Urine Crystals in Dogs

What Are Urine Crystals in Dogs?

While there are many conditions that can cause changes in urination frequency or urine color, urine crystals are one of the more common causes. Occasionally, crystals are present in a dog’s urine without causing any symptoms at all. 

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 then stored in the bladder until it’s time to pee. 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 and form a sand-like sediment. This sediment can make urination very uncomfortable. It can continue to accumulate until actual bladder stones are formed. They 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, Bichon Frise, Maltese, Yorkshire Terriers, Lhasa Apsos, and Miniature Poodles.

• Struvite crystals: Another common type, this crystal usually occurs in conjunction with a urinary tract infection (UTI). They are seen more often in younger female dogs, with Labradors, Cocker Spaniels, Shih Tzus and Bichon Frises being more commonly affected.

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

• Cystine crystals: This is a rare crystal type. Like urate crystals, cystine crystals are radiolucent, meaning they form into bladder stones and are not visible on X-rays. These crystals develop in dogs that have inherited an issue with their kidneys so that they are unable to reabsorb the cysteine amino acid like normal. This crystal type is often found in Labradors and Newfoundlands.

Symptoms of Urine Crystals in Dogs

• Frequent urination

• Increased drinking

• Straining or discomfort when urinating

• Blood in urine

• Urinary accidents in the house

• Discolored urine 

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 are involved in crystal formation. Some dogs are more prone to crystal formation than others, based on how their kidneys break down compounds. 

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 can also play a big role in crystal formation in the urine. 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 shallow plastic container or 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 there will be time 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 an over-the-counter food, but often a prescription diet is recommended. Your veterinarian may prescribe a diet to dissolve crystals or recommend one that has a target pH and mineral composition aimed at minimizing future crystal formation.

Common prescription dissolution urinary diets for struvite crystals include:

Other prescription urinary diets more commonly used for different crystal types include Hill®'s u/d and Royal Canin®/MD UC. 

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 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 culture to help determine the type of bacteria growing in their 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 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 5 days to 2 weeks. It is not uncommon, however, for prescription 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.