Salam Dear Rosemary,
Thank you for your question and for contacting Ask About Islam.
I am afraid I might not be able to give you a clear cut answer to your question. In fact, the four schools of fiqh (jurisprudence) have different answers to questions about pigs. Even questions of using pig parts for external use—such as the bristles for brushes and the skin for leather—receive different answers from different scholars.
Most Muslim sources cite the pig’s habit of wallowing in its own filth as the reason for abhorring it.
Non-Muslim sources, however, such as Web sites on raising pigs, usually state that pigs are clean by nature and naturally keep their dunging areas away from their eating and sleeping areas.
However, if the animals are overcrowded and overheated, they may wallow in their own filth. Pigs do not have sweat glands and need to wallow in mud or sit in water to cool off when they are hot. If they don’t have a clean place to wallow, they will where they can.
Pigs do have some other nasty behaviors. If left to forage on their own, they do not stick to a vegetarian diet but will also eat carrion. And when stressed such as by being placed with strange pigs in crowded conditions, they may resort to cannibalism.
I’m afraid that’s the best I can tell you, Rosemary. Most likely you are surrounded by Muslims who follow one particular school (madhhab) of fiqh, and that is why you hear of pigs being so reviled. While the Maliki School is more tolerant of pigs as animals, I doubt that you would find any Maliki scholar “embracing” pigs.
Since we are forbidden to eat them, we are also forbidden to raise them for non-Muslims to eat, just as we are forbidden to produce alcohol for others to drink.
I hope this has answered your question. If you have any other questions, please contact us.
Thank you and salam.