Contraceptive implants used by cat breeders in France: a study of 140 purebred cats

Abstract

Objectives Deslorelin 4.7 mg and melatonin 18 mg subcutaneous implants were studied in purebred male and female cats, via questionnaires sent to French cat breeders, to assess breed, age, duration of the contraceptive effect, fertility after use, changes in behaviour and side effects. Methods Reproductive data were collected in 57 tom cats and 41 queens implanted with deslorelin 4.7 mg, and 42 queens implanted with melatonin 18 mg, for a total of 140 purebred cats, from 38 different catteries, representing 18 breeds. Results Using deslorelin (Suprelorin 4.7 mg; Virbac), sexual behaviour in males was inhibited for a mean ± SD of 13.4 ± 3.2 (range 8–21) months in 37/57 cats. Of these, 24/37 mated successfully and produced litters at a mean of 15.5 ± 3.6 (range 9–20) months. Inhibition lasted 11 ± 1.1 (range 9–12; n = 6), 13.2 ± 2.4 (range 12–18; n = 6) and 15 ± 3.5 (range 9–18; n = 6) months in Norwegian Forest Cat, Singapura and Ragdoll males, respectively. In 26/41 females implanted with deslorelin 4.7 mg, oestrus was inhibited for a mean of 16.0 ± 5.7 (8–38) months; 12/26 went on to produce a litter. Of the side effects specific to females: two presented persistent oestrus, leading to the removal of the implant; two developed lactation; one had fibroadenomatosis; and one was sterilised owing to cystic endometrial hyperplasia. Using melatonin (Melovine 18 mg; Ceva), 33/42 females had oestrus inhibited for a mean of 86 ± 50 (range 21–277) days after implantation with a peak return to oestrus in March, and 12/33 had a subsequent litter. No side effects were reported. Conclusions and relevance This study is the first to collect a large amount of field data, in 140 purebred male and female cats where a deslorelin 4.7 mg or a melatonin 18 mg implant was used. These field results may allow for more accurate clinical advice and open up new avenues of research.

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

“…In cats, administration of a 4.7 mg deslorelin implant caused an initial increase in T concentration and peaking 2 days later [12]. 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].…”

Small animal reproduction: Scientific facts versus dogmas or unverified beliefs

“…Veterinarians should not consider this study as giving a definitive scientific conclusion. Recent unpublished work in our group tend to show that there are considerable variations depending on the breed and on the environment [55]. Thereforeit is recommended to remain prudent in drawing any conclusion until there is enough datacollected.…”

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

“…in general, side effects seem to be more common in females than in males, as reported for bitches. 120,126 The duration of efficacy of the 4.7 mg deslorelin SRi varies between studies -16.0 ± 5.7 months (n = 26; range: 8-38 months) 120 versus 22.7 ± 2.1 months (n = 19; range: 16-37 months) 122 -and high individual variation is also seen. Nevertheless, reversibility has been proven in terms of the oestrous cycle and return of fertility, with reports of normal-sized healthy litters after the end of treatment.…”

“…117,118 Reversibility in terms of suppression of oestrus has been proven in different studies, and data about subsequent fertility in breeding queens are also available, albeit in a limited number of cases. [119][120][121][122] in the aforementioned questionnaire-based study, GnRH agonist SRi treatment for contraceptive purposes was reported for approximately 12% of adult breeding queens. 4 When used in adult queens in seasonal anoestrus or during post oestrus (with basal progesterone concentrations), oestrus induction is possible or even likely.…”

“…Surgical removal of both deslorelin implants might be an option to shorten the duration of efficacy, 128,129 but the time point for return to oestrus seems to be extremely variable 120 and might be influenced by season (authors' personal observations). A recent study described resumption of ovarian function after an interval of 3-7 weeks, depending on the photoperiod.…”