Benazepril in feline chronic kidney disease — LIKELY

In cats with spontaneous chronic kidney disease, does benazepril vs placebo reduce proteinuria and improve survival or renal outcomes?

Shelf #246 · gate-verified and displayed under the developer's blinded-trial rule

LIKELY: Benazepril reduces proteinuria in cats with chronic kidney disease, but a survival benefit has not been shown — in the largest trial the treatment made no difference to renal survival. In King 2006 (192 cats, double-blind, placebo-controlled), benazepril significantly reduced proteinuria, assessed by urine protein-to-creatinine ratio (UPC, P = .005), yet mean renal survival was 637 ± 480 days on benazepril vs 520 ± 323 days on placebo (P = .47); in the small subgroup with initial UPC ≥ 1 (13 cats) survival was 402 ± 202 vs 149 ± 90 days, also not significant (P = .27). Mizutani 2006 (61 cats, double-blind, placebo-controlled) likewise found lower urine protein/creatinine ratios on benazepril at days 120 and 180 and more cats staying out of IRIS stage 4 (non-progression 93 ± 5% vs 73 ± 13%). The verified claim on this shelf is therefore proteinuria reduction, with a possible slowing of progression — not longer life — so this pack makes no survival claim and is not a Tier C pack. Drafted Nov 10, 2026 (VetMed build, topic #246); all figures from abstracts fetched and verified at drafting.

King 2006: benazepril cut proteinuria in 192 cats with CKD (P = .005) but renal survival did not differ (P = .47)

Randomised, double-blind, parallel-group, multicentre placebo-controlled trial (up to 1,119 days)

Who: Cats: 192 cats with chronic kidney disease, initial plasma creatinine ≥ 2 mg/dL (≥ 177 micromol/L) and urine specific gravity ≤ 1.025, recruited into a double-blind, parallel-group, prospective, randomized clinical trial — placebo (n = 96) or benazepril HCl 0.5–1.0 mg/kg PO once daily (n = 96) for up to 1,119 days. Most cats were fed exclusively a diet low in phosphate, protein and sodium.

Result: Benazepril produced a significant reduction in proteinuria, assessed by the urine protein-to-creatinine ratio (UPC, P = .005), present in all subgroups tested and largest in cats with higher UPCs. There was no difference in renal survival time between the groups: mean ± SD renal survival was 637 ± 480 days with benazepril and 520 ± 323 days with placebo (P = .47). In the 13 cats with initial UPC ≥ 1, mean renal survival was 402 ± 202 days on benazepril vs 149 ± 90 days on placebo (P = .27); those cats had better appetite on benazepril (P = .017). Benazepril was well tolerated.

Watch out: Survival was a stated outcome and it was not improved overall or in the proteinuric subgroup — the subgroup numbered only 13 cats, so it can neither prove nor exclude a subgroup benefit. The low-phosphate/protein/sodium diet fed to most cats is part of the treatment context, not a benazepril effect.

King JN, Gunn-Moore DA, Tasker S, Gleadhill A, Strehlau G, Benazepril in Renal Insufficiency in Cats Study Group. Tolerability and efficacy of benazepril in cats with chronic kidney disease. J Vet Intern Med. 2006;20(5):1054-64. PMID: 17063696. Registry ID: none in the record. MeSH: Angiotensin-Converting Enzyme Inhibitors · Animals · Area Under Curve · Benzazepines · Blood Cell Count · Blood Chemical Analysis · Blood Proteins · Cat Diseases · Cats · Creatinine · Double-Blind Method · Female · Kidney Failure, Chronic · Male · Prospective Studies · Proteinuria · Statistics, Nonparametric · Survival Analysis

Mizutani 2006: benazepril lowered urine protein/creatinine at days 120–180 and fewer cats reached IRIS stage 4

Prospective, randomised, double-blind, placebo-controlled trial (6 months)

Who: Cats: 61 cats with naturally occurring chronic renal insufficiency, enrolled into a prospective, randomized, double-blind, placebo-controlled clinical trial — placebo or benazepril 0.5–1 mg/kg once daily for up to 6 months. Cats were classified into 4 stages of chronic renal insufficiency by the International Renal Interest Society (IRIS) scheme.

Result: Urine protein/urine creatinine ratios were significantly (P < .05) lower with benazepril than placebo at days 120 and 180. Three cats on placebo and 1 cat on benazepril were removed prematurely because of deterioration of chronic renal insufficiency or death. The incidence of cats in IRIS stage 2 or 3 that remained in stage 2 or 3 without progressing to stage 4 was higher with benazepril (93 ± 5%) than with placebo (73 ± 13%). The authors concluded the results suggest a potential for benazepril to delay progression of disease, extend survival time, or both.

Watch out: Six months is short for a survival claim, and the trial itself did not demonstrate one — removals for deterioration or death were 1 (benazepril) vs 3 (placebo) cats, numbers far too small to carry a survival claim. The stage-progression figures are reported as incidence rates with ± values as printed in the record.

Mizutani H, Koyama H, Watanabe T, Kitagawa H, Nakano M, Kajiwara K, King JN. Evaluation of the clinical efficacy of benazepril in the treatment of chronic renal insufficiency in cats. J Vet Intern Med. 2006;20(5):1074-9. PMID: 17063698. Registry ID: none in the record. MeSH: Angiotensin-Converting Enzyme Inhibitors · Animals · Benzazepines · Blood Urea Nitrogen · Cat Diseases · Cats · Creatinine · Double-Blind Method · Female · Kidney Failure, Chronic · Male · Prospective Studies · Proteinuria · Quality of Life · Survival Analysis

Synthesis: proteinuria falls, progression may slow — survival does not move on the evidence carded

Synthesis

Who: Synthesis of the cards above: King 2006 (randomised double-blind placebo-controlled trial, 192 cats) and Mizutani 2006 (randomised double-blind placebo-controlled trial, 61 cats).

Result: Two independent double-blind, placebo-controlled trials agree on the kidney measures: benazepril lowers urine protein loss in cats with chronic kidney disease, and one trial found fewer cats progressing to the most advanced IRIS stage over 6 months. They do not show longer life: the one trial powered and followed long enough to report renal survival found no difference (P = .47). A clinician should therefore reach for benazepril as an antiproteinuric drug in a proteinuric cat, and not promise the owner extra time on the basis of these trials.

Watch out: Both trials come from the same era and overlapping investigator/manufacturer circles (King JN is an author on both), and both used dietary co-management; the LIKELY stamp rests on two concordant blinded trials for proteinuria, not on hard-outcome benefit, which is absent.

Synthesis of King JN et al. PMID: 17063696; Mizutani H et al. PMID: 17063698. Registry IDs as on the individual cards.

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