A video on pasture management hosted by Ben Watson Amtra SQP with Wendy Talbot BVSc Cert EM (Int Med) DipECEIM MRCVS from Zoetis.
Do I need to worm my horse?
Yes horse worming is essential, it is possible to reduce the frequency at which one worms one's horse, but only through excellent pasture strategy; worm tests and their correct interpretation. However, you always need to worm for encysted small redworm in autumn through to the back end of winter, and of course for tapeworm if you have not done so for six months, it is also wise to worm a new horse entering the yard, and if you do use a FWEC if the results are over 200 epg.
There are so many different types of horse wormers; are they all the same?
The short answer is no they are not all the same, but of course some wormers do have the same active ingredient. Let us look at the main types by drug name:
Horse Wormer brand
Moxidectin & Praziquantel
Ivermectin & Praziquantel
Equitape (not available)
Thanks, but what horse wormers should I use and how long do they last?
This table below may help, it compares the common horse wormers active ingredients against the type of worms, remember some horse wormers may have more than one active ingredient such as Pramox: this contains moxidectin and praziquantel making it effective against tapeworm and all of the other worms.
|Encysted small redworm||yes||no||no||no||no|
|Tapeworm||no||yes||no||yes as a double dose||no|
|Adult small redworm||yes||no||yes||yes||yes|
|Length between worming||13 weeks||26 weeks||8-10 weeks||4-8 weeks||6-8 weeks|
What is strategic worming?
It is the process of using effective pasture management, as well as various diagnostic tests such as FWEC and tapeworm antibody test to reduce unnecessary or inneffective worming thereby reducing possible resistance to wormers.
What is a FWEC test?
FWEC stands for faecel worm egg count, this test checks the horses dung for the number of worm eggs per gram of faeces and this is how the results are written so a worm count of 200 epg means that your horse has 200 worm eggs per gram.
What is a tapeworm antibody test?
This test checks for antibodies to tapworm to see if your horse has been exposed to tapeworm at any point.
So if I test my horses and collect droppings I do not need to worm anymore?
No as you can see from the table below FWEC tests will not detect every type of worm and although a tapeworm antibody test will detect that a horse has been exposed to tapeworm at some point in its life it will not quantify any infection.
|Type of Worm||
FCEW (faecel worm egg count) effective?
|Tapeworm antibody effective?|
|Encysted small redworm||no||no|
|Large adult redworm||yes||no|
|Small adult redworm||yes||no|
As you can see a worm egg test will not detect the encysted small redworm which can be extremely dangerous for horses, nor will it detect pinworm or bots, and horses with several million encysted larvae may still show a low worm egg count.
Will worm egg counts save me money?
Testing is unlikely to save money as it is an additional cost. While it is possible that you may not need to worm for that particular period it is also possible that you will.
So are horse worm tests worth doing?
Yes worm egg counts used strategically can provide an effective worming programme for example if one tests ones horse in spring and the worm count is low it is possible that worming is not necessary. They are also handy to:
Check a horses adult worm burden
Determine the adult parasites in a new horse
Establish pasture contamination
Test if a worming programme is effective by testing the horse before treatment and after
Should I worm foals?
Yes foals should be wormer from four weeks of age, they need special treatment as they have no resistance to worms. Mares with foals should be treated prior 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 thius is not possible delay turning them out until June.
What horse wormers can I use on foals?
|Ingredient||Age of foal|
|Pyrantel Embonate||4 weeks|
** May be used to treat diarrhoea caused by Strongyloides westerei in 2-3 week old suckling foals at a rate of one syringe per 90kg bodyweight.
*** Equitape can be used in foals of any age but they are unlikely to have tapeworm before 2 months of age so earlier treatment is generally not advised.
NB drug names are used here, horse wormer brands may differ in licensing, always check the data sheet and ask a pharmacist or SQP before buying.
Should I worm pregnant mares?
Yes mares in foal may be more susceptible to a worm burden so should be treated with an effective horse wormer to keep them healthy an increased worm burden can also result in increased pasture contamination. Mares should also be wormed just before foaling as some worms may pass through the milk.
What wormers can I use on pregnant mares?
|Equitape Paste||ask vet||ask vet|
|Strongid P paste||yes||yes|
|Panacur Equine Guard||yes||no|
|Strongid P granules||yes||yes|
|Panacur liquid 10% Bulk||yes||no|
|Panacur horse paste||yes||no|
|Pyratape P paste||yes||yes|
|Eqvalan duo||ivermectin-praziquantel combination can be used after the first three months of gestation||yes|
|Embotape paste||Not stated||It has been shown that reduction of strongyle challenge to the suckling foal at pasture can be achieved by using clean pasture (re-seeded or not grazed the previous year by horses), dosing the mare 3-4 days before turning out and then at intervals of 2-4 weeks until the end of Autumn|
|Vectin chewable tablets||yes||yes|
|no||Not permitted for use in lactating mares producing milk for human consumption|
Do I have to weigh my horse?
It is a good idea but not the most practial! An easier way of judging the weight of your horse is to use a weight tape.
Underdosing with horse wormers is not going to do the horse any immediate harm but may promote resistance.
What is good Pasture management?
Horses only had natural barriers in the past our man made walls, hedges and fences have stopped our horses naturally finding new clean pasture. This can be overcome by reducing the number of worms in the pasture thereby stopping reinfection.
This can be acheived by good pasture management:
Horse worms are not the same as cow or sheep worms so having sheep and cattle grazing can help 'clean' the pasture.
Pick up, eggs develop into larvae in the dung, pick it up to stop worm reinfestation.
Keep down the stock, try not to keep to many horses on one grazing pasture.
Rest the land, even a three month rest during a frost or heat wave can help to reduce the land worm burden.
I still do not know what to do. Help?
Don't worry you are not alone! For expert advice give us a ring on 01833 641112 to speak with one of our pharmacists or SQP's check uot our complete list of horse wormers for more information.
By Ben Watson Amtra SQP updated 28/09/2021