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Oestrus suppression in queens using melatonin implants

In 2016, we started using melatonin implants to stop queens calling. The background to this is that queens have high levels of circulating melatonin between breeding cycles and when not calling. Melatonin is a hormone secreted by the pituitary gland. Melatonin is rapidly metabolised in the body so implants have been used to achieve sufficiently high and continuous concentrations. The potential advantage of using melatonin may allow for short-term control of calling with minimal impact to the queen, to the owner and with return to normal fertility at the completion of treatment.

Research conducted in Argentina1 achieved suppression of calling for 61.1 ± 6.8 days using 18mg implants that were inserted when the queens were calling and 113.3 ± 6.1 days when the implants were inserted when the queens were not calling. Another study conducted in Italy2 using similar implants achieved suppression durations of 80 ± 24.7 days.

There are no melatonin implants licensed or registered for use in cats in Australia. We have used 18 mg Regulin® implants produced by Ceva and 18 mg implants Dermatonin implants from Melatek. These implants are approximately one third of the size of a standard microchip and are implanted under the skin in a similar fashion.


Our experience to date has given us a maximum suppression of 71 days. Our observations so far indicate that there is no difference in effect between the Regulin or Dermatonin implants, Oriental breed queens seem to have a lesser duration of suppression than non-Oriental breeds and increasing the number of simultaneous implants (including 8 implants into one queen) does not extend the length of suppression. We have not seen any complications with return to fertility after the implant effect has worn off.


For more information please contact the clinic and make an appointment to see one of our veterinarians.


1.Gimenez F, Stornelli MC, Tittarelli CM, Savignone CA, Dorna IV, de la Sota RL and Stornelli MA. Suppression of estrus in cats with melatonin implants. Theriogenology (2009) 72:493–499.

2.Nequinio M, Romagnoli S, Beccaglia M, Trovò C, Banzato T, Mollo A, Milani C. Clinical use of melatonin implants to control reproduction in breeding queens. ISCFR VIII International Symposium on Canine and Feline Reproduction PARIS, FRANCE JUNE 22-25, 2016.

3. Kutzler MA. Alternative methods for feline fertility control. Use of melatonin to suppress reproduction. Journal of Feline Medicine and Surgery (2015) 17:753–757.