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Cat urinary stones
Urinary stones are hard concretions that form from minerals dissolved in urine. They can appear in the kidneys, ureters, bladder or urethra. In cats, the two most common types are struvite stones and calcium oxalate stones. This distinction...
What is it?
Urinary stones are hard concretions that form from minerals dissolved in urine. They can appear in the kidneys, ureters, bladder or urethra.
In cats, the two most common types are struvite stones and calcium oxalate stones. This distinction is crucial: the former can often be dissolved by a suitable diet, the latter must be removed.
The stones can remain silent for a long time, then suddenly cause intense pain or blockage when they enter a narrow duct.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Frequent trips to the litter box with the emission of small quantities of urine.
Efforts to urinate, prolonged squatting, complaints.
Pink or red urine.
Insistant licking of the genital area.
Pain on palpation of the abdomen.
Loss of appetite, depression, vomiting when the kidneys are affected or in case of blockage.
Some kidney stones give no signs and are discovered by chance during an x-ray or ultrasound done for another reason.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
A stone forms when urine contains too many certain minerals compared to the volume of water available to dissolve them. The crystals gradually agglomerate until they form a stone.
The degree of acidity of the urine plays a determining role: struvite is formed more in weakly acidic urine, calcium oxalate more in very acidic urine.
Too concentrated urine, in a cat that drinks little, promotes all types of stones.
Certain metabolic diseases and high blood calcium levels promote oxalate stones.
In cats, unlike dogs, urinary infections are only exceptionally the cause of struvite stones.
Low water consumption and exclusively dry diet.
Overweight and lack of activity.
Middle to older age for oxalate stones, younger cat for struvite.
Certain long-haired breeds, notably the Persian, are more often affected by oxalate stones.
Personal history of stones: the risk of recurrence is real and justifies lifelong follow-up.
Unbalanced diet or mineral supplementation given without veterinary advice.
To be a male, not to form stones, but to hang with them.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
Urinalysis looks for blood, crystals, and possible infection, and measures the acidity of the urine.
The abdominal x-ray shows most of the struvite and oxalate stones, which appear clearly.
Ultrasound completes the examination, identifies stones invisible on the x-ray and evaluates the kidneys and ureters.
A blood test checks kidney function and calcium levels.
When a stone is removed, it is sent to the laboratory to be analyzed: knowing its exact composition is essential to choose the appropriate prevention. Never throw away a stone that your cat has eliminated, take it to your veterinarian.
Treatment
Treatment depends on the nature of the stone, its size and its location.
Bladder struvite stones can often be dissolved by a specific veterinary diet, given exclusively for several weeks, with imaging checks to check for melting.
Calcium oxalate stones do not dissolve: they are surgically removed when they are bothersome, or evacuated by rinsing techniques under anesthesia for the smallest ones.
A stone blocked in a ureter is a serious situation that requires a specialized center.
Pain is managed systematically, and an infusion is put in place when the kidneys suffer.
An antibiotic is only added if an infection is demonstrated.
Never give an acidifying or alkalizing supplement on your own initiative: without knowing the type of stone, you risk making the situation worse.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
The main objective is to produce more diluted urine: this is what makes the difference in the long term.
Give wet food, which provides much more water than kibble.
Increase the number of clean water points, in large bowls, far from the litter box.
Follow strictly the veterinary diet prescribed after an episode, without treats or supplements which cancel out the effect.
Have the recommended urine and imaging checks carried out: recurrence can be detected before it becomes painful.
Maintain a healthy weight and stimulate activity.
Possible complications
Blockage of the urethra in males, with inability to urinate: life-threatening emergency.
Blockage of a ureter, which can silently destroy the corresponding kidney.
Acute kidney failure or worsening of existing kidney disease.
Chronic inflammation of the bladder maintained by the friction of stones.
Recurrences, frequent in the absence of followed dietary measures.
When to see a veterinarian
Your cat strains to urinate or only emits a few drops.
His urine contains blood.
He complains when urinating or his stomach is painful.
Your male cat is no longer able to urinate at all: vital emergency, consult immediately.
He vomits, stops eating or remains prostrate.
He has already had stones and you notice the slightest change in his urinary habits.
Prognosis
The prognosis is good for bladder stones managed in time, whether they are dissolved or removed.
Recurrences are frequent, in particular for calcium oxalate which cannot be dissolved: dietary monitoring and regular checks clearly reduce the risk.
Ureteral stones cloud the prognosis because they can permanently damage a kidney even before causing visible signs.
Frequently asked questions
Can all stones be dissolved with diet?
No. Only certain types, mainly struvite, can melt under the influence of a suitable veterinary diet. Calcium oxalate stones, very common in cats, do not dissolve and must be removed.
My cat has eliminated a small stone, should I consult?
Yes, and bring the stone. Its laboratory analysis indicates its composition, therefore the prevention to be implemented. Without this information, prevention is done blindly.
Does tap water cause stones?
This is not the determining factor in cats. What matters is the total volume of water consumed: a cat that drinks enough and eats wet produces diluted urine, which is more protective than the choice of water.
Can stones come back after surgery?
Yes, because surgery removes stones but does not correct the tendency to produce them. It is diet, hydration and regular monitoring that limit recurrences.
References
AAFP — American Association of Feline Practitioners
WSAVA — World Small Animal Veterinary Association
Content reviewed by the TunisieVet editorial team · Updated 09 August 2026
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