Section: Overview
Hydronephrosis is the distension or enlargement of the pelvis of the kidney with urine as a result of obstruction of the ureter, which is the tiny tubular structure that allows the passage of urine from the kidney to the urinary bladder. It can be caused by anything that blocks the ureters, including narrowing, cancer or scarring. Other causes include:
Urolithiasis (stones in the urinary tract)
Prostatic enlargement
Inadvertent ligation (tying off) of the ureter during abdominal surgery
Masses in the retroperitoneal area, which is the area within the abdomen located around the kidneys
Bladder masses of the trigone area, which is the area of the bladder where the ureters empty
Dogs are affected more often than cats. There is no particular age, sex or breed predilection.
What to Watch For
Excessive drinking and urinating
Abdominal or back pain
Bloody urination
In cases where there is associated infection or kidney failure watch for systemic signs of illness:
Vomiting
Diarrhea
Lethargy
Inappetence
Diagnosis
Baseline tests to include a complete blood count (CBC), biochemical profile, and urinalysis are recommended in all patients. Although these tests are often within normal limits, there may be changes consistent with kidney failure or urinary tract infection. Additional tests include:
A bacterial urine culture to check for associated infection
Abdominal radiographs (X-rays) to rule out calculi (stones), masses, prostatic changes, and other diseases that might mimic hydronephrosis
Abdominal ultrasound to help visualize the urinary tract, in particular, the renal pelvises and in some cases dilatation of the ureter, as well as other abdominal structures.
Excretory urography, which is a dye study of the upper urinary tract including the kidneys and ureters, to help determine the location and cause of blockage
Treatment
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 consist of:
Fluid and electrolyte therapy
Dietary modification in those patients with concurrent renal (kidney) failure or urinary calculi
Antibiotic administration based on urine culture and sensitivity
Surgical intervention, although this is usually not necessary, although it may be indicated in select cases. In severe cases, the affected kidney and ureter are surgically removed.
Home Care and Prevention
Administer all medication and diet as directed by your veterinarian and return for follow- up. If any change is noted in your pet's condition, notify your veterinarian.
Eliminate factors predisposing to urinary tract infections or stones. Dietary manipulation may be of benefit in helping to prevent the formation of certain stones, and in turn, urinary obstruction and hydronephrosis.
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