Fecal Calprotectin Concentrations in Cats with Chronic Enteropathies

SIMPLE SUMMARY: Intestinal diseases in cats are challenging to diagnose, particularly when intestinal inflammation is to be distinguished from lymphoma, a neoplastic condition. In this study, levels of the protein complex known as calprotectin in fecal samples are investigated in both diseases and in comparison to healthy controls. The authors also investigated potential correlations between fecal calprotectin levels and clinical severity or intestinal microscopically visible changes of these diseases. There were no differences found between cats with lymphoma and inflammation in the intestines or cats with other diseases of the intestines, but calprotectin levels were higher in fecal samples of cats with intestinal diseases compared to healthy cats and cats with diseases located elsewhere in the body. This may indicate that calprotectin plays a role in gastrointestinal lymphoma as well as gastrointestinal inflammation and that these two diseases can not be separated by fecal calprotectin levels. While calprotectin may not be suitable as a marker to differentiate different chronic intestinal diseases, it can distinguish intestinal diseases from other diseases with overlapping clinical signs and from health. Further insights into the role of calprotectin will help better understand the disease pathogenesis and discover novel treatment avenues. ABSTRACT: Diagnosis of feline chronic inflammatory enteropathies (CIE) and the differentiation from small cell intestinal lymphoma (SCL) can be challenging. Intestinally expressed calprotectin (S100A8/A9 protein complex) appears to be part of the complex pathogenesis of feline chronic enteropathies (FCE). Fecal calprotectin is a non-invasive biomarker for intestinal inflammation in humans and dogs but has not yet been evaluated in cats. We hypothesized that fecal calprotectin (fCal) concentrations are increased in FCE, correlate with clinical and/or histologic disease severity, and distinguish cases of CIE from SCL. This case–control study included fecal samples and patient data from cats with CIE (n = 34), SCL (n = 17), other gastrointestinal (GI) diseases (n = 16), and cats with no clinical signs of GI disease (n = 32). fCal concentrations were measured using the immunoturbidimetric fCal turbo assay (Bühlmann Laboratories). Compared to healthy cats, fCal concentrations were significantly increased in CIE, SCL, and other diseases (all p < 0.0001), but were not different between these three groups (all p > 0.05), or between cats with extra-GI diseases and healthy controls. These findings suggest that fCal may have utility as a clinical biomarker for FCE but not for intestinal disease differentiation. It further supports the role of calprotectin in the pathogenesis of the spectrum of FCE, which includes CIE and SCL.