I've heard a lot of different things. All I know is mom was a Jack russell Terrier
(She is 20lbs, very calm, and she loves food, and she loves to give kisses, she is super strong though for such a small dog. She has been able to pull over a 200 pound man to go after a squirrel)
So since mom was a Jack russell Terrier I'm thinking dad was probably a mutt, maybe made up of 2 or 3 breeds (there is no way she is just a Jack Russell Chihuahua mix
This is her.
Now her pictures can be deceiving on her size. she is only 20 lbs. I know that for a fact because she was just weighed at the vets.
Here is a picture of her with our Minature Poodle (14lbs)
More pictures coming soon