28/02/2025
Urolithiasis in Dogs:
Urolithiasis, or urinary stone formation, is a common condition in dogs that can lead to significant discomfort, urinary obstruction, and complications if left untreated. These stones, or uroliths, develop due to an imbalance in urinary pH, mineral concentrations, and predisposing genetic or dietary factors. Early detection and appropriate management are crucial to prevent severe complications such as bladder rupture or renal damage.
A 3-year-old, 70 kg Great Dane presented with stranguria (straining to urinate). Physical examination and radiographs confirmed multiple cystoliths (bladder stones). Given the dog's large size and the confirmed presence of calcium oxalate stones, surgical intervention was deemed necessary. A cystotomy was performed, successfully removing multiple cystoliths. The dog recovered well postoperatively with dietary and hydration management to prevent recurrence.
This case highlights the importance of early diagnosis and intervention, especially in large breeds predisposed to calcium oxalate stones.
Causes and Risk Factors
Several factors contribute to urolithiasis in dogs, with the type of stone determining the underlying cause. The most common uroliths include:
Struvite Stones: Often associated with urinary tract infections (UTIs) caused by urease-producing bacteria (e.g., Staphylococcus spp.).
Calcium Oxalate Stones: Form in acidic urine and are influenced by genetic predisposition, diet, and metabolic factors.
Urate Stones: Common in Dalmatians and dogs with liver disease due to defective purine metabolism.
Cystine Stones: Result from a genetic defect in renal tubular reabsorption of cystine.
Silica Stones: Less common and associated with high-silica diets.
Case Study: A Giant Breed with Urolithiasis
Clinical Signs and Diagnosis
Dogs with urolithiasis may present with:
Stranguria (straining to urinate).
Pollakiuria (frequent urination).
Hematuria (blood in urine).
Dysuria (painful urination).
Urinary obstruction, which can become a life-threatening emergency.
Diagnostic Workup:
1. Physical Examination – Palpation may reveal a distended bladder or discomfort.
2. Urinalysis – Identifies crystalluria, pH abnormalities, and presence of infection.
3. Radiography – Detects radiopaque stones (e.g., calcium oxalate, struvite).
4. Ultrasound – Useful for radiolucent stones like urates and cystine.
5. Stone Analysis – Essential for determining preventive strategies post-removal.
Treatment Options
The treatment approach depends on stone type, location, and severity.
Medical Management:
Dietary Modification – Prescription diets can dissolve certain stones (e.g., struvite) but are ineffective for calcium oxalate.
Urinary Alkalinization/Acidification – Adjusting pH based on stone type (e.g., potassium citrate for calcium oxalate).
Increased Water Intake – Promotes urine dilution and reduces stone formation risk.
Antibiotic Therapy – If concurrent UTI is present.
Surgical and Non-Surgical Interventions:
Voiding Urohydropropulsion – For small, passable stones.
Lithotripsy – Laser or shockwave fragmentation (not widely available).
Cystotomy (Surgical Removal) – The preferred option for calcium oxalate uroliths, as seen in the Great Dane case.
Urethrostomy – Indicated in recurrent urethral obstructions.
Prevention Strategies
Breed-Specific Screening – Regular monitoring in predisposed breeds.
Dietary Adjustments – Tailored to stone type (e.g., low-oxalate diet for calcium oxalate).
Hydration Management – Ensuring optimal water intake to reduce urine supersaturation.
Routine Urinalysis and Imaging – Early detection of crystalluria or recurrent uti.
