Evaluation of serum biochemical and urinary parameters suggesting renal involvement in a population of dogs with primary chronic enteropathy

Approximately a half of IBD human patients show extra-intestinal manifestations, in which 4-23% may develop renal and urinary involvement. These findings may be linked to several conditions, such as the immune-system response of the primary chronic enteropathy (CE), reduction in short-chain fatty acids, or endotoxemia. No specific studies have been conducted in dogs, except for those describing familiar protein-losing nephropathy and enteropathy in soft-coated wheaten terriers.The aim of this study was to describe alterations of selected serum biochemical and urinary parameters suggesting renal injury in dogs with CE. Retrospective bi-centric study including dogs with CE. CE diagnosis was made after the exclusion of intestinal diseases of other etiologies and extra-intestinal diseases. Dogs with history of previous kidney or low urinary tract diseases (previous clinicopathological finding and/or imaging alterations) and with severe proteinuria (urine protein-to- creatinine ratio >2, [UPC]) were excluded. Canine Chronic Enteropa- thy Activity Index Score (CCECAI), muscular condition score (MCS; 3-point scale), serum albumin, urea, creatinine, presence of glycosuria, proteinuria (UPC>0.5) and urinary casts were recorded for each dog. Dogs with albumin <2.7 mg/dL were classified as protein-losing enter- opathy (PLE). Dogs with glycosuria, proteinuria and/or urinary casts were classified as having kidney injury. Mann-Whitney u-test was used to compare CCECAI of dogs with and without kidney injury. Chi- square test was used to evaluate the association of PLE and presence of kidney injury, and proteinuria. One-hundred-six dogs with CE were included. Fifty-two dogs (49%) had mild-to-severe reduction in MCS. Only 6/106 dogs (6%) had azo- temia (median creatinine 1.6 mg/dL; range 1.5-2.4 mg/dL), whereas 40/106 dogs (38%) showed kidney injury. In particular, 2 dogs had glycosuria, 23 dogs had proteinuria, and 23 dogs had urinary casts. CCECAI was not different between dogs with, and without kidney injury (both median=4; p=0.9). Forty-four dogs were classified as having PLE. The prevalence of kidney injury was not different between PLE, and non-PLE (p=0.3) dogs, whereas PLE dogs showed a higher frequency (61%) of proteinuria, than non-PLE dogs (p=0.03 OR 2.8 95%CI 1-6.8). Serum markers of kidney injury should be inter- preted with caution in CE dogs, since approximately half of our dogs showed a reduction in muscular mass. On the other hand, assessment of urinary markers of kidney injury may be useful and advisable, espe- cially due to the high risk of proteinuria in PLE dogs.