The nucleotide sequence of dog catalase was determined from cDNA obtained by reverse transcriptase-polymerase chain reaction (RT-PCR) and 5'- and 3'- rapid amplification of cDNA ends (RACE) using dog liver mRNA. The deduced amino acid sequence was compared with the sequences of other mammalian catalases and was found to show 93.0, 92.0, 93.3 and 91.7% similarity with mouse, rat, bovine and human catalases, respectively.