How old is it? Especially if its urine is not very yellow, it could be a sign of kidney failure, which is terminal if not treated, and then sometimes, even then.
The dog is marking it's territory. It's normal for a dog to do that.
Take your dog to the vet. Mine just had the same problem. Got back from the vet 10 minutes ago. It could be infected anal glands. Especially if your dog is also peeing more than normal. Apparently these usually empty during peeing, and can get infected. A simple antibiotic treatment for 2 weeks and all is well again.
If your dog is still peeing on the couch, then you have not trained him/her well enough yet.
If a small dog no more than 2 litters if a larger dog no more than 4 litters it does start to get harder on the dog.
Diet Underlying illness
A dog can stay without peeing for max of 4 and a half hours
You need to take the dog to the vet ASAP.
Peeing.
get him used to peeing with the leash on, so he'll get used to it.
By peeing
urine trouble!
shoot it