Litter box problems

Question
Hello!
I have a 4 month old pig who has started having accidents in the past 2-3 weeks. He is going pee and poop in his litter box however, when I let him out of his cage he has a tendency to pee in the living room. He usually pees in the same spots when he has accidents. I am firm with him and I let him know he has made a mistake after he does it and then I clean it vigorously. I am not sure if he is remembering the location or if he can smell his pee after such deep cleaning. He seems to know he has done something wrong, yet he has done it multiple times in the last few weeks. I have tried letting him out and putting him back in repeating intervals to give him a chance to use his box but he still continues to pee downstairs.

Previously he would pee when no one was looking so I started to only bring him downstairs when  he is on his leash. I thought that this would not only serve as additional leash training time but it would keep him in close sight so he wouldn't pee. Today he proved this theory wrong when he started to pee over my foot.

We have ordered the book by Priscilla Valentine but until it arrives I was hoping you would have some suggestions to help correct our guy's behavior.

Thanks!

Answer
Piggy can both smell the problem spot and remembers that it is there.

He seems reluctant to go in his box. Make sure it's big enough for him, he must be able to stand in it slightly stretched with all four feet a comfortable distance apart. Also, it needs to be shallow, because pigs hate to step up to go potty. If the bottom is slippery add a rubber textured liner or bathtub no-slip stickers.

If there is no room in the cage for a bigger box, get a bigger box anyway and put it somewhere fairly close to his cage and easily accessible.

Make him potty in his box, either the old one or a new, bigger one, before letting him go anywhere. Do not take him out of the cage room or away from the new box until he has actually gone potty. Tell him to potty and praise him when he finally does. This may take several minutes the first few times, because he is used to waiting and then pottying on the accident spot. But if he's already gone in his box, he's far less likely to have the urge to potty on the problem spots.