Lungworm is carried by slugs.
Hogs eat slugs, if the hogs need to eat a lot of slugs because they can't find anything else to eat such as beetles etc, then they increase their chances of getting invaded by the lungworm that is inside the slugs.
Lungworm are worms similar to the ones that can live in the gut of an animal,during the worms lifecycle the lung worm can invade the lung tissue of a hog to such an extent that the tissue can't work properly and infection can set in, symptoms similar to pneumonia, breathing probs, sometimes accompanied by a hacking cough, a hog with a lungworm cough can sound like a heavy smoker with a smokers cough, the hog may not eat and can fail to gain weight, if the condition is caught in time then the correct medication can rid the hog of the lungworm but sometimes there is so much infection caused that the hog can rapidly deteriorate and die.
Incidentally pet dogs can also get lungworm by eating slugs or eating the grass that slugs have been on but the vets can now give vaccinations to dogs against this, not sure if it can affect cats too but i would presume so as they eat grass sometimes.