It will depend on what was actually wrong with your piggy, whether you will get answers or not. If you need to have samples sent away, or the entire body, this can get expensive and more often than not unfortunately you will not get any remains back. Your vet will likely be able to give you answers on findings based on how their organs are looking or the presence of any tumours etc.
I've had 4 post mortems done on my piggies now, 3 were done by my regular vet and 1 by a locum who trained in pathology. Each one gave me peace of mind and the answers I was looking for without having to send them away. My regular vet didn't charge me very much, about £30 I think? although bless him he doesn't charge me as much as he should for most things, the locum charged me £60 and I was able to have the remains back to have them cremated. You'll have to specify if you want them back.
2 of mine were lost to tumours, 1 of which also had a massively enlarged heart, 1 just had an enlarged heart and the last passed due to an accident but they'd felt a mass that they didn't know what it was, turned out to be a failed kidney caused by internal damage during the accident.
You can only ask, one of the staff said they don't really do many of them but I don't think many people even ask so it's worth a try.
