The present invention relates to a canine pre-proGHRH polypeptide, a canine mature GHRH peptide, an isolated polynucleotide which encodes the canine pre-proGHRH or the canine mature GHRH. The invention also encompasses vectors encoding and expressing the canine pre-proGHRH or the canine GHRH which can be used to treat disease and growth hormone deficiencies by gene therapy in vertebrates, in particular in dogs.