When to see a vet urgently
A urethral blockage is an emergency. Seek treatment immediately if:
- your cat repeatedly tries to urinate but passes no urine;
- difficulty urinating is accompanied by vomiting or clear weakness;
- your cat is painful, unusually lethargic or collapses.
Do not wait to see whether changing food helps. To get help, find a vet near you.
Overview
Uroliths form when mineral salts in urine crystallise. The most common stone types in cats are:
- struvite, or triple phosphate: forms in alkaline urine; unlike in dogs, feline struvite almost always develops without infection and usually dissolves with a therapeutic diet;
- calcium oxalate: forms in acidic urine and with calcium metabolism disturbances;
- less commonly, urate, cystine and mixed stones.
Stones and microscopic urinary crystals are different findings. Crystals alone do not establish bladder stones, and stones are not always accompanied by crystals. Urine acidity cannot reliably identify stone composition either.
Female cats also develop urinary stones. The particular danger for males concerns their narrow urethra and blockage. A blockage is not always caused by a true stone: a plug containing inflammatory material, mucus and crystals can also stop urine flow. You cannot therefore determine the cause of an inability to urinate at home by comparing symptoms.
Urinary stone disease develops gradually and may cause no early symptoms, or become very sudden when the urethra blocks completely.
Causes
- unbalanced feeding, particularly poor-quality dry foods high in magnesium and phosphorus;
- too little drinking and concentrated urine;
- chronic urinary tract infections;
- inherited predisposition;
- obesity and inactivity;
- sex and lifestyle: a male's urethra is narrower and longer, with risks increased by excess weight, inactivity and dry feeding; neutering itself does not narrow the urethra.
Dietary effects cannot be judged simply from dry food or an undefined quality rating. Urine concentration, acidity and stone type are among the factors involved. Dry therapeutic foods are also used to dissolve struvite. Ordinary feline struvite stones usually form without bacterial infection, so infection does not explain every stone.
High blood calcium is investigated with calcium oxalate stones. Nevertheless, not every cat forming these stones has one identifiable cause. Stone formation and urethral blockage are also different problems: not every stone type and urinary symptom should be grouped under the same risk list.
Risk factors
- Neutered males aged 2–6 years.
- Predisposed breeds, including Persians, British Shorthairs and Maine Coons.
- Inactive cats.
- Cats receiving too little fluid, with dry food alone and inadequate water intake.
- Overweight cats.
Risk factors vary by stone type, and this whole list is not consistently established for all feline urinary stones. Struvite often affects young and middle-aged adults, for example, while calcium oxalate stones are also found in older cats. Age or breed does not rule out disease. A male's blockage risk does not mean females are protected against stones.
Typical symptoms
- frequent, painful attempts to urinate;
- blood in the urine, or haematuria;
- passing small amounts or drops;
- frequent litter tray visits without urine;
- abdominal tenderness when examined by touch;
- lethargy and reduced appetite;
- inability to urinate with urethral blockage, followed by vomiting, weakness and dehydration, requiring immediate help.
A cat may also lick its genital area, vocalise in the tray or urinate outside it. This is not automatically a behavioural problem. Idiopathic cystitis, bladder inflammation without another identifiable cause, can produce the same signs. Symptoms alone cannot distinguish a stone, inflammation and a blockage.
A bladder stone can irritate the lining and cause bleeding. It may also obstruct urine flow partially or intermittently. Passing urine earlier or producing a few drops therefore does not guarantee safety. Tell the vet about continuing attempts to urinate even if your cat is not yet vomiting.
Complications and consequences
- chronic bladder inflammation;
- enlargement of the renal pelvis, or hydronephrosis, from obstructed urine flow;
- kidney failure;
- bladder rupture during acute urinary retention;
- death without urgent help.
A complete blockage raises urinary tract pressure and disrupts the kidneys' ability to remove waste and regulate fluid and electrolyte balance. Blood potassium can rise dangerously and cause arrhythmias. A serious condition can therefore develop before bladder rupture. Do not judge urgency by waiting for every listed complication to appear.
Diagnosis at the vet
- routine urinalysis for crystals, blood and inflammation;
- blood biochemistry to assess kidney function;
- bladder and kidney X-rays or ultrasound to detect stones and sediment;
- bacterial urine culture if infection is suspected.
Tests also establish stone location and any obstruction. Plain X-rays show most struvite and calcium oxalate stones, but not every type shows equally well. Ultrasound or a contrast study may add information. Small stones may not be felt through the abdomen, so normal palpation does not rule them out.
Urine specific gravity indicates concentration. A removed stone is analysed so recurrence prevention can target the correct type. Sample freshness and handling affect interpretation of crystals and acidity, so agree collection and delivery with the practice. A home pH measurement alone does not replace investigation. Blood tests may also look for predisposing conditions such as calcium metabolism changes when a stone type is suspected.
Treatment and follow-up
The first aim in a blockage is to restore urine flow and correct problems threatening the cat's condition. A catheter may be passed into the urethra under sedation or general anaesthesia. Pain relief, fluids and monitoring are also needed according to the situation. Actual stone removal or dissolution is planned once its location and likely composition are known.
Struvite dissolution uses a diet designed for this purpose under veterinary guidance. It must replace other food as agreed: ordinary food and treats can interfere with the intended effect. Success is confirmed with imaging because symptom relief alone does not show that stones have disappeared. Blockage remains possible during dissolution, so a new inability to urinate requires emergency assessment.
Calcium oxalate stones do not dissolve with diet. Removal is chosen according to location, size and the cat's condition; surgery or less invasive methods may be options. A general urinary health claim on food packaging does not guarantee suitability for this cat's stone type. Kidney or ureteral stones need assessment based on their own location.
After catheter removal, the team checks that the cat can urinate. Surgery to widen the urethral outlet may be considered for recurrent or severe blockages. It can reduce obstruction but does not prevent bladder inflammation or new stones. An operated cat therefore still needs monitoring and an individual prevention plan.
Prevention
- Provide a balanced diet, using therapeutic food if needed for a cat prone to stones.
- Keep enough fresh water available.
- Encourage drinking with a fountain.
- Maintain a healthy weight and activity.
- Arrange regular urine tests for an at-risk cat.
Choose food according to the confirmed stone type and other illnesses. The same urine acidification does not suit every cat, and do not independently add acidifying products to a therapeutic diet. If homemade feeding is needed, its balance and intended urinary effect are planned with a vet or animal nutrition specialist.
Wetter food or more water provided with food may help dilute urine. Monitor drinking changes and appetite to ensure the new diet is actually eaten. Report refusal of prescribed food. A diet needed for another illness is matched individually to stone prevention.
Keep the litter tray clean and quiet, with access unblocked by other animals. It must remain accessible if mobility declines. When changing litter, retaining a familiar option alongside the new one helps adjustment. Improving the tray environment supports urination but does not dissolve an existing stone.
Monitoring may include imaging as well as urine samples. Check-up needs depend on stone type, treatment response and recurrence history. At home, record successful urination, visible blood, appetite and whether the diet is followed. Do not automatically attribute new symptoms to recurrence of an old stone, as another cause may be responsible.
Important for cat owners
Urinary stone disease is among the most common and dangerous conditions in cats. Remember especially that difficulty urinating or inability to urinate needs an urgent veterinary visit: it can be life-threatening. Appropriate feeding, adequate drinking and regular checks clearly reduce stone formation risk.
This article provides general information and does not replace veterinary care. If you notice signs of illness in your cat, contact a vet.
Frequently asked questions
Are urinary crystals the same as urinary stones?
No. Crystals can occur without stones, and stones may be present without visible crystals in a sample. Findings are combined with symptoms and imaging before treatment decisions.
Can food dissolve a urinary stone?
Struvite stones can often be dissolved with a vet-selected diet. Calcium oxalate stones do not dissolve this way. Composition and blockage risk determine whether a dissolution attempt suits the cat.
Why does my cat have symptoms again after stone removal?
Stones can reform, but another urinary tract disease can cause similar signs too. New pain, blood in urine or difficulty urinating therefore needs investigation. If no urine is passed, treatment is needed immediately.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- 2025 iCatCare consensus guidelines on the diagnosis and management of lower urinary tract diseases in cats, International Cat Care / Journal of Feline Medicine and Surgery, accessed 2026-11-03.
- Feline Lower Urinary Tract Disease, Cornell Feline Health Centre, accessed 2026-11-03.
- Bladder Stones in Cats, VCA Animal Hospitals, accessed 2026-11-03.
- Urinary Obstruction in Male Cats, American College of Veterinary Surgeons, accessed 2026-11-03.
- Litter Boxes, The Ohio State University, accessed 2026-11-03.
- Urolithiasis in Cats, MSD Veterinary Manual, accessed 2026-11-03.
- Treatment recommendations, University of Minnesota College of Veterinary Medicine, accessed 2026-11-03.