Pyelonephritis in Cats
Dr. Bari Spielman
A complete blood count (CBC) may be within normal limits, but an elevated white blood cell count may be present.
Certain diagnostic tests must be performed to diagnose pyelonephritis definitively and to exclude other disease processes that may cause similar symptoms. A complete history, description of clinical signs, and thorough physical examination are all an important part of obtaining a presumptive (probable) diagnosis of pyelonephritis. In addition, the following tests are recommended:
A biochemical profile may be within normal limits, but it may reveal elevations in kidney enzymes or electrolyte abnormalities.
A urinalysis may reveal blood, white blood cells, protein or bacteria in the urine. The absence of any or all of these does not rule out pyelonephritis.
A bacterial urine culture is performed to confirm a urinary tract infection, however may be negative in some cases of pyelonephritis.
Abdominal radiographs (X-rays) are an important part of any baseline work-up. Although they may be within normal limits, they may reveal changes in kidney size, urinary calculi, or help to rule out other diseases and causes of the patients' clinical signs.
Abdominal ultrasound is recommended in most cases suspect of having pyelonephritis. It is helpful in evaluating the kidney and potentially differentiating between upper and lower urinary tract infection. There are characteristic changes seen within the renal pelvis (inside of the kidney) that are consistent with pyelonephritis. Kidneys may be enlarged in acute (sudden onset) cases, and small in chronic (long term) cases. Ultrasound is also helpful in evaluating for the presence of stones throughout the urinary tract. It is a noninvasive procedure that often necessitates the expertise of a specialist and/or referral hospital.
Your veterinarian may recommend additional tests to exclude or diagnose concurrent conditions. These tests are not always necessary in every case, although they may be of benefit in certain individuals, and are selected on a case-by-case basis. These include:
Excretory urography. This intravenous dye study "lights up" the upper urinary tract (kidneys and ureters) and is helpful in documenting pyelonephritis. It also helps detect stones in the urinary tract, and may identify other abnormalities, such as ectopic ureters. An ectopic ureter is a congenital abnormality in which the ureter (the tube that drains the kidney into the bladder) joins the bladder in an abnormal position, causing a host of clinical signs, most commonly, urinary incontinence (leaking) and recurrent infections.
A bacterial culture of the renal pelvis. With the guidance of abdominal ultrasound, this test may be particularly important in the patient who has a negative urine culture obtained from the bladder.
Kidney biopsy. In a few cases, this invasive procedure may be of benefit in diagnosing pyelonephritis and may necessitate exploratory surgery in certain cases.
Stable patients can be treated as outpatients as long as they are monitored closely. With appropriate therapy, most patients do quite well, and can expect to see a full recovery. In more chronic cases, response to therapy can take longer and occasionally response may be poor. It is important that you follow all recommendations by your veterinarian very closely, and that you address any questions or concerns that arise during the treatment protocol immediately.
Correction of any underlying predisposing factors such as ectopic ureters, urolithiasis or prostatitis is imperative to treatment.
Antibiotic therapy selected on the basis of bacterial culture and sensitivity of the urine or renal tissue is the most important part of therapy. It is important to administer all medication as directed by your veterinarian. Usually, a treatment protocol of at least four to six weeks is indicated.
Dietary modification is recommended in animals with concurrent kidney failure or urolithiasis.
Hospitalization, intravenous fluid therapy, and antibiotic administration may be necessary in certain cases of pyelonephritis.
Surgical intervention may be necessary in cases of pyelonephritis that are associated with or secondary to urinary calculi.