Giardia intestinalis is a parasitic protozoan commonly seen in dogs and causes intestinal mucosal barrier damage. In this study, serum intestinal fatty acid binding protein (I-FABP), intestinal akaline phosphatase (IAP), and intestinal trefoil factor-3 (TFF-3) concentrations were assessed in Giardia intestinalis-infected dogs to determine their association with intestinal mucosal epithelial barrier damage and their potential to be used as a non-invasive diagnostic method. The study was conducted on 39 dogs (26 with giardiasis and 13 healthy dogs) of different breeds and sex. Giardiasis was diagnosed from fecal samples by rapid antigen test kit and fecal flotation test. Serum I-FABP (p=0.024), IAP (p=0.04), and TFF-3 (p=0.028) levels were significantly higher in dogs with giardiasis compared to the healthy group. These findings indicate that Giardia infection causes damage to the intestinal mucosa which triggers release of these compounds as protective mechanism. The positive correlation between the biomarkers and the giardiasis infection in dogs, indicate that they could be used as a non-invasive diagnostic method.