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Ingredients That Minimize Stone Formation in Dogs

Ingredients That Minimize Stone Formation in Dogs

Dogs that develop calcium oxalate stones have a high chance of recurrent stones, and treatment often involves costly surgery and a long recovery. For these reasons, it's important for pet owners to take steps that can help prevent a recurrence.

But first, it's important to understand what can cause calcium oxalate stones in dogs.

The Cause of Calcium Oxalate Stones

Understanding what causes calcium oxalate stones in dogs is key when analyzing the different factors that can help minimize kidney stone formation. A few characteristics that increase a dog's risk of developing calcium oxalate bladder stones include:

  • Urine high in calcium, oxalates, or citrates
  • A diet that causes urine to be too acidic (urine pH less than 6)
  • An increased dietary intake of oxalate

Common symptoms of bladder stones in dogs include discomfort, blood in the urine, and straining to urinate. In some cases, bladder stones will result in an obstruction in the bladder or urethra, which can cause serious issues.

Prevention Goals

Because calcium oxalate stone formation is not fully understood, preventing calcium oxalate stones is complex. In general, the goals of prevention include:

  • Decreasing calcium and oxalate concentration in the urine
  • Promoting neutral or alkaline urine (pH 6.8 to 7.0)
  • Promoting a high concentration of crystal formation inhibitors in the urine
  • Decreasing urine concentration
  • Promoting less acidic, more dilute urine while maintaining a low urine specific gravity (less than 1.020)

Diet plays a major role in preventing the formation of calcium oxalate crystals and stones. Dogs that have developed bladder stones in the past will often be fed a therapeutic diet for the rest of their lives. It’s also important to increase water consumption and dilute the urine. Supplements that either break down oxalates or help reduce oxalate formation are often given to dogs to minimize the likelihood of stone formation.

However, not all calcium oxalate supplements are created equal. When choosing a supplement for your dog, it’s important to analyze the ingredients to ensure they are beneficial and effective.

Here are a few ingredients that are beneficial and effective in helping minimize calcium oxalate formation in dogs and preventing recurrent stones!

Potassium Citrate

Potassium citrate is the most effective crystal formation inhibitor for calcium oxalate stones. This ingredient has a two-part function. First, it attaches to calcium in the urine, preventing the formation of mineral crystals that can develop into calcium oxalate stones. Second, it acts as an alkaline agent to prevent urine from becoming too acidic, creating an environment less suitable for calcium oxalate stone formation. Potassium citrate is currently the main ingredient used to help prevent calcium oxalate stones in dogs.


Magnesium also has a two-part function. First, it can lower the risk of stone formation as it bonds with oxalates, which reduces the number of free oxalate ions that can bond with calcium and form stones. Second, it acts as an alkaline agent and prevents the urine from being too acidic.

Vitamin B6

Many veterinarians suggest supplementing with vitamin B6 because it increases the metabolism of glyoxylate, a precursor of oxalic acid. Additionally, a deficiency in vitamin B6 can contribute to increased oxalate production.

Vitamin E

Studies have shown that supplementing with vitamin E can help reduce the ability of calcium oxalate to crystallize in the kidneys.

Fenugreek Powder

Fenugreek has been found to increase the levels of antioxidants in the kidneys and decrease oxidative stress. A recent study found that animals who had received fenugreek supplementation had significantly less calcification in their kidneys and less total calcium in the kidney tissue compared to untreated animals.

Fennel Seed Powder

This ingredient has been used as a digestive aid for centuries. Fennel is a natural diuretic that can help minimize the minerals, crystals, and uric acid associated with oxalate stones.

Hydrangea Root Powder

Hydrangea root stimulates the kidneys to release retained fluid and helps prevent the formation of gravel and stones. It also contains properties that minimize the likelihood of urinary mineral crystals sticking to each other. (While the buds and leaves of this plant are toxic to dogs, the root is the medicinal portion of the plant.)

IP6 (Inositol Hexaphosphate)

IP6 has been studied at Harvard, where it was shown to help reduce the frequency of calcium-based stones. IP6 helps inhibit the crystallization of calcium salts (both oxalate and phosphate).

Marshmallow Root

Marshmallow possesses diuretic properties to encourage increased urine flow. This helps the body flush the kidneys and bladders, which helps minimize the buildup of toxins. Marshmallow also has high levels of glucuronoxylan, a potent antioxidant found to protect cells from free radical damage and promote health along the urinary tract. Marshmallow seems to soothe and lubricate the mucous membranes that line the colon and urinary tract.

Additional Note on Ingredients

Supplements that contain vitamin D, cranberries, or vitamin C should be avoided as they can increase the potential of stone formation. Although many supplements contain cranberries, it's important to note that they are considered a moderate oxalate producer. Therefore, giving cranberry supplements to dogs could potentially increase their risk of developing oxalate urinary crystals or stones.

How Cal Ox Can Help

Cal Ox from Thomas Labs® is formulated with all of the ingredients above in order to support urinary tract health in dogs that have had or are predisposed to calcium oxalate stone formation. Cal Ox helps diminish the likelihood of bladder stone formation by minimizing available oxalates, limiting crystallization, and supporting ideal urine pH and flow.

The materials and information provided on this website are not intended to replace the medical advice or services of your veterinarian or other pet healthcare professional. Consult your own veterinarian if you have medical questions concerning diagnosis, treatment, therapy, or medical attention.

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