The senior cat
kidney protocol.
A 13-year-old indoor cat. Annual SDMA flagged at 18 µg/dL — meaningfully elevated, IRIS Stage 1 CKD. The vet is unworried but watchful. Here is how a Care Partner and PETVITY-aware owner would structure the next 90 days to slow decline, hydrate seriously, and turn a flag into the best 5–7 years that biology allows.
The starting state.
Luna lives in a Zürich apartment with one human, no other animals. She has been on a "premium" dry-kibble diet her whole life, with twice-weekly wet-food top-ups. She drinks from a single ceramic bowl in the kitchen. Annual exam at 13 picked up the SDMA elevation; creatinine and BUN remain in range. USG (urine specific gravity) was 1.038 — adequate but trending toward dilute.
- Subtle weight loss over 18 months — from 5.0 kg to 4.6 kg, dismissed as "old age."
- Slight increase in water intake; the owner now refills the bowl twice a day instead of once.
- Litter box stays a touch wetter than it used to be.
- No vomiting, no inappropriate elimination, normal energy, plays for short bursts.
This is the textbook Stage 1 CKD presentation in cats — caught by SDMA before creatinine rose, which is exactly why we run SDMA. Most cats at this point have lost ~30% of kidney function but are clinically stable. The intervention window is real.
"Stage 1 caught early is the single best gift a cat owner can give a senior cat."
The 90-day plan.
Make water the easiest decision in the apartment.
Cats evolved from desert ancestors with a low thirst drive. By Stage 1 CKD their kidneys are starting to lose concentrating ability — hydration becomes the single highest-leverage intervention.
- Multiple water sources. Three bowls in three rooms — kitchen, living room, bedroom. Ceramic or glass, not plastic.
- One running fountain. Cats prefer moving water. A quiet pump-fountain in the location they frequent most.
- Wet-food share to ≥75% of daily calories. Wet food is 75–78% moisture vs. dry at 8–10%. This single change adds more water than any bowl ever will.
- Low-sodium bone broth (1 tbsp twice daily) as a flavour enhancer over wet food. Boosts intake on the days she's been less interested.
Feline-appropriate, kidney-aware, but not aggressive.
At Stage 1, full prescription renal diets are usually premature — they can be unpalatable and the protein restriction isn't yet warranted. Modern guidance favours a high-quality, moderate-protein, lower-phosphorus diet with the WSAVA five-question vetting (Module 2) — without committing to a full therapeutic renal formula yet.
- Primary food: complete-and-balanced wet, ≥35% protein on dry-matter, moderate phosphorus.
- Treat fraction reduced to ≤5% of calories (cats over 12 have less metabolic room).
- FEDIAF 2024-aligned brand verified through the WSAVA 5 questions.
- Fresh-food share introduced gradually, 20-day transition (cats need slower transitions than dogs).
Dental disease loads the kidneys, not just the mouth.
By age 13, ~70% of cats have some periodontal disease. The bacteria don't stay in the mouth — they translocate via the bloodstream and put chronic inflammatory load on the kidneys, heart and liver. For a Stage 1 CKD cat, this is non-trivial.
- Vet dental assessment + cleaning under anaesthesia if indicated. Done early, while she's relatively healthy.
- Daily gentle dental support — VOHC-sealed dental treat or topical product, where tolerated.
- Marine omega-3 EPA/DHA at 30 mg/kg combined per day for chronic inflammation reduction.
- SAMe + silybin on the table if liver markers are elevated at the next panel.
Chronic cortisol is silent kidney load.
Stress in cats is silent and chronic — hiding, withdrawal, reduced upper-territory use, over-grooming. For a Stage 1 cat, reducing cortisol load matters more than most owners expect.
- Vertical territory audit — at least three elevated places (cat tree, shelf, window perch).
- Quiet rest corner, away from foot traffic and noise.
- Three short play sessions/day (5 min each) matching feline sprint-rest biology.
- Feliway diffuser if any household disruption (renovation, new household member, etc.).
Day 90 · the panel that tells you what's working.
- SDMA + creatinine + BUN + USG — same lab as baseline.
- Phosphorus, calcium, total T4 (rule out concurrent hyperthyroidism, common in this age).
- Body weight (target stable at 4.6–4.8 kg).
- Decision tree: if SDMA stable or improved → continue. If trending up → vet conversation about Stage 2 protocols.
The stack.
Nutrition
≥75% wet food, complete-and-balanced moderate-protein lower-phosphorus. WSAVA-vetted brand.
Hydration
3 water bowls + fountain. Bone broth top-up. The single biggest lever.
Dental
Anaesthetic clean if indicated. VOHC dental support daily where tolerated.
Bond & territory
3× short daily play. Vertical territory. Quiet rest corner. Feliway if disrupted.
Supplements
Marine omega-3 EPA/DHA · SAMe + silybin if liver flags · probiotic if antibiotic recovery.
Monitoring
Quarterly SDMA + creatinine + USG. Monthly weight. Twice-yearly dental check.
The realistic outlook.
Stage 1 CKD in a 13-year-old well-managed indoor cat with this kind of structured response can buy 3–7 additional years of good quality life. The IRIS framework doesn't promise reversal — kidney tissue, once lost, doesn't regenerate — but progression slows substantially when the four big levers (hydration, diet, dental, stress) are all addressed simultaneously. Most of the cats in our member base who reach 19, 20, 21 in good shape were caught at exactly this stage and supported exactly this way.
Run this protocol on your cat.
The Pet Profile asks the cat-specific questions and the Pet-Harmony Score™ reweights for feline biology. Premium members get the personalised version, the supplement stack at 25% off, and the quarterly Harmony box that delivers what your cat actually needs.
Read the cat longevity guide