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Part 1: A guide to bladder stones in dogs

Uroliths, or bladder stones, are a very common health concern in dogs. When a dog urinates more often than usual, strains to urinate, or has pink-tinged urine, this may be due to the presence of one or more stones. This blog post aims to help dog owners understand various types of bladder stones, their formations and common causes. 

What are Uroliths?

Uroliths develop when individual crystals in urine combine and form a solid stone. This typically occurs in the urinary bladder, but stones can also form in the kidney or ureters. Uroliths can vary greatly in size, shape, composition and their presence can irritate the bladder wall causing discomfort. This can contribute to the development of other diseases, such as urinary tract infections or urethral blockages.  

In the bladder, uroliths can exist as either a single, large stone or a cluster of stones that range in size from tiny sand-like particles to larger gravel-sized pieces. It is not uncommon to find a combination of small and large stones together. A urolith can form within just a few weeks or it may take up to several months to form. How quickly a stone grows will depend primarily on the number of crystals in the urine. 

Possible Signs of the Presence of a Urolith

  • Blood in the urine
  • Changes in urine color (can be cloudy or dark-colored urine)
  • Straining to urinate
  • Urinating frequent, small amounts
  • Discomfort and pain in the abdomen
  • Nausea and vomiting

Main Causes

Although there is no one way in which uroliths are formed, multiple factors are known to contribute to the development of bladder stones. Urinary tract infections (UTI) are a common factor because the bacteria from the infection can change the acidity of the urine, and this creates a favorable environment for the development of specific stone types. Another risk factor is urinary stasis, or a slowing of urine flow caused by defects in the urinary tract, or by a blockage of the urethra or weak bladder muscles. Under these circumstances, debris and waste material usually removed from the bladder in the urine is not flushed out as frequently, resulting in a higher chance of stone formation. 

Image of black Miniature Schnauzer

Different Types of Stones

As previously mentioned, uroliths can be different shapes, sizes, and even made up of different components. Specifically, uroliths can be composed of several different types of crystals. Below are brief descriptions of the most common stones.  


This urolith is the most common bladder stone found in dogs and forms when urine pH is high (less acidic or more basic) in the bladder. The likelihood of developing struvite stones is greater in dogs with UTIs. Struvite stones are most often seen in large breed, female dogs between the ages of 2-4 years old. Breeds such as Shih Tzu, Bichon Frise, Miniature Schnauzer, Lhasa Apso, and Yorkshire Terrier are more commonly associated with struvite uroliths.  

Calcium Oxalate

Calcium oxalate is the second most common type of urolith in dogs. Calcium oxalate stones tend to form when there is an excessive amount of calcium in the urine. This type is more common in older, male neutered dogs, between the ages of 2-10 years. Small breeds like Miniature Schnauzers, Lhasa Apsos, Yorkshire Terriers, Bichon Frises, Shih Tzus, and Miniature Poodles are at higher risk.  


Purine stones are formed due to an accumulation of uric acid crystals in the urinary system. Compared to struvite and calcium oxalate, this type of stone is much less common. Dalmatians are the breed most prone to purine stones. Check out the previous post on Before the Bowl Blog “10 + 1 Nutritional Considerations for Dalmatians” for more information.


Dogs with a genetic disorder called cystinuria are likely to form stones made up of cystine crystals. Typical breeds associated with this urolith include English Bulldogs, Newfoundlands, Dachshunds, and Staffordshire Bull Terriers. Genetic testing is available to determine if a dog is at risk for developing cystinuria. 


The factors contributing to the development of uroliths containing silica remain uncertain, but high dietary intake of silicates, silicic acid, or magnesium silicate can induce this formation. Dry food with a high proportion of plant-derived ingredients is also considered a potential risk factor for the formation of silica crystals in susceptible breeds. Silica is more common in large breeds such as Golden retrievers, Labradors, German Shepherds. The average age of occurrence is approximately 6 years and most common in males.  

In summary

Uroliths can cause detrimental effects on the health of dogs if not properly addressed. If your dog urinates more often than usual, strains to urinate, or has blood in their urine, this may be due to the presence of bladder stones, and veterinary care is required. Also, regular veterinary visits to perform urinalysis can help catch stone development early and increase the chance of treatment success. By staying vigilant and well-informed, we can promote the overall health and quality of life for dogs affected or at risk of bladder stones.  

If you suspect that your dog has a type of bladder stone, seek veterinary care immediately. Stay tuned for Part 2 of Canine Bladder Stones, coming soon!

Written by:

Kehan (Coco) Zhang, BScH, MSc Candidate

Reviewed by:

Dr. Erico Ribeiro, DVM, MSc, PhD, DVSc Candidate, ECVCN Resident | Sarah K. Abood, DVM, PhD, Associate Professor, Nestlé Purina Professorship in Companion Animal Nutrition | Dr. Adronie Verbrugghe, DVM, PhD, Dip ECVCN, Associate Professor and Royal Canin Veterinary Diets Endowed Chair in Canine and Feline Clinical Nutrition


  • Syme H. M. (2012). Stones in cats and dogs: What can be learnt from them?. Arab journal of urology, 10(3), 230–239.
  • Ling, G. V., Franti, C. E., Ruby, A. L., Johnson, D. L., & Thurmond, M. (1998). Urolithiasis in dogs. I: Mineral prevalence and interrelations of mineral composition, age, and sex. American journal of veterinary research, 59(5), 624–629.
  • Houston, D. M., Moore, A. E., Favrin, M. G., & Hoff, B. (2004). Canine urolithiasis: a look at over 16 000 urolith submissions to the Canadian Veterinary Urolith Centre from February 1998 to April 2003. The Canadian veterinary journal = La revue veterinaire canadienne, 45(3), 225–230.

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