Bladder stones almost never announce themselves as bladder stones. What owners notice is a dog squatting six times on a short walk, producing a teaspoon each time. Or a puddle by the back door from a dog who has never had an accident. Or a faint pink tinge in the snow. It looks like a urinary tract infection, gets treated like a urinary tract infection, and improves briefly on antibiotics — and then it comes back.
Underneath, in a meaningful number of these dogs, there are stones: mineral concretions ranging from sand-fine grit to objects the size of a walnut, grinding against the bladder wall. What matters most about them is something owners rarely hear up front — some types of bladder stone can be dissolved with food alone, and others can never be dissolved at all. Knowing which kind your dog has changes the entire plan.
What Bladder Stones Actually Are
Urine is a concentrated chemical soup. It carries dissolved minerals — magnesium, calcium, phosphate, ammonium, urate — that stay in solution as long as their concentration and the urine's pH keep them there. Push the concentration too high, shift the pH too far in one direction, or let urine sit too long in the bladder, and those minerals begin to crystallize. Crystals clump, clumps grow, and the result is a urolith: a bladder stone.
Stones do damage in two ways. Mechanically, they abrade the bladder lining, which causes inflammation, pain, and bleeding. And if a stone is small enough to enter the urethra but too large to pass through it, it can lodge there and block urine from leaving the body — a true emergency, and one that male dogs are far more prone to because of the narrow, bone-supported anatomy of the male urethra.
The Signs to Watch For
Bladder stones and urinary tract infections look almost identical from the outside, which is exactly why recurrent "UTIs" deserve imaging rather than another round of antibiotics. Watch for:
- Straining to urinate or spending an unusually long time in position.
- Frequent urination of small volumes — many trips, little output.
- Blood in the urine, sometimes only visible at the end of the stream.
- Accidents indoors from an otherwise reliably house-trained dog.
- Licking at the genital area more than usual.
- Cloudy or strong-smelling urine.
Some dogs with stones show nothing at all, and the stones turn up incidentally on an X-ray taken for another reason.
The emergency version: a dog who is straining hard and producing nothing, or only a few drops, may be obstructed. Add vomiting, lethargy, loss of appetite, or a painful, distended abdomen and this is a same-hour problem, not a next-morning one. A complete urethral obstruction causes toxins and potassium to build up in the bloodstream and can be fatal within roughly 24 to 48 hours. Do not wait to see if it resolves.
The Main Types — and Why the Type Decides Everything
Two mineral types account for the large majority of canine stones. Of the 63,762 canine urolith submissions analyzed by the Minnesota Urolith Center in 2023, roughly 41% were struvite and 33% calcium oxalate. The remainder were urate, cystine, silica, calcium phosphate, and mixed or compound stones.
Struvite (magnesium ammonium phosphate) stones in dogs are usually infection-induced. Certain bacteria — Staphylococcus and Proteus species in particular — produce an enzyme called urease that splits urea in the urine, releasing ammonia. That raises urine pH and floods it with the exact ingredients struvite needs. This is why struvite stones are markedly more common in female dogs: females get more urinary tract infections. The important consequence is that struvite stones are the classic dissolvable stone. On a therapeutic dissolution diet plus appropriate antibiotics, they can shrink and disappear over roughly 8 to 12 weeks, sometimes faster, with no surgery at all.
Calcium oxalate stones are the opposite story. They form in acidic, calcium-rich urine, are more common in male dogs, and are strongly overrepresented in small breeds — Miniature Schnauzers, Bichon Frises, Lhasa Apsos, Shih Tzus, Yorkshire Terriers, Pomeranians. Some affected dogs excrete excess calcium in their urine; some have elevated blood calcium; in many, the underlying cause is never identified. The critical point: calcium oxalate stones cannot be dissolved by any diet or medication. They have to be removed physically. Diet's role afterward is purely preventive.
Beyond the big two: urate stones are tied to a genetic defect in uric acid metabolism that is near-universal in Dalmatians and also found in English Bulldogs; they can also signal a liver shunt in a young dog of any breed. They are often dissolvable. Cystine stones arise from an inherited kidney transport defect and appear mostly in intact males of certain breeds; neutering alone resolves many cases.
How Vets Diagnose Them
Diagnosis is straightforward, but it takes more than one test. Palpation may detect larger stones through the abdominal wall, though it misses plenty. Urinalysis shows blood, inflammatory cells, urine pH, and any crystals present — but crystals are a hint, not proof. Plenty of dogs have crystals and no stones, and some stones shed no crystals at all.
Imaging settles it. Struvite and calcium oxalate stones are radiopaque and show clearly on plain X-rays. Urate and cystine stones are often radiolucent — effectively invisible on standard radiographs — so ultrasound is the more reliable tool overall, and is also better at catching very small stones. A urine culture identifies whether infection is driving the process.
The last step is the one that shapes long-term care: after stones are removed or passed, they should be sent for quantitative mineral analysis. Guessing the composition from urine pH and crystal appearance is unreliable, and the wrong guess means the wrong prevention diet for the rest of the dog's life.
Treatment: Dissolve, Remove, or Extract
The 2016 ACVIM Small Animal Consensus Recommendations on urolith treatment favor the least invasive option that will actually work.
Medical dissolution is first choice when the stone type allows it. For struvite, that means a therapeutic diet formulated to lower urine pH and reduce the minerals struvite needs, combined with antibiotics chosen by culture, and follow-up imaging every few weeks to confirm the stones are shrinking. Dissolution is not appropriate for a dog who is obstructed or nearly so.
Non-surgical removal covers several techniques. Voiding urohydropropulsion flushes small stones out through the urethra under sedation. Cystoscopy with basket retrieval or laser lithotripsy breaks up and removes stones through the urethra with no abdominal incision. Both spare the dog a cystotomy where the stone size and the dog's anatomy allow.
Surgery (cystotomy) remains necessary for large stones, non-dissolvable stones in a symptomatic dog, and any urethral obstruction that cannot be relieved. Recovery is generally quick, but post-operative imaging is worth insisting on — small stones are left behind more often than anyone would like.
Preventing the Next One
Recurrence rates are significant, particularly for calcium oxalate. Prevention rests on a few principles that apply regardless of stone type:
- Dilute the urine. This is the single most effective measure. More water means lower mineral concentration. Feeding canned food, adding water to kibble, and keeping multiple fresh water sources available all help. Some vets target a specific urine specific gravity.
- Let the dog empty the bladder often. Urine that sits gives crystals time to aggregate. More frequent walks are genuinely therapeutic here.
- Use the right diet — and only the right diet. A diet that prevents struvite acidifies urine, which actively promotes calcium oxalate. This is why mineral analysis matters so much. Follow the prescription for the stone your dog actually had.
- Skip the calcium and vitamin C supplements unless your vet has specifically prescribed them. Both can raise oxalate risk.
- Treat infections properly and completely, since struvite in dogs is usually infection-driven.
- Recheck. Periodic urinalysis and imaging catch new stones while they are still small enough for non-surgical options.
Breed-specific measures apply on top: low-purine diets and sometimes allopurinol for urate formers, urine alkalinization and a low-cystine diet for cystine formers, and neutering for intact males with cystine stones.
The Takeaway
If your dog has been treated for two or three urinary tract infections in a year, ask for imaging rather than another prescription. If stones are found, ask two questions: what type are they, and was that determined by laboratory analysis or by guesswork? Struvite stones can often melt away on a diet. Calcium oxalate stones never will, and a diet aimed at the wrong stone can make things worse. And if a male dog is straining without producing urine, treat it as the emergency it is.