How can I tell if my 1 yr old golden has a urinary tract infection?

You can't tell without taking a urine sample to the vet. That means following your dog around the day of the visit.
One possible sign is frequent urination, and another is spotting around the house, because of PAIN!

The most common signs of a UTI is excessive urination without much output. You will see a lot of straining with a few drops of urine actually coming out. If you're lucky, you may even see some blood. Infected urine has a stronger odor. Your dog will also act uncomfortable.. panting, pacing.. things like that. Your dog will be unable to really hold it until potty time. BUT some UTI's are very suble and the above symptoms are not seen. It is best to have your dog checked by a vet. There are more things that can happen with the urinary tract besides infection.. such as cancer or stones.