Forequarters For effective underground work, the front must be strong, deep, long and cleanly muscled. Forequarters in detail: Chest -The breast-bone is strongly prominent in front so that on either side a depression or dimple appears. When viewed from the front, the thorax appears oval and extends downward to the mid-point of the forearm.
Yup. Normal. I used to wonder about this too because I feel like it became more prominent as they started to mature. For my guys you can fit a good finger on top of the bone it sticks out so much.
It is called the keel bone on a Dachshund, like the keel of a ship. It makes their chest cavity larger to have the stamina to dig deep into Badger dens. The larger chest cavity also is attributed to the Dachsunds loud bark.