Originally, treif and treifah referred to the meat of an animal that was found already dead or which has been killed by another animal - such as venison which has been killed by hounds (Torah, Leviticus 22:8: "× Ö°×‘Öµ×œÖ¸×” וּטְרֵפָה לֹא יֹאכַל, לְטָמְאָה-בָהּ: ×Ö²× Ö´×™, יְהוָה." or "That which dieth of itself, or is torn of beasts, he shall not eat to defile himself therewith: I am the LORD").However, over the years, the term has come to mean any food that is not kosher no matter how it was obtained. Thus pork is trief and would be even if was slaughtered in accordance with the Jewish shechita slaughtering laws, as would be rabbit, hare, dolphin, birds of prey, sturgeon and any dish which combines meat and dairy.
From Wikipedia (http://en.wikipedia.org/wiki/Judaism) The laws of kashrut ("keeping kosher") are the Jewish dietary laws. Food in accord with Jewish law is termed kosher, and food not in accord with Jewish law is termed treifah or treif. The Torah cites no reason for the laws of kashrut, but the rabbis have offered various explanations, including ritual purity, teaching people to control their urges, and health benefits. Kashrut involves the abstention from consuming birds and beasts that prey on other animals, and creatures that roam the sea floor eating the excretions of other animals. Major prohibitions exist on eating pork, which is considered an unclean animal, and seafood. Meat is ritually slaughtered, and meat and milk are not eaten together, based on the biblical injunction against cooking a kid in its mother's milk.
Kosher hot dogs are prepared following all the rules of kashrut. Muslims have a similar food process called Halal foods.Answer:Kosher rules that would apply to hot dogs specifically include:The method of killing and bleeding the animalThe absence of blood in the mixThe absence of meat from animals that are not allowed according to the rules of kashrut (pork, rabbit, etc)The absence of milk or milk products in a meat hotdogThe absence of grain in the mix during PassoverThe cut of the meat (in most places, the hind quarter of an animal isn't used because the difficulty of removing the necessary veins, arteries, etc to make it kosher is cost prohibitive.)Non-kosher hot dogs have anything that resembles meat that can't be sold as a cut of meat - lips, snouts, muscle scrapings from bones, whey powder, odd animals. Kosher is much the same, but from a much more limited set of possible ingredients.The most important difference to the average non-kosher consumer is that non kosher hot dogs are usually a mixture of beef and pork, while kosher ones are usually all beef.