Frequency and progression of azotemia during acute and chronic treatment of congestive heart failure in cats

Background: Azotemia is common in cats with congestive heart failure (CHF) and might be exacerbated by diuretic therapy.

Hypothesis/objectives: Determine frequency, risk factors, and survival impact of progressive azotemia in cats treated for CHF.

Animals: One hundred and sixteen client-owned cats with kidney function testing performed at least twice during acute or chronic CHF treatment.

Methods: Serum creatinine (sCr) and electrolyte concentrations were determined at multiple clinical timepoints to detect azotemia and kidney injury (KI; sCr increase ≥0.3 mg/dL). Furosemide dosage between timepoints was calculated. Multivariable modeling was performed to identify predictors of KI, change in serum biochemistry results, and survival.

Results: Azotemia was common at all timepoints, including initial CHF diagnosis (44%). Kidney injury was documented in 66% of cats. Use of a furosemide continuous rate infusion was associated with increased risk of KI during hospitalization (odds ratio, 141.6; 95% confidence interval [CI], 12.1-6233; P = .01). Higher furosemide dosage was associated with increase in sCr during hospitalization (P = .03) and at first reevaluation (P = .01). Treatment with an angiotensin converting enzyme inhibitor was associated with fewer lifetime KI events (P = .02). Age in years was the only variable associated with shorter survival (hazard ratio, 1.1; 95% CI, 1.0-1.1; P = .03). Neither sCr nor KI were associated with long-term outcome.

Conclusions and clinical importance: Azotemia and KI were common in cats during CHF treatment but did not impact survival.