For 11 tumor samples, which immunohistochemically displayed nuclear translocation of β-catenin (score 1, 2 or 3), Sanger sequencing identified somatic missense mutations in exon 2 of the feline CTNNB1 gene in 4 colonic tumors (case 14: colonic ANOS score 1; case 20: colonic ANOS score 3; case 22: colonic ANOS score 1; case 31 colonic SAC score 1; 36.4% of all samples). Here, CTNNB1 is linked to neoplasm.