Worming has changed over the past 50 years since broad spectrum wormers were introduced in the 1960’s. Back then the main worm being targeted was the large redworm (strongylus vulgaris). This parasite can cause damage to blood vessels that can lead to fatal colic. However over the past 50 years this parasite has become uncommon and is now only present in very low numbers in the population.
The small redworms (cyathastomins) have adapted over this time by rising to the challenge of the wormers. Wormer chemicals are called anthelmintics, and when these stop working by not reducing the worm burden by a set level we call this anthelmintic resistance. Resistance has been reported worldwide in small redworms and round worms. Because there are no plans to develop new worming chemicals for horses in the near future, it is paramount that we make the drugs we have last for as long as possible. Unfortunately anthelmintic resistance is inevitable in the long term.
The problem with blanket worming all horses at a yard at the same time with the same wormer is that we are treating them for worms when they might not have enough to need treating. It would be unlikely that you would feed each horse on a yard exactly the same feed because some will be good doers, some poor doers, some sharp and some not so sharp. We feed them individually because we take into consideration their individual needs. Worming is exactly the same, some horses immune systems will help suppress parasitic infections whereas others will have weaker immune systems that will require more chemical wormer support.
The first step is to check how effective your past worming programme has been by doing a worm egg count. Worm egg counts are by no means new, they have been used in veterinary practice for over 50 years. Only in the past decade have the use of worm egg counts become common practice in sustainable worming programmes. Worm egg counts give us an indication of a horses intestinal parasite status, when used as a tool in an Intelligent Worming programme it is possible to get a much clearer picture of a horses worm burden.
There is a danger with worm egg counts that if the results are not interpreted correctly and are not acted on by a professional who understands them, then the horse in question will not be treated appropriately. One worm egg count is a snapshot of the adult parasite egg laying activity at that time, a pattern of scheduled egg counts over time will provide a much clearer picture of a horses worm burden than just one .
It is also important to take into consideration all of the risk factors a horse is exposed to by which it may pick up intestinal worms. By looking at the all the risk factors it is possible to then build an Intelligent Worming programme for each horse treating their individual needs.
When looking at a group of horses 80% of the parasite population is found in 20% of the horses. There will generally be one or two with high worm burdens that will require more treatments and those with lower worm burdens that will need much less wormer support because the body’s immune system can cope much better fighting off the worms.
Worm egg counts cannot pick up all of the intestinal parasites of horses. Firstly they can only detect adult females that are laying eggs. Worm egg counts cannot detect any larvae present because they are not adult worms and therefore they are not laying eggs. Worm eggs counts cannot detect encysted small redworms either as these are also immature larvae during the encysted stage.
Worm egg counts cannot reliably detect tapeworm in a standard test due to the tapeworms life cycle, there are other faecal tests that can be used or there is a blood test that can be used to detect tapeworm. The blood test is a handy tool if an infection is expected but is not commonly used in routine worming programmes. Tapeworms due to their lifecycle only need treating twice per year.
Additionally both bots and pinworms cannot be detected in worm egg counts due to the way they complete their life cycles. Because these worms cannot be detected some wormers will be required to treat against the parasites that cannot be detected. In the case of pinworms if they are present they will often emerge in the dung and at this stage appropriate management and treatment can follow.
By only treating horses when it is necessary it is possible to make the use of wormers much more sustainable. Intelligent Worming is the only company that specialise in equine intestinal parasite control. Each horse is looked at as an individual, they are risk assessed, worm egg counted and programmes are individually written for each horse. At the end of each year the programme is reviewed so the strategy going forward can be planned. The long term aim, where possible, is to reduce the use of chemical wormers which will save you money and ensure your horses health is not at risk of parasitic infections.
For further information on how Intelligent Worming can work for your horses please contact our Equine Advisors on 01267 22 33 22 or visit www.intelligentworming.co.uk .