고양이 요관 결석·요관 폐색 자주 묻는 질문 Q&A — 보호자가 꼭 알아야 할 핵심

What is feline ureteral obstruction? — Why is it an emergency?

KidneyQ&AMeongsiljang Veterinary Advisory Board

Feline ureteral obstruction is a life-threatening emergency in which stones block the ureter, making urination difficult. Early detection is crucial to saving your cat’s life. Here’s the essential information every pet owner should know.

What are feline ureteral stones and ureteral obstruction?

An anatomical illustration showing urethral obstruction caused by urethral calculi in a cat.

Feline ureteral obstruction is an emergency condition in which stones block the ureters—the tubes that carry urine from the kidneys to the bladder—preventing proper urine flow. When the ureters are blocked, pressure builds up toward the kidneys, causing pain and potentially damaging kidney function. Among the types of stones found in cats, calcium oxalate (whewellite) is becoming increasingly common. It’s important to clarify a common misconception: the life-threatening “obstruction” often associated with male cats is actually urethral obstruction, which occurs because male cats have a narrower urethra. Although ureteral and urethral obstructions occur in different locations, both are life-threatening emergencies, making early detection crucial. - Ureteral obstruction: A condition in which stones block the ureters, preventing urine from flowing properly from the kidneys to the bladder, requiring immediate treatment. - Causes of stones: When urine becomes supersaturated with minerals, components such as calcium and magnesium precipitate out, forming stones. - Emergency nature: Prolonged urinary obstruction can lead to life-threatening complications, including electrolyte imbalances like hyperkalemia and kidney damage. Do not delay—seek veterinary care immediately.

Why do feline ureteral stones form?

Feline ureteral stones form when urine becomes oversaturated with minerals, causing components such as calcium, magnesium, and oxalates to precipitate. Inadequate water intake concentrates the urine, creating an environment prone to stone formation. Risk factors for lower urinary tract obstruction include a diet primarily consisting of dry food, indoor living, crystalluria, urinary tract infections, and stress. Please note that the common belief that "males are at higher risk" is because the male urethra is narrower, making urethral obstruction more likely, not because the ureter itself is narrow. - Dehydration: High urine concentration creates an environment conducive to stone formation. - Dietary factors: Feeding only dry food or diets excessive in protein, calcium, oxalates, or sodium is associated with an increased risk of calcium oxalate stones. - Physiological characteristics: Males have a narrower urethra, which can lead to more rapid progression of urethral obstruction. - Impact of infection: Bacterial urinary tract infections can be linked to stone formation and recurrence, so improving daily habits is important.

A cat drinking water, emphasizing the importance of hydration

What are the main symptoms of ureteral obstruction?

Your cat may strain to urinate but produce little or no urine, often repeating the effort in obvious distress. They may cry out in pain or crouch as if clutching their abdomen. Vomiting, lethargy, loss of appetite, frequent urination attempts, decreased urine volume, and blood in the urine may also occur. If your cat continues to strain for more than an hour or fails to pass any urine at all, seek veterinary care immediately. - Painful urination: A blocked ureter prevents urine flow, causing severe pain. - Frequent straining: Your cat may keep trying to urinate even when the bladder is empty. - Systemic symptoms: Overall condition may deteriorate, with signs such as vomiting and lethargy. - Possible hematuria: Ureteral damage can cause blood to appear in the urine. Early detection significantly improves treatment success rates.

A cat showing signs of pain while attempting to urinate

Emergency signs requiring immediate veterinary visit

If your cat is straining to urinate but no urine comes out, or if they show severe pain while trying to urinate, you should take them to the vet immediately. Prolonged urinary obstruction can lead to rapid progression of electrolyte imbalances, such as hyperkalemia, and kidney dysfunction, which can be life-threatening. Do not delay; seek emergency veterinary care as soon as possible.

How is diagnosis performed?

Veterinarians diagnose feline ureteral obstruction through abdominal palpation, blood tests, urinalysis, ultrasound, and radiography. Blood tests assess whether kidney function is impaired, while urinalysis detects inflammation or hematuria. Ultrasound is particularly useful for accurately determining the location and size of stones, as well as checking for renal swelling. Radiography helps identify the presence of calcium-based stones. - Ultrasound: Allows precise identification of stone location and size. - Blood tests: Essential for evaluating kidney function. - Urinalysis: Checks for inflammation, infection, and hematuria. Early diagnosis enables timely initiation of appropriate treatment.

A veterinarian performing an abdominal ultrasound on a cat.

What are the treatment methods?

Treatment depends on the type, size, and location of the stones, as well as your cat’s overall health. In emergency cases involving urinary obstruction, the priority is correcting dehydration and electrolyte imbalances—especially hyperkalemia—and stabilizing circulation. Sterile struvite stones can sometimes be dissolved with a prescription diet, but calcium oxalate stones, which are common in feline ureteral stones, cannot be dissolved medically or through diet and must be removed. Large stones or severe blockages may require emergency surgery for stone removal. Post-treatment care includes pain management, antibiotics if infection is present, and dietary adjustments to prevent recurrence. - Emergency Stabilization: Correct electrolyte and fluid imbalances first, then stabilize circulation in cases of obstruction. - Dissolution Therapy: Only sterile struvite stones may be treated with a prescription diet aimed at dissolving them. - Removal/Surgery: Stones that cannot be dissolved, such as calcium oxalate, or large stones require surgical removal. - Recurrence Prevention: Reduce the risk of recurrence with a prescription diet and increased water intake; regular check-ups remain important even after treatment.

Home care management tips

After a ureteral obstruction is relieved, your cat will need to follow your veterinarian’s instructions regarding medication, increased water intake, and a special therapeutic diet. Offer fresh water frequently and place multiple water bowls around the home to encourage drinking. The prescribed diet contains ingredients that help prevent stone recurrence. Keep the litter box clean and provide a quiet environment to minimize stress. Regular check-ups are essential to monitor kidney function and urine status. - Hydration: Encouraging frequent water intake dilutes the urine, reducing the risk of stone formation. - Therapeutic Diet: Feed a diet formulated with ingredients that help prevent stone recurrence. - Environmental Management: Provide a quiet, stable environment to reduce stress. - Litter Box Hygiene: Keep the litter box clean to prevent discomfort during urination. - Regular Check-ups: Continuously monitor kidney function and urine status through regular veterinary visits.

Differences between male and female cats

Male cats are at a significantly higher risk of urethral obstruction caused by stones or urethral plugs because their urethra is narrower. It’s a common misconception that the ureter is narrow; in fact, it’s the urethra—the tube connecting the bladder to the outside of the body—that is narrow, not the ureter, which connects the kidneys to the bladder. While female cats can also develop stones, male cats are more prone to rapid progression to a life-threatening emergency due to urethral obstruction, so extra vigilance is essential.

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 ureteral obstruction be completely cured?

Once the stones are removed and diet and hydration are properly managed, symptoms can improve. However, because feline urinary stones are known to recur frequently, it’s important not to assume a permanent cure and instead focus on ongoing management and regular check-ups.

How can I tell if my pet isn’t urinating at home?

If your cat frequently visits the litter box and assumes a squatting position but fails to urinate, strains while urinating with signs of pain, or produces only small amounts of urine, suspect a urinary blockage and seek immediate veterinary care.

What kind of diet should I feed my pet to help prevent this condition?

Feeding a veterinarian-recommended prescription diet can be helpful. Diets formulated to prevent calcium oxalate stones contain ingredients such as potassium citrate, which alkalinizes the urine and inhibits stone formation. It is also important to increase water intake to dilute the urine.

How long does the recovery period last after surgery for ureteral obstruction?

The recovery period varies depending on the location of the stone, the surgical method used, and the cat's overall condition. It's difficult to specify an exact timeframe, but after surgery, it's important to closely monitor urine output and kidney function while following your veterinarian's care instructions.

Does a pet with bladder stones always need surgery?

The approach depends on the type, size, and location of the stones. Sterile struvite stones may be dissolved using a prescription diet, but common calcium oxalate stones do not dissolve and may require removal. Surgery is considered for large stones or severe obstructions.

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References

[1] The Cat, Clinical Medicine and Management, 2nd Edition, 2020

[2] Specht AJ, Kruger JM, Fitzgerlad SD, et al. Light microscopic features of chronic feline idiopathic cystitis. J Vet Intern Med. 2003;17(3):436.

[3] Adams LG, Williams Jr. JC, McAteer JA, et al. In vitro evaluation of canine and feline calcium oxalate urolith fragility via shock wave lithotripsy. Am J Vet Res. 2005;66(9):1651–1654.