Why does my three year old dog nurse on toys and blankets?

For some reason my dog (spayed female three years old, frequently will nurse on a toy or blanket until saturated with saliva. This is bad because pretty soon everything near her gets all wet.

Generally, dogs that were either weaned too soon (for whatever reason) and/or taken away from their mothers and siblings before the age of eight weeks will do this sort of thing.

You don't say what kind of dog?? I have a 3 yr. old boston terrier that constantly chews and drools (only on his own toys) until his feet are totally soaked. Some dogs are just "chewers". I wouldn't worry unless she is chewing on things she's not supposed to. If It's her blanket let her do her thing! That's just my advice based on my dog.