It depends when they come into season on the weather and where they are kept, if they are kept indoors with heat and artificial light they can come in season from nov/dec, ideally they shouldnt come into season until spring but even outdoor ferrets have been coming into season much earlier due to warmer weather.

Jills can be spayed from 6 months old although some like to leave them longer due to the possible link with early neutering and adrenal later in life.

If they come into season early its highly likely they will come back in season during the same year.

Incidently my friend has an 8 month old who has just come in season!

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Tiggy, 13 yr old Collie x Alsation, Lucy 11 yr old epileptic cross breed, Kara, collie x whippet