Cat Kidney Disease IRIS Stages, Renal Diets, Subcutaneous Fluids, Phosphate Binders

Cat Kidney Disease

Feline chronic kidney disease (CKD) affects 30-50% of cats over age 10, progressing through IRIS stages 1-4 with survival times averaging 1151 days stage 2 vs 35 days stage 4. IRIS staging uses creatinine, SDMA, urine concentration, and proteinuria: Stage 1 (<1.6 mg/dL creatinine, SDMA <14 mcg/dL), Stage 2 (1.6-2.8 mg/dL), Stage 3 (2.9-5.0 mg/dL), Stage 4 (>5.0 mg/dL). This comprehensive guide examines CKD management across USA, UK, Australia, and Asian markets, analyzing renal diets reducing azotemia progression 2-3x, subcutaneous fluids (SQFL) 100-150ml 2-3x weekly improving survival 1.5-2x, phosphate binders (aluminum hydroxide, lanthanum carbonate) controlling hyperphosphatemia, supportive therapies including potassium supplementation, anti-nausea drugs, and blood pressure control extending quality life years.

IRIS Staging and Diagnostic Approach

Stage 1 (non-azotemic): SDMA ≥14 mcg/dL or urine concentration <300 despite creatinine <1.6 mg/dL; screen seniors annually; focus prevention.
Stage 2 (mild azotemia): Creatinine 1.6-2.8 mg/dL; 2-3 year survival; initiate renal diet/phosphate control.
Stage 3 (moderate): Creatinine 2.9-5.0; 1-1.5 year survival; SQ fluids, nausea control.
Stage 4 (severe): Creatinine >5.0; <6 months survival; palliative care.

SDMA Advantage: Rises earlier than creatinine (1-2 IRIS stages ahead), detects 50% more stage 1-2 cases. Annual screening ≥7 years recommended.​

Renal Therapeutic Diets

Renal diets extend survival 2-3x through protein restriction (quality > quantity), phosphorus control (<0.5%), potassium supplementation, omega-3s, alkalinization. Prescription brands (Hill’s k/d, Royal Canin Renal, Purina NF) show superior outcomes vs standard diets.

Compliance Challenges: Palatability issues affect 20-30%; warming food, toppers, transition over 7-10 days improve acceptance. Mixed feeding allowed if 50%+ renal diet.​

Subcutaneous Fluid Therapy (SQFL)

Indications: Stage 2-4 dehydration, anorexia, constipation; 100ml 2-3x weekly stage 2-3, daily stage 4. Lactated Ringer’s or Normosol-R standard.​

Home Administration: Owners trained using 18-20g butterfly needle, tent skin scruff/back, administer 100-150ml over 5-10 minutes. 80% owners master technique after 1-2 sessions; survival improves 1.5-2x.​

Benefits: Improves appetite/hydration, flushes uremic toxins, reduces vomiting/constipation. Complications rare (edema 5%, infection <1%).​

Phosphate Management

Hyperphosphatemia (>4.6 mg/dL stage 2+) accelerates progression 3x; binders reduce serum phosphorus 30-60%.

Binders:

• Aluminum hydroxide: 10-30mg/kg BID with meals
• Lanthanum carbonate: 60-90mg/kg/day
• Calcium acetate/carbonate: Monitor calcium (hypercalcemia risk)
• Chitosan/ipakitine: Natural alternatives

Evidence: 59% phosphorus reduction in 60 days with multimodal binders.

Additional Supportive Therapies

Anti-Nausea: Mirataz (mirtazapine transdermal), Cerenia (maropitant) improve appetite stage 3-4.​
Potassium: Supplementation stage 2+ hypokalemia (20%).​
Blood Pressure: Amlodipine/ACEi for hypertension (>160 systolic).​
Anemia: Darbopoetin stage 3-4 PCV <20%.​

International CKD Guidelines

USA: IRIS staging standard; SQFL widely taught.​​
UK: ISFM consensus emphasizes SDMA screening.​
Australia: Similar protocols; home SQFL common.​
India: Renal diets/SQFL emerging; cost barriers.​

Common Questions About Feline CKD

SQFL frequency? Stage 2: 100ml 2x/week; Stage 3: 150ml 3x/week; Stage 4: daily.​​
Renal diet protein? Restricted quantity, high quality.​
Phosphate binder timing? With meals for efficacy.​
Survival by stage? Stage 2: 2-3 years; Stage 4: 1-3 months.​
SDMA vs creatinine? SDMA detects earlier.​

Multimodal IRIS-guided management significantly extends quality life years for CKD cats.