Overview of Canine Pyelonephritis
Pyelonephritis is an inflammation of the kidney. We generally refer to pyelonephritis as a bacterial infection of upper urinary tract including any part of the kidney. Pyelonephritis is often referred to as a “kidney infection”.
General Causes of Pyelonephritis in Dogs
Ascending urinary tract infections (originating from the lower urinary tract) caused by bacteria
Hematogenous (from the bloodstream) seeding of infection is much less common
What to Watch For
Signs of pyelonephritis in dogs may include:
Excessive drinking and urinating
Abdominal or back pain
Straining to urinate
Loss of appetite
Diagnosis of Pyelonephritis in Dogs
Baseline tests to include a complete blood count, biochemical profile, and urinalysis are recommended in all patients. Although often within normal limits, there may be changes consistent with kidney failure or urinary tract infection. Additional tests may include:
A bacterial urine culture to check for associated infection
Abdominal radiographs (X-rays) to rule out calculi (stones) and other diseases that might mimic pyelonephritis
Abdominal ultrasound to visualize the urinary tract (in particular, the renal pelvises) and other abdominal structures
Excretory urography (a dye study of the upper urinary tract including the kidneys and ureters)
Treatment of Pyelonephritis in Dogs
It is most important to determine whether the patient’s condition warrants admission to the hospital for treatment or treatment at home as an outpatient. Treatment may include:
Dietary modification in those patients with concurrent renal (kidney) failure or urinary calculi
Antibiotic treatment, based on urine culture and sensitivity
Administer all medication and diet as directed by your veterinarian. Return for follow up as recommended and notify your veterinarian if any change is noted in your pet’s condition.
In-depth Information on Pyelonephritis in Dogs
Pyelonephritis is an inflammation of the kidney, and is most often due to a bacterial infection that has made it’s way from the lower urinary tract (urinary bladder) to the kidney. There may be factors that enhance the susceptibility to infection such as congenital abnormalities, metabolic disorders or systemic immunosuppression; however, no underlying disorders need exist.
The clinical signs associated with pyelonephritis may be mild, or may even go unnoticed, although pyelonephritis can lead to kidney failure, sepsis (infection throughout the bloodstream) and even death, if not addressed. Depending on the specific case, certain diagnostics and therapeutics are usually recommended and tailored to each individual.
Several diseases or disorders can present similarly and need to be differentiated from pyelonephritis. These include:
Urolithiasis (stones) anywhere throughout the urinary tract
Lower urinary tract infection
Chronic kidney failure
Bacterial prostatitis (inflammation of the prostate)
Metritis (inflammation of the uterus)
Other causes of fever and painful abdomen such as pancreatitis (inflammation of the pancreas) or peritonitis (inflammation of the abdominal cavity), as a percentage of animals with pyelonephritis present for abdominal pain
Other causes of increased thirst and increased urination include hyperadrenocorticism (Cushing’s disease), diabetes mellitus, kidney disease and liver disease
In-depth Information on Diagnosis
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 complete blood count (CBC) may be within normal limits, but an elevated white blood cell count may be present.
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 patient’s 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.