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Presence of Crystals in Dog Urine

Dog Urine Test

The presence of crystals in dog urine is often detected through a urinalysis which is a test where the dog's urine is evaluated. The crystals being microscopic, are only detected by looking at a urine sample under the microscope during a urinalysis. If your dog's urine test detected the presence of crystals, with the help of your vet, you may want to tackle the issue sooner than later. Left untreated, the presence of crystals in dog urine can lead to annoying urinary tract infections, stone formation and expensive surgeries (it's not unusual for them to cost between $1200 to $2000). Following is some information about the presence of crystals in dog urine from veterinarian Dr. Ivana Crnec.

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Presence of Crystals in Dog Urine 

Dogs of any age and breed can develop mineral sediments called crystals, or mineral stones called uroliths and they can occur in any part of the urinary tract. However, they usually develop in the bladder and are then passed down into the urethra. Renal crystals and stones are extremely rare in dogs.

The composition of the urinary tract crystals and stones varies. Each type develops due to different and specific reasons and each type requires a different treatment approach. Depending on their composition, there are several types of crystals and stones: struvite or magnesium ammonium phosphate, calcium oxalate, cystine, urate and silica.

While some dogs with bladder crystals and stones have no signs, others have lower urinary tract pain manifested with a crouched posture. Affected dogs may also have difficulties urinating or dogs can urinate frequently but in small amounts.

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The presence of crystals in dog urine warrant further investigation. The first step is determining exactly what types of crystals or stones are present. There are different types of crystals and stones that may affect dogs, following is a list of them.

dog struvite stones picture

Struvite Stones

Struvite stones are also called magnesium ammonium phosphate stones and are the most common type of bladder and urethral stones in dogs.

Their development is usually triggered by bacterial infections of the lower urinary tract caused by Staphylococcus or Proteus species. These bacteria create alkaline urine and an alkaline environment offers the perfect conditions for the formation of struvite stones.

Since the underlying cause is an infection, the primary goal would be to fight that infection. This step requires persistent and efficient antibiotic treatment. Additionally, the dog must be put on special veterinary diets that promote more acidic urine.

These diets are very low in calcium, phosphorus and magnesium which is beneficial for preventing future stone forming. Although these special diets are designed for short-term use, if used long enough, over time, they can make the small struvite stones to dissolve. If the struvite stones are large, they need to be surgically removed.

Dogs suffering from recurring and persistent urinary tract infections are very likely to develop struvite stones. In such cases, preventative antibiotic treatment is recommended.

calcium oxalate stones in dogs picture

Calcium Oxalate Stones

Calcium oxalate stones are the second most common type of bladder and urethral stones in dogs. They are usually found in the Bichon frise', the Cocker Spaniel, the Lhasa Apso, the miniature poodle, the miniature Schnauzer, the Shi-Tzu and the Yorkshire terrier.

Calcium oxalate stones usually develop as a result of mild but chronic dehydration. Dogs with calcium oxalate stones should be encouraged to drink more water. The easiest way to do this is switch them from dry food to wet food diet.

Calcium oxalate stones cannot be dissolved. Fortunately they can be controlled through dietary means. Dogs with this type of stones should eat diets with reduced protein, calcium and sodium and diets that generally promote more acidic urine.

The diet should be fortified with vitamin A, vitamin B6, vitamin K and the amino acid lysine. Vitamin D and ascorbic acid supplements should be avoided because they encourage the stones formation. Treats with chocolate traces should also be avoided due to potential chocolate toxicity and because they contain oxalates.

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It should be noted that specifically designed urinary acidifying diets, used for treating struvite stones, promote the growth and development of calcium oxalate stones. Therefore, before making the treatment strategy, it is of utmost importance to know what type of stones you are dealing with. Large stones and stones that are causing urinary tract blockages need to be surgically removed.

Cystine stones

Cystine stones are generally rare in dogs. They are most frequently recorded in male Dachshunds and moderately recorded in Bulldogs and Basset Hounds. Cystine stones are the result of a metabolic disorder that leads to a condition called cystinuria.

The usual treatment approach includes a specialized veterinary diet that is very low in protein, supplemented with a little sodium bicarbonate to boost the urine pH just above neutral.

Urate Stones

urate stones in dogs picture

Urate stones are almost uniquely found in the Dalmatian. They rarely occur in other breeds, although the Bulldog seems to have a slight predisposition. Urate stones develop as a consequence of inherited alterations in the urate metabolism.

The goals of the treatment are to maintain a neutral urine pH and to restrict dietary sodium and purine (a nitrogen-containing compound found in livers, kidneys and poultry). To achieve these goals, the affected dog is prescribed with specialized veterinary diet.

Silica Stones

Silica stones are the rarest type of bladder and urethral stones in dogs. They have only been reported in three dog breeds – German Shepherds, Golden Retrievers and Labrador Retrievers.

It is postulated that silica stones occur in the above mentioned dog breeds as a result of feeding diets high in corn gluten and soybeans. Silica stones can be treated and prevented by switching to a diet low in plant-derived proteins.

At the Vet's Office 

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Have your vet evaluate the presence of crystals in dog urine.

A proper diagnosis of the presence of crystals in dog's urine can only be set by examining the urine sediment. Crystals and stones can be detected by plain or contrast X-ray or ultrasound. However, they type of crystal or sediment can only be determined through urine sediment examination.

The treatment depends on the type of stone, but generally speaking it involves 3 steps: 1) eliminating the underlying cause, 2) reducing the amount of sediment in the bladder and 3) preventing sediment recurrence through diet management.

If left untreated, large stones from the bladder can travel down the urethra and become stuck behind the penile bone in male dogs, thus preventing the flow of urine out of the body.

The anatomy of the urinary tract in male dogs places them at greater risk of urethral blockage than female dogs.

About the Author 

Dr. Ivana Crnec is a graduate of the University Sv. Kliment Ohridski’s Faculty of Veterinary Medicine in Bitola, Republic of Macedonia. She is a certified nutritionist and is certified in HAACP food safety system implementation.

ivana crnec

She currently practices as a veterinarian in Bitola and is completing her postgraduate studies in the Pathology of Domestic Carnivores at the Faculty of Veterinary Medicine in Zagreb, Croatia.

Ivana’s research has been published in international journals, and she regularly attends international veterinary conferences.

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Photo Credits:

  • Joel Mills - Own work, Picture of Struvite (magnesium ammonium phosphate) stones removed from a dog's urinary bladder. CC BY-SA 3.0
  • Joel Mills - Own work, Photo of calcium oxalate stones found in the urinary bladder of a dog CC BY 2.5
  • Joel Mills Own work Picture of Urate stones removed from a dog's urinary bladder. CC BY-SA 3.0

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