Feline Hydronephrosis: Symptoms, Causes, Diagnosis, Treatment, and Management Essentials

UrinaryDiseasesMeongsiljang Veterinary Advisory Board

Feline hydronephrosis is a condition in which urine accumulates in the kidneys, making early detection crucial. The main symptoms include pain, abnormal urination, and decreased kidney function.

What is Feline Hydronephrosis?

Anatomical diagram of a cat's kidneys and ureters, showing hydronephrosis

Feline hydronephrosis is a condition in which urine backs up and accumulates in the kidneys, causing them to swell. This occurs when urine flow is obstructed due to a blockage in the ureters or urethra. In the early stages, symptoms are often minimal, making early detection difficult; however, if left untreated, it can lead to kidney damage. The condition is classified as either acute or chronic, and the treatment approach depends on the underlying cause. Early diagnosis and appropriate management are key to preventing complications. If kidney damage progresses, it can lead to chronic kidney disease.

What are the Main Causes of Hydronephrosis?

The most common cause of feline hydronephrosis is a blockage in the ureter that prevents urine from draining out of the kidney. - Ureteral obstruction: This occurs when urine cannot flow from the kidney into the ureter and may be caused by stones, tumors, inflammation, or congenital abnormalities. - Uroliths: Urinary stones composed of substances such as calcium oxalate or struvite can block the ureter and obstruct urine flow. - Congenital abnormalities: Some cats are born with abnormally shaped or narrowed ureters. - Tumors: Both malignant and benign tumors developing in the ureter or kidney can obstruct urine flow. - Inflammatory responses: Inflammation around the ureter or conditions such as pyelonephritis can make it difficult for urine to drain.

A view of a cat's urethra blocked by a stone

What are the Main Symptoms of Hydronephrosis?

Feline hydronephrosis may show few or no symptoms in its early stages. However, as the condition progresses, your cat may begin to display the following signs:

Difficulty urinating: Your cat may visit the litter box frequently but pass only small amounts of urine or none at all.

Abdominal pain: The abdomen may appear distended, and your cat may react when it is touched.

Decreased appetite: Your cat may eat less or refuse food entirely.

Recurrent vomiting: Gastrointestinal dysfunction can lead to frequent vomiting.

Lethargy: Your cat may remain inactive, stay in one place, and appear weak or collapsed throughout the day.

Weight loss: As health deteriorates rapidly, your cat may start losing weight.

Your cat acting awkward while searching for the litter box

Symptoms Requiring Immediate Veterinary Attention

If your cat tries to urinate but no urine comes out, or shows severe pain, you should go to the vet immediately. This is an emergency situation where the ureter may be completely blocked, potentially leading to kidney damage.

How is Hydronephrosis Diagnosed?

Hydronephrosis is most accurately diagnosed through ultrasound, which allows us to check for kidney swelling and urine retention. Blood and urine tests are also performed alongside the ultrasound.

Ultrasound: Provides a detailed assessment of kidney size and structure.

Blood tests: Evaluate kidney function markers, such as creatinine and BUN levels, which may be elevated.

Urine tests: Check for signs of infection or protein leakage.

CT or MRI: May be used in complex cases to pinpoint the underlying cause.

A veterinarian examining a cat's abdomen with an ultrasound.

What are the Treatment Options for Hydronephrosis?

Treatment depends on the underlying cause. The key is to relieve the ureteral obstruction or repair it surgically.

Ureteral drainage: A catheter is inserted into the blocked area to drain urine externally.

Surgical intervention: Surgery may be required to remove stones or tumors, or to reconstruct the ureter.

Medication: If an infection is present, antibiotics are administered. Pain relievers can also be used to alleviate discomfort.

Fluid therapy: Intravenous fluids are provided to prevent dehydration and help restore kidney function.

Long-term management: If the cause is chronic, ongoing monitoring and medication management are necessary.

A veterinarian performing surgery to insert a stent into a cat's ureter

Home Management Points

Consistent care remains essential even after treatment. There are several key points to keep in mind at home.

Ensure adequate hydration: Offer water frequently and place multiple water bowls around the house to improve accessibility.

Facilitate litter box access: Provide a litter box with low sides or one that is easy for your pet to enter.

Adhere to medication schedules: Administer medications precisely at the times prescribed by your veterinarian.

Monitor weight and appetite: Closely track any changes in weight or decreases in appetite.

Regular check-ups: Visit the clinic every 1 to 3 months to monitor kidney function.

Preventing Recurrence and Breed Considerations

While certain breeds may be more susceptible to hydronephrosis, current evidence has not yet established clear differences between breeds. Congenital malformations or pathophysiological factors can cause hydronephrosis, making early diagnosis crucial. Whether the condition recurs depends on the underlying cause and the response to treatment, and regular diagnostic tests can be helpful for monitoring kidney function.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Can feline hydronephrosis be cured?

Once the underlying cause is removed, most pets can make a full recovery. However, if the condition becomes chronic, ongoing management will be necessary.

Is polycystic kidney disease common in cats?

Overall, it's relatively uncommon. However, older cats are at a higher risk of developing kidney disease, and there is no clear evidence yet of significant differences among breeds.

What complications can arise from hydrocephalus?

It can lead to decreased kidney function, kidney failure, or the spread of infection. Early treatment is essential.

Can a veterinarian diagnose hydronephrosis directly?

An ultrasound can provide an accurate diagnosis, and blood and urine tests are also performed.

What should I watch out for at home after my pet’s hydrocephalus treatment?

Carefully monitor your pet’s water intake, medication administration, changes in appetite, and weight fluctuations, and be sure to schedule regular veterinary check-ups.

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References

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[3] The Cat, Clinical Medicine and Management, 2nd Edition. Elsevier, 2020.