Whether a cat’s kidney stones can be dissolved depends entirely on what type of stone it is. Struvite stones, one of the two most common types in cats, can be dissolved with a prescription diet in as little as one to three weeks. Calcium oxalate stones, the other common type, cannot be dissolved by any means and must be physically removed or managed to prevent growth.
Stone Type Determines Everything
Cats form two main types of kidney stones: struvite and calcium oxalate. Your vet needs to identify which one your cat has before any treatment plan makes sense, because the approaches are completely different.
Struvite stones form when urine is too alkaline and contains high concentrations of magnesium, ammonium, and phosphate. These stones respond well to dietary dissolution. Calcium oxalate stones form when calcium and oxalate bind together in the urine, and no diet or medication can break them down once they’ve formed. The only options for calcium oxalate are surgical removal, specialized procedures like laser lithotripsy (available at a limited number of veterinary referral centers), or in many cases, simply monitoring the stones and preventing them from growing.
Your vet will typically use a combination of X-rays and ultrasound to locate stones. CT scans detect significantly more stones than ultrasound alone, catching bilateral stones in roughly twice as many cats in one study, but they aren’t always necessary. A urinalysis and sometimes a urine culture help determine the stone type before removal, though definitive identification requires lab analysis of the stone itself.
Dissolving Struvite Stones With Diet
Sterile struvite stones (those without an active urinary infection) are dissolved by feeding a prescription diet that acidifies the urine and restricts the minerals that form struvite. According to the Minnesota Urolith Center, these therapeutic diets are 100% effective at dissolving feline struvite stones, typically within one to three weeks. In one documented case, a stone dissolved in just seven days.
Both wet and dry prescription formulas work. The diet lowers urine pH into a mildly acidic range and reduces magnesium content, creating conditions where the stone gradually breaks apart. Your cat needs to eat only the prescription food during dissolution, with no treats, table scraps, or other foods that could alter urine chemistry. If your cat has a urinary tract infection alongside struvite stones, your vet will prescribe antibiotics at the same time, since bacteria can serve as a scaffold for stone formation.
Despite how effective and fast dietary dissolution is, many general practice vets skip it and go straight to surgery. If your cat has confirmed struvite stones in the kidney or bladder, it’s worth asking your vet about trying the dietary approach first.
Managing Calcium Oxalate Stones
Calcium oxalate stones are not amenable to medical dissolution. That’s a firm limitation, not something a special diet or supplement can overcome. If these stones are causing problems like a blockage, pain, or kidney damage, they need to be physically removed. Options include traditional surgery or, at a small number of veterinary specialty hospitals, techniques like laser lithotripsy or a subcutaneous ureteral bypass (SUB) device, which reroutes urine around a blocked ureter. SUB placement carries a good to excellent prognosis with lower complication rates than traditional surgery for ureteral obstructions.
Many calcium oxalate kidney stones, especially small ones discovered incidentally on imaging, are managed with what vets call “benign neglect.” This means leaving the stones in place and focusing on preventing them from growing or new ones from forming. That prevention strategy has several components:
- Maximize water intake. The single most important step is diluting your cat’s urine. Feed canned or high-moisture food (over 75% water content), add water to dry kibble, and encourage drinking with fountains or multiple water bowls. The goal is a urine specific gravity below 1.030.
- Avoid acidifying the urine. Unlike struvite management, calcium oxalate prevention requires keeping urine pH above 6.5. Acidic urine promotes calcium oxalate formation.
- Limit excess animal protein. Diets very high in animal protein increase calcium excretion in the urine and decrease citrate, a natural inhibitor of stone formation.
- Skip high-sodium diets. Some vets previously recommended added salt to increase thirst, but high-sodium dry foods should not replace high-moisture diets for stone prevention.
Potassium Citrate for Prevention
For cats with persistently acidic urine or recurrent calcium oxalate stones, vets often prescribe potassium citrate. It works through three mechanisms: citrate binds to calcium in the urine so less calcium is available to form stones, it reduces crystal clumping, and it alkalinizes the urine, which further decreases calcium excretion. The Minnesota Urolith Center recommends a starting dose of 75 mg/kg twice daily, aiming for a urine pH near 6.5. Your vet will adjust the dose based on follow-up urinalysis results.
For cats that keep forming calcium oxalate stones despite dietary changes and potassium citrate, a thiazide diuretic may be added. In clinically normal cats, this type of medication reduced urinary calcium oxalate saturation by 65%. It’s not a first-line treatment, but it’s an option for stubborn cases.
Hydration Strategies That Actually Work
Increasing your cat’s water intake is the cornerstone of both treatment and prevention for all stone types. Cats evolved as desert animals and have a naturally low thirst drive, so you often need to be creative.
Switching from dry food to canned food is the single biggest change you can make. Canned food is roughly 75-80% water, while dry kibble is around 10%. If your cat won’t eat wet food, adding warm water or low-sodium broth to dry kibble can help. Cat water fountains encourage drinking in many cats, since moving water is more appealing than a stagnant bowl. Placing multiple water stations around your home, away from food bowls and litter boxes, also increases intake. Some cats prefer wide, shallow bowls that don’t touch their whiskers.
Ongoing Monitoring
Cats that have had kidney stones are at significant risk of forming new ones. Regular veterinary check-ups with urinalysis and imaging help catch new stones early, before they cause blockages or kidney damage. For cats on a dissolution diet, your vet will recheck imaging every few weeks to confirm the stones are shrinking. For cats with calcium oxalate stones being managed conservatively, periodic ultrasounds track whether existing stones are growing or new ones are forming.
Underlying conditions can drive stone formation. Cats with elevated blood calcium levels (idiopathic hypercalcemia is relatively common in cats) are prone to calcium oxalate stones, and treating the underlying condition is essential. Your vet may run blood work alongside urine tests to check for metabolic contributors. Consistent use of a urinary-focused prescription diet, combined with high water intake and any prescribed supplements, gives your cat the best chance of staying stone-free long term.