye abstain from meats offered to idols, and from blood, and from things strangled ..." Bible (King James)/Acts#Chapter 15
The commonly held theological position is that with the death and resurrection of Jesus, the "Old Covenant" and its restrictions no longer apply (See Christian View of the Law for the different viewpoints).
In the First Epistle to Timothy it states:
"...commanding to abstain from meats, which God hath created to be received with thanksgiving of them which believe and know the truth. For every creature of God is good, and nothing to be refused, if it be received with thanksgiving: For it is sanctified by the word of God and prayer." Bible (King James)/1 Timothy#Chapter 4
In the Epistle to the Colossians it states:
"...Beware lest any man spoil you through philosophy and vain deceit, after the tradition of men, after the rudiments of the world, and not after Christ....Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross; 15 And having spoiled principalities and powers, he made a shew of them openly, triumphing over them in it. 16 Let no man therefore judge you in meat, or in drink, or in respect of an holyday, or of the new moon, or of the sabbath days." Bible (King James)/Colossians#Chapter 2
However, there are Torah-submissive Christians who hold different interpretations of passages such as those cited and believe that the dietary restrictions continue under the new covenant. For example, in Bible (King James)/Acts#Chapter 11 Peter was convinced that it would be out of character for the Lord to recommend an unclean diet. (See also Bible (King James)/Acts#Chapter 10 for context.) Bible (King James)/Acts#Chapter 11 clarifies Peter's vision. These verses indicate that God was instructing him not to refer to gentiles as "unclean" as it was common in Israel, indicating that salvation had been extended to the gentiles. One modern example of a Torah-submissive group is the Seventh-day Adventist Church whose co-founder Ellen G. White was a proponent of vegetarianism. Many Seventh-day Adventists avoid meat for health reasons, though vegetarianism is not a requirement.
In the Roman Catholic Church, it was forbidden to eat meat (defined as the flesh of any warm-blooded animal) on Friday, but as a penance to commemorate Christ's death rather than for meat's being regarded as "unclean" (exceptions are few, such as when Christmas falls on a Friday, in which case Thursday is the day of abstinence). After the Second Vatican Council, the mandatory Friday abstinence from meat was limited to Lent, although some traditionalist Catholics still maintain the abstinence year-round. In Eastern Orthodoxy, both Friday and Wednesday were similarly considered off-limits. Many Protestants on the other hand have never observed the tradition, and may consider the tradition to be pagan in origin.
In 1966, British anthropologist Mary Douglas published the influential study Purity and Danger: An Analysis of Concepts of Pollution and Taboo. In Purity and Danger, Douglas first proposed that the kosher laws were not, as many believed, either primitive health regulations or randomly chosen as tests of Jews' commitment to God. Instead, Douglas argued that the laws were about keeping symbolic boundaries. Prohibited foods were those which did not seem to fall neatly into any category. Her theory was that pigs were declared unclean in Leviticus because pigs' place in the natural order was ambiguous since they shared the cloven hoof of the ungulates, but did not chew cud.
A 1985 study by Nanji and French found that there was a significant correlation between cirrhosis and pork consumption. Modern day swine raising is very different from earlier times with greater exposure to toxins but reduced exposure to pests and disease.