Feline Ureteral Stones: A Complete Guide to Symptoms, Causes, Diagnosis, Treatment, and Management

UrinaryDiseasesMeongsiljang Veterinary Advisory Board

Feline ureteral obstruction is an acute condition in which stones block the ureter, making it difficult for urine to pass. It can cause significant pain and poses a risk of kidney damage. Early diagnosis and treatment are essential.

What Are Feline Ureteral Stones?

An anatomical diagram showing a cat’s urethra blocked by a stone.

Feline ureteral obstruction is a condition in which the ureters, the tubes connecting the kidneys to the bladder, become blocked by stones, dried or solidified blood clots, strictures, tumors, or external compression, making it difficult to pass urine. When the ureters are obstructed, pressure builds up inside the kidneys, leading to hydronephrosis (swelling of the renal pelvis) and potential kidney damage. The extent of damage caused by the obstruction depends on whether one or both sides are affected, whether the blockage is partial or complete, how long it has persisted, and whether there is underlying kidney disease. In particular, complete bilateral obstruction can be life-threatening because little to no urine is produced. Common stone compositions include calcium oxalate, struvite, and mixed stones, with calcium oxalate stones being increasingly identified in obstructive cases. Male cats are at higher risk for lower urinary tract (urethral) obstruction due to their narrower urethra; in these cases, urethral plugs composed mainly of struvite are a more common cause than stones. - Ureteral obstruction: Urine flow is impaired. - Severe pain: Your cat may scratch at its abdomen, linger in the litter box, and cry while straining to urinate. - Risk of kidney damage: Obstruction can lead to hydronephrosis, causing the kidneys to swell. - Immediate veterinary care required: If your cat is unable to urinate, consult a veterinarian promptly.

What Are the Main Causes of Ureteral Stones?

Feline urinary stones don’t form from a single cause; they result from a combination of factors. Key influences include matrix proteins that serve as a scaffold for stones, the concentration and saturation of solutes that promote crystal formation, and urine pH. Acidic urine favors the formation of calcium oxalate crystals, while alkaline urine promotes struvite crystals. Ureteral obstruction is most commonly caused by ureteral stones (primarily calcium oxalate or struvite), dry or solidified blood clots, or strictures. In contrast, urethral obstruction, which is common in male cats, is frequently caused by urethral plugs composed mainly of struvite. Urinary tract infections are closely linked to struvite stone formation, and male cats are at higher risk because their narrow urethra is more prone to blockage. Additionally, stress and environmental changes can contribute to lower urinary tract signs. - Insufficient hydration: Inadequate water intake leads to concentrated urine. - Crystal and matrix factors: Matrix proteins and crystal-promoting factors in the urine contribute to stone formation. - Infection and inflammation: Urinary tract infections are particularly associated with struvite stone formation. - Risk in male cats: Their narrow urethra makes them more susceptible to obstruction.

How cats drink water and the process of crystal formation in urine

Check for Key Symptoms and Signs

Because symptoms of feline urinary obstruction can worsen rapidly, early detection is crucial. Please watch closely for the following signs:

Recurring pain: Your cat may repeatedly scratch at the floor or abdomen, strain while attempting to urinate, and vocalize in distress.

Difficulty urinating: Your cat may visit the litter box but produce little to no urine, or struggle to pass urine despite straining.

Vomiting and lethargy: If the obstruction impairs kidney function (leading to azotemia), your cat may refuse food and experience repeated vomiting.

Abdominal distension: The bladder may become firm, swollen, and painful to the touch.

Restless behavior: Your cat may hide frequently or remain stationary in one spot.

These symptoms may indicate a urinary obstruction. In male cats, this is a medical emergency requiring immediate veterinary attention.

Emergency Situations Requiring Immediate Veterinary Visit

If your cat is unable to urinate at all and shows symptoms such as vomiting, lethargy, and abdominal distension, you should take them to the vet immediately. A complete blockage of the ureter can cause kidney damage and may be life-threatening.

Diagnostic Tests for Accurate Diagnosis

To accurately diagnose ureteral stones in cats, a combination of diagnostic tests is necessary. First, an ultrasound exam allows for precise evaluation of the stone’s location and size, as well as any ureteral dilation or hydronephrosis (swelling of the renal pelvis). Radiographs (X-rays) are relatively effective at visualizing calcium-containing stones, helping to quickly determine their presence and location; however, dried blood clots and certain types of stones may not be clearly visible on X-rays, and imaging alone cannot definitively confirm stone composition. Urinalysis checks for inflammation, hematuria (blood in the urine), and infection, while also assessing urine concentration and pH. If needed, blood tests evaluate kidney function, azotemia, and electrolyte levels to assess overall health. - Ultrasound: Confirms the stone’s location and size, and checks for hydronephrosis. - Radiographs: Calcium-rich stones are clearly visible, but imaging alone cannot definitively determine stone composition. - Urinalysis: Identifies inflammation, infection, and hematuria. - Blood tests: Evaluates kidney function and electrolyte balance. - Combined testing: Multiple tests are performed together for an accurate diagnosis.

An image of a cat's abdomen being scanned with an ultrasound.

Treatment Methods and Step-by-Step Management

Treatment for feline ureteral stones varies depending on the stone’s composition, size, location, degree of obstruction, and the presence of underlying kidney disease. The immediate priorities are pain relief, fluid therapy to rehydrate, and correction of electrolyte imbalances. Struvite stones can often be dissolved using prescription diets that reduce urine saturation, whereas calcium oxalate stones do not dissolve with medication or diet; in these cases, we focus on diluting the urine to help pass the stones, or perform removal procedures or surgery. If the obstruction is severe or the stones are large, surgical or interventional removal may be necessary based on the veterinarian’s assessment. After treatment, consistent management with adequate water intake and prescription diet is essential for recovery. To prevent recurrence, long-term dietary control and regular urine and ultrasound examinations are crucial. - Pain relief: Pain medication is used to alleviate discomfort. - Hydration: Intravenous or oral fluids prevent dehydration and correct electrolyte imbalances. - Stone-specific treatment: Struvite stones are dissolved with prescription diets, while calcium oxalate stones require removal procedures or surgery. - Surgical removal: Performed if the stones are large or causing severe obstruction. - Recovery care: Consistently provide prescription diet and water. - Recurrence prevention: A long-term management plan is necessary.

A veterinarian removing a urethral stone from a cat using an endoscope.

Home Care and Recovery Points

Proper care at home after treatment is key to preventing recurrence. Please follow these guidelines closely:

Ensure adequate hydration: Place water bowls in multiple locations and keep the water fresh at all times.

Dietary management: Consistently feed the special diet recommended by your veterinarian.

Litter box care: Provide a clean and quiet litter box.

Activity restriction: Avoid excessive running or jumping during recovery.

Regular check-ups: Have urine tests and ultrasounds performed every 1–2 months.

Consistent adherence to these care practices is essential for a stable and lasting recovery.

A cat-friendly space with a clean litter box, a water mister, and a water bowl

Preventing Recurrence and Breed-Specific Considerations

While certain breeds may have a slightly higher risk of lower urinary tract disease, the evidence presented does not clearly identify distinct breed-specific differences directly linked to ureteral stones. Urethral obstruction is more common in male cats due to their narrower urethra, and factors such as indoor living, stress, or environmental changes can trigger or worsen lower urinary tract symptoms. Therefore, it is advisable to consult with your veterinarian to develop a comprehensive plan that includes long-term dietary management, adequate hydration, and regular check-ups. Consistent care is crucial, as recurrent episodes can have a serious impact on 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

Are ureteral stones common in cats?

In cats, lower urinary tract obstruction is most commonly caused by urethral plugs composed primarily of struvite crystals, rather than stones. While ureteral stones themselves are relatively rare, their diagnosis has been steadily increasing since 2000, and calcium oxalate stones are being identified with growing frequency in obstructive diseases. Urethral obstruction is particularly common in male cats.

What happens if a stone blocks the urinary tract?

When the ureter becomes blocked, pressure builds up inside the kidney, causing the renal pelvis to swell—a condition known as hydronephrosis—which leads to severe pain. If the blockage persists, it can damage kidney function and progress to azotemia or acute kidney injury.

Can stones pass on their own?

Small stones may pass on their own with treatment aimed at diluting the urine to facilitate passage. Struvite stones can be dissolved using prescription diet, but calcium oxalate stones do not dissolve spontaneously and often require removal procedures or surgery.

How can I prevent it from coming back?

Increasing water intake is the most important step, and it’s best to consistently feed the prescription diet recommended by your veterinarian. Additionally, regular urine tests and ultrasounds are essential for early detection of recurrence.

Are ureteral stones and urinary tract stones different?

Urinary tract stones refer to stones that can form anywhere in the urinary system, including the kidneys, ureters, bladder, and urethra. Ureteral stones specifically refer to stones that have formed in the ureter and are causing a blockage. The treatment approach may vary depending on the composition and location of the stone.

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References

[1] The Cat, Clinical Medicine and Management, 2nd Edition. Elsevier, 2023.

[2] Feline Emergency and Critical Care Medicine, 2nd Ed. Wiley-Blackwell, 2021.

[3] Plumb's Veterinary Drug Handbook, 9th Edition. Wiley-Blackwell, 2022.