Claude vs Mistral: Urinary diet for Devon Rex in multi-cat home. Join the debate.: Royal Canin Size Health Nutrition Adult

My opening assessment: Devon Rex at 4 years old needing urinary support — that's the priority. The wrinkle is making sure whatever you choose doesn't undermine the senior cat's joint supplement routine, and that ideally both cats can eat together without issues. My initial lean is Royal Canin Urinary Care (the standard over-the-counter version, not the veterinary SO) — it's formulated to support a healthy urinary tract through controlled mineral levels, it's widely available, and it's not so aggressively therapeutic that it would cause problems if the senior cat occasionally eats from the wrong bowl. But before I commit fully: is the Devon Rex on this food because of a diagnosed condition (crystals, FLUTD, previous blockage), or is it more preventative? And is the senior cat eating wet, dry, or both? Those two answers will tell me whether this recommendation holds or needs adjusting.

That's a fair and important challenge. High sodium in urinary diets works by increasing thirst and urine dilution — useful for the Devon Rex, potentially problematic for a senior cat with any renal or cardiac vulnerability. And you're right that age alone makes that a real consideration, even without a confirmed diagnosis. So the shared-bowl scenario becomes genuinely risky if the senior has any kidney or heart involvement — which at senior age is common enough that I shouldn't assume it away. This shifts my thinking. Rather than finding one food both cats can share, the safer route is separate feeding — which then frees the Devon Rex to eat the most appropriate urinary food without compromise. With separate feeding confirmed, I'd move my recommendation to Hill's Science Plan Urinary & Digestive Care for the Devon Rex — lower sodium profile than Royal Canin Urinary Care, still effective for urinary health. Can the owner feed them separately? That's the pivot point here.

Glucosamine in the senior cat's supplement won't be negatively affected by proximity to the Devon Rex's food — cross-contamination from occasional shared mouthfuls isn't a meaningful pharmacological concern there. That's not the risk to manage. The real answer here is separate feeding, full stop. It protects the senior cat from chronic sodium exposure, and it frees you to feed the Devon Rex exactly what he needs. My final recommendation: Hill's Science Plan Adult Urinary & Digestive Care dry food for the Devon Rex, fed separately. It supports urinary tract health through controlled magnesium and phosphorus levels, has a more senior-friendly sodium profile than Royal Canin Urinary Care if there's any bowl-sharing, and suits a Devon Rex's typically sensitive digestion too. Feed them in different rooms or on a timed schedule. One thing worth confirming with your vet: whether the Devon Rex needs veterinary urinary food specifically, or whether this over-the-counter option covers his situation.