What recent developments have changed the management of feline CKD?

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The most clinically significant recent development in feline chronic kidney disease (CKD) management is the investigation of AB070597, a novel oral agent evaluated specifically for disease modification in IRIS stage 2–3 cats. In a controlled trial, AB070597 demonstrated efficacy in managing CKD progression, with cats classified as IRIS stage 2 or 3 based on creatinine — though a notable discrepancy emerged: 71.4% of enrolled cats were simultaneously classified as IRIS stage 1 based on symmetric dimethylarginine (SDMA), underscoring ongoing uncertainty about which biomarker most accurately reflects glomerular filtration rate in clinical patients.1 The reliability of SDMA as a staging biomarker has been called into question. SDMA has long been considered more sensitive than creatinine for detecting decreased glomerular filtration rate, but recent data show that the sensitivity and specificity of SDMA for detecting decreased glomerular filtration rate are comparable to those of creatinine — not superior.1 Until further validation is available, kidney function should be assessed using multiple biomarkers simultaneously rather than relying on any single marker.1 IRIS staging itself remains the foundation of management decisions, with staging based on fasting serum creatinine and/or SDMA measured in a stable, well-hydrated patient on at least two separate occasions, and substaging based on urine protein-to-creatinine ratio assessed on at least two samples collected at least 2 weeks apart, plus systolic blood pressure measurement.2 The evidence base supporting individual interventions varies considerably. Dietary phosphorus restriction via a renal diet is the most evidence-supported intervention, particularly for IRIS stages 2–4.6 Phosphate binders are recommended when dietary phosphorus restriction alone fails to control serum phosphate.6 Fluid therapy addresses dehydration and electrolyte and acid-base imbalances.6 Angiotensin-converting enzyme (ACE) inhibitors, angioten