🐾 Vet Urology 2025: Understanding and Preventing Calcium Oxalate Bladder Stones in Cats 🐱🧪

By Dr Duncan Houston BVSc

Bladder stones—also known as uroliths—can cause discomfort, infections, and urinary blockages in cats. Among the various types, calcium oxalate bladder stones are now one of the most common and persistent forms, especially in middle-aged and older felines. Unlike some other stone types, calcium oxalate stones cannot be dissolved with diet alone, making management and prevention all the more important. 🚫🥫

🔬 What Are Calcium Oxalate Stones?

These stones are hard mineral deposits that form in the bladder when urine becomes overly concentrated or acidic. Made from calcium and oxalate compounds, they often develop silently and are only discovered when symptoms arise—or incidentally during X-rays for another issue. 🩻

Common discovery scenarios include:

• 🔴 Straining to urinate or bloody urine
• 🦠 Recurrent urinary tract infections
• 🩻 Imaging done for other health concerns

❓ Why Do Cats Develop Oxalate Stones?

A major shift in feline nutrition over the past few decades—particularly the acidification of cat food to reduce struvite crystals—has contributed to the rise of calcium oxalate stones. 🧫📉

💡 Key risk factors include:

• 🐱 Breed: Burmese and Himalayan cats are genetically predisposed
• 📅 Age: Most cats are affected between 5–14 years
• ⚖️ Obesity
• 🧪 Acidic urine pH
• 💉 Hypercalcemia (high blood calcium) in ~35% of cases

🔍 How Are They Diagnosed?

Stones are usually detected via:

• 🩺 Physical exam + urinalysis
• 🩻 X-rays or ultrasound
• 🧪 Lab stone analysis after removal

Urinalysis may show acid urine and the presence of oxalate crystals, but definitive identification requires sending the stone to a lab. 🧬

🛠️ Treatment Options

1️⃣ Surgical Removal (Cystotomy)

The most common and direct method. Under anesthesia, the bladder is opened and stones are removed manually. 🩹 Recovery typically takes a few days. This method is available at most veterinary hospitals. 🏥

2️⃣ Cystoscopy + Laser Lithotripsy

Less invasive. A scope and laser are used to break up and retrieve stones. Limited to female cats due to anatomical access. 💡🔦

3️⃣ Percutaneous Cystolithotomy (PCCL)

Minimally invasive. Involves a small incision and the use of a camera and tools to remove stones. Can be performed on both males and females. 🛠️

4️⃣ Voiding Urohydropropulsion

For small stones only. Involves sedating the cat, filling the bladder with fluid, and manually expressing stones. Rarely effective in male cats due to narrow urethras. 💧

🚫 Diet will NOT dissolve calcium oxalate stones

Unlike struvite stones, these do not respond to dissolution diets and must be physically removed. 🍽️✖️

🔁 Preventing Recurrence

Prevention is often more difficult than treatment. Here's the strategy:

🟩 Step 1: Adjust the Diet

• 🥫 Feed a non-acidifying canned diet (high moisture, moderate protein, and magnesium)
• 💧 Increase water intake to dilute urine
• 🍽️ Avoid vitamin C supplements (which convert to oxalate)

Goal: Urine pH between 6.8–7.5 and specific gravity < 1.030. A urinalysis should be repeated after 2–4 weeks. 🔬

🟨 Step 2: Troubleshooting

If the urine is too concentrated or still acidic, consider:

• 💊 Potassium citrate (to raise pH)
• 🥣 More wet food, less dry food
• 🚰 Pet fountains or hydration additives like Purina Hydra Care®

🟥 Step 3: Persistent Crystal or pH Problems

• 💊 Add thiazide diuretics to help dilute urine
• 🔬 Vitamin B6 supplementation (especially if B6 deficiency suspected)
• 🧪 Consider switching to a different veterinary diet

📅 Ongoing Monitoring

Even after success, long-term prevention requires:

• 🧪 Urinalysis every 3–6 months
• 🩻 Radiographs every 6–12 months

Females may be able to pass small stones, but males will almost always require surgery due to the small diameter of the urethra. ⚠️

📍 Final Thoughts

Calcium oxalate bladder stones are painful, recurrent, and require diligent veterinary management. With proper diet, hydration, and regular monitoring, you can greatly reduce your cat’s risk of recurrence and ensure a long, comfortable life. 🐾💧

Need a personalized prevention plan? 🐱💬 Visit AskAVet.com or download the Ask A Vet app to speak with Dr Duncan Houston or another licensed veterinarian today. 🩺📱