Differentiating canine chronic inflammatory enteropathies using faecal amino acid profiles: Potential and limitations

The aims of this study were to characterise the faecal amino acid profile of dogs with different chronic digestive diseases (food-responsive enteropathy (FRE), immunosuppressant-responsive enteropathy (IRE)) prior to dietary change, and Giardia infection (GIA), compared to healthy control (HC), and to evaluate their discriminating potential. The HC group presented lower faecal tyrosine (Tyr) and aromatic amino acids (AAAs) compared to FRE or IRE dogs (p = 0.0001). Additionally, the HC group had lower levels of threonine (Thr) (p = 0.0005) than the IRE group, while FRE dogs showed intermediate values. No statistically significant differences in faecal amino acids were observed between FRE and IRE dogs. In contrast, the GIA group had higher faecal amino acid values (except glutamic acid (Glu)) compared to the other dogs. The most determinant variables contributing to the discriminant functions were Tyr, Glu, arginine, and phenylalanine. Validation results of the discriminant functions showed that 44% of stool samples were misclassified, resulting in a 56% success rate. The faecal amino acid profile did not accurately distinguish FRE from IRE dogs; however, faecal excretion of AAs was generally higher in dogs with GIA.

[Simple Summary] This study explores the potential of faecal amino acids as non-invasive biomarkers for distinguishing different forms of canine chronic inflammatory enteropathies. The findings suggest that faecal amino acid profiles, particularly threonine and aromatic amino acids such as tyrosine, could serve as indicators of chronic digestive disorders. However, the faecal amino acid profile alone cannot fully differentiate dogs that respond to diet from those that do not. Dogs with clinical signs but infected with Giardia spp. show significantly greater excretion of faecal amino acids compared to the others.

C.H. received a grant for PhD development from Becas Santander at the Complutense University of Madrid (CT15/23).

Peer reviewed