Is your cat or dog having difficult in urination…?


Sometimes cats and dogs experience difficulty in passing urine. The difficulty can be expressed either through:-


  1. Painful or difficult urination (dysuria),

  2. Blood appearing in urine (haematuria),

  3. Increased frequency of urination (pollakiuria),

  4. Dogs leaving puddles in the house and cats in and out of the litter box with increased frequency,

  5. Painful, frequent urination of small volumes that are expelled slowly only by straining (stranguria),

  6. Increase in thirst levels (polydipsia),

  7. Non-passage of urine (anuria/oliguria),

  8. Excessive licking of private parts,

  9. Lethargy,

  10. Lack of appetite and

  11. Cranky behaviour.

It could be kidney or bladder stones.

Kidney or Bladder stones (uroliths), what are they?

Dogs and cats can develop stones anywhere in the urinary tract system. They can develop in the kidney, ureter, bladder, or urethra, referred to as nephroliths, ureteroliths, urocystoliths, and urethroliths, respectively. These stones are formed in many different shapes and sizes. Bladder and kidney stones are toughened deposits of minerals found in urine. The minerals involved include struvite, calcium oxalate, cystine, urate and silica stones.


1. Struvite stones

These contain magnesium ammonium phosphate in both dogs and cats. They may also contain calcium phosphate or calcium carbonate. High dietary intake of protein and minerals encourages urine to be supersaturated. Urinary tract infection (UTI) is a predisposing factor in the formation of this stone. About 50% of uroliths (bladder stones) are struvites.


2. Calcium oxalate stones

Calcium oxalate stones are associated with the increased use of acidifying diets; changes in dietary content of calcium, magnesium, phosphorus, and oxalate; more sedentary lifestyles; decreased water intake; small breeds that are more prone to developing calcium oxalate stones; increased incidence of overweight dogs; and/or dogs living to more advanced ages. About 70% of canine and feline oxalate sones are from males which is related to an increase in the hepatic production of oxalate mediated by testosterone. Conversely, estrogens in female dogs may increase the urinary excretion of citrate, which facilitates the formation of soluble calcium citrate. Abou30% of uroliths (bladder stones) are calcium oxalate.


3. Cystine stones

Cysteine is found in most high-protein foods, including pork, poultry, eggs, and dairy products, as well as oats and wheat germ. Cystine is absorbed by the small intestine, freely filtered, and then reabsorbed by an active process in the kidneys. Decreased reabsorption of cystine results in cystinuria (cystine in urine), a predisposing and required factor for—but not the sole cause of—cystine stones. Not all dogs have cystine in uroliths or even have cystine crystals in their urine; the exact mechanism of cystine stones formation is unknown, but there is a genetic condition that increases cystine in the urine. About 1% of uroliths (bladder stones) are cysteine.


4. Urate stones

Ammonium urate bladder stones (urate stones) are a type of bladder stones in dogs and cats that occur as a result of a genetic deficiency in the way uric acid is metabolized in the body. Urate stones are the third most common urolith type in dogs and cats. In dalmatians, a recessive gene that causes a defect in hepatic uric acid metabolism leads to increased urinary urate excretion. This trait in the dalmatians s responsible for their predisposition to urate stones. In other dog breeds and in cats, urate stones are predominantly associated with liver disease. Idiopathic urate uroliths may occur in animals without liver disease. Urate stones are amenable to medical dissolution. Approximately 8% of uroliths (bladder stones) are urate stones.


5. Silica stones.

Silica stones account for about 0.1–4% of canine urinary stones worldwide. Silica stones in dogs are mainly caused by silica-rich drinking water or specific brands of pet foods. The type of silica molecule (not the amount of silica) in the food is the crucial factor resulting in silica stones formation. Silica stones are relatively rare in dogs. Male dogs are far more commonly affected by silica stones than females. Silica stones are more commonly found in the lower urinary tract (94%) than the upper urinary tract (1.2%). Silicate stones are tan, hard, rough stores with spicules.


What is the cause of these stones?

These stones are frequently caused by an underlying situation that alters the balance of minerals or other substances that are excreted in the urine. Factors that could influence the risk for the formation of stones include:

  1. Nutrition

  2. Urinary tract infections

  3. Metabolic diseases

  4. Genetic predisposition (the breed of the animal)

Which breeds are prone to kidney or bladder stones?

Certain breeds of animals are more likely to form certain kinds of stones.


  1. Urate urolithiasis

  2. Dalmatian *They have a genetic defect in hepatic uric acid metabolism which leads to increased urinary urate excretion.

  3. Miniature Schnauzer

  4. Yorkshire Terrier

  5. Bulldogs 

  6. Shih Tzu

  7. West Highland white terrier

  8. Pekingese

  9. Calcium oxalate urolithiasis

  10. Miniature Schnauzer

  11. Yorkshire Terrier

  12. Lhasa Apso

  13. Bichon Frise

  14. Shih Tzu

  15. Miniature Poodle

  16. Cystine urolithiasis

  17. Dachshund

  18. Bulldogs

  19. Newfoundland

  20. Mastiff 

  21. Basset Hound

  22. Silica urolithiasis

  23. Mixed breeds

  24. Labrador retrievers

  25. Shih Tzus

  26. Golden retrievers

  27. German shepherd dogs

  28. Pugs

  29. Miniature schnauzers

  30. Chihuahuas

  31. Yorkshire terriers

  32. Lhasa apsos

  33. Old English sheepdogs

  34. Struvite urolithiasis

  35. Miniature schnauzer

  36. Miniature poodle

  37. Bichon Frise

  38. Cocker spaniel *The high prevalence of struvite uroliths in the cocker spaniel suggests a familial predisposition in this breed.

Age susceptibility

  • Struvite: adult/puppies

  • Calcium oxalate: adults.

  • Cystine: 3-5 years.

  • Urate: 1.5-7 years.

Sex susceptibility

  • Cystine: males predominance.

  • Calcium oxalate: male predominance.

  • Struvite: female predominance.

  • Urates: male predominance (unless associated with portosystemic shunt).

Is it painful for my dog or cat?

Stones can have sharp edges and can irritate or become embedded in the lining of the bladder, causing the tissue to become thickened and inflamed. They can also form inside the kidneys. Stones can cause serious problems when they lodge in the ureters (the thin tubes connecting each kidney to the bladder) or the urethra (the narrow tube that allows urine to flow from the bladder out of the body). When the normal flow of urine from the kidney to the bladder is obstructed, urine (and pressure) can build up in the kidney, potentially causing kidney infections or kidney failure. If a stone obstructs the urethra, the pet is unable to urinate, and the urine builds up inside the urinary tract. This occurs more commonly in male pets because, compared with females, as they have a long and very narrow urethra. When pets are unable to urinate, it's a medical emergency, and a vet should see the pet immediately.

Can my cat or dog die from this urinary bladder stones?


Urinary obstructions are a veterinary emergency. Without treatment, death occurs in as little as two to three days as toxins build up in your dog's or cat's body. Bladder stones cause frequent urinary tract infections, pain, and blockages, which can be potentially fatal if untreated. So, it's important a vet is contacted immediately bladder stones are suspected.

What is the treatment?

  1. Cats and dogs with blockages may require surgery to remove the bladder stones, and most will also require hospitalization.

  2. Increase in fluid intake is indicated provided there is no obstruction to outflow.

  3. Antibiotics for urinary tract infection.

  4. Dietary modification or provision of prescription diets.

How can this be prevented?

  • Dietary manipulation.

  • Treat urinary tract infections promptly.

  • Avoid breeding from predisposed lines.

Works Cited

Brody, R. S., Thomson, R., & Sayer, P. E. (1977). Silicate renal calculi in Kenyan dogs. Journal of Small Animal Practice, 18(8), 523-528. doi:10.1111/j.1748-5827.1977.tb05924.x


Hesse, A., & Neiger, R. ((2009). .). Colour Handbook of Urinary Stones in small animal medicine. Manson Pub.


Houston D.M., M. A. (2010). Stone Disease in Animals. (P. G. Rao N., Ed.) London: Springer. doi:10.1007/978-1-84800-362-0_10


McCue, J., Langston, C., Palma, D., & Gisselman, K. (2009, October 31). Urate urolithiasis. Compendium: Continuing Education for Veterinarians, 31(10), 468-475.


Osborne, C. A., Jacob, F., Lulich, J. P., Hansen, M. J., Lekcharoensul, C., Ulrich, L. K., . . . Swanson, L. L. (1999). Canine silica urolithiasis: Risk factors, detection, treatment and prevention. Veterinary Clinics of North America: Small Animal Practice, 29, 213-230. doi:10.1016/s0195-5616(99)50012-0


Syme, H. M. (2012). Stones in cats and dogs: What can be learnt from them?. Arab journal of urology, 10(3), 230-239.

Want to know more…?

Call us directly to answer questions about your pet's wellness and more about this topic +254 (0713) 036 765; +254 (0736) 144 759 or

Email us at andysloresho@andysvetclinic.com



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