Epidural vs intramuscular administration of lecirelin, a GnRH analogue, for the resolution of follicular cysts in dairy cows

Bovine follicular cysts are an ovarian disorder of dairy cows associated with abnormal estrous behaviour and infertility. The treatment of choice is intramuscular administration of a GnRH analogue, which acts by triggering pituitary release of LH. However, the presence of GnRH and GnRH receptors on spinal cord and ovary in some species, and the kind of innervation of the ovary, let us hypothesize that GnRH and its analogues may also act when administered by epidural route, as happens for other drugs. Therefore the aim of this study was to compare the effects of epidural vs intramuscular administration of lecirelin (a GnRH analogue) on FC regression, estrus detection and pregnancy outcomes.The study was conducted on 220 Friesian cows affected by follicular cysts, divided among 4 groups: Group Lepid and Group Lim received, respectively 50 μg of lecirelin in the epidural space and intramuscular; Group Cepid and Group Cim were used as control groups. In Group Lepid, estrus induction and pregnancy rates were significantly higher than in Group Lim.The results of this study show that the epidural administration of lecirelin promoted the remission of follicular cysts and an improvement of reproductive parameters compared to intramuscular administration.Thus, an alternative therapeutical approach is available for FC treatment, in order to obtain an easier restoration of the ovarian activity, especially in those cases refractory to classical therapeutic approaches.