Well, I'm no expert, but from what I see, they look like lymph nodes. Are they egg-shaped and kind of rubbery? That's how they palpate on a mammography exam. And they are in the axilla. That goes along with your description. Maybe the pigs were fighting an infection. The first picture is with a knife inserted into something. That looks like an artery to me. Do they all taste bad? Maybe some are infected glands and some are not.
Peggy