I have a miniature dachshund who is going to turn 1 years old next month. I currently feed her NutriSource Small Breed Puppy food. Should I now switch her to adult food?

I would. It is a good practice to make a switch to adult chow for large breeds as early as 4 months. It slows growth giving more time to develop sturdy joints. Since even Mini Dachshunds are prone to back problems, it might be a good idea to switch now. Over weight definitely will lead to early back problems. Check your dog as illustrated in this link, http://www.puppychow.com/products/popup_body_condition.aspx You can have your vet confirm your judgment. Adjust food and exercise as needed to maintain ideal body condition. One of the great things about small dogs is their long, active lives with good care.