Urinary Stones in Dogs: Types, Causes, and Prevention

Urinary stones, or uroliths, are mineral formations that develop within a dog’s urinary tract (most commonly in the bladder). These stones can vary in size and may cause symptoms ranging from mild discomfort to serious complications such as obstruction, infection, and kidney damage. Early recognition, proper diagnosis, and informed prevention strategies are essential to managing this condition effectively.

Types of Urinary Stones in Dogs

There are five primary types of urinary stones in dogs. Each differs in composition, cause, and management approach:

1. Struvite Stones

• • Composition: Magnesium ammonium phosphate

• • Cause: Primarily caused by infections with urease-producing bacteria (e.g., Staphylococcus pseudintermedius), which raise urine pH and promote crystal formation

• • Risk Factors: Alkaline urine, recurrent urinary tract infections (UTIs)

• • Common Breeds: Miniature Schnauzers, Bichons, Cocker Spaniels 

According to the University of Minnesota Urolith Center, over 80% of struvite stones in dogs are infection-induced, particularly in females.

2. Calcium Oxalate Stones

• • Composition: Calcium oxalate

• • Cause: Hypercalciuria (excess calcium in urine), low urinary citrate, acidic urine, genetic predisposition

• • Risk Factors: Male dogs, obesity, low-moisture diets

• • Common Breeds: Miniature Schnauzers, Yorkshire Terriers, Shih Tzus, Lhasa Apsos 

These stones do not dissolve through dietary changes and often require surgical or procedural removal. High-oxalate foods can increase risk. Examples include spinach, beet greens, Swiss chard, sweet potatoes, almonds, and rhubarb. Avoiding these foods for dogs prone to calcium oxalate stones.

3. Urate Stones

• • Composition: Ammonium urate

• • Cause: Genetic disorders affecting purine metabolism or the presence of portosystemic (liver) shunts

• • Common Breeds: Dalmatians, English Bulldogs, Black Russian Terriers 

Dalmatians are genetically predisposed due to a mutation that impairs uric acid processing, increasing urate stone risk. Dogs with liver shunts may also form these stones.

4. Cystine Stones

• • Composition: Amino acid cystine

• • Cause: Inherited defects in renal tubular reabsorption of cystine

• • Common Breeds: Mastiffs, Newfoundlands, Dachshunds, English Bulldogs 

These stones are more prevalent in intact males and may require specialized diets or medications (e.g., urinary alkalinizers, thiol-binding agents) to manage effectively.

5. Silica Stones

• • Composition: Silicon dioxide

• • Cause: Rare; may be linked to consumption of silicate-rich plant materials or environments high in natural silica

• • Common Breeds: German Shepherds and other large-breed working dogs 

How Stones Form: The Science Behind It

Urinary stones form when the chemistry of the urine becomes imbalanced. Common contributing factors include:

• • Mineral Supersaturation: High concentrations of stone-forming minerals in urine

• • Urine pH Imbalance:
    

     

    • • Alkaline urine (pH > 7) promotes struvite formation
    • • Acidic urine (pH < 6.2) favors calcium oxalate stones

• • Dehydration: Low water intake concentrates urine, increasing crystallization risk

• • UTIs: Bacterial infections, especially those caused by urease-positive organisms, directly contribute to struvite stone formation

• • Genetics & Metabolic Disorders: Inherited issues with cystine or purine metabolism increase risk for specific stone types 

Proven Prevention Strategies

1. Promote Hydration

• • Feed moisture-rich diets: raw, gently cooked, or high-quality canned foods

• • Add low-sodium bone broth to meals

• • Use water fountains or place multiple water bowls around your home 

A 2019 study in Frontiers in Veterinary Science showed that increased moisture intake reduces calcium oxalate stone recurrence.

2. Monitor Urine pH

• • Target pH: 6.2 to 6.8, depending on your dog’s health profile

• • Use vet-recommended urine test strips at home

• • Report consistently high or low pH to your vet 

3. Treat UTIs Promptly

• • Always request urinalysis and a culture test—not just a physical exam

• • Re-check post-treatment to ensure the infection has cleared

• • Chronic or untreated UTIs are a leading cause of struvite stones 

4. Feed With Purpose

• • Avoid high-oxalate foods (e.g., spinach, sweet potatoes, almonds) for dogs prone to oxalate stones

• • Reduce purine intake (e.g., organ meats, sardines) in dogs prone to urate stones

• • Choose foods with balanced protein and controlled minerals

• • Seek advice from an independent or board-certified veterinary nutritionist if needed 

5. Stay on Top of Vet Visits

• • Schedule urinalysis every 3–6 months for dogs with a stone history

• • Consider annual imaging (ultrasound or x-ray)

• • Seek immediate care for straining, bloody urine, or frequent urination 

Final Thoughts

Urinary stones are complex and often linked to multiple underlying causes—but they’re not inevitable. With the right knowledge, diet, and care routine, you can significantly reduce your dog’s risk. Focus on hydration, avoid problematic foods, and work closely with your vet to tailor prevention to your dog’s unique health needs.

Because when it comes to urinary wellness, proactive care makes all the difference.

Sources:

• • University of Minnesota Urolith Center

• • Cornell University College of Veterinary Medicine

• • Frontiers in Veterinary Science

• • National Library of Medicine