Blood urea nitrogen and creatinine in dogs affected by chronic degenerative mitral valve disease

Cardiorenal syndromes (CRS) are a complex pathophysiologic disorder of the heart and kidneys whereby acute or chronic dysfunction in one organ may induce acute or chronic dysfunction of the other. Chronic CRS indicates lingering abnormalities in cardiac function causing progressive chronic kidney disease. The most common heart disease affecting dogs is degenerative mitral valve disease (DMVD). The aim of this study was to evaluate blood urea nitrogen (BUN) and creatinine levels in dogs affected by DMVD to assess the degree of renal function impairment in relation to the severity of the disease and therapy. A retrospective evaluation in 96 dogs (34 females and 62 males; 12.20 ± 2.37 years and 12.47 ± 9.69 kilos body weight) affected by DMVD, treated with cardiovascular drugs (furosemide/torsemide and/or ACE-I and/or pimobendan and/or spironolactone) was performed. Overall, data from 158 examinations were reviewed. Plasma creatinine levels were at 1.23 ± 0.79 mg/dl (mean ± standard deviation); BUN levels were at 78.29 ± 70.99 mg/dl (mean ± standard deviation). Based on a Kendall’s Tau test no significant correlation was found between each one of the selected variables (age, left atrium/aorta ratio, diastolic and systolic left ventricle diameters, end-diastolic volume index, end-systolic volume index) and BUN or creatinine values (Kendall correlation p>0.05). Dogs treated with furosemide/torsemide showed significantly higher BUN levels (Wilcoxon test p=0.01) and trends towards higher creatinine levels (Wilcoxon test p>0.05), compared to those receiving the other drugs (BUN: 81.41 ± 73.26 median 63 mg/dl vs 48.99 ± 33.1 median 35.8 mg/dl; Creatinine: 1.25 ± 0.82 median 1.08 mg/dl vs 1.08 ± 0.42 median 1.10 mg/dl, respectively). Creatinine but not BUN was significantly higher in dogs treated with spironolactone in addition to furosemide/torsemide (1.63± 1.23 median 1.25 mg/dl vs 1.05 ± 0.34 median 0.99 mg/dl) (Wilcoxon test p=0.001). Overall, the results show that diuretic therapy rather than the severity of the disease mostly affects renal function, estimated by BUN and creatinine, in dogs suffering from DMVD.