I have a small female Dachshund dog. She was born March 31, 2014. How can I tell when she is done with bone growth, as compared to fatty growth from eating everything she can put her teeth to?
For all breeds of dog, there are two main stages of puppy growth. The first is the rapid part where the main part of your puppy's skeleton develops. During this time, his bones grow and lengthen – a process made possible by the growth plates at the ends of long limb bones. This is from birth to around 4-5 months old.
The second phase is slower, where muscles develop and the skeleton continues to develop and the dog gain weight until he has reached full growth. There will be some bone growth in this phase, but not nearly as much. When a puppy reaches about one year of age, the growth plates close. After this point, an injury to the leg is not nearly as serious a problem as in a younger puppy, where it can result in overwhelming damage or deformity. The duration of this second phase varies considerably, depending on the ultimate size of the adult dog.
According to The Journal of Nutrition, adult body weight (which I think is what you are asking about) is reached when growth rates fall to zero. A small-breed dog that will weigh 20 pounds or less as an adult reaches its mature body weight between 9 and 12 months of age. (In contrast, something like a Great Dane might continue to grow until he is 2 to 3 years old.)
General consensus on this forum post seems to be that people have found their dachshunds stop growing around 12 months.
As you have realised, dachshunds can have problems with weight gain, and I suspect this might be part of the reason you want to find out when your dog has stopped growing - so you know whether to start keeping an eye on her weight or not. A good way of doing this seems to be to feel their ribcage to see if you can still feel the ribs, and check that you can still see a definite waistline as viewed from above.