Some dogs will experience pain with a UTI and will yelp or whimper while urinating. Other signs that your dog may have a UTI is possible weight loss, vomiting and anorexia. Be advised that not all UTI's in dogs will show symptoms. It's always best to consult your dog's vet.
The most common symptom of a urinary tract infection in dogs is frequent urination or inappropriate urination (wetting in the house when otherwise properly housetrained). A simple urinalysis can diagnose an infection and antibiotics are usually curative.