Urinary stones in dogs

Definitions & Key takeaways

Urinary stones, also known as uroliths or bladder stones, are a common problem in dogs. They are hard, rock-like formations that can develop anywhere in the urinary tract, including the kidneys, ureters, bladder, or urethra. Urinary stones can vary in size, shape, and composition, and their presence can cause a range of symptoms and complications.

The formation of urinary stones in dogs is influenced by a variety of factors, including breed, age, diet, and urinary tract infections. The symptoms of urinary stones in dogs can vary depending on the location and size of the stones and includes difficulty urinating, blood in the urine, urinating more frequently or in inappropriate places, and abdominal pain or discomfort. Treatment options are surgery or lithotripsy. Recurrence is often a problem, but a diet low in oxalate, protein, and sodium may help prevent new stones from forming.

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Uroliths, also known as urinary calculi or stones, are caused when minerals in urine form crystals, which then clump together and grow large enough to become visible.
Blockage of urine flow caused by stones may lead to pain, difficulty urinating, and blood in the urine. Physical examination, radiography, and urinalysis are typically used for diagnosis.
The most common types found in dogs are struvite, calcium oxalate, urate, cystine, and silica stones. Struvite stones are the most common type in dogs and are primarily made of magnesium ammonium phosphate.
In most cases they form in the presence of urinary tract infections. Treatment by changing the diet to dissolve the stones is often successful.Any urinary infection must also be treated.
Other options are surgery or lithotripsy (breaking up the stones with ultrasound). Calcium oxalate stones may develop in any dog breed, but Miniature Schnauzers, Lhasa Apsos, Yorkshire Terriers, Bichon Frises, Shih Tzus, and Miniature Poodles may be predisposed.
Treatment options are surgery or lithotripsy. Recurrence is often a problem, but a diet low in oxalate, protein, and sodium may help prevent new stones from forming.
Keeping urine dilute and acidic may also be beneficial. Urate stones are most common in Dalmatians and dogs with congenital portosystemic vascular shunts.
Formation of these stones depends on urine concentrations of ammonium, urate, and other unknown factors. Urine alkalinization (pH > 7) lowers renal ammonia production and helps dissolve urate stones and prevent new stones from forming.
A low-purine, low-protein diet may also help. Urine concentration should be reduced, which can be aided by feeding a canned diet.
Adding salt to the food, or mixing dry food with water are other options. These management approaches are designed for Dalmatians, and may not be safe in dogs with portosystemic shunts.
Such dogs tend to develop hypoalbuminemia, edema, and ascites when fed a low-protein diet. Cystine stones form in dogs with a renal amino acid reabsorption defect known as cystinuria.
Cystine is a relatively insoluble amino acid, so it may form stones when concentrations are high.The defect is thought to be inherited and has been reported in Newfoundlands, Dachshunds, Basset Hounds, English Bulldogs, Chihuahuas, Yorkshire Terriers, Irish Terriers, and mixed-breed dogs.
It almost exclusively occurs in male dogs. Low-protein, alkalinizing diets help dissolve stones and prevent recurrence.Urine pH should be raised above 7.5, and high urine output encouraged.
Salt should not be used to increase drinking, though, because high sodium can increase cystine secretion.