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Fluid Buildup in the Kidney Due to Kidney or Ureter Obstruction in Dogs


Hydronephrosis in Dogs


Hydronephrosis is usually one-sided and occurs secondary to complete or partial obstruction of the kidney or ureter by kidney stones, tumor, retroperitoneal (the anatomical space behind the abdominal cavity), disease, trauma, radiotherapy, and accidental binding of the ureter during spaying and after ectopic ureter surgery.


In most patients, hydronephrosis occurs when fluid builds up in the kidney, causing progressive distention of the renal pelvis (the funnel-like dilated proximal part of the ureter in the kidney) and diverticula (out pouching, with atrophy of the kidney secondary to obstruction).


Bilateral hydronephrosis (distention and dilation of the renal pelvis) is rare. When it does occur, it is usually secondary to trigonal (a triangular smooth area at the base of the bladder), prostatic, or urethral disease.


Symptoms and Types


Some dogs may be without overt symptoms, while others may display one or many of the following:





Any cause of ureteral obstruction:


  • Kidney stones
  • Ureteral stenosis (narrowing of the ureters)
  • Atresia (closed)
  • Fibrosis (formation or development of excess fibrous connective tissue)
  • Tumor
  • Trigonal mass
  • Prostatic disease
  • Vaginal mass
  • Retroperitoneal (anatomical space behind the abdominal cavity) abscess, cyst, hematoma, or other mass occupying this space
  • Accidental ureteral ligation during spaying
  • Postoperative complication from ectopic ureter surgery
  • Perineal hernia (abnormal displacement of pelvic and/or abdominal organs into the region around the anus called the perineum)
  • Secondary to congenital ectopic ureters




You will need to give your veterinarian as much information on your dog's health and recent activities as possible. Your veterinarian will perform a complete physical exam on your dog after taking a thorough medical history from you. Standard laboratory tests include a blood chemical profile, a complete blood count, an electrolyte panel and a urinalysis to rule out or confirm other causes of disease.


Abdominal X-rays and an ultrasound are important tools for diagnosing hydronephrosis and its underlying cause. Also essential is a transurethral urethrocystoscopy or vaginoscopy, procedures that are performed using a small camera to visualize the inside of the vagina or the urethra (two tubes which drain from the kidneys to the bladder).





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