Influence of Breed Size, Age, Fecal Quality, and Enteropathogen Shedding on Fecal Calprotectin and Immunoglobulin A Concentrations in Puppies During the Weaning Period

Grellet, A.; Heilmann, R.M.; Polack, B.; Feugier, A.; Boucraut-Baralon, C.; Grandjean, D.; Grützner, N.; Suchodolski, J. S.; Steiner, J.M.; Chastant-Maillard, S.

In young children with gastroenteritis, several fecal markers are used to assess shedding of enteropathogens excreted, and to evaluate intestinal inflammation or local immunity. 15 Calprotectin and immunoglobulin A (IgA) are 2 of these markers. Calprotectin is a heterodimeric protein complex mainly present in neutrophils, monocytes, and reactive macrophages. In humans, fecal calprotectin concentrations were reported to be increased in patients with Crohn's disease or ulcerative colitis compared to healthy controls. 16, 17 Moreover, they also correlated with disease severity as quantified by endoscopy and histologic examination of biopsy specimens. 18 In adult dogs with chronic diarrhea, significantly higher serum and fecal calprotectin concentrations have been reported compared to healthy dogs. 19, 20 Sensitivity and specificity of fecal calprotectin for discriminating adult dogs with severe chronic diarrhea (Canine Chronic Enteropathy Clinical Activity Index [CCECAI] ≥ 12) from dogs with mild to moderate clinical signs (CCECAI < 12) were 53 and 92%, respectively, when a cut-off value of 49 lg/g was used. 19 Secretory IgA is the predominant immunoglobulin subtype present in secretions, protecting mucosal surfaces from infectious agents. Therefore, fecal IgA concentration may serve as a marker of mucosal immunity. 21 In dogs, fecal secretory IgA concentrations previously have been used to evaluate intestinal immunity. 22, 23 For interpretation of fecal IgA and calprotectin concentrations, how they are affected by physiological factors such as breed size or age must be taken into account. The canine species is characterized by large interbreed variations, primarily by stature. The digestive physiology of dogs is also known to differ slightly according to breed size. In large breed dogs, such as German shepherds or Great Danes, fecal moisture content is higher, soft stools are more frequent and the number of defecations is higher than in small breed dogs. 7, 10, 11, 24 This difference may be a result of lower mineral absorption, higher fermentative activity reflecting higher intestinal permeability and a longer transit time, or both. [25] [26] [27] [28] [29] [30] The same variation has been described in puppies, with large breed puppies having feces of lower consistency compared to small breed puppies. 6 Age also affects concentrations of markers. Indeed, lower fecal IgA concentrations were described in puppies <6 months of age compared to adult dogs. 31, 32 In humans, an effect of age on fecal calprotectin concentration has been described with higher concentrations being observed in healthy children compared to healthy adults. 33 The same variation has been described between healthy puppies and healthy adults, but these results were obtained from dogs housed in the same breeding kennel. 32 Therefore, the aims of our study were to determine if calprotectin and IgA are influenced by fecal moisture (Study 1) and to evaluate if these fecal markers can be useful to detect infection by an enteropathogen (virus, parasite, or both) in puppies, taking into account the effect of 2 potential biases, age and breed size (Study 2).