Interval between Removal of a 4.7 mg Deslorelin Implant after a 3-, 6-, and 9-Month Treatment and Restoration of Testicular Function in Tomcats

Deslorelin implants have been used to produce a reversible sterilization in several species. In cats, the prolonged duration (12-15 months in tomcats and 18-22 months in queen) is often too much for cat breeders who request early implant removal. The interval between implant removal and resumption of reproductive function in cats has never been investigated. Eighteen tomcats received a 4.7 mg deslorelin implant placed in the periumbilical area and surgically removed during all seasons of the year after 3, 6, or 9 months (n = 6, 6, and 6 cats, respectively). Following implant removal, all cats received a clinical exam every two weeks, including testicular ultrasonographic measurement, observation of penile spikes, and blood collection for serum testosterone assay. Restoration of serum testosterone secretion occurred after 23 ± 6, 23 ± 6, and 22 ± 7 days in the 3-, 6-, and 9-month groups, respectively. Restoration of testicular function was confirmed by histology in 13/15 cats undergoing orchiectomy at the end of the study while the owners of the remaining two cats opted to maintain their animals intact. Removal of a 4.7 mg deslorelin implant after 3, 6, or 9 months is followed by resumption of serum testosterone secretion after about 3 weeks independent of age or season.