What would cause a dogs lower jaw to be shorter in length than the top of mini Dachshund puppy?

It's not common for a puppy's lower jaw to be shorter than its upper jaw. It sounds like you might be describing a condition called undershot jaw, also known as brachygnathism.

Here are some possible causes:

* Genetics: This is the most common cause. Some dog breeds are predisposed to undershot jaws due to their genetics. Dachshunds, while not typically known for this condition, can be affected.

* Injury or Trauma: Trauma to the jaw during birth or early development could cause the jaw to grow improperly.

* Nutritional Deficiency: Inadequate nutrition during puppyhood can sometimes impact bone development, potentially leading to jaw deformities.

Important Note: It's crucial to consult a veterinarian if you suspect your puppy has an undershot jaw. They can diagnose the condition, determine the cause, and discuss potential treatment options. Early intervention can help minimize complications.

Possible Treatment Options:

* Observation: In some mild cases, the jaw may correct itself as the puppy grows.

* Surgery: In more severe cases, surgery may be recommended to correct the bite.

* Braces: In rare instances, braces can be used to help align the jaw.

Remember, a veterinarian is the best resource for determining the cause and appropriate treatment for any condition affecting your puppy.