Unfortunately, I've had my share of hardware disease. Learned the hard way and now, every cow, bull & retained heifer has a magnet. But still lose some to glass (thank you, booze cruisers that throw your bottles in my pastures) or other sharp objects. It is generally a slow death but if the size of the object they ingested is long enough, when it penetrates the reticulum and subsequently heart, they're gone pretty fast. That said, yes, generally swelling of the brisket and sometimes legs - congestive heart failure. Drooling, runching of the back, laying down with their head up for better air flow. Temp is quite often normal. Loss of appetite and poo will become hard and dark. There's not a darn thing you can do if they already have a magnet. Antibiotics may help but generally just prolongs the inevitable.