Do you have a dog that seems to always be having blood in its urine or frequent urinary tract infections? This article will discuss the different types of urinary crystals in dogs and while urinary crystals can be painful and uncomfortable for your pup, the good news is that they can be treated. Urinary crystals in dogs are small mineral fragments and deposits that form in the urinary tract. There are several different types of urinary crystals, including struvite, calcium oxalate, cystine, and urate crystals. The type of urinary crystal present will determine the course of treatment.

What are urinary crystals in dogs?

Urinary crystals in dogs are small mineral fragments and deposits that form in the urinary tract. The urinary tract includes the kidneys, bladder, and urethra. The urinary tract is responsible for filtering waste products from the blood and eliminating them from the body in the form of urine. When urine contains high levels of certain minerals, such as struvite or calcium, these minerals can form urinary crystals in dogs.

How are urinary crystals in dogs diagnosed?

Urinary crystals in dogs are typically diagnosed through urinalysis. A urinalysis is a test that analyzes the urine and measures the levels of various minerals and compounds in urine. The results of a urinalysis can help to determine if urinary crystals are present and the type of urinary crystal.

What causes urinary crystals in dogs and the different types?

The causes of urinary crystals in dogs depend on the type of crystal that is present. Struvite and calcium oxalate crystals are usually caused by a diet high in these minerals. Cystine crystals are usually seen in dogs with a genetic disorder that causes abnormal excretion of cysteine in the urine. Urate crystals are seen in dogs with liver disease or on a diet that is high in purines.

Struvite crystals

In dogs, most struvite crystals are most commonly caused by urinary tract infection with urease-producing bacteria. Urease breaks down urea, which is common in urine, into ammonium and bicarbonate. Ammonium then joins with magnesium and phosphate in urine to create struvite crystals. Bicarbonate that isn't used raises the pH of urine, making struvite crystals less soluble. Ammonium allows struvite crystals and bacteria to attach themselves to walls of the urinary tract or bladder. Once attached, the struvite crystals form stones together. Bacteria may become trapped within layers of these stones as they enlarge.

As most cases of struvite crystals in dogs are a result of a urinary tract infection, successful treatment of the urinary tract infection is essential. This will help to prevent the formation of new struvite crystals and stones. Treatment of struvite crystals in dogs may also require a change in diet to one that is low in magnesium, phosphorus, and protein. Having a slightly acidic urinary pH can also help reduce struvite urinary crystal formation.

Calcium oxalate crystals

Calcium oxalate crystals are most commonly seen in small breeds of dogs. Calcium oxalate is a white, crystalline substance that forms two crystal forms: calcium oxalate monohydrate and calcium oxalate dihydrate. There are numerous causes of calcium oxalate crystals in dogs and can include:

Hypercalcemia: Elevated blood calcium levels will result in elevated levels of calcium in the urine. This can be caused by cancer, hyperparathyroidism, or renal failure.

Dietary Factors: Dietary factors can affect the formation of calcium oxalate crystals. In some studies, diets higher in carbohydrates were linked to a greater risk of calcium oxalate crystals in dogs. Dogs that are obese also have a higher likelihood of developing calcium oxalate crystals.

Genetics: Some breeds of dogs are predisposed to developing calcium oxalate crystals. These include Miniature Schnauzers, Yorkshire Terriers, Lhasa Apsos, Bichon Frise, and Havenese for example.

The goal of treatment of calcium oxalate crystals in dogs is guided towards preventing stone formation. Dietary changes are key to preventing calcium oxalate crystals, according to studies. Diets that make the urine more alkaline, as well as those high in moisture (i.e. >75% water), potassium, sodium, and chloride, can help reduce calcium oxalate crystal formation. Increasing the dog's overall water consumption is also a beneficial preventive measure. Having a slightly alkaline urinary pH can also help reduce struvite urinary crystal formation.

Cystine urinary crystals

Cystine urinary crystals are a result of a genetic disorder that causes abnormal excretion of cystine in the urine. Cystine is an amino acid that is part of the protein structure. In dogs with this disorder, there is a mutation in the gene that results from defective renal reabsorption of cystine. Therefore there will be elevated levels of cystine in the urine, resulting in cystine urinary crystals. The genetic defect has been found in Newfoundland and Labrador retrievers.

The goal of treatment for cystine urinary crystals is to prevent stone formation. This can be done by increasing the dog's water consumption and by feeding a diet that is low in protein and sodium.

Urate urinary crystals

Urate urinary crystals form when there is an excess of uric acid in the urine. Uric acid is a waste product that is produced when the body breaks down purines. Purines are found in foods such as organ meats (e.g. liver) and seafood for example. Dogs suffering from liver issues are more likely to form urate crystals due to the decreased ability of the liver to convert ammonia into urea and uric acid into allantoin. The dogs most at risk for forming urate crystals in association with liver disease are those with congenital portosystemic shunts (PSS).

Additionally, some breeds of dogs are more prone to developing urate urinary crystals including Dalmatians, English Bulldogs, and Spanish water dogs. Because of a hereditary defect, these breeds have an inability to transport uric acid into liver cells.

The goal of treatment for urate urinary crystals is to prevent stone formation. This can be done by increasing the dog's water consumption and by feeding a diet that is low in purines and protein. Treating any underlying hepatic disease or dysfunction can also help prevent urate urinary crystals. Having a slightly alkaline urinary pH can also help reduce struvite urinary crystal formation.

What are the symptoms of urinary crystals in dogs?

The symptoms of urinary crystals in dogs can vary depending on the type of urinary crystal that is present. In general, the symptoms of urinary crystals in dogs include small, frequent urination, hematuria (blood in urine), and chronic urinary tract infections.

What happens if urinary crystals in dogs are not treated?

If urinary crystals in dogs are not treated, they can lead to urinary or bladder stones. Urinary stones are a buildup of urinary crystals that can cause obstruction of the urinary tract. This can be a very serious condition and can lead to serious medical issues such as renal failure and bladder rupture.


Urinary crystals in dogs are a common problem that can cause a range of symptoms. The most common types of urinary crystals in dogs are struvite, oxalate, cystine and urate crystals. The goal of treatment for urinary crystals in dogs is to prevent stone formation, which can be done by feeding the appropriate diet for the type of urinary crystal present. If you notice any of the symptoms of urinary crystals in your dog or have general questions about urinary crystals, please reach out to your veterinarian.