Translation:

173. He hath only forbidden you dead meat and blood and the flesh of swine and that on which any other name hath been invoked besides that of Allah but if one is forced by necessity without wilful disobedience nor transgressing due limits then is he guiltless. For Allah is Oft-Forgiving Most Merciful.

Notes (Tafseer)

173. Dead meat: maitat: carrion; animal that dies of itself; the original Arabic has a slightly wider meaning given to it in Fiqh (Religious Law); anything that dies of itself and is not expressly killed for food with the Takbir duly pronounced on it. But there are exceptions, e.g., fish and locusts are lawful, though they have not been made specially halal with the Takbir. But even fish or locusts as carrion would be obviously ruled out.

174. For prohibited foods, cf. also Q. v. 4-5; vi. 121, 138-146; etc. The teachers of Fiqh (Religious Law) work out the details with great elaboration. My purpose is to present general principles, not technical details. Carrion or dead meat and blood as articles of food would obviously cause disgust to any refined person. So would swine's flesh where the swine live on offal. Where swine are fed artifically on clean food, the objections remain: (1) that they are filthy animals in other respects, and the flesh of filthy animals taken as food affects the eater; (2) that swine's flesh has more fat than muscle-building material; and (3) that it is more liable to disease than other kinds of meat; e.g., trichinosis, characterised by hair-like worms in the muscular tissue. As to food dedicated to idols or false gods, it is obviously unseemly for the Children of Unity to partake of it.