Effects of a novel recombinant Gonadotropin-Releasing Hormone-1 vaccine on the reproductive function of mixed-breed dogs (Canis familiaris) in Taiwan.

Immunocastration is an effective alternative to surgical castration for controlling the population of animals. As gonadotropin-releasing hormone (GnRH) regulates the reproductive endocrine system in mammals, it is a target antigen for vaccine formulation. Through this study, we evaluated the effectiveness of a recombinant subunit GnRH-1 vaccine for the immunocastration of the reproductive function of 16 mixed-breed dogs (Canis familiaris) provided voluntarily by different households. All the dogs were deemed clinically healthy prior to and during the experiment. A specific anti-GnRH immune response was detected at Week 4, which was maintained for at least 24 weeks after vaccination. Moreover, decreased levels of sexual hormones (testosterone as well as progesterone and estrogen, respectively) were observed in both male and female dogs. Estrous suppression was apparent in female dogs, and testicular atrophy and poor semen quality (concentration, abnormality, and viability) were observed in male dogs. In conclusion, the recombinant subunit GnRH-1 vaccine could successfully suppress fertility and delay the estrous cycle in canines. These results support the efficacy of the recombinant subunit GnRH-1 vaccine; thus, it is a suitable candidate for fertility control in dogs.