Clinical progression of cats with early-stage chronic kidney disease fed diets with varying protein and phosphorus contents and calcium to phosphorus ratios.

Abstract

BACKGROUND\nDietary protein and phosphorus (P) restriction is the mainstay for nutritional management of chronic kidney disease (CKD). However, adequate restriction levels for cats with early CKD remain unclear.\n\n\nOBJECTIVES\nTo investigate responses in cats with early CKD to varying dietary protein, P, and calcium (Ca)\xa0:\xa0P ratio.\n\n\nANIMALS\nNineteen research colony cats with International Renal Interest Society stages 1-2 CKD.\n\n\nMETHODS\nIn an opportunistic longitudinal case study, cats were fed a low protein (59\u2009g/Mcal), low P (0.84\u2009g/Mcal) dry diet (LP-LP; Ca\xa0:\xa0P\xa0=\xa01.9) for 18\u2009months and later transitioned onto a moderate protein (76-98\u2009g/Mcal), moderate P (1.4-1.6\xa0g/Mcal) dry-wet diet regimen (MP-MP; Ca\xa0:\xa0P\xa0=\xa01.4-1.6) for 22\u2009months. Fold-changes in serum creatinine, total Ca (tCa) and P (primary outcomes) and fibroblast growth factor 23 (FGF23) were assessed by linear-mixed models.\n\n\nRESULTS\nWhile feeding LP-LP, mean serum creatinine decreased (0.87-fold, 95% confidence interval [CI] 0.81, 0.93, P\u2009<\u2009.001) to within reference range after 6\xa0months, while increases in total Ca (tCa; 1.16-fold, 95% CI 1.11, 1.22, P\u2009<\u2009.001) and FGF23 (2.72-fold, 95% CI 1.72, 4.31, P\u2009<\u2009.001), but not in P (1.03-fold, 95% CI 0.945, 1.124, P\xa0=\xa0.94), were observed after 17\u2009months. On MP-MP, mean creatinine, tCa and P remained within reference ranges and did not significantly change (P\xa0=\xa0.11, P\xa0=\xa0.98, and P\xa0=\xa01, respectively), while FGF23 significantly decreased (0.58-fold, 95% CI 0.36, 0.95, P\xa0=\xa0.02) after 22\u2009months.\n\n\nCONCLUSIONS AND CLINICAL IMPORTANCE\nCats with early CKD developed hypercalcemia after long-term feeding of a highly P-restricted diet. Increasing dietary P and reducing Ca\xa0:\xa0P ratio maintained renal markers, while improving Ca-P balance. Cats with early CKD could benefit from moderately protein- and P-restricted diets.