Hydronephrosis in Dogs

Overview of Canine Hydronephrosis

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

Signs of hydronephrosis in dogs may include:

• 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 of Hydronephrosis in Dogs

Baseline tests to include a complete blood count (CBC), biochemical profile, and urinalysis are recommended in all dogs. 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 of Hydronephrosis in Dogs

It is most important to determine whether the dog’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 dog’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.