Painful or difficult urination is indicated with the medical term of dysuria. A painful urination is normally accompanied by other symptoms such as hesitancy, or straining, prior to, during or after urination.
The above symptoms together with an increase of frequency of urination, (pollakiuria), are clinical signs indicating to the bladder or the urethra ( the duct that conveys the urine from the bladder out of the body).
The most common cause of dysuria in dogs is bacterial cystitis. On the other hand bacterial cystitis is unusual in cats and occurs only in cats that seem to have a reduced ability to resist infection.
Other causes of dysuria include: presence of stones or crystals, tumours, conditions affecting the reflex of urination, anatomical abnormalities, obstruction caused by other structures compressing the urinary tract and a minority of other uncommon causes.
If your pet shows difficulty or pain when urinating, he should be examined by a vet ASAP, to establish possible causes and set up a diagnostic and treatment plan.