I'm asking you not to breed a 10 year old female, I've seen some horrible things happen from this. When I worked at a vets office in Connecticut, these people used their poor dog as a breeding machine only to make money, and that dog was so sick when they brought her in. She was 12 years old and pregnant, and had mummified babies inside her. When he cut her open, infection shot all over the room, and she was in an isolation tank for about a week, poor thing.
When the owners came in to get the dog, the vet (GOD BLESS HIM, HE WASN'T JUST OUT FOR THE MONEY!) wouldn't give the dog to them and said they were mistreating the dog and he would fight in court to not let them have her, they walked away and although she was sick for a long time, she got better and lived with the vet.
Dogs are like people in that they get too old to reproduce even though they can still go into heat. Just don't do it. It takes a horrible toll on the poor old body. Get one of the fixed.
This could be what's called "False Pregnancy", like chasha says. It's caused by a hormonal imbalance after the heat cycle ends, usually a few weeks after. In itself is pretty harmless and usually passes after a short time. Nipple discharge is common, so are behavior changes (like starting to 'mother' toys, etc)
But I would be quite watchful and careful, as you mention she has extreme lethargy, and a very swollen belly. Does she have a vaginal discharge? Does she have excessive thirst, or has she vomited?
I think if her lethargy worsens, or if she will not eat, or you notice anything which makes you think she's sick (even slightly) -then take her to the vet immediately, because it could be Pyometra.
Pyometra is a serious infection of the uterus. There are two kinds: Open Pyometra (in which a discharge, usually unpleasant-smelling is present) -and Closed Pyometra (the more serious of the two, in which there is usually no discharge, and no other signs, except that there can be swelling of the belly, often vomiting, or inability to eat, great thirst, often fever, and extreme lethargy.
If it is Pyometra, she will need a complete hysterectomy (emergency spaying) There really is no other good solution.
"Fixed" male dogs are very frequently able to mate quite fully with a female, even achieving the "tie" exactly as an entire male would. But there would be no likelihood of a fixed male making a female pregnant, unless, of course, he had only recently been neutered. In that case, sperm do survive for some time, and it's advisable to wait a few months before letting a recently-neutered male mount an entire female.
discharge from the nipples can also mean an infection. may want to get her checked out.
If your male was fixed ,Then he cannot get her pregnant.He can have sex with her,But you dont have to worry about any puppies.If she is producing milk and swollen then she could be having a false pregnancy.My pekingese did that a few years ago and she produced milk and gained weight.Well keep us posted Take care and God Bless