The present invention discloses a canine TSLP protein and a nucleic acid that encodes that protein. Peptide fragments of the protein that comprise specific epitopes of the canine TSLP protein are also disclosed. The canine TSLP protein and related peptide fragments may be used as an antigen for immunological assays, as well as for vaccines that induce anti-TSLP antibodies. The present invention further discloses methods of making and using the canine TSLP gene, the canine TSLP protein, and the related peptide fragments.