Bladder & Kidney Stones in Dogs & Cats
Urinary stones (uroliths or calculi) are mineral deposits that form in the kidneys, ureters, bladder, or urethra of dogs and cats. They can cause pain, bloody urine, frequent urination, and life-threatening urinary obstruction — particularly in male cats. Accurate imaging is essential to determine stone location, size, number, and the best treatment approach.
At Sage Veterinary Imaging, abdominal ultrasound provides real-time visualization of urinary stones and their effects on the kidneys, ureters, and bladder. Ultrasound detects stones of all mineral compositions (including those invisible on X-rays), identifies urinary obstruction, and assesses kidney health — information that directly guides whether surgery, dietary dissolution, or other treatments are most appropriate.
SVI offers advanced ultrasound services at our centers in Round Rock, Texas; Spring, Texas; and Sandy, Utah.
Urinary Stones at a Glance
Urinary Stones in Dogs & Cats
Urinary stones form when minerals in the urine crystallize and aggregate into solid deposits. The mineral composition determines the treatment approach: struvite stones can often be dissolved with dietary management, while calcium oxalate stones require surgical or minimally invasive removal. Accurate identification of stone type is therefore critical.
In dogs, struvite stones (magnesium ammonium phosphate) are the most common type and are frequently associated with urinary tract infections. In cats, calcium oxalate stones have become the most common type and are associated with metabolic factors rather than infection. Urate stones are strongly associated with portosystemic shunts (liver shunts), particularly in Dalmatians.
Stones can form anywhere in the urinary tract. Bladder stones (cystoliths) are most common and typically cause hematuria (bloody urine) and dysuria (straining to urinate). Kidney stones (nephroliths) may be incidental or cause renal pain and kidney damage. Ureteral stones (ureteroliths) are increasingly recognized, especially in cats, and can cause life-threatening kidney obstruction.
Signs & Symptoms of Urinary Stones
Signs depend on stone location and whether urinary obstruction is present. Some stones are incidental findings, while others cause severe clinical signs requiring emergency intervention.
🚨 Urinary Obstruction Is a Life-Threatening Emergency
If your pet (especially a male cat) is straining to urinate without producing urine, crying in pain, or has not urinated in more than 12–24 hours, seek emergency veterinary care immediately. Complete urinary obstruction causes rapid potassium accumulation and kidney failure that can be fatal within 24–48 hours.
How Ultrasound Evaluates Urinary Stones
Ultrasound is the preferred first-line imaging study for urinary stone evaluation because it detects stones of all mineral compositions, identifies obstruction in real-time, and assesses kidney health without radiation.
What Ultrasound Reveals
Stone detection — Ultrasound detects stones of all mineral types, including radiolucent stones (urate, cystine) that are invisible on X-rays. Stones appear as bright (hyperechoic) structures with acoustic shadowing.
Stone location and number — Ultrasound maps stone location throughout the urinary tract — kidneys, ureters, bladder, and proximal urethra — to guide treatment decisions.
Urinary obstruction — Ureteral stones causing obstruction produce hydronephrosis (kidney swelling) and hydroureter (ureteral dilation) that are immediately visible on ultrasound. The degree of kidney dilation helps determine urgency.
Kidney health assessment — Ultrasound evaluates kidney size, architecture, and cortical thickness, revealing whether chronic stone disease has caused irreversible kidney damage.
Bladder wall assessment — Chronic irritation from bladder stones can thicken the bladder wall and predispose to urinary tract infections. Ultrasound shows bladder wall changes and helps monitor resolution after treatment.
Ultrasound vs. Other Imaging for Urinary Stones
Ultrasound
Detects all stone types including radiolucent stones. Shows obstruction, kidney health, and bladder wall changes. No radiation.
X-Ray
Shows radiopaque stones (struvite, calcium oxalate) but misses radiolucent stones (urate, cystine). Cannot assess kidney obstruction or parenchyma.
CT
Highest sensitivity for small stones and ureteral stones. Used when ultrasound findings are equivocal or for surgical planning of complex ureteral cases.
Which Breeds Are Most at Risk?
Breeds at Higher Risk
Dalmatians are uniquely predisposed to urate stones due to a genetic defect in uric acid metabolism. Miniature Schnauzers, Shih Tzus, Bichon Frises, and Lhasa Apsos have high rates of calcium oxalate stones. Cocker Spaniels and Labrador Retrievers are predisposed to struvite stones. In cats, Persians, Himalayans, and Burmese have higher rates. Male cats are at greatest risk for life-threatening urethral obstruction.
What to Expect During Urinary Ultrasound
Abdominal ultrasound focused on the urinary tract takes approximately 15–25 minutes and typically does not require anesthesia. A full bladder improves visualization, so your veterinarian may ask you not to let your pet urinate immediately before the appointment.
Results are interpreted by a board-certified veterinary radiologist, often in real-time. For emergency cases (suspected urinary obstruction), findings are communicated immediately. The report includes stone location, number, and size, as well as kidney and bladder assessment, providing all the information needed for treatment planning.
Why Choose Sage for Urinary Stone Evaluation
Schedule Urinary Tract Imaging
If your pet has bloody urine, straining to urinate, or suspected urinary stones, ultrasound provides the complete evaluation needed to guide the most effective treatment.
Urinary Stone Imaging FAQ
Get Answers for Your Pet
Urinary stones require accurate diagnosis for effective treatment. Ultrasound provides the complete picture of stone location, kidney health, and obstruction status.