Doxies sometimes have this problem. It's called Alpecia or pattern baldness. In the past I had a 8# mini with very little hair on her chest and belly. Sometimes during the winter some of the hair would appear to grow back, but it never lasted long. Some people think it could be a seasonal allergy. You might start with having her examined by your vet and having her Thyroid checked, if the Thyroid is off it can cause baldness. However, if there is no problem with the Thyroid and it is pattern baldness, there is nothing you can do. Here's a couple of links that will help you understand Alopecia. Good luck.
Hmmm, I checked the links out and that sounds pretty much like my Doxie. Well, at least I shouldn't have much to worry about as far as her health goes. Thank you so much for the help!! It puts my mind more at ease.
Just a note to let you know my Boston Terrier is having a hair thinning problem. I had her Thyroid checked and it is low, so she will be starting on meds and hopefully it will correct the fall out. So I would have your Doxie's Thyroid checked, possibly simple meds might help. Good luck!
It's probably either her thyroid or seasonal alopecia . My first doxie (smooth coat) had thyroid issues, and her hair loss matches your description. She went on meds, and although the hair grew back, she was always thing through the chest and at the top of her ears.
Our current doxie (long hair) had thinning on her hind quarter which developed into a bald spot last winter. It turned out to be seasonal alopecia. This spot totally lost it's hair and turned black. Dr. said it was the lack of sunlight exposure. We gave her a melatonim tablet twice a day and exposed her to as much sun as possible. Her spot was totally cleared up and the hair grew back. So far no bald spot this year...