Hill's Prescription Diet u/d is a veterinary wet food for dogs diagnosed with urate, calcium oxalate, or cystine bladder stones. It requires a veterinary prescription and is intended as a long-term dietary management tool, not a general urinary support food.

The formulation works by reducing the urinary concentration of the minerals involved in stone formation. It is low in protein and purines, which specifically targets urate stones — a distinction from other urinary diets that focus primarily on struvite or oxalate crystals. The canned format aids hydration, which is important for diluting urine and slowing stone recurrence.

This food is prescribed when dietary management is a central part of a dog's stone treatment or prevention plan. It is not interchangeable with other Hill's urinary diets — the formulation is specific to non-struvite stone types.