Petwatch – Persistent oestrus in ferrets

November 2009

In America, many ferrets are “de-scented” at an early age by having their anal glands removed, though it is now known that the characteristic musky odour is actually associated with secretions from the sebaceous glands in their skin, not their anal glands. Indeed, in the UK it is illegal to “de-scent” ferrets in this way, though castration of males is thought to reduce their sebaceous secretions during the breeding season, and thereby reduce their aroma.

Some male ferrets (hobs) are presented to the surgery for castration, as it also reduces their dominant behaviour, though for keepers of female ferrets (jills), it may be advisable to keep at least one male interested in mating, but to have him sterilised by vasectomy instead.

Jills come into season around March or April, when the length of daylight begins to exceed twelve hours a day, and they stay in season until daylight length reduces again around September. This prolonged period of being on heat causes some serious medical problems for jills, in particular hair loss and severe bone marrow failure, often resulting in death.

The season is naturally interrupted and foreshortened by breeding. Both the act of coitus and the process of being held firmly by the scruff of the neck, which occurs during mating, are required to induce ovulation, and thereby lower the dangerous levels of oestrogens that build up during a season. In order to allow this to happen without the likelihood of pregnancy ensuing, a vasectomised hob can be employed.

If breeding is not desired, clearly the jill can be spayed, thereby preventing further seasons; if breeding is to be delayed for a year, another option is to inject jills with hormones to suppress their season for a year. The only option which should not be allowed is for a jill to remain in season for many months, as she is very likely to become seriously ill somewhere along the line.

Domestic ferrets are close relatives of the European polecat, and while Aristophanes made reference in his writing as early as 450 BC to an animal that may well have been a ferret, the earliest clear references to the use of ferrets for hunting rabbits comes from Pliny and Strabo in literature from around 2000 years ago. While some people do still keep ferrets for hunting purposes, they have also surged in popularity as domestic house pets – something I personally find a little odd, as they certainly do emit a notable odour!.

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