Fertility control potentially offers a humane management tool for wild animal populations. Generally there are two different types of immuno-contraception available. Firstly PZP (manufactured from pig ovaries) and secondly GnRH (GonaCon).
A trial of PZP on the Kaimanawa horses in the mid 1990’s regrettably failed. (Part of the cause was a faulty batch used.) However PZP has quite a number of unpleasant side effects both in terms of the health and well-being of the animals, but in addition has significant behavioural side effects. It has also proven to be unpractical and uneconomic.
GnRH is a naturally occurring hormone in all mammals; it works with other hormones to control the functioning of ovaries in females and testes in males. In humans GnRH is used in IVF, breast and prostate cancer treatment etc.
To use GnRH as a contraceptive it needs to be linked to a protein then combined with an adjuvant to create an immune response, this induces infertility by reducing reproductive hormones. None of this is new, and has been successfully used for years, but the problem has been to create a long-term effect which would enable the vaccine (GonaCon) to be used efficiently in wild animal populations. Recently a new adjuvant has been developed which could allow up to four years of infertility. The effects and durability of the vaccine reduce over the time period and it is believed that repeated vaccinations will not create issues with permanent infertility. To date it also appears safe to treat pregnant animals with no significant effects on behaviour, birth rates, survival rates or neonatal growth rates and fertility.
GonaCon is also proving safer in terms of side effects and behavioural changes and does not constitute a bio-hazard (unlike PZP). Unfortunately to date long-term trials on horses using repeated vaccinations have not yet been completed, but it has proven effective in quite a number of other species (including deer).
Recently we have been corresponding with Dan Baker, research biologist from Colorado State University. Dan is currently undertaking a long-term study (around eight years) to evaluate the use of GonaCon as an immuno-contraceptive vaccine in feral horses. Efficacy, durability of effects over time, behaviour and side-effects of treatment are being trialed in controlled experiments with captive, domestic horses and in a field application with wild horses at Theodore Roosevelt National Park in North Dakota.
There are many questions yet to be answered, and still many years before Dan’s study is completed, but the concept is gathering speed, albeit slowly at present. The Department of Conversation is showing cautious interest, and there is also some guarded optimism from their representatives at the New Zealand Veterinary Association. We also have on board Kevin Stafford and Erica Gee from the veterinary school at Massey University and Clare Veltman from the Department of Conservation. Kevin and Clare were part of the previous PZP study and along with Erica have a wealth of knowledge and resources to help make informed decisions. We believe there may be the option to trial the GnrH vaccine with the Kaimanawa horses perhaps in the future – all things going to plan of course! This would obviously require quite a lot of work to be done in terms of population studies and getting approval for the drug to be used in New Zealand, costings, Department of Conservation and the Kaimanawa Advisory Group approval etc.
We may have to look at assisting with the costs of this but if this enables us to reduce the slaughter of our Kaimanawa Heritage Horses we believe it will all be worth it.
Well I am surprised you say that horses cannot be vacetomised as there are instances on the net that say it can be done and even in one instant a reversal was successfully accomplished. All it is is a crushing or a nick and the horse can be done standing under a local(sedated of course,who would want to tackle a wild colt otherwise ). Possibly you mean that it would be unneccessary (no benefits) to do domestic horses. This would only be done to lead stallions that would be set free again so are wild . Young colts would still be captured until the numbers reduced with the low conception rates of the mares and fillies.The young colts are chased out and live in mobs away from the herd .The way it is breeding hundreds of unwanted kaimanawas horses that have to go a stressful situation of one kind or another .Thanks for your thoughts .
Well Deb, it appears you are correct, it seems it can be done, although interesting to note my Google search did not net a lot of info or anything newer than a couple of years old. So perhaps not a popular option?
These horses are completely WILD and there is no way that I think you would find giving them a local & getting them to standstill while you had a go at their privates an easy job or in fact one that anyone at the muster yards would be lining up to have a go at if they valued their lives.
Probably more to the point is the social & behavioual impact that this would cause in the bands. PZP trials have shown that mares that continue to cycle but not get pregnant will leave their stallion & go in search of another who will do the job. Therefore for this option to work you would need to do a lot more than just the dominant stallion in each band. Also remembering that just becasue he may be the man in charge when they are mustered doesn’t mean he will still be holding down that job next month or even next week.
The next issue is that DoC don’t want to have a “managed” herd so that is why at present whole bands are taken from the more populated areas & the “no go” zones. Basically once you’re in you’re out.
Again you are correct – the present system isn’t ideal, they are being allowed to breed to be slaughtered & that is why developing an effective & efficient immuno contraceptive vaccine & then getting its use here approved is so important.
However this is a better solution than the helicopter massacres that were proposed in the mid 1990′s & still continue today in Aussie.
what happens to horses after they have been rounded up??? are they ? a) given away as pets b) turned into dog food c)sold to race horse trainers d) set free around the hills of nelson
Check out the rest of the website.
DoC allow us to home most of the horses, to experienced approved applicants, those that they deem to be suitable to be re-homed are sent to slaughter. They are not racehorses. There is a Kaimanawa Sanctuary in Nelson, which is privately owned.
Whoops that was supposed to read “UNSUITABLE”
Thankyou for taking the time to reply. Lets just hope someone can find an answer soon,I have no time for DOC they are all fools who do no commensense research … eg ask local people talk to local vets etc No wonder they think they are “so high and mighty” but make so many blunders .Deb PS I know they did have locals that approched THEM and helped them out of alot of “trouble” in the end, but they should now remember that and learn now.Manage the horses and stop the abbatoir & army killing immediately thats what I believe .
Hi Deb, thanks for your question. Firstly vasectomies are only performed on humans, other animals are castrated. Which removes the testes all together. The results of castration (or “gelding” as it is known in horses) reach beyond just infertility, in particular the change of hormones levels this causes creates behavioural changes, good in captivity, but not good for the social behaviour of the bands of wild horses. Secondly the Department of Conversation decided many years ago that they did not want the Kaimanawa Horses to be a”managed herd”. The result of this decision is that the horses are interfered with as little as possible, but in order to keep the population levels to the level required by DoC horses need to be removed. Hence the muster process. KHH endeavour to home as many horses as possible from these musters but this is the reason that we are keen to see to possible introduction of a GnRh based contraceptive as soon as possible.In other areas of the world this is gaining converts but as usual NZ is lagging behind. At the moment the horses are being allowed to breed only to be slaughtered & at a large financial cost to boot.
Sue. KHH
WHY arn’t the colts and stallions vacetomised and then released ? There is only one stallion in the herd.the other colts are chased out. Surely the sires can be identified when the mob is caught in the yards ?