The Countryman's Weekly

Jill jab vs vasectomised hob

June 30
15:13 2015

IT’S that time of year again, and as the days get longer jill ferrets will be coming into season. Many Countryman’s Weekly readers will have heard the old countrymen’s tales that state that a jill ferret must have a litter every time she is in season or she will die.  While there is certainly some truth in this, today we have methods at our disposal which were not available to our forefathers and which can eliminate the risks of prolonged oestrus in jills without producing unwanted litters.

In common with many other animals, including chickens and horses, the ferret’s oestrus (season) is regulated by the ratio of light to dark, a phenomenon known as photoperiodism. In other words, her seasons will start when the days get longer and the nights shorter (spring/early summer). Unless taken out of season, either by injection of hormones or by mating, she will remain in season throughout the summer months and this will affect her wellbeing and potentially shorten her life .

If a jill is not mated immediately she is on heat, the levels of oestrogen (the female sex hormone) will build up in her system, causing progressive depression of the bone marrow. This can result in a condition known as pancytopenia – the abnormal depression of all three cell types of the blood – which is potentially fatal.

In other words, if a jill is left in oestrus for any length of time she will almost inevitably die before reaching her full life expectancy. This is not speculation, fancy or rumour, it is a scientifically proven fact.

In 1981 I mentioned the problem of prolonged oestrus in ferrets to my friend, Chris Charlesworth MRCVS, and made the suggestion that a vasectomised hob should be able to induce ovulation in the jill without her becoming pregnant. After some discussion, Chris agreed to try it and carried out what I believe to be the first ferret vasectomy.

In his book, Fred J. Taylor’s Guide to Ferreting (Buchan & Enright, 1988), Fred mentions that he had heard about a vasectomy in a ferret, and I believe that this could only have been the one that Chris operated on. The operation was tricky but a complete success and ‘Roger,’ as the ferret was aptly nicknamed, began a long career of taking jills out of season.

The term for a vasectomised hob, hoblet, was coined in the first edition of my book, The Complete Guide to Ferrets (Swan Hill Press, 1995), and the term is now in common usage around the world.

Where the owner of jills does not wish to have a litter from their ferrets, the animals are best neutered (both jills and hobs).  Neutering will reduce the smell of the animals (particularly during the summer months), reduce the risk of fighting between hobs and allow any combination of ferrets to be kept together in safety, as well as solving the problem of oestrus in the jills. Neutering does not affect the working abilities of either hobs or jills.

However, if it is desirable to keep open all options, the best methods of removing the risk of serious health problems linked to prolonged oestrogenic exposure are to either have the jill mated with a vasectomised male ferret (a hoblet), or given a ‘jill-jab’ (a hormone injection) by a vet. To my mind, where large numbers of jills are kept, a ferret owner really cannot afford not to have at least one hoblet.

To have a hob vasectomised costs between £80 and150 and, with such a large variation, it is well worthwhile ringing a few vets and asking prices. The hoblet will be able to take jills out of oestrus for about seven to eight years, thereby repaying this investment several times over. Savings will be made on food, time and the work that kits would cause their owner and, of course, the fact that there will be fewer unwanted ferrets to be abandoned by unscrupulous people.

A jill mated with a hoblet will usually have a pseudo-pregnancy (phantom pregnancy) following the mating. This may result in the jill’s stomach swelling, she may produce milk, and she may nest build. In other words, she will exhibit all of the symptoms of being pregnant, with one major difference – at the end of the 42-day ‘pregnancy’ she will not produce a litter.

The jill will, however, come back into oestrus about three to four weeks after the end of the pseudo-pregnancy, when she will require mating again. By the end of the second ‘pregnancy’ the summer will be almost over and the jill will not come on heat again until the following spring.

The reason that a hoblet can take the jill out of season without getting her pregnant is that ferrets are induced ovulators – ie. the physical act of mating induces the jill to ovulate. As a vasectomised hob cannot produce viable ejaculate, there is no sperm to fertilise the eggs and the jill will come out of season without becoming pregnant.

Some ferret clubs recommend and even encourage owners of hoblets to lend them to owners of jills in heat, but this practice is potentially fraught with dangers. The risk of the spread of diseases such as Aleutian disease, distemper, enteritis and influenza is far too great to risk. Encouraging the loan of hoblets, while better than leaving jills in season, dissuades some people from making the investment for themselves and is not a sign of responsible animal ownership.

If owners do not wish to invest in a hoblet of their own, or have only a small number of jills, ‘jill jabs’ – injections with drugs such as proligestone (Delvosteron) – are often a viable alternative which allows owners to keep their options open without endangering their ferrets or producing unwanted litters.

Sometimes jills will need more than one such injection during a year, ie. if she comes back into season. These injections vary from about £5 to £10 per ferret per injection. Shop around vets to get the best price.

One minor side effect of jill jabs is temporary hair loss at the injection site, but the hair quickly regrows and there is no long-term ill effect from the jab.

Over the years I have spoken to ferret keepers who have other, often outlandish ideas for taking their jills out of season. One theory is that, if a suitably shaped stone or similar object is placed in the cage with a jill which is on heat, she will copulate with it, bringing herself out of season. Others state that if two or more jills are kept together, and never allowed the company of a male ferret, they will ‘turn lesbian’ and remove each other from heat by using their paws on each other.

Some ferret owners even try to simulate the coitus of a hob by gripping the jill firmly by the neck and using either a glass rod or even a cotton bud to stimulate the vagina; there is obviously a great risk of injury to the jill – and very little hope of success – in such actions, which should never be attempted. Of course, no credence should be given to any of these weird theories, but it is easy to understand why the users of such methods believe they work.

Although a jill comes into season early in the spring and will remain so until she is removed from season by a mating or hormone injection, the obvious signs of her condition will not always be present.

When she first comes into season her vulva will swell noticeably, often protruding from her body by over a centimetre. Within seven to ten days of mating this swelling will reduce, but it will also reduce (albeit temporarily) after a couple of weeks even if she is not mated. This does not, however, mean that she is not in season and, in the next few weeks, her vulva will again swell to very large proportions.


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