Urinary calculi in dogs (stones in the bladder or urethra)
Urinary calculi are stones that form in the urinary system. Crystals present in the urine clump together and grow, most often in the bladder, sometimes in the kidneys. In the bladder, stones rub against the wall and irritate it: the dog str...
What is it?
Urinary calculi are stones that form in the urinary system. Crystals present in the urine clump together and grow, most often in the bladder, sometimes in the kidneys.
In the bladder, stones rub against the wall and irritate it: the dog strains to urinate, urinates frequently in small amounts, and sometimes passes blood in the urine.
The real danger is mainly in males, whose urethra is long and narrow: a small stone can become lodged and completely block the outflow of urine. A male straining without passing urine is an absolute emergency. This blockage is often mistaken for constipation.
Key point
A male dog straining to urinate with nothing coming out requires urgent evaluation, day or night: a stone can block the urethra, and this blockage can be fatal within a short time.
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:
Straining to urinate, with the dog spending long periods in position.
Very frequent urges to urinate, passing only a small amount each time.
Urine tinged with blood.
Accidents in the house in a dog previously housetrained.
Some dogs show no signs: stones are discovered by chance on imaging.
If blockage occurs in a male: he strains with nothing coming out, or just a few drops; the belly becomes tense and painful, then he vomits, stops eating, and becomes lethargic.
Kidney stones often cause no signs; a stone stuck between the kidney and bladder can cause pain and vomiting.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Stones form when urine contains too much of certain minerals and conditions favour their crystallization: very concentrated urine, urine acidity, diet, infection, or inherited abnormality in kidney or liver function depending on the stone type.
Urine sitting in the bladder for long periods, when the dog drinks little or goes out infrequently, also promotes their formation.
Each stone type has its own causes: only analysis of the stone allows identification of which is present.
Male: urethral blockage is common.
Previous episodes of calculi or urinary signs: recurrence is possible.
Dog that drinks little or has few opportunities to urinate.
Recurrent urinary tract infections.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian palpates the bladder: a very full, firm bladder in a dog that is straining suggests blockage.
X-rays and ultrasound show the size, number, and position of stones; some stones are poorly visible on radiographs and require ultrasound.
Urine analysis looks for crystals, blood, and infection.
Blood work evaluates kidney function and blood electrolytes in case of blockage.
Stones that are removed or passed are sent to the laboratory to determine their composition: this is the foundation of prevention.
Treatment
In case of blockage, the priority is to restore urine flow: the veterinarian pushes the stone back into the bladder using a catheter, empties the bladder, and corrects blood abnormalities caused by the blockage through IV fluids.
Some stones, such as struvite stones, can be dissolved with special diet prescribed by your veterinarian; others, such as calcium oxalate stones, cannot dissolve and must be removed.
Removal is done by bladder surgery or other techniques in certain equipped centers.
Any associated infection is treated with an antibiotic chosen by your veterinarian.
Diet adjustment is decided with your veterinarian based on stone type: do not change your dog's diet on your own, as a diet suitable for one type of stone may promote another.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Keep your dog well hydrated: provide fresh water at all times, and wet food if your veterinarian recommends it.
Take him out frequently to allow regular emptying of the bladder.
After a first stone, follow the diet and urine and imaging checks planned by your veterinarian—recurrence is common without ongoing monitoring.
Have any passed or removed stone analyzed.
In a male dog, learn to recognize blockage: straining without passing urine is never harmless.
Possible complications
Complete urethral blockage: urine cannot flow, toxins accumulate in the blood, and the heart may be affected. Without rapid treatment, this is fatal.
Bladder rupture if blockage persists.
Kidney damage, sometimes permanent, if a ureter or the urethra remains blocked.
Recurrent urinary tract infections.
Recurrent stone formation.
When to see a veterinarian
Your male dog is straining to urinate with nothing coming out, or only a few drops: seek immediate emergency care, day or night.
He is vomiting, refusing food, or appearing depressed after straining to urinate: seek immediate emergency care.
His belly is tense and painful to touch: consult without delay.
You suspect constipation but notice he is not urinating: consult without delay—it may be urinary blockage.
He is urinating frequently in small amounts, straining, or his urine contains blood.
He has had stones before and the signs are returning.
Prognosis
When treated promptly, urinary calculi respond well to treatment and urinary obstruction is relieved in most cases.
The outlook is more guarded when obstruction has persisted for a long time before veterinary evaluation, or when the kidneys are affected.
Recurrence is possible; it becomes less likely when the stone composition has been identified and follow-up care is maintained.
Frequently asked questions
Is your dog straining: is he constipated or obstructed?
Watch to see if he strains to urinate or defecate, and whether urine actually comes out. A male who strains without urinating is an emergency, even if he appears to be straining as if to defecate: this is a common mistake. When in doubt, seek immediate veterinary care.
Kidney stones or simple urinary tract infection: what's the difference?
Signs can be identical. X-ray or ultrasound shows stones, urinalysis detects infection, and both can coexist. Urinary signs that persist despite antibiotics should prompt a search for calculi.
Can diet dissolve stones?
For certain types of stones, yes, with a special diet followed strictly and monitored by the veterinarian. For others, no: they must be removed. This is why the choice of diet is made with the veterinarian, depending on the nature of the stone.
Can gallstones return after surgery?
Yes, if the conditions that caused them persist. Analysis of the removed stone, good hydration, a recommended diet, and regular check-ups reduce this risk.
References
Content reviewed by the TunisieVet editorial team · Updated 30 October 2026
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