Test before you worm if possible – a major step to avoid resistance in your horse.
WHAT IS THE DIFFERENCE BETWEEN ROUTINE AND STRATEGIC WORMING?
Routine worming is the use of equine anthelmintics throughout the year (in accordance with dosing intervals recommended by the manufacturer) to treat for roundworms, tapeworms and bots.
A strategic worming programme involves using Faecal Worm Egg Counts (FWEC) throughout the year with extended dosing interval periods between treatments. Horses on this programme are treated only when FWEC results are above a specified level i.e. 200 eggs per gram (epg). Care must be taken with this strategy, as FWEC do not give an accurate measure of the worm burden, as they do not account for larval stages including encysted small redworm larvae present in the horse.
WHY ARE TAPEWORMS NOT DIAGNOSED USING FAECAL WORM EGG COUNTS (FWEC) ?
Tapeworms release their eggs sporadically (irregular intervals) and so FWEC could show a false negative i.e. the result would indicate no eggs are present, but in reality the horse does have a tapeworm burden. A tapeworm antigen blood test will give some indication of any tapeworm burden.
WHAT IS GOOD PASTURE MANAGEMENT?
Dung should be removed regularly, at least twice weekly during the grazing season, and once a week between November and March as a minimum . Although harsh frosts may kill infective larvae on the pasture, with the milder and wetter climate now experienced in the UK, high levels of infective larvae can occur at any time of the year. Therefore there is an increased likelihood of grazing animals acquiring parasite burdens throughout the year. If the autumn and winter remain mild and wet, the twice-weekly removal of dung will be necessary all year round to help with the control of parasites.
WHICH WORMERS CONTAIN WHICH CHEMICALS? AND WHAT DO THEY TREAT?
Brand Chemical Treats
Animec Ivermectin Roundworms, pinworms, neck threadworms, bots
Equest Pramox Moxedectin + Praziquantel Roundworms, bots, tapeworms, all stages of encysted small redworm.
Equest Oral Gel Moxedectin All stages of encysted small redworm
Eqvalan paste Ivermectin Large & small redworms, pinworms, large roundworms, threadworms, hairworms, bots. NOT tapeworm.
Eqvalan Duo Ivermectin + Praziquantel Roundworms, bots, tapeworm.
Equimax Ivermectin + Praziquantel Tapeworm, bots, roundworm. Use in spring and autumn for maximum control.
Eraquell Ivermectin Roundworms, bots, small & large redworms, pinworms, large roundworms, threadworms, hairworms.
Panacur Paste Fenbendazole Non-resistant large & small redworms, pinworms.
Panacur 5 day liquid Fenbendazole All stages of non-resistant encysted small redworms inc larvae, large redworms, pinworms.
Panacur granules Fenbendazole As above
Pyratape -P Pyrantel Embonate Large & small redworms, ascarids, pinworms. Tapeworms using a double dose.
Strongid -P paste Pyrantel Embonate Gut dwelling roundworm. Double dose for tapeworm. Also benzimidazole resistant strains of small redworms.
SHOULD I ROTATE WORMERS EACH SEASON TO HELP FIGHT RESISTANCE?
There are a number of factors which may be involved in the development of resistance, with it having been suggested that the most important factors in delaying the onset of resistance is the anthelmintic’s initial kill of resident resistant worms, and secondly reducing the frequency of use of anthelmintic (Dobson R et al, 1996). This means that the ideal anthelmintic is a highly potent one to which there is no resistance, and which can be given as infrequently as possible.
With widespread resistance to benzimidazole-based wormers, and reported resistance to pyrantel and ivermectin-based wormers, there may be little room for choice as to what to rotate onto, as such it is recommended that you consult your vet prior to using one of these.
It has also been shown that of the macrocyclic lactones (moxidectin and ivermectin), moxidectin selects more slowly for resistance (Ranjan S et al) and should therefore be your first choice when using a macrocyclic lactone wormer.
An alternative strategy to rotation is to use a highly effective wormer with no resistance in horses, such as a moxidectin-based wormer. By using moxidectin, you can worm your horse as infrequently as possible (13 week dosing interval), while still protecting his health.
In addition, pasture management and faecal worm egg counts (FWEC) can also play a role in delaying the onset of resistance. Removing dung from the pasture removes most sources of re-infection, including resistant worms (Wolstenholme A et al, 2004) and so breaking their lifecycle. It is possible to extend dosing intervals by using FWEC: only treating animals when they are producing eggs above a specific level. It is important to note, however, that FWEC do not give an indication of larval burden as eggs are only produced by adult worms, therefore FWEC will not give an indication of encysted small redworm larvae harbouring inside your horse.
THE MAIN TYPES OF WORMS AFFECTING HORSES ?
Ascarids and threadworms – very important in foals and young horses
Lungworms – uncommon, except in donkeys
Bots – the adult worms in the stomach rarely cause disease but the worms cause annoyance, as they lay their eggs on the skin.
Redworm – very common, cause ill-thrift and disease. These worms migrate through the wall of the gut, the large strongyles entering the circulation and the small strongyles encyst in the gut wall.
Tapeworms – less common, implicated in some forms of colic
Pinworms – lay eggs around rectum causing irritation.
WHEN SHOULD MY HORSE BE WORMED?
You should routinely worm your horse throughout the year for the control of roundworms, with strategic treatments given at specific times for the control of tapeworms, bots and most importantly encysted small redworm. Talk to us if you would like some advice on what you need to treat at any point.
WHEN DO I NEED TO WORM MY HORSE FOR TAPEWORMS?
Treatment for tapeworm is recommended every 6 months . As exposure to tapeworm is greatest during periods of prolonged grazing, treatment should be undertaken in the autumn following summer turnout, and thereafter 6 months later in the spring. Tapeworm can be controlled by a single dose of a praziquantel-based wormer or by a double dose of a pyrantel-based wormer.
WHAT IS THE MAIN PARASITE THAT CAN AFFECT MY HORSE?
The most common parasite to affect horses today is the small redworm (small strongyle/cyathostomin), which can cause diarrhoea, rapid and severe weight loss, as well as life-threatening colic.
In 2003 a moxidectin-based wormer was granted a licence for the control of all stages of encysted small redworm with a unique single standard dose. The use of fenbendazole is not advisable where resistance is present
Furthermore recent research has found that a 5-day course of fenbendazole may cause damage to the horse’s gut wall, mirroring the situation caused by the actual mass emergence of encysted larvae. Whereas a single dose of moxidectin was found in the same research not to cause severe damage to the horse’s gut wall.
I HAVE TESTED AND MY HORSE ALREADY HAS A HEAVY WORM BURDEN? WHAT SHOULD I DO?
If you are concerned that your horse has a very high worm burden it is advisable to contact your Veterinary surgeon to establish a treatment specific to your horse’s needs. One possible strategy would be to use a wormer that controls adult worms only, such as a pyrantel-based wormer. This treatment can then be followed 7-10 days later with a moxidectin-based wormer to treat for the remaining larval parasites. A tapeworm treatment should also be given if necessary, but your Vet will advise you.
IF I OVERDOSE MY HORSE WHAT HAPPENS?
Although a slight overdose of an anthelmintic is unlikely to have harmful effects, as with all drugs it is important to dose accurately and in accordance with the manufacturer’s recommendations or those given by your vet, especially in low bodyweight foals.
Knowing your horses accurate weight is important anyway, so we recommend buying and keeping a weight tape so you can monitor this throughout the year for your horses general health.
AND IF I UNDERDOSE ?
Underdosing will not do the horse any harm, but you would in fact be administering a sub therapeutic level of the drug and thereby exposing the worms to the drug but perhaps not at a sufficient dosage to kill them. Worms that survive treatment may pass on their “immunity” to subsequent generations and so causing the potential for resistance to develop to that drug. In the long term, your future treatments will then not be successful.
DO I REALLY NEED TO WEIGH MY HORSE ? CAN’T I JUST ESTIMATE OR GIVE HIM A WHOLE SYRINGE TO BE SURE?
Establishing a horse’s weight by guessing and not using a weigh tape or weigh bridge means you risk giving your horse an insufficient dose of wormer. By not giving your horse enough treatment for its body weight you risk giving a sub-lethal dose of the drug which will not be enough to kill all resident worms. These will not only be left to continue their life cycle and breed in your horse, but are also given the opportunity to build up immunity and resistance by being exposed to, but not killed by the drug. A small overdose however, is unlikely to do your horse any lasting harm.
IF I DON’T USE A WHOLE SYRINGE THIS TIME , CAN I USE THE REMAINDER NEXT TIME?
Always refer to the packaging of the product or the Data Sheet enclosed to see how long the product can be safely used for once it is opened. Remember the product must be stored according to the package instructions ( not too hot or cold too ) and not accessible to children, or other animals. Empty syringes must be disposed of safely. If you use a product after this time, it`s effectiveness cannot be guaranteed to treat the problem.
HOW CAN I GIVE MY HORSE A WORMER IF IT DOESN`T LIKE SYRINGES?
Many products now have at least two alternatives, a syringe method and a tablet which is like a treat. In-feed wormers ( some are powdered ) are also available. However, if the active ingredient or product that you plan to use is only available in a syringe, then the correct dose of product can be administered and mixed into the horse’s feed. It is very important that you ensure the horse eats all of the feed and therefore gets the full dose of wormer.
If wormer is added to the horse’s feed, dogs and cats must be kept away and the feed container cleaned thoroughly afterwards, clear up any spills and wash your hands afterwards too.
DO I WORM MY PREGNANT MARE?
It is very important to worm pregnant mares, not only for their own health, but also that of the foal when it is born. Always check that the product you want to use is licensed to treat pregnant and lactating mares and try to worm her before foaling and throughout lactation according to manufacturer’s instructions.
WHAT WORMERS CAN I USE ON PREGNANT MARES?
Animec – Pregnant / lactating
Bimectin – Pregnant / lactating
Embotape – Pregnant / lactating
Equimax – Pregnant / lactating
Equimax Tablets – Pregnant / lactating
Equitape – Ask Vet
Equest – Pregnant / lactating
Eraquell – Pregnant only
Eqvalan Paste – Pregnant only
Eqvalan duo – Pregnant (after 3 Months Of Gestation) / lactating
Maximec Paste – Lactating only but not permitted for use in lactating mares producing milk for human consumption
Noromectin – No
Panacur Granules – Pregnant only
Panacur Paste – Pregnant only
Panacur 10% Liquid – Pregnant only
Panacur 5 Day Guard – Pregnant only
Pramox – Pregnant / lactating
Pyratape P Paste – Pregnant / lactating
Strongid p paste – Pregnant / lactating
DO I WORM FOALS, AND IF SO FROM HOW OLD ?
Foals should start to get wormed from 4 weeks of age onward.They need special treatment as they have no resistance to worms themselves . Mares with foals should be treated before to foaling with an appropriate wormer and preferably grazed on pasture that has not been grazed by other horses in the previous 12 months – if this is not possible delay turning them out until June if possible.
As foals have a low tolerance to worms, they can quickly acquire massive worm burdens. Therefore worming of foals should start at four to six weeks of age, and be repeated every four weeks until 6 months of age. Thereafter, worming can continue as per your wormers recommended dosing intervals. Always check ‘the age from use’ of any wormer prior to use.
WHAT HORSE WORMERS ARE SAFE TO USE ON FOALS?
Ingredient Age of foal Suitable wormers to use
Pyrantel Embonate 4 weeks Embo tape, Pyratape p, Strongid p
Ivermectin 6-8 weeks Eqvalan, Eraquell, Animec, Noromectin, Maximec, Bimectin
Fenbendazole 6-8 weeks Panacur 5 day guard, Panacur granules, Panacur paste
Moxidectin 4 months Equest
Praziquantel Any age Equitape
WHAT CAN I USE ON DONKEYS?
As in the case of treating horses you must be competent to do so before administering animal medicines such as wormers to donkeys. The products selected for use should chosen on the same grounds as you would do so for other equines which means taking in all the factors involved and developing a worming strategy suitable to the environment and your donkeys circumstances. The range of licensed products for donkeys is more limited than for the horse but there are still a range which will enable you to plan over a longer period without over reliance on any one chemical group. There is a limited range of worming products available for worming donkeys on the UK market.
Here is a list of those products currently licensed for the treatment of donkeys.
Brand Name Package Declaration
Panacur Equine Horses and other Equines
Panacur Equine Granules Donkeys and Horses
Panacur Equine Paste Horses and Other Equines
Telmin Paste Donkeys and Horses
Ivermectin paste Donkeys and Horses
Strongid P Paste Donkeys and Horses
Pyratape P Horses and Other Equines
MY HORSE OR I HAVE HAD AN ADVERSE REACTION TO A PRODUCT PURCHASED ON YOUR SITE. HOW DO I REPORT IT, AND TO WHO ?
to tell the VMD direct, and please do report it to us too.