Urine Crystals in Dogs: Causes and Treatment

Urine crystals in dogs are common to find upon urinalysis (microscopic exam of a urine sample). Should you be concerned if your dog’s urine contains crystals? It depends.  

Certain types of crystals are considered normal in dogs. Crystals form in a dog’s urine anytime the urine becomes supersaturated with minerals, like when salt crystals form in a bucket after ocean water evaporates. When present in large numbers or if the crystals are of a certain type, it may mean your dog may have an underlying medical condition or even an uncommon genetic issue. 

What Are Urine Crystals in Dogs?

Often, crystals are present in a dog’s urine without causing any symptoms at all. But if your dog has urine crystals along with changes in urination frequency or urine color, crystals may be an important part of the picture. 

Anytime a dog eats and drinks, nutrients are absorbed, and waste products need to be eliminated. Some waste products are broken down and eliminated through stool, while others are eliminated in urine.  

Urine is made by the kidneys filtering the blood and removing salts, waste products, and water—together, these make up urine. The urine passes from the kidneys through tiny tubes, called ureters, to the bladder. It is stored in the bladder until it’s time to urinate. It then travels out another tube, the urethra, to leave the body. 

Normal urine is a balance of water, minerals, acids, and protein breakdown products such as urea. This balance is important. If there is too much of a particular mineral, it will precipitate out into a solid. 

Sometimes enough urine crystals form that they clump together. If there are certain conditions in the bladder—such as excessive minerals from the diet, crystals, dilute (unconcentrated) urine, a bladder infection, or a certain pH— bladder stones can potentially form.   

Bladder stones look like pebbles inside the urinary bladder and can lead to extreme discomfort. 

As long as your dog is able to urinate and has a good stream of urine, crystals can be addressed over time, often with nutritional management. If at any time your dog is straining to urinate or not able to urinate, this is considered a medical emergency. Untreated urinary blockages can lead to kidney failure and death when not immediately addressed. 

What Do Crystals in Dog Urine Look Like? 

Crystals are typically not visible to the naked eye. Pet parents are more likely to notice their dog urinating more frequently, seeming to take longer when urinating, only urinating small amounts, or having blood in their urine.  

Crystals can only be seen under a microscope. Some look like clear, square or rectangular gemstones, while others look more like crystal fireworks or hexagons. 

Occasionally, a dog will have enough crystals that they clump together and make a sandy grit or sediment that can be observed in the urine. 

Types of Urine Crystals in Dogs

• Calcium oxalate crystals: This crystal type is one of the most common in dogs. Certain breeds are more genetically predisposed to forming this type of crystal, including Pomeranians, Miniature Schnauzers, Bichons Frise, Maltese, Yorkshire Terriers, Lhasa Apsos, and Miniature Poodles. When present in large amounts, it can even help confirm a diagnosis of antifreeze poisoning. 

• Struvite crystals: Another common type, this crystal usually occurs in conjunction with a urinary tract infection (UTI). Labradors, Cocker Spaniels, Shih Tzus and Bichons Frise being more commonly affected, but dogs of all ages and breeds can have struvite crystals. 

• Ammonium urate crystals: These crystals occur more often in dogs that have liver shunts or a genetic mutation. The Miniature Schnauzer, West Highland White Terrier, Yorkshire Terrier, and Pekingese breeds are more likely to get this type of crystal due to liver shunts, and the Dalmatian can develop them due to a genetic issue associated with abnormal metabolism of urate. 

• Cystine crystals: This is a rare crystal type. These crystals develop in dogs that have inherited an issue with their kidneys so that they are unable to reabsorb the cystine amino acid like normal. This crystal type is often found in Labradors and Newfoundlands. 

Symptoms Associated With Urine Crystals in Dogs

• Frequent urination 

• Increased drinking 

• Straining or discomfort when urinating 

• Blood in urine 

• Urinary accidents in the house 

• Discolored urine  

• No symptoms 

Causes of Urine Crystals in Dogs

Urinary crystals form in a dog’s bladder when the urine becomes supersaturated with minerals and the pH and concentration favors crystallization. Minerals become supersaturated in the urine due to a combination of genetics, nutrition, and underlying medical conditions.

• Genetics: As mentioned above, some dogs are more prone to crystal formation than others, based on how their kidneys and liver break down compounds.  

• Nutrition: Nutrition plays a large role in both formation of crystals and treatment/management of urine crystals. Two dogs in the same household may eat the same food, but only one develops urine crystals. This is because the dog has a genetic predisposition to an overabundance of minerals. 

• Underlying medical conditions: Urinary tract infections can alter the pH, or acidity, in the bladder, as well as cause inflammation and debris to form inside the urinary bladder. 

Other medical issues, like high levels of calcium in the blood, can also lead to crystal formation. High levels of calcium in the blood can be caused by other conditions, including kidney disease, parathyroid disease, Addison’s disease, and some cancers. 

How Veterinarians Diagnose Urine Crystals in Dogs

Urine crystals are diagnosed by a veterinarian while examining dog urine under a microscope. If your dog is having issues with abnormal urination, your vet will likely ask you to bring a urine sample into the clinic.  

The best time to try to catch this urine sample is first thing in the morning. The first morning urine will likely be the most concentrated sample, since your dog has held their bladder all night while sleeping. 

To collect your dog’s urine, use a clean, shallow plastic container or clean soup ladle and slip it under their urine stream while they’re urinating. Your vet will prefer as fresh a urine sample as possible, so ideally, bring a urine sample gathered the same day.  

If you anticipate a time delay between when you catch the urine and when you bring it into the veterinary office, store it in the refrigerator until you can bring it in.  

Once a veterinarian has a urine sample, they will run a complete urinalysis. 

Treatment of Urine Crystals in Dogs

Urine crystals are typically managed with some component of nutrition therapy. Sometimes your veterinarian may recommend that you switch your dog’s current diet to a therapeutic diet that is formulated to promote a healthy urinary environment unfavorable to the development of certain crystals and stones. Therapeutic diets are only available with your vet’s approval.  

A therapeutic urinary diet may help dissolve urine crystals in dogs or have a target pH and mineral composition aimed at minimizing future crystal and stone formation. 

Common prescription dissolution urinary diets for struvite crystals in dogs include Royal Canin Veterinary Diet Urinary SO Adult Dry Dog Food, Hill's Prescription Diet c/d Multicare Urinary Dog Food, and Purina Pro Plan Veterinary Diets UR Urinary Ox/St Dry Dog Food.  

Other prescription urinary diets more commonly used for different crystal and bladder stone types include Royal Canin Veterinary Diet Urinary UC and Hill’s Prescription Diet Urinary Care u/d. 

Royal Canin makes a breed-specific dog food for Dalmatians. This diet has been specially formulated with a low purine content to lower the risk of crystal formation.  

In some cases, diet therapy is not possible, or a veterinarian recommends the addition of oral medications. The medications more commonly prescribed for urine crystals are: 

• Potassium citrate: helps normalize the pH by lowering the acidity of urine and helps reduce the formation of calcium oxalate stones by binding calcium rather than leaving it free to precipitate out into crystals 

• Hydrochlorothiazide: works to minimize calcium oxalate stone formation by decreasing the amount of calcium excreted in urine 

• DL-methionine: acidifies the urine, helping to dissolve struvites and prevent their formation 

• Tiopronin: works to bind extra cysteine in the urine and allow it to be eliminated safely 

• Allopurinol: decreases the production of uric acid to decrease formation of ammonium urate crystals 

If a urinary tract infection is also present, such as in the case of struvite crystals, your veterinarian will likely prescribe antibiotics.  

Often it is recommended that your veterinarian take a urine sample for urine culture and sensitivity to help determine the type of bacteria growing in the urinary tract and which antibiotic can best clear the infection. It is important that you follow the instructions on the antibiotic and give it until it is gone. 

Recovery and Management of Urine Crystals in Dogs

Recovery from urine crystals varies depending on the type of crystal and the individual dog. Some crystal types, like struvite, can be treated and eliminated by curing the urinary tract infection and feeding a recommended diet.  

UTIs are often treated quickly with antibiotic courses lasting anywhere from  five days to two weeks. It is not uncommon, however, for therapeutic urinary diets to be recommended for the rest of your dog’s life. 

Other crystal types may be more challenging to eliminate if a dog has a hereditary predisposition to forming that crystal type. If an underlying medical condition, like hypercalcemia or liver shunts, is present, it is important to manage the medical condition to reduce future formation of crystals. 

It is very common for crystals to reoccur in the urine. If a prescription diet is recommended, talk to your veterinarian before taking your pet off that diet.  

Additionally, if you discontinue the prescription food, rechecking their urine periodically after transitioning to a new diet will help determine if the problem is returning. 

While your dog is recovering from urine crystals, watch their urine output daily. If you notice any increase in frequency of urination, straining to urinate, or blood/discoloration to the urine, bring a sample to your veterinarian immediately.