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

Abstract

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.

What Happens in Male Dogs after Treatment with a 4.7 mg Deslorelin Implant? I. Flare up and Downregulation

“…Implantation sites of five out of seven deslorelin-treated dogs showed mild, transient local reactions that disappeared within three days in all but one dog, where the reddening remained up to five days after treatment. The good local tolerance is in agreement with previous observations of the 4.7 mg deslorelin implant in dogs [ 30 ] and cats [ 49 , 50 , 51 , 52 ]. All implants could be easily removed during general anesthesia necessary for hemicastration, as described earlier in anesthetized cats [ 49 ].…”

Resumption of ovarian activity following removal of a 4.7 mg deslorelin implant in queens

“…In the present study, resumption of ovarian function (based on observation of oestrous behaviour and vaginal cytology) after the removal of a 4.7 mg deslorelin implant ranged from 3 to 7 weeks depending on the season of implant removal (increasing and decreasing photoperiod, respectively), irrespective of whether the implant was left in situ for 3, 6 or 9 months and independent of age of the queen. The interval of 3 weeks from implant removal to resumption of behavioural oestrus mirrors the interval of 3 weeks observed in tomcats between removal of a 4.7 mg deslorelin implant and return to testicular function (Ferré‐Dolcet, Carniello, et al., 2020).…”

“…Once normality of general and reproductive health conditions as well as basal P4 concentration were confirmed (and queens in dioestrus eliminated from the study), queens were treated with a 4.7 mg deslorelin implant placed subcutaneously approximately 1.5 cm cranial to the umbilical scar following hair clipping and local scrubbing (Ferré‐Dolcet, Carniello, et al., 2020; Romagnoli et al., 2018; Zambelli et al., 2015). A 0.3 ml lidocaine (Lidocaina 2%™; Ecuphar) dose was injected cranial to the umbilical scar 2 min prior to implantation.…”

Reproductive Management in Catteries: Optimising health and wellbeing through veterinarian-breeder collaboration

“…Reversibility of testicular endocrine function has been shown to occur quickly once efficacy wanes, 143 as well as after implant removal. 146 Testosterone concentrations were >0.1 ng/ml 23±6 days (following 3[n = 6]or6 [n = 5] months of treatment) and 22 ± 7 days (9 months of treatment, n = 4) after removal of a 4.7 mg deslorelin SRI in a recent study. 146…”

“…146 Testosterone concentrations were >0.1 ng/ml 23±6 days (following 3[n = 6]or6 [n = 5] months of treatment) and 22 ± 7 days (9 months of treatment, n = 4) after removal of a 4.7 mg deslorelin SRI in a recent study. 146…”