Cat hydronephrosis: causes, symptoms, treatment

Hydronephrosis is basically the dilation of the renal pelvis usually caused by an obstruction of the urinary flow. Consistent in the stagnation of urine following obstruction of the ureter. Hydronephrosis can be both unilateral and bilateral. Let’s say that it is not a very frequent pathology, it is rarely seen, but especially in dogs and cats suffering from stones it must be taken into consideration as a possible complication.


Hydronephrosis can be caused by any condition that can obstruct the ureters. The causes can be both congenital and acquired. Congenital causes of urinary tract obstruction are:

  • urethral atresia
  • stenosis
  • torsion of the ureter
  • ureterocele
  • ectopic ureter

Acquired causes of urinary tract obstruction are:

  • calculations
  • blood clot
  • tumors
  • inflammatory polyps
  • stenosis
  • trauma
  • Surgical ligation of the ureter

If the obstruction occurs at the urethral level, bilateral hydronephrosis is frequent, which means rapid acute post-renal failure with the patient’s death in a short time. When unilateral obstruction occurs, if the other kidney is functioning normally, the kidney affected by hydronephrosis will atrophy and become a fibrous pouch.


The kidney produces urine, but with an obstruction in the urinary system, the bladder and ureters, urine accumulates until both the bladder and ureter dilate. The urethral pelvis dilates more and more, compresses the renal parenchyma which atrophies and thins until it disappears completely. And all this causes kidney failure.

  • excessive thirst
  • frequent urine
  • abdominal pain
  • urine with blood
  • He retched
  • diarrhea
  • lethargy
  • lack of appetite


A type B biochemical profile blood test with urine included is ideal. Although such tests often reveal values ​​within normal limits, they can still reveal notable changes in the case of kidney failure or urinary tract infection. Urine culture will also be indicated to diagnose renal failure.


It is of fundamental importance to determine whether the cat’s conditions require hospitalization or treatment on an outpatient basis. Initial therapies will be:

  • Fluid therapy and electrolyte therapy
  • Change in diet in cats with renal insufficiency or concomitant urinary stones
  • Administration of antibiotics based on the outcome of urine culture and antibiogram
  • Surgical intervention. In severe cases, the affected kidney and ureter are surgically removed.

Administer all the prescribed medications to the cat, strictly following the procedures indicated by the veterinarian. The same is true if changes to the diet have been recommended, so it will be a good idea to keep the cat with any brand of URINARY nutrition.

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