NU09 - Urinary Ammonia Excretion is Impaired in Dogs with Kidney Disease

Abstract:

Background: Metabolic acidosis is common in dogs with chronic kidney disease (CKD). Inadequate ammonia excretion drives the development of metabolic acidosis in people with CKD and is correlated with worse clinical outcomes. Limited information exists about ammonia excretion in dogs with CKD. Hypothesis/

Objectives: Our objective was to determine if urine ammonia-to-creatinine ratio (UACR) correlates with serum creatinine as a renal function marker in healthy dogs and dogs with CKD and whether UACR is related to the presence of CKD. Animals: The study population comprised 46 healthy and 49 stable IRIS stage II-IV CKD dogs.

Methods: Serum biochemistry parameters were measured. Urinary ammonia and creatinine concentrations were measured using commercially available assays and used to calculate UACR. Group comparisons were made using the Mann-Whitney Test. Correlation between UACR concentrations and serum renal and electrolyte values used Spearman’s correlation test. Relationships between UACR, renal parameters, electrolytes, urine specific gravity, age, and body weight were explored with multiple linear regression.

Results: CKD dogs (median 2.2; range 0.9-5.8) had lower UACR than healthy dogs (median 7.1; range 0.7-40.0) (P< 0.0001). UACR was inversely correlated with creatinine concentration (P < 0.0001, rs= -.524). The relationship between UACR and creatinine persisted after controlling age, body weight, electrolytes, and urine-specific gravity. Conclusions and Clinical Importance: These findings suggest that ammonia excretion becomes impaired with declining renal function in dogs with kidney disease. Future research is warranted to determine if impaired ammonia excretion in dogs with kidney disease can provide prognostic information or become a therapeutic target.