Male marking his territory

My cousin owns a male Doberman, almost 2 years old (named Sire). He was neutered a while ago and has the sweetest disposition. There is one problem though. Recently, he began urinating, or "marking his territory" more often than before. Just the other night he peed on my cousin's mattress so much, he had to throw it out! My cousin also took Sire to work with him the other day, and he ended up peeing on three different pieces of furniture. There were no other people present, but dogs have been there before (although never used the bathroom!). Any ideas on why he might be doing this now? Or what might help to fix the issue.. He's never had a problem before, there are no new changes or other dogs he is living with. It's just him & his owner. Thanks!

google N.I.L.F.

have him on a leash inside and watch him closely.

I did this with Charlie. He was doing the same thing. But with Charlie, after he pottied outside I let him off leash for a while. He then associated being good and getting to be free. It took him about a week to get it.

Tho I think with a puppy or a dog that is fully using potty inside might take longer.

Also, is there somthing that is making him territorial? My daughter and cat made him nuts sometimes. But when he realized I was boss, he listened to me better and stopped too.

Now going into petsmart where there are other dogs is a whole nuther story. He peed like 4 times while I was in there. :rolleyes:

ALSO a big tip. go buy some natures miracle and clean up previous spots from him and other dogs. Then maybe he won't smell the other dogs and feel he needs to remark.

Thank you!! Good tips!