"My cat keeps going back and forth to the litter box but only passes a little urine, and there's blood in it. It's been 2 days like this. Yesterday it even vocalized at the litter box. Is this a urinary tract infection or a stone? I'm worried because I've been reading about male cat urinary blockage being fatal." This urgent question often reaches the Prabasavet team. Several possibilities: cystitis (bladder inflammation), FLUTD (Feline Lower Urinary Tract Disease), or urolithiasis — stones in the urinary tract. The distinction matters because treatment differs, and if a male cat appears to strain and cannot pass any urine at all, that is an emergency.
Urolithiasis is the formation of stones (calculi) in the urinary tract — they can form in the kidney (nephrolithiasis), ureter (ureterolithiasis), bladder (cystolithiasis, the most common), or urethra (urethrolithiasis). In cats and dogs, the bladder and urethra are the most frequent locations. Understanding the stone type is very important because management can differ greatly — some stones can be dissolved with diet, others must be removed surgically.
This article helps you understand the 5 main stone types in cats and dogs, recognize the clinical signs, understand how a vet diagnoses them, and know the treatment options + long-term prevention.
The 5 main stone types in cats and dogs
The mineral composition of a stone determines treatment. The five main types most frequently found in veterinary practice:
1. Struvite (magnesium ammonium phosphate hexahydrate)
One of the most common stone types, especially in the bladder. Characteristics:
- In cats: often forms in alkaline urine without infection (sterile struvite), sometimes related to a high-calorie or high-magnesium diet. Alkaline urine pH is the main driver
- In dogs: almost always related to a UTI (urinary tract infection) caused by urease-producing bacteria (especially Staphylococcus, Proteus, some Klebsiella). Urease breaks down urea into ammonia → urine becomes alkaline → struvite precipitates. Because of this, struvite in dogs almost always requires UTI management alongside stone dissolution
- Important trait: struvite is the stone type that can most often be dissolved with a prescription diet without surgery. This makes an accurate struvite vs other-type diagnosis very impactful for treatment
2. Calcium oxalate
The second most common stone type, and its prevalence has trended upward over recent decades (partly because modern cat diets are acidified to prevent struvite, but over-acidification increases the oxalate risk). Characteristics:
- Forms in acidic urine — the opposite of struvite. An excessively acidifying diet actually worsens the oxalate risk
- Predisposed dog breeds: Miniature Schnauzer, Yorkshire Terrier, Lhasa Apso, Bichon Frise, Shih Tzu, Pomeranian — small breeds with certain metabolic tendencies
- In cats: there is no strong breed predisposition, but geriatric cats and cats with idiopathic hypercalcemia are at higher risk
- Important trait: calcium oxalate cannot be dissolved with diet. Definitive treatment is surgical removal (cystotomy), voiding urohydropropulsion for small stones, or lithotripsy (where available). Long-term prescription diet to prevent recurrence
3. Urate (uric acid and its derivatives)
A stone type specifically related to purine metabolism. Characteristics:
- Dalmatian — a breed with a genetic defect in purine metabolism (insufficient conversion of uric acid to allantoin), with a very high urate risk as a population group. Not every Dalmatian will get stones, but all have the metabolic predisposition
- Dogs with portosystemic shunt (PSS) — a venous shunt that bypasses the liver causes uric acid to be poorly metabolized. A young dog (young puppy) with hepatic signs + urate stones needs a PSS evaluation
- Other breeds reported as predisposed: English Bulldog, Black Russian Terrier
- Important trait: urate can be dissolved with a low-purine diet + urine alkalinization + allopurinol in some cases, but if the dog has PSS, correcting the shunt is definitive. Plumb's 7e lists an allopurinol protocol for urate stone management in predisposed dogs
4. Cystine
A relatively rare but specific stone. Characteristics:
- Genetic origin — caused by a renal transport defect that leads to excessive cystine excretion in the urine, which then precipitates into stones
- Predisposed dog breeds: Cocker Spaniel, Bulldog, Dachshund, Newfoundland, Mastiff, Basset Hound — several breeds with a hereditary cystinuria pattern
- The majority occur in male dogs because of the longer, narrowing urethral anatomy (more predisposed to obstruction)
- Important trait: cystine management is complex — a low-methionine diet + urine alkalinization + sometimes a chelating agent (tiopronin) in refractory cases. Strong long-term monitoring
5. Silica
Rare compared to the 4 types above, but worth mentioning. Characteristics:
- Related to a diet high in silica (especially plant-based protein from corn gluten or soybean hulls in some formulations)
- Distinctive "jackstone" shape — a stone with multiple radial protrusions, very characteristic radiographically
- Trait: cannot be dissolved with diet, treatment is surgical removal + long-term diet modification
Besides the 5 main types above, there are also mixed stones that have layers of different composition — usually a core of one type + a shell of another. Stone analysis is mandatory for a definitive diagnosis, usually sent to a specialist lab after the stone is removed via surgery or voiding.
Clinical signs of urolithiasis — recognize non-obstructive vs obstructive
Clinical signs vary depending on the stone location and whether there is partial or total obstruction. Two important categories to distinguish:
Non-obstructive signs (urgent but not an emergency)
- Hematuria — blood in the urine, which can be obviously red or only detected via dipstick / urinalysis. Often the first sign owners notice
- Stranguria — straining when urinating, often passing only small amounts
- Pollakiuria (frequency) — repeatedly going to the litter box or asking to go out to urinate but passing only a little
- Vocalizing at the litter box or while urinating — cats meowing/growling while urinating, dogs whining — a signal of urinary pain
- Periuria — urinating in unusual places (outside the litter box, on the floor), often a sign that the cat is avoiding the litter box it associates with pain
- Excessive licking of the genital area
- In chronic cases: muscle wasting, decline in body condition
Obstructive signs (EMERGENCY — see a vet immediately)
If a stone blocks the urethra (or in male cats, a urinary plug of crystals + mucus + inflammatory cells blocks the urethra), the situation becomes life-threatening within hours. See the article signs of a cat emergency: bring it to the vet immediately for a complete emergency discussion. Signs of urinary obstruction:
- No urine passed at all despite repeated straining
- The bladder is palpably large and firm in the lower abdomen — very painful on palpation
- Loud vocalizing, restlessness, anorexia
- Vomiting, progressive lethargy
- In the advanced phase (12–24 hours +): collapse, bradycardia, hyperkalemia (high blood potassium because it cannot be excreted), risk of cardiac arrest
A male cat with urinary obstruction is one of the most critical veterinary emergencies — the male cat's urethra is long and narrow at the penile tip, so even a small plug or stone can cause total obstruction. Mortality is high if treatment is delayed more than 24–48 hours. If you see the signs above, don't wait — contact an emergency veterinarian immediately.
For owners in Jakarta and Greater Jakarta who notice urinary signs but aren't sure whether it's urgent, WhatsApp Prabasavet for an initial triage — we help assess whether this is an urgent emergency that needs immediate referral to a clinic with surgical facilities, or a non-obstructive condition that can be evaluated with a home visit.
How a vet diagnoses urolithiasis
History and physical examination
The vet starts with a detailed history: symptom onset, breed, age, sex (male vs female — implications for obstruction risk), diet, water intake, observed urination frequency. The physical exam focuses on: bladder palpation (distended? tense? painful?), abdominal evaluation, vital signs to rule out systemic decompensation.
Urinalysis — first-line test
Urine examination is the most important and most cost-effective test for evaluating urolithiasis. What is assessed:
- pH — alkaline (>7) suggestive of struvite, acidic (<6) suggestive of calcium oxalate or urate
- Specific gravity (SG) — urine density, an indicator of hydration and kidney function
- Microscopic sediment — identifying urine crystals is an important clue: struvite (coffin-lid shape), calcium oxalate (envelope or dumbbell shape), urate (yellow-brown rosettes), cystine (hexagonal). Crystal identification on urinalysis is not a definitive stone diagnosis, but it gives a strong direction
- Leukocytes, erythrocytes, bacteria — clues to a comorbid UTI
Radiograph (x-ray) of the abdomen
Most bladder stones are radiopaque (visible on x-ray). Struvite and calcium oxalate are usually clearly visible. Urate and cystine are sometimes radiolucent (transparent) — not visible on a plain radiograph. The radiograph is important for confirming the location, number, and size, and for evaluating the ureters and kidneys.
Ultrasound of the abdomen
Ultrasound can detect radiolucent stones that are not visible on x-ray, and provides additional information about the bladder wall (thickening suggestive of chronic cystitis), bladder volume, and the presence or absence of hydronephrosis (kidney enlargement due to obstruction). Ultrasound is also superior for evaluating ureteral stones.
Urine culture + sensitivity
Mandatory for struvite (especially in dogs) because UTI is the main driver. Even if no bacteria appear on urinalysis, the culture can be positive. The sensitivity test guides antibiotic choice.
Stone analysis
After the stone is removed (via cystotomy surgery or voiding urohydropropulsion), the stone must be sent to a specialist lab for definitive composition analysis. This guides the long-term prevention diet — there is no point feeding a struvite diet to a dog whose stone turns out to be calcium oxalate, and vice versa.
Treatment per stone type
Struvite — dissolution diet (medical management)
For struvite without obstruction, the first-line treatment is a dissolution prescription diet that acidifies the urine + restricts magnesium-phosphorus + increases diuresis. Common prescription brands used:
- Hill's Prescription Diet c/d (urinary care formulation)
- Royal Canin Urinary SO
- Purina Pro Plan Veterinary Diets UR Urinary
Typical duration: 4–6 weeks for complete dissolution, with periodic radiograph monitoring. Plus antibiotics if there is a comorbid UTI (duration also 4–6 weeks, or up to 2 weeks after the stone is gone and the follow-up culture is negative). After dissolution, transition to a long-term maintenance prescription diet to prevent recurrence — many dogs and cats need a prescription diet for life because of a high metabolic recurrence tendency.
Calcium oxalate — surgical or procedural removal
Calcium oxalate cannot be dissolved with diet. Definitive treatment:
- Cystotomy — surgery to open the bladder and remove the stones. Standard for stones too large for voiding
- Voiding urohydropropulsion — a manual technique to push small stones out via the urethra. Only for small stones that can pass through the urethra without obstruction
- Lithotripsy (laser or shockwave) — at specialist facilities that have it, stones are broken into small fragments that can pass via urine. Limited access in Indonesia
Long-term: an oxalate-prevention prescription diet (maintaining a moderate urine pH, restricting oxalate precursors, optimizing calcium-phosphorus), urinalysis monitoring every 3–6 months, medical therapy if there is underlying hypercalcemia.
Urate — low-purine diet + allopurinol
For predisposed dogs (Dalmatian, other breeds), combination treatment:
- A low-purine prescription diet (Hill's u/d, Royal Canin Urinary UC) that restricts purine precursors
- Allopurinol — a xanthine oxidase inhibitor that lowers uric acid production. Plumb's 7e lists a dosing protocol for dogs with urate urolithiasis
- Urine alkalinization (target pH 7–7.5) — makes uric acid more soluble
- If there is an underlying portosystemic shunt, correcting the shunt is definitive
Cystine — low-methionine diet + alkalinization + chelator
Cystine management is more complex because it is a genetic defect:
- A low-methionine prescription diet (cystine precursor)
- Urine alkalinization to increase cystine solubility
- Tiopronin (alpha-mercaptopropionylglycine) for refractory cases — a chelating agent that forms a soluble mixed disulfide with cystine
- High hydration for dilution
Silica — surgical + diet change
Cannot be dissolved, treatment is surgical removal. Long-term: identify the silica source in the diet (corn gluten heavy, soybean hull heavy) and switch to a different formulation.
Long-term prevention — diet + hydration + monitoring
After a stone is resolved, recurrence prevention is a long-term game involving several pillars:
1. Optimal hydration
The most important pillar for all stone types. More dilute urine (low specific gravity) means lower mineral concentration and a harder time precipitating into crystals/stones. Strategies:
- Switch to wet food (can or pouch) — wet food contains ~70–80% water vs dry food ~10%. For cats especially, this is the most impactful intervention. Cats don't have a strong thirst drive like dogs — they rely on the moisture content of their diet
- Provide multiple water bowls in different locations around the home
- Try a pet water fountain — many cats prefer running water
- For dogs: ensure the water bowl is always fresh, clean, and accessible
- Monitor water intake and urine output — a significant change is worth discussing with the vet
2. Long-term prescription diet
For animals with a history of urolithiasis, a urinary-formulated prescription diet is often mandatory for life. Not every case, but the majority with high recurrence risk. Do not switch to a regular commercial diet without discussing with the vet — a diet change can trigger recurrence within weeks to months.
3. Periodic monitoring
For animals with a stone history, the ISFM/AAFP Feline Lower Urinary Tract Disease 2014 and ACVIM Small Animal Internal Medicine recommend periodic monitoring:
- Urinalysis every 3–6 months to monitor pH, SG, crystals
- Abdominal radiograph or ultrasound every 6–12 months to screen for recurrence
- Periodic urine culture for dogs with a struvite-UTI history
- Adjust the diet based on the monitoring response
4. For predisposed dog breeds — early screening
If you have a Schnauzer, Yorkshire, Lhasa Apso, or another oxalate-predisposed breed, or a Dalmatian, or a Cocker Spaniel — discuss with your vet a baseline screening urinalysis and a diet prevention strategy even before the first stone occurs.
FAQ on urolithiasis in cats and dogs
Can I check my pet's stone type myself?
No. The mineral composition of a stone can only be determined via stone analysis at a specialist lab (X-ray diffraction or infrared spectroscopy). Crystal identification on urinalysis gives a directional clue but is not a definitive diagnosis. Don't guess — a type-identification mismatch means a treatment mismatch (feeding a dissolution diet to calcium oxalate is a waste of time; the stone won't dissolve).
How long is the dissolution diet for struvite?
Typically 4–6 weeks for complete dissolution, with periodic radiograph monitoring. Some cases need longer (up to 12 weeks). Don't stop the diet before the vet confirms the stone is gone via imaging — stopping prematurely means rapid recurrence.
Is cranberry good for cats/dogs with stones?
Unlike the popular myth in humans, cranberry in animals is not strongly evidence-based for preventing stones or UTIs. For struvite-UTI in dogs, the standard treatment is antibiotics per culture + sensitivity. To prevent stone recurrence, a urinary prescription diet + optimal hydration is far more impactful. Don't substitute cranberry for a medical-grade diet and antibiotics if the vet recommends them.
What is the cost of urolithiasis treatment in Jakarta?
It varies greatly depending on the stone type and the procedure needed. Medical treatment for struvite (dissolution diet 4–6 weeks + antibiotics if UTI + urinalysis monitoring + radiograph), cystotomy surgery for calcium oxalate at a clinic with facilities, and managing male cat urinary obstruction (unblocking + catheterization + 3–5 days of hospitalization + IV fluids + monitoring) all have very different cost components. A long-term prescription diet is also an ongoing cost; a 4 kg animal generally consumes about 4–6 kg/month. Because the range is wide, the most accurate estimate comes after the animal's condition is evaluated. For a discussion of consultation and home visit costs, WhatsApp Prabasavet for a free consultation.
My cat has already been unblocked once, is the recurrence risk high?
Yes — a male cat with a history of urinary obstruction has a significant recurrence risk, especially in the first 6–12 months. Strict post-unblock management (a urinary prescription diet for life, optimal hydration with wet food, environmental enrichment to reduce the stress that triggers FLUTD, periodic urinalysis monitoring) is very important. Discuss with your vet a long-term prevention plan that fits your cat's condition.
Can a cat/dog with stones get pregnant/be bred?
It depends on the stone type. Cystine has a strong genetic component → breeding is not recommended. Dalmatian urate → genetic, not recommended. Struvite and calcium oxalate have a genetic component but are more multifactorial — discuss the risk-benefit with your vet. For an animal with an active urinary issue, pregnancy itself adds a metabolic load that can worsen the urinary problem — it is usually advised to resolve the urinary issue + be stable first before considering breeding.
Closing
Urolithiasis in cats and dogs is a condition frequently found in veterinary practice, with the stone type strongly determining treatment and prevention. The five main types (struvite, calcium oxalate, urate, cystine, silica) have different breed and diet predisposition patterns — an accurate diagnosis via urinalysis + imaging + stone analysis is the key to well-targeted treatment.
The main key: don't ignore subtle urinary signs — hematuria, stranguria, frequency at the litter box, or vocalizing while urinating in any cat/dog deserves evaluation. In male cats, urinary obstruction is a life-threatening emergency that needs action in the first hours. For long-term prevention, optimal hydration (wet food + multiple water sources) and a urinary-formulated prescription diet are the most impactful pillars.
For owners in Jakarta and Greater Jakarta who find urinary signs in their pet, WhatsApp Prabasavet for an initial discussion — we help assess the situation, schedule a home visit for examination + urinalysis if non-obstructive, or direct you immediately to a clinic with surgical facilities if an obstructive emergency is detected.
Read also: Signs of a cat emergency: when to bring it to the vet immediately (urinary obstruction emergency), Senior cats with CKD: signs and management (sibling chronic kidney), Pet Emergency Guide (pillar), Pet Care Guide (pillar).
Medical references used in this article
This article was prepared with reference to the following sources, verified per clinical statement:
- Ettinger SJ, Feldman EC, Cote E (Eds.) Textbook of Veterinary Internal Medicine (ACVIM Small Animal Internal Medicine) — stone composition, predisposed breeds, formation mechanism, treatment per type, long-term monitoring
- ISFM/AAFP Feline Lower Urinary Tract Disease (FLUTD) Consensus Guidelines — diagnostic approach, environmental enrichment, prevention strategy, imaging indications
- BSAVA Manual of Canine and Feline Nephrology and Urology — urinalysis interpretation, crystal identification, treatment protocol per stone type, surgical vs medical management
- Plumb's Veterinary Drug Handbook 7e — dosing and safety profile for allopurinol (urate), antibiotics for struvite-UTI (amoxicillin-clavulanate, enrofloxacin, marbofloxacin per culture), tiopronin (cystine), and prescription diet protocols
This article is general guidance based on international ACVIM + ISFM/AAFP + BSAVA + veterinary urology textbook guidelines. For the diagnosis and management plan of your specific animal's urolithiasis — including stone-type identification, the choice of dissolution vs surgical treatment, and a long-term prevention strategy — consulting a veterinarian is the right step.
