To produce a sufficient amount of hormones for markedly increasing an endohematocrit level in an animal during the sustainable duration and treat canine anemia by administering an expression vector encoding a recombinant human erythropoietin thereto.

This expression vector includes a separated recombinant human erythropoietin (abbreviated to EPO thereafter), substantially comprising a nucleotide encoding a canine EPO, and the vector further includes a promoter element actably linked to the EPO sequence element and the vector is administered in such a sufficient dose to cause the statistically significant increase in the canine hematocrit. In a preferred embodiment, the vector is given without the transfection-promoting substance, complexed with a cationic liquid, followed by administration as a part of a ribosome.