Calcium Oxalate Urolithiasis
Also known as: CaOx Urolithiasis, Calcium Oxalate Uroliths, Calcium Oxalate Urinary Stones
CatDogUrgency: Moderate
Also known as: CaOx Urolithiasis, Calcium Oxalate Uroliths, Calcium Oxalate Urinary Stones
In short
Calcium oxalate urolithiasis is a common metabolic condition where painful mineral stones form in the urinary tract of dogs and cats. Unlike some other stone types, these cannot be dissolved with medicine or diet and often require surgical removal. Learn the signs, diagnostic steps, and long-term prevention strategies.
TL;DR. Calcium oxalate urinary stones are common, painful mineral deposits in dogs and cats that cannot be dissolved medically and often require surgical removal or lifelong management to prevent recurrence.
Both dogs and cats can develop calcium oxalate stones, requiring tailored veterinary care.
Calcium oxalate urolithiasis is a common metabolic disorder affecting the urinary tract of both dogs and cats. It occurs when microscopic minerals in the urine clump together to form hard, rock-like deposits called calculi, or stones. These stones can develop anywhere in the urinary tract, including the lower urinary tract (the bladder and urethra) or the upper urinary tract (the kidneys and ureters, which are the tubes connecting the kidneys to the bladder).
Understanding the specific type of stone is critical because different stones behave differently. For example, struvite stones can often be dissolved using specialized prescription diets. Calcium oxalate stones, however, cannot be medically dissolved. Once they form, they remain in the urinary tract unless they are physically removed or, if small enough, passed in the urine.
If these stones are left untreated, they can cause chronic pain, severe inflammation, and life-threatening urinary blockages. In cats, these stones are particularly troublesome when they develop in the upper urinary tract. As noted in a leading veterinary surgery textbook:
"A more recent case series of cats treated for ureterolithiasis found that approximately 98% of ureteroliths contain calcium oxalate. Veterinary surgeons are increasingly faced with the challenge of surgical management of upper tract uroliths in cats."
Calcium oxalate stones form when the urine becomes supersaturated with calcium and oxalate. When these two substances are highly concentrated in an acidic environment, they bind together to form crystals, which eventually grow into stones.
Several factors contribute to this metabolic imbalance. In dogs, the rise in cases is linked to multiple lifestyle and dietary influences. According to a standard veterinary internal medicine reference:
"The reasons for the increase in submissions of CaOx from dogs are likely multifactorial and could include demographic and nutritional changes that occurred during this period. Some factors might include feeding a more acidified diet, changes in mineral content of the diets, increase in canine obesity, and possibly a trend favoring ownership of breeds that are more prone to CaOx urolith formation."
In cats, a significant underlying risk factor is a condition called idiopathic hypercalcemia, which means the cat has high levels of calcium in their blood for unknown reasons. The same internal medicine reference notes:
"An idiopathic hypercalcemia is reported to occur in approximately 35% of cats with calcium oxalate uroliths."
Additionally, historical data shows that the prevalence of these stones in cats has shifted dramatically over the last few decades, with calcium oxalate stones becoming far more common than they once were.
Symptoms of calcium oxalate stones can vary depending on whether the stones are located in the bladder or the kidneys, and whether they are causing a physical blockage.
When stones form in the upper urinary tract of cats, the signs can be very subtle and easy to miss. As a leading veterinary surgery text explains:
"Clinical signs of cats with ureteroliths or nephroliths tend to be nonspecific and include anorexia, vomiting, lethargy, and weight loss."
A hunched posture or abdominal discomfort can be a sign of urinary tract pain or stone formation.
Your vet will begin with a thorough physical examination, paying close attention to your pet's abdomen. However, because many urinary conditions share the same symptoms, diagnostic testing is required to confirm the presence of stones and determine their type.
If surgery is required to remove the stones, your vet will also perform pre-operative blood work. For complex cases, they may recommend blood typing or cross-matching beforehand, as "a cross-match or blood typing should be performed in case administration of blood is needed during or after surgery."
Because calcium oxalate stones cannot be dissolved with medication or diet, treatment focuses on physical removal (if the stones are causing pain or blockages) followed by long-term medical management to prevent new stones from forming.
If a stone is blocking the flow of urine or causing severe pain, it must be removed. This can be done through traditional surgery (opening the bladder or kidneys) or through minimally invasive interventional procedures, such as using a scope to retrieve the stones or bypass blockages.
Once active stones are cleared, your vet will prescribe a long-term medical plan to alter your pet's urine chemistry. This typically involves a combination of specialized diets and specific medications:
"High-sodium diets should be avoided in cats with renal compromise and in those with hypertension."
Long-term prognosis data for calcium oxalate urolithiasis in dogs and cats is limited, and individual outcomes vary widely depending on the stone's location, whether kidney damage has occurred, and how strictly the preventative plan is followed.
Calcium oxalate is a highly recurrent disease. Even with successful surgical removal and excellent home care, many pets will form new stones within their lifetime. This means management is a lifelong commitment. Regular veterinary check-ups, repeated imaging (X-rays or ultrasounds), and frequent urinalyses are necessary to catch new stones while they are still small enough to manage without major surgery.
While you cannot change your pet's genetics, you can take active steps to reduce the risk of stone recurrence:
You should contact your veterinarian if you notice any changes in your pet's urination habits, such as increased frequency, straining, or blood in the urine.
If your pet is straining to urinate and producing little to no urine, this is a life-threatening medical emergency. A complete urinary blockage can cause acute kidney failure and life-threatening electrolyte imbalances within hours. Seek emergency veterinary care immediately.
Certain breeds have a higher genetic predisposition to developing calcium oxalate stones. If you own one of these breeds, you should be especially vigilant about monitoring their urinary habits:
For these breeds, proactive screening with routine urinalysis during annual vet exams is highly recommended.
Treatment must be prescribed by a licensed veterinarian based on your pet. Specific drug doses are intentionally not shown here.
Calcium oxalate urolithiasis is a common metabolic condition where painful mineral stones form in the urinary tract of dogs and cats. Unlike some other stone types, these cannot be dissolved with medicine or diet and often require surgical removal. Learn the signs, diagnostic steps, and long-term prevention strategies.
Hematuria、dysuria、pollakiuria、stranguria、Anorexia、Lethargy、Lumbar pain、Polydipsia
Quantitative mineral analysis、Abdominal ultrasonography、Survey abdominal radiographs、Urinalysis、Urine Culture
Treatment must be prescribed by a licensed veterinarian based on your pet. Specific drug doses are intentionally not shown here.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
Peqaboo’s AI helps you track symptoms, understand lab reports, and know when to see a vet.
Get the Peqaboo app