Bailey had a UTI a few months back. She was urinating often and her stomach was upset. It took a round of antibiotics to clear it up. She is five though and I know they are fairly common in adult dogs.
Make sure your puppy is getting enough water and going to the bathroom enough. I read awhile ago that moistening their food with water and giving them citrus fruit juices help also. I do moisten her food but have never tried the juice. Your vet will be able to give you more information, though!
Stella had a UTI recently (but she is an older girl at 8 years!). IMO, the best thing to remember is water, and lots of it! Make it distilled or filtered. This is important. You might also want to add a cranberry supplement. I use Solid Gold's Berry Balance. I also add can food to the dry and mix with water. Stella is notorious for not drinking alot, so I feel this is what contributed to her UTI because at the time she was eating a high-protein dry food without any moist additions. That has changed. She now gets a moderate protein dry (Eagle Pack Holistic Select Anchovy), can food (varieties like EPHS, Innova, Wellness 95%, Instinct, etc.), supplements (SG Berry Balance, and Wholistic Canine Complete Joint Mobility) and plenty of filtered water added in. Good Luck!