Hill's Prescription Diet c/d Urinary Stress
Why this is your pick
The only cat food clinically proven to address both urinary crystals AND stress-induced urinary episodes simultaneously. Dissolves struvite stones in an average of 27 days. Reduces recurrence by 89% in maintenance use. The Urinary Stress formulation adds hydrolyzed casein for the stress component that triggers ~50% of feline urinary cases.
Pros
- Dissolves struvite stones in average 27 days (clinical trial)
- 89% recurrence reduction in maintenance use
- Addresses stress-induced FIC — unique among urinary foods
- Extensive peer-reviewed clinical evidence
- Available in both wet and dry formats
Cons
- Requires veterinary consultation for prescription version
- Most expensive cat food option
- Not appropriate as general prevention without diagnosis
Frequently asked questions
What causes urinary crystals in cats?
Two main crystal types: struvite (magnesium ammonium phosphate — from high dietary magnesium and alkaline urine) and calcium oxalate (from low urine pH and high calcium). The majority of urinary blockages in cats are struvite, which is completely diet-manageable. Oxalate crystals are more complex and may require surgery. Your vet can identify the crystal type via urinalysis.
Does my cat need a prescription urinary food or will OTC work?
For cats with diagnosed struvite crystals or existing stones: prescription Hill's c/d Multicare or Royal Canin Urinary S/O is strongly recommended — these are clinically proven to dissolve existing stones. For cats with recurrent mild symptoms but no current stones: OTC options like Purina Pro Plan Urinary Health may be sufficient. Always consult your vet before choosing.
How long does Hill's c/d take to dissolve struvite stones?
In clinical trials, complete struvite stone dissolution took an average of 27 days (range: 7–63 days). Recheck urinalysis at 4 weeks is standard practice. After dissolution, continuing c/d as maintenance reduces recurrence by 89% versus cats returned to regular food.
Is wet or dry urinary food better for cats?
Wet urinary food is meaningfully better. Increased water intake through wet food dilutes urine, reducing mineral concentration and crystal formation. Many cats with urinary issues show improvement from diet quality alone combined with switching from dry-only to wet food. Wet urinary formulas provide both benefits simultaneously.
Can stress cause urinary problems in cats?
Yes — feline idiopathic cystitis (FIC), which accounts for roughly 50% of all feline urinary cases, is primarily stress-related with no infection or crystals present. Hill's c/d Urinary Stress is specifically formulated to address this — it includes hydrolyzed milk protein (Hydrolyzed casein) shown to reduce stress markers in cats.