# What Causes Bladder and Kidney Stones in Dogs? What causes dog bladder stones? Most stones form when minerals in urine become too concentrated and stick together, often because of a urinary tract infection, an alkaline urine pH, diet, or genetics. Different stone types have different causes, so identifying the mineral is the first step toward the right treatment. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Struvite stones, the most common type in female dogs, usually form because of a urinary tract infection with bacteria that make urine more alkaline [1]. - Calcium oxalate stones are the most common bladder stone in dogs in some regions, and they often require surgery because they do not dissolve with diet [2]. - Crystals are the early building blocks of stones. They can be present without stones, and stones can be present without visible crystals. - Stones can form anywhere in the urinary tract, including the kidney, ureter, bladder, and urethra [3]. - A blocked urethra is a life-threatening emergency. If your dog strains to urinate and nothing comes out, call an emergency clinic right away [1]. ## What Bladder and Kidney Stones Are "Urolithiasis" is the medical term for stones, also called uroliths or calculi, anywhere in the urinary tract [3]. They can sit in the kidney (nephroliths), the ureter (ureteroliths), the bladder (urocystoliths), or the urethra (urethroliths) [3]. Stones start small. Minerals dissolved in urine can precipitate into crystals, and those crystals can clump and grow into a stone you can see on an X-ray or ultrasound [3]. So crystals and stones are related, but they are not the same thing. A dog can have crystals in the urine and never form a stone. Yes, dogs can have kidney stones. Kidney stones tend to dissolve more slowly than bladder stones, but dissolving infection-related kidney stones has been described successfully [4]. ## What Causes Dog Bladder Stones and Crystals? Several forces have to line up for a stone to form. The urine has to be concentrated enough, the minerals have to be supersaturated, and the crystals have to stay in the urinary tract long enough to clump [3]. Urine pH, diet, infection, how often your dog urinates, and genetics all affect those conditions [3]. ### Infection and urine pH Struvite stones are the classic infection-driven stone. They form when urease-producing bacteria break down urea and push urine pH toward alkaline. That alkaline, concentrated urine lets struvite minerals become supersaturated, and crystals begin to stick together [1]. Bacteria can even get trapped between the layers as the stone grows [1]. This is why struvite stones are especially common in female dogs. Their shorter urethra makes urinary tract infections more likely [1]. ### Diet, water, and urine concentration Diet changes what is dissolved in the urine. The mineral content of urine relative to its concentration, plus stone promoters and inhibitors, all influence which stone type can develop [3]. Low water intake and infrequent urination give crystals more time to sit and grow [3]. ### Genetics and breed Some dogs inherit a higher risk. In one review of dogs with ureteral stones, Yorkshire Terriers and Shih Tzus made up most of the cases [5]. Genetics also shape how the intestines absorb stone-forming minerals and how the kidneys handle them [3]. ### Other health conditions Underlying disease can change urine chemistry. Dogs with calcium oxalate stones should be checked for metabolic disorders that raise urinary calcium, such as hypercalcemia, hyperadrenocorticism, and primary hyperparathyroidism [4]. They should also be evaluated for chronic kidney disease and heart disease, which affect treatment and prevention choices [4]. Liver abnormalities can play a role too. In a study of dogs with primary portal vein hypoplasia, 28.5% had urolithiasis, and all of those dogs had crystalluria, mostly ammonium biurate crystals [6]. ### The immune system's role Newer research suggests the immune system helps stones grow. Neutrophils release web-like structures made of DNA and antimicrobial proteins, and these structures have been found inside canine urinary stones and the tissue around them. Common urinary pathogens trigger this response, and the structures promoted crystal nucleation, aggregation, and stone growth in lab experiments [7]. This may help explain why some stones keep growing even when the usual urine chemistry factors are addressed [7]. ## What Dog Kidney Stones and Bladder Stones Look Like Owners rarely see a stone. Most are found on imaging. When stones are passed or removed, struvite calculi often look smooth, round, or faceted [4]. Size varies widely. In one case series, larger bladder stones measuring 10 to 20 mm were more common in female dogs [2]. Kidney and ureteral stones are usually smaller and can be multiple. In a review of 14 dogs with ureteral stones, the median number per dog was 2.5, and 10 of the 14 dogs had at least two stones [5]. ## Signs Owners Notice The signs of bladder stones overlap heavily with urinary tract infections and cystitis. In a study of working dogs, those with urolithiasis showed abdominal pain, painful urination, blood in the urine, and urinary retention [8]. Bloodwork showed lower red blood cell counts and hemoglobin, plus higher white blood cells, neutrophils, and platelets, and urinalysis showed protein and blood [8]. Watch for these signs at home: - Peeing small amounts frequently, or squatting with little output - Blood in the urine or pink-tinged spots - Straining, whining, or licking at the genital area - Accidents in the house in a previously reliable dog - Vomiting, lethargy, or abdominal pain If your dog is passing blood, our guide to [bloody urine, cystitis, bladder stones, and UTIs](/knowledge/veterinary-medicine/symptom-guides/why-is-my-dog-having-bloody-urine-cystitis-bladder-stones-and-uti-guide) walks through what each pattern can mean. Frequent urination without much urine is another pattern worth reading about in [dog urinating frequently](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-urinating-frequently-causes-when-to-call-vet). A complete blockage is different. Signs can escalate to vomiting, abdominal pain, lethargy, dehydration, and possible bladder rupture, and this is a medical emergency [1]. ## How Veterinarians Diagnose Stones and Crystals Your veterinarian starts with a physical exam. Large bladder stones can sometimes be felt by palpating the abdomen [1]. Testing usually includes: - Urinalysis to check pH, concentration, crystals, blood, and protein - Urine culture to find infection and choose the right antibiotic - Bloodwork to assess kidney values and look for metabolic disease - Imaging, typically X-rays or ultrasound, to confirm stones and their location Ultrasound is useful for seeing stones and secondary changes. In the ureteral stone review, 12 of 14 dogs had pyelectasis, which is dilation of the renal pelvis from partial or complete urine flow obstruction [5]. That finding tells your vet how much the kidney is being affected. The stone's mineral type matters more than anything else for treatment. If a stone is passed or removed, it can be analyzed. Knowing the composition guides whether diet can dissolve it or whether surgery is needed. For a deeper look at the testing process, see [canine urolithiasis diagnosis and medical management](/knowledge/veterinary-medicine/clinical-methods/canine-urolithiasis-diagnosis-medical-management). ## Stone Types and What They Mean | Stone type | Main drivers | Can diet dissolve it? | Typical approach | |---|---|---|---| | Struvite | UTI with urease-producing bacteria, alkaline urine [1] | Often yes, when infection is treated | Antibiotics plus prescription dissolution diet [1] | | Calcium oxalate | Metabolic disorders, high urinary calcium, genetics [4] | No | Surgery or removal, then prevention [4] | | Ammonium biurate | Liver abnormalities such as portal vein hypoplasia [6] | Sometimes | Address liver disease, manage diet | | Mixed | More than one mineral | Varies | Based on the dominant mineral [2] | Stone type also varies by region and population. In one 5-year study of bladder stones, calcium oxalate predominated in dogs at 65%, followed by struvite at 30% and mixed stones at 5% [2]. Struvite remains one of the most common types overall, especially in females [1]. ## Treatment Options Treatment depends on the stone type, location, size, and whether your dog can urinate. ### Medical dissolution Struvite stones can often be dissolved with a prescription diet plus treatment of the underlying infection [1]. Kidney stones dissolve more slowly than bladder stones, but successful dissolution of infection-induced kidney and urinary stones has been reported [4]. ### Surgery and procedures Calcium oxalate stones do not dissolve with diet, so they are usually removed surgically [4]. Stones lodged in the ureter may need specialized procedures. When obstruction is widespread and surgery is not practical, a urethral stent can be placed as a palliative option to restore urine flow. In one case report, a dog with multifactorial obstruction had rapid return of urine flow and improved kidney values within 3 days of stenting [9]. ### Emergency unblocking If a stone blocks the urethra, your dog needs immediate care to relieve the obstruction. This situation can be life-threatening [1]. ## Recovery, Outlook, and Long-Term Management Recurrence is the main long-term concern. Sterile struvite stones, meaning those not caused by infection, are more likely to come back because the underlying cause is not fully understood and persists after the stones are gone [4]. Some prescription diets are made for long-term feeding to reduce struvite recurrence, though data on how well they work are limited [4]. Dogs prone to struvite stones should ideally keep urine pH around 6 to 6.5, with a specific gravity your vet sets based on your dog [4]. Your veterinarian will recheck urine and imaging on a schedule, often more often in the first months after treatment. If your dog has calcium oxalate stones, long-term care includes managing any metabolic disorder and monitoring for chronic kidney disease and heart disease, since those conditions change what prevention plan is safe [4]. Learn more about ongoing care in [canine urolithiasis medical dissolution and prevention](/knowledge/veterinary-medicine/clinical-internal-medicine/canine-urolithiasis-medical-dissolution-prevention). ## Prevention You cannot change your dog's genetics, but you can change several things that feed stone formation. - Treat urinary tract infections promptly and fully. Infection is the main driver of struvite stones [1]. - Encourage drinking. More water means more dilute urine and less time for crystals to clump [3]. - Offer frequent bathroom breaks. Prolonged crystal transit time in the urinary tract supports stone growth [3]. - Feed the diet your veterinarian prescribes. Therapeutic diets change urine pH and mineral levels for a reason [3]. - Keep follow-up appointments. Recheck urinalysis and imaging catch recurrence early. - Manage underlying disease. Liver, kidney, heart, and hormonal conditions all influence stone risk [4][6]. ## Limitations and When to Contact a Veterinarian This article covers general patterns. Your dog's case needs a veterinarian who can examine, test, and treat your individual pet. Call an emergency clinic now if your dog is straining to urinate with little or no urine coming out, has a hard or painful belly, is vomiting, or is collapsing. A urinary obstruction can be life-threatening [1]. Call your veterinarian the same day if you see blood in the urine, repeated attempts to urinate, crying while urinating, or a sudden increase in accidents. For bloody urine with straining, our guide to [blood in urine and emergency steps](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-blood-in-urine-causes-emergency-steps) can help you decide how urgent it is. Schedule a routine visit if your dog has a history of stones and you notice any change in urination habits, even mild ones. Recurrence is common, and early detection is easier to manage [4]. ## Frequently Asked Questions ### Can dogs have kidney stones without showing signs? Yes. Some kidney stones are found incidentally during imaging for another problem. Others cause subtle signs like changes in appetite or energy before more obvious urinary signs appear [5]. ### Do all bladder stones need surgery? No. Struvite stones can often be dissolved with a prescription diet and infection treatment [1]. Calcium oxalate stones do not dissolve and are usually removed surgically [4]. ### Are urine crystals always a sign of stones? No. Crystals can be present in urine without any stone forming. They are a warning sign that urine conditions favor crystallization, so your vet may recommend diet changes or monitoring [3]. ### Can a urinary tract infection cause stones in male dogs too? Yes. Struvite stones are more common in females because of their anatomy, but any dog with a urease-producing infection can form them [1]. ### What should I feed a dog that has had stones? Feed the specific therapeutic diet your veterinarian prescribes for that stone type. Different minerals require different diets, and the wrong food can make recurrence more likely [4][3]. ## Related Articles - [Why Is My Dog having bloody urine? Cystitis Bladder Stones and UTI Guide](/knowledge/veterinary-medicine/symptom-guides/why-is-my-dog-having-bloody-urine-cystitis-bladder-stones-and-uti-guide) - [Canine Urolithiasis: Diagnosis and Medical Management](/knowledge/veterinary-medicine/clinical-methods/canine-urolithiasis-diagnosis-medical-management) - [Canine Urolithiasis: Medical Dissolution and Prevention](/knowledge/veterinary-medicine/clinical-internal-medicine/canine-urolithiasis-medical-dissolution-prevention) - [Dog Blood in Urine: Causes and Emergency Steps](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-blood-in-urine-causes-emergency-steps) - [Dog Urinating Frequently: Causes and When to Call the Vet](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-urinating-frequently-causes-when-to-call-vet) - [Signs Of Uti In Dogs](/knowledge/veterinary-medicine/clinical-methods/signs-of-uti-in-dogs) - [Bladder Stones in Dogs: Treatment, Diet and Surgery](/knowledge/veterinary-medicine/digestive-and-urinary-care/bladder-stones-dogs-treatment-diet) - [Dog Kidney Stones: Diet and Home Care](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-kidney-stones-diet-home-care) - [Cystine Crystals in Dog Urine: Causes and Diet](/knowledge/veterinary-medicine/digestive-and-urinary-care/cystine-crystals-dog-urine) ## References 1. [Struvite bladder stones in dogs](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-topics/struvite-bladder-stones-dogs). Cornell University College of Veterinary Medicine. 2. [A 5-year retrospective epidemiological and compositional study of canine and feline uroliths in Tehran, Iran (2019 - 2024)](https://pubmed.ncbi.nlm.nih.gov/42626433/). Veterinary research forum : an international quarterly journal, 2026. 3. [Overview of Urolithiasis in Small Animals - Urinary System](https://www.merckvetmanual.com/urinary-system/urolithiasis-in-small-animals/overview-of-urolithiasis-in-small-animals). Merck Veterinary Manual. 4. [Urolithiasis in Dogs - Urinary System](https://www.merckvetmanual.com/urinary-system/urolithiasis-in-small-animals/urolithiasis-in-dogs). Merck Veterinary Manual. 5. [Presentation, diagnosis, mineral findings, and management of ureteral calculi in 14 dogs (2010-21)](https://pubmed.ncbi.nlm.nih.gov/41167254/). New Zealand veterinary journal, 2026. 6. [Urolithiasis and crystalluria in dogs with primary portal vein hypoplasia: a retrospective study (2010-2023)](https://pubmed.ncbi.nlm.nih.gov/42420192/). The Journal of small animal practice, 2026. 7. [Neutrophil Extracellular Traps Promote Urolithiasis Formation in Dogs: A Preliminary Study](https://pubmed.ncbi.nlm.nih.gov/41897919/). Animals : an open access journal from MDPI, 2026. 8. [Comprehensive diagnostic evaluation of urolithiasis and cystitis in K9 dogs in Iraq: Clinical, laboratory, and imaging correlates](https://pubmed.ncbi.nlm.nih.gov/41630760/). Open veterinary journal, 2025. 9. [Case Report of Urethral Stenting in a Dog with Multifactorial Lower Urinary Tract Obstruction Associated with Suspected Transitional Cell Carcinoma and Severe Cystolithiasis](https://pubmed.ncbi.nlm.nih.gov/42188942/). Veterinary sciences, 2026. ## Further Reading - [Merck Veterinary Manual: Dog Owners](https://www.merckvetmanual.com/dog-owners) - [Cornell Richard P. Riney Canine Health Center: Canine Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information) - [American Veterinary Medical Association: Pet Care](https://www.avma.org/resources-tools/pet-owners/petcare)