Bacterial inflammation of the bladder can make a dog need to pee often, pass only small amounts, seem uncomfortable or get blood in its urine. But urinary stones, inflammation without bacteria and other diseases can cause almost the same symptoms. A urinary tract infection therefore cannot be reliably diagnosed from how the dog behaves alone.
The vet analyses the urine and may recommend a urine culture, especially with recurring problems or when the infection may be more complicated. International guidelines stress that antibiotics should be used when a bacterial infection is likely or confirmed, and that recurring infections should lead to an investigation of underlying factors.
Contact a vet for blood in the urine, frequent peeing or obvious pain. Fever, a reduced general condition, vomiting or a suspected kidney infection call for a quicker assessment. A dog that cannot pass urine needs emergency care.