When my female chihuahua came in season, my mini dashund would not leave her side. He is incredibly obsessed with her. He follows her everywhere and guards her against our other dogs. He won't let anyone near her. Is this normal?

Is he neutered? If not please don't breed them. There are enough puppies in the world, being taken to shelters every day.

As far as him "guarding her" I'm not a canine behavioral expert so I'm not sure, but it sounds like he's "claiming her" as his mate, neutered or not.

I echo buzzworthy's post.
I hope all male dogs in the house are neutered.
I also agree that it sounds more like he is claiming her and not wanting anyone else to go near HIS girl.

If he is neutered you may need to separate the Chi girl anyway before she gets frustrated with him.