Foods That Cause Oxalate Stones

Don't give your pup treats high in oxalates, such as carrots or spinach.
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Calcium oxalate stones can form in a dog's bladder or kidneys, which may lead to pain and trouble urinating, a potentially life-threatening condition. Calcium oxalate stones are usually caused by hereditary or medical issues, but diet can contribute to their formation. While a special diet can't help to dissolve these stones, which require surgical removal, it can help prevent their formation in dogs susceptible to them.

Calcium Oxalate Stones

Calcium oxalate stones are the second most common type of urinary calculi to affect dogs. These stones form in acidic urine with pH value of less than 6.5, according to the Michigan Ave. Animal Hospital website. Your dog's urine naturally contains his metabolic waste products, including mineral salts and other chemicals. When the urine is acidic and high in waste products, including calcium, oxalates and citrates, calcium oxalate stones can form. A substance called nephrocalcin in urine usually prevents stone formation, but some dogs produce a defective version of it, according to While diet alone won't usually cause calcium oxalate stones, it can increase his risk of developing them when coupled with this genetic predisposition or a metabolic disorder that affects Fido's urine composition.

Foods to Avoid

Foods that are high in oxalates usually include plant-based products, such as vegetables, advises Dr. Ron Hines of Avoid feeding Fido foods high in oxalates if your dog has been diagnosed with calcium oxalate stones in the past because they can contribute to their formation. These include beets, carrots, celery, kale, okra, spinach and collard greens, according to the University of Pittsburgh Medical Center. Organ meats like liver and sardines are also high in oxalates, as are foods that are naturally dangerous to dogs like chocolate, nuts and grapes. Other high-oxalate ingredients include corn and soy, along with the ingredients derived from them, according to Dr. Hines.

Wet vs. Dry

Dogs who are predisposed to calcium oxalate stones require a diet that contains high amounts of water. Water helps to dilute your dog's urine, keeping it at a neutral value and free of urinary stones, the VCA Animal Hospitals website says. For this reason, avoid feeding your dog dry kibble and instead opt for canned food diets, which contain much more water. Your vet may recommend a prescription canned food diet for your pup, which has a different balance of ingredients than commercially available foods to discourage the formation of calcium oxalate stones. Such foods include Hill's Prescription k/d, w/d and u/d, according to the Long Beach Animal Hospital website.


Many therapeutic diets that serve to prevent calcium oxalate stones are lower in certain ingredients, such as protein, calcium, magnesium and phosphorus, than other dog foods. These foods may help prevent the formation of calcium oxalate stones and other stones, such as those composed of struvite or urate. While some scientific studies have shown that restricting the amount of protein and minerals in a dog's diet may not actually help prevent calcium oxalate stones, such diets are considered the norm for dogs predisposed to them. Consult your vet if you're concerned about how your particular dog is reacting to his prescription diet. When feeding Fido any treats, stick to lean meats like poultry, beef and lamb, which are low in oxalates.