Long-term contraception in a small implant

Abstract

Rationale:Deslorelin (Suprelorin®; Virbac) is a gonadotropin-releasing hormone (GnRH) agonist licensed in select countries for the long-term suppression of fertility in adult male dogs and male ferrets. This article summarizes studies investigating the use of deslorelin implants for the long-term suppression of fertility in male and female domestic cats.Evidence base:Slow-release deslorelin implants have been shown to generate effective, safe and reversible long-term contraception in male and female cats. In pubertal cats, a 4.7 mg deslorelin implant suppressed steroid sex hormones for an average of approximately 20 months (range 15–25 months) in males and an average of approximately 24 months (range 16–37 months) in females. Reversibility has been demonstrated by fertile matings approximately 2 years post-treatment in both male and female adult cats. In prepubertal female cats of approximately 4 months of age, puberty was postponed to an average of approximately 10 months of age (range 6–15 months) by a 4.7 mg deslorelin implant.Challenges:The large variability in the duration of suppression of gonadal activity makes the definition of the optimal time for reimplantation quite challenging. In addition, the temporary stimulation phase occurring in the weeks following deslorelin implantation can induce in adult female cats a fertile estrus that needs to be managed to avoid unwanted pregnancy. Longer duration and larger scale controlled field studies implementing blinding, a negative control group and a carefully controlled randomization to each group are needed. Furthermore, the effects of repeated treatment need to be investigated. Finally, the effect of treatment on growth and bone quality of prepubertal cats needs to be assessed. However, the ease of use, long-lasting effects and reversibility of deslorelin implants are strong positive points supporting their use for controlling feline reproduction.

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

“…Thereafter, serum testosterone of treated cats undergoes a rapid decline to <1.0 ng/mL persisting around basal levels for 61.7 to 100.7 weeks [12,13]. The interval between implant administration and the decrease of reproductive hormones has been defined as "time to downregulation" [14]. Such downregulation is reported to occur within 10 or 16 weeks in 90% [14,15] and 100% [16] of tomcats, respectively, and is accompanied by behavioral (decreased roaming and urine marking), physical (decrease in testicular size, disappearance of penile spike) and histological (suppression of spermatogenesis) changes [12,[16][17][18][19].…”

“…The interval between implant administration and the decrease of reproductive hormones has been defined as "time to downregulation" [14]. Such downregulation is reported to occur within 10 or 16 weeks in 90% [14,15] and 100% [16] of tomcats, respectively, and is accompanied by behavioral (decreased roaming and urine marking), physical (decrease in testicular size, disappearance of penile spike) and histological (suppression of spermatogenesis) changes [12,[16][17][18][19]. Because of these relevant and reversible changes in fertility, the off-label use of deslorelin in cats has acquired importance among cat breeders, as temporarily reproductive suppression of a tomcat in a breeding establishment may be useful when there is more than one male (to prevent fighting or alternate the use of males), or to prevent excessive weight loss in show tomcats during the breeding season.…”

GnRH‐agonist deslorelin implant alters the progesterone release pattern during early pregnancy in gilts

“…The GnRH-agonist used as a slow-release pellet (containing 4.7 mg deslorelin) and was reported to have a long-term suppressive effect on reproductive steroids in dogs (Borges et al, 2015;Junaidi et al, 2009;Kaya et al, 2015;Trigg et al 2001) and cats (Camila et al, 2016;Fontaine, 2015;Romagnoli et al, 2017). These treatment properties are usually applied for time-limited sterilization and contraception or for postponing oestrus, which is of high relevance in other species such as the horse.…”

“…Deslorelin is a GnRH analogue, and has been developed in a slow-release formulation to prevent oestrus and pregnancy in the bitch and to suppress testosterone chronically (thereby sexual behaviour) in the male dog (Borges et al, 2015;Junaidi et al, 2007;Kaya et al 2015;Trigg et al, 2001) and the tomcat (Camila et al, 2016;Fontaine, 2015;Romagnoli et al, 2017). In the male dog, insertion of a deslorelin implant led to a peak in LH within an hour of treatment (Junaidi et al, 2009); the vertex was over within 3 hr and LH returned to the basal level by Day 3 after treatment.…”

Resurrecting FUS: Adrenal Androgens as an Ultimate Cause of Hematuria, Periuria, Pollakuria, Stranguria, Urolithiasis and Obstruction in Neutered Cats

“…In ferrets, deslorelin implants have been very effective in suppressing adrenal steroid production for about a year. In cats, the suppression of adrenal steroid production lasts for 20 months in males, and 24 months in females ( 45 ).…”