Worming Routines for Youngstock
The adult worming routine is not suitable for horses under the age of five. Foals and youngsters up to four years need more careful monitoring because their natural immunity to worms has not yet had time to develop. We strongly advise that owners of young horses contact Tower Equine for advice, as this can vary depending on individual premises. However, a basic guide is as follows:
From foal to one year old
- Do not start worming until the foal is two months of age.
- Then start with a single dose of fenbendazole (Panacur) as a roundworm treatment. Repeat this every six weeks up to the age of six months.
- Perform a WEC at 3 and 6 months of age.
- Give a single dose of a combined wormer in the December of the foal’s first year.
- Your vet will advise you what is appropriate
- Treat pregnant mares as normal adult horses with a 3 x yearly WEC and a single dose of wormer in December.
- In addition, give a dose of an ivermectin based wormer just before foaling.
- Do not worm in the two weeks after the mare has foaled.
- Continue with WECs as normal after foaling.
Yearlings to 4-year-olds
- WEC every three months with worming where indicated and a post-worming WEC to check effectiveness of any treatment.
- Treat every six months with a wormer with combined effect against cyathostomin and tapeworms.
- An optional third treatment in mid-summer using a different wormer if stocking levels are high.
- Manage pasture effectively, ideally with a system of rotation and resting. In particular, ensure that yearlings do not graze the same fields in successive summers.
Worming Control Package
Tower Equine have put together an annual package that will make sure your horse is appropriately tested and wormed throughout an entire year.
How it Works
- Contact the practice to register.
- On registering your horse, you will be sent an Annual Worming Pack containing all you need to take three worm egg counts (WECs) at three month intervals.
- You will be sent an email reminder at the start of the appropriate month for taking each WEC.
- You will be contacted by email with the result of each WEC. If this shows treatment is necessary, you will be advised on a suitable wormer to use which can be supplied by Tower Equine.
- You will be sent an appropriate wormer to use once a year, at the beginning of December. This will have a combined action including against tapeworm.
The price is £40 (plus vat) per horse per year. This will include
- Three worm egg count kits and testing.
- One wormer per year which will have combined action including against tapeworm.
- Advice and information from our vets at any time.
*Please contact the office on 01778 591082 to register for a Worm Control Package
*The package does not include additional wormers if tests show these are necessary.
*The package is not suitable for horses below the age of five.
Why Use the ‘Tower Equine Worming Programme’?
To explain how our worming programme works, we first need to look at why wormer resistance happens.
The key point to understanding why overuse of wormers is such a big problem is to appreciate that no wormer is going to kill every single worm. No matter which wormer you give your horse, a small number of the worms will survive - usually because they have a genetic mutation that gives them resistance to the wormer. Does this matter? If only a tiny number of worms survive, you might be tempted to think it doesn’t. But this small number of adults will go on to produce eggs which hatch into a new generation of worms, and some of these will have inherited the resistance of their parents. We have, unwittingly, selected for resistant worms. Each time we worm, we increase the number of resistant worms. In fact, the position is even worse than this, because we have wiped out all of the non-resistant worms, meaning that the resistant ones have a lot less competition. We haven’t just selected resistant worms, we have given them a helping hand! Remember, this happens every time we worm our horses, and this is why giving repeated heavy doses of wormers is adding to the problem.
Resistance to wormers is already widespread – some species of worm are currently no longer killed by two or even three of the different wormer types. Remember, we only have five different types of wormers, and new ones aren’t coming along any time soon! The problem is exactly the same as the NHS has with antibiotic resistance – people in hospitals are suffering infections and dying because the bacteria have become resistant to all the antibiotics available. We have to change what we are doing or soon we will no longer be able to properly protect our horses from worms.
How does this affect me?
Sometimes the temptation is to think that wormer resistance is somebody else’s problem. Surely it is up to the government or some other authority to sort out things out? If a good wormer is available, why not keep using that because at least then you can be sure your horse will be protected? You don’t want to take any risks, and as long as most people cut back, it won’t matter if you don’t…... This is a tempting line of thought, but unfortunately it is WRONG. If you overuse wormers, you aren’t increasing the general level of resistance in the UK, you are directly selecting for resistance on your very own fields! Resistance is local – you create it on your own paddocks.
The solution – Worm Egg Counting.
After all the bad news of wormer resistance, it is time for some good news. As they grow up, horses develop their own immunity to many of the most common types of worm. As the horse become resistant, adult worms are no longer able to live inside them, and worming is often no longer necessary. Fit, healthy adult horses generally carry only low levels of worms, and don’t need repeated worming. Of course this immunity only develops because the horse has had some exposure to worms when it was growing up –a completely worm free environment is not only rare, but also undesirable. The way to prove a horse has good immunity is to perform a Worm Egg Count (WEC). This simply means counting the worm eggs in a sample of the droppings using a microscope. From the number of eggs seen, we can get an idea of how many adult worms a horse is carrying in its intestines. If the WEC is low then worming is not necessary.
So far so simple, but there are a couple of things to be aware of. With one particular type of worm known as small strongyles or cyathostomins, the damage to a horse’s gut is done by the larvae, not by the adult worms. Because the larvae are not yet producing eggs, this means we cannot identify horses with a high level of larvae on a WEC. The good news is that cyathostomins are mainly a problem for young horses – adults are rarely affected – which is why the worming advice for youngsters is different to that for horses five years old or more.
The second small complication comes with tapeworms. Again, tapeworm eggs are not detectable on worm egg counts. Once again however, there is still an effective solution. There is not the same selection for wormer resistance with tapeworms as for some other worm types. Owners can therefore simply choose to treat horses with a wormer effective against tapeworms (once a year is fine for adults, twice a year for youngsters). Alternatively, an active tapeworm infection can be picked up with a kit that tests antibodies in the horse’s saliva. Both control methods work, so the choice is mainly down to cost and owner preference.
Undoubtedly, some of the confusion around wormers arises from all the different brand names. Trying to remember your Animec from your Equest, or your Noropraz from your Molemec is enough to make anyone’s head spin. The best way to simplify things is to classify wormers by their active ingredient. There are only five different active agents, and all brand name wormers contain one or more of these. The five active ingredients are:
1) Ivermectin - Examples of ivermectin based wormers include Eqvalan and Noromectin. There is roundworm and some small redworm resistance to ivermectin.
2) Moxidectin - Equest is the only commercially available moxidectin wormer and has been considered as the ‘go-to’ wormer for effectiveness, but resistance is now being reported, particularly with regard to roundworms.
3) Praziquantel - This is effective against tapeworms. Now only available in combination, usually with ivermectin or moxidectin.
4) Fenbendazole - Panacur is the best known example of this. Main current use is in foals to control roundworms. Significant small redworm resistance.
5) Pryantel - Strongid P is the best known of the pyrantel wormers. Effective against tapeworms at a double dose.
Are you confused about the correct way to worm your horse? If so, don’t worry because you are not alone. Almost every website you turn to seems to give different advice, whilst wormer manufacturers and even vets often make it sound equally complicated.
There are good reasons why correct worm control can seem difficult:
- Horses are susceptible to different worm species at different ages.
- Failing to monitor and treat appropriately can lead to serious worm related disease.
- Overuse of wormers is causing drug resistance, meaning some wormers no longer work against some worm species.
- However, many adult horses have good immunity to worms and only need worming once a year.
- Using worm egg counts in place of wormers can reduce costs and is the only way to reduce resistance.
All these factors mean that worming four times a year and considering the job sorted is no longer good enough. Fortunately, worming doesn’t have to be difficult – there are still some basic rules to wormer use, and, if you follow these, your horse will remain properly protected.
Below is a simple summary for a worm control programme that is suitable for most adult horses. It is followed by further information explaining how the plan works. Tower Equine offer a complete worm control package that includes regular worm egg counts. We are always happy to answer worm-related questions from livery yards and one-horse owners alike.
How to Worm
A Simple Worming Routine for Adult Horses, five years old or over:
- Perform a worm egg count (WEC) three times a year, in spring, summer and autumn (typically February/March, June/July and Sep/Oct). No worming treatment is necessary unless the WEC results are high.
- A single wormer treatment in winter (ideally December). This once a year strategy targets any low levels of tapeworms, bots, roundworms or large strongyles that may still be lurking. This does not need to be the ‘strongest wormer’ available, and the vet will advise which is the best one to use.
- Optional tapeworm testing every six months with ‘Equisal’. A low result means that the once-a-year worming in winter need not include a tapeworm treatment.
It really is that simple! Stick to this plan and, not only will your horse be well protected from worm damage, you will also avoid increasing wormer resistance. It is worth adding that the WEC are most likely to be negative if paddocks are well managed. This means:
- picking up droppings at least twice a week.
- avoiding overstocking.
- testing new arrivals before they are turned out onto the same pasture.
This plan is suitable for horses over the age of four on well-maintained pasture. It is not suitable for younger horses and advice for owners with youngstock is included below. We would always recommend that studs and larger livery yards contact us for an individual worming plan tailored to their premises.