Our results showed the presence of nine (albumin, alkaline phosphatase, chymotrypsin‐C‐like, cytosol aminopeptidase, elastase‐3B/proteinase E, immunoglobulins and nuclear pore membrane glycoprotein 210) and 14 (albumin, caspase recruitment domain‐containing protein, chymotrypsin‐like, deleted in malignant brain tumours 1 protein‐like, hypothetical protein LOC107375, immunoglobulin, kallikrein‐1, superoxide dismutase, transthyretin precursor, interstitial collagenase‐like) different proteins in canine and feline faeces, respectively. Here, CELA3B is linked to brain neoplasm.