Cardiorenal sindrome in dogs with chronic valvular heart disease: a retrospective study

In human medicine, primary disorders of the heart often result in secondary dysfunction or injury to the kidneys. The coexistence of the two problems in the same patient is referred to as cardiorenal syndrome (CRS). Just little information about CRS is available in veterinary medicine. The aim of this study was to define the prevalence of chronic kidney disease (CKD) complicating chronic valvular heart disease (CVHD) in dogs and to investigate the relationship between class of cardiac insufficiency (ACVIM) and class of renal insufficiency (IRIS). Medical records of dogs presented at the Cardiology Service of the Department of Veterinary Science and Public Health, University of Milan, between January 2003 and December 2012 were retrospectively evaluated. Dogs with a complete physical examination, thoracic radiographs, a CVHD diagnosis based on echocardiographic examination, and a serum biochemical panel, including assessment of serum creatinine (sCr) and serum urea (BUN), were included in the study. Dogs with other heart disease, neoplasm, or systemic diseases were not included in the study. One hundred eighteen dogs of both genders (73 males and 45 females), 5 to 18 years of age (11.64 ± 2.66 years), 3 to 48 kg of bodyweight (11.38 ± 8.84 kg) fulfilled the inclusion criteria. The 20% of males and the 37% of females were neutered. The most represented breeds were mongrel (44%), miniature Poodle (9.32%), Yorkshire Terrier (8.5%), Shih-Tzu (4.24%), Pinscher (4.24%), and Dachshund (3.38%). Dogs were classified as follows: 0% ACVIM A, 23% ACVIM B1, 9% ACVIM B2, 59% ACVIM C, and 9% ACVIM D. While 73% of the dogs were normoazotemic (sCr < 1,4 mg/dl), 16% were staged in IRIS 2, 11% in IRIS 3, and 0% in IRIS 4. Statistical analysis was performed using JMP 7.0 (SAS Institute, Inc.). A p value < 0,05 was considered significant. The prevalence of CKD associated with azotemia in dogs affected by CVHD was 27%. There was a statistically significant direct correlation between ACVIM and IRIS class (Pearson's test p = 0.0114). Unexpectedly, the 58% of dogs receiving drugs for medical management of heart failure (ACVIM classes C and D) were normoazotemic. Despite that a definite conclusion about the role of CVHD on the induction and/or progression of CKD cannot be drawn from this cross-sectional study, these results suggest that there is a direct correlation between the severity of CKD and CVHD.