How can you tell the difference between a kidney and bladder infection?

Bladder/kidney infx: Sometimes it is impossible to tell the difference, but often the difference is in the degree of symptoms. A simple bladder infection has mostly local discomfort with urinating, an urge to void with little urine, and possibly blood in the urine. A kidney infection is more systemic, with fever, chills and sweats, and pain more in the mid back or flanks. A cat scan can sometimes show which it is.

Kidney infection: Kidney infection (pyelonephritis) generally causes fever, chills and very significant flank pain. One generally feels "sick". Bladder infection (cystitis) rarely causes systemic symptoms. Discomfort in the pelvic area and irritative voiding symptoms are typical.