MALE DOGS can breathe a sigh of relief. The days of removing their testicles to stop them breeding or to curb aggressive behaviour may be numbered. A contraceptive implant that halts testosterone and sperm production for months at a time is expected to gain European approval within weeks, which will allow the implant to go on sale in the UK. Meanwhile, the necessary legal steps are being taken to enable the drug to be sold in the US.
Both egg and sperm production is controlled by the release of sex hormones from the pituitary gland, which is in turn controlled by gonadotrophin releasing hormone (GnRH).
The implant was developed by Peptech in Macquarie Park, Australia. It is inserted under the skin between the dog’s shoulder blades and contains a drug called deslorelin or Suprelorin, which works as a synthetic hormone when slowly released and binds to GnRH receptors and overstimulates them so that they become desensitised to the hormone. As well as making the dogs temporarily infertile, deslorelin blocks testosterone production, curtailing aggressive behaviour.
Last week, Daniela Braga of the Assisted Fertilization Centre in Sao Paolo, Brazil, and colleagues told a meeting of the European Society for Human Reproduction and Embryology in Lyon, France, that they have used the drug as an alternative to surgical sterilisation in female cattle and to time their pregnancies for when pastures are available.