Updated October 14, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: Royal Canin Veterinary Diet Urinary SO is a prescription diet designed to dissolve struvite stones and help reduce the risk of struvite and calcium oxalate crystals by creating less concentrated, less stone-friendly urine. It’s used for cats with diagnosed urinary crystals or stones. Other companies make comparable prescription urinary diets. Your vet should diagnose the problem first, since the right diet depends on the stone type.
Who may need a urinary diet
- Cats with struvite stones or crystals
- Cats with a history of urinary blockage
- Some cats with idiopathic cystitis, often alongside more water and stress reduction
How these diets work
- Adjust minerals and urine pH to discourage crystal formation
- Promote more dilute urine
- Wet versions add water, which is especially helpful
Comparable options
- Other prescription urinary diets from major veterinary diet makers
- Wet vs. dry formulas of the same diet
- Calm or stress-support urinary formulas for cats with cystitis
Important tips
- Feed the urinary diet only, without mixing in other foods, especially while dissolving stones
- Follow up with urine tests or X-rays as your vet advises
- Encourage water intake with fountains and wet food
- A male cat straining with little or no urine is an emergency
More: urinary problems in cats.
Sources
- Lulich JP, et al. ACVIM small animal consensus recommendations on the treatment and prevention of uroliths in dogs and cats. J Vet Intern Med. 2016
- Royal Canin: Veterinary Diet Urinary SO product information
- Cornell Feline Health Center: Feline lower urinary tract disease
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.