Worming Advice


Worming Mares

Suitability of the worming brands with regard to Foals, Pregnant and Lactating Mares

A quick guide to ease your worries when worming your Foals, Pregnant and Lactating Mares.


Equest Pramox


Eraquell Paste, Eqvalan, Noromectin, Bimectin

Pyratape P, Strongid P, Embotape


Suitable for Pregnant Mares






Suitable for  Lactating Mares 






Suitable for Foals

From Six & Half Months of age

From Four Months of age


From Four Weeks of age



Panacur Paste

Panacur Granules

Eqvalan Duo



Suitable for Pregnant Mares











Suitable for  Lactating Mares (It is recommended that mares are not wormed until 2 weeks after giving birth)






Suitable for Foals

Foals weighing more than 101kg


From Two Months of age

From two weeks of age 



From 2 weeks of age

From 2 weeks of age






Panacur Equine 


Vectin Paste

 Noropraz, Eraquell and Equimax Tablets


Suitable for Pregnant Mares





Suitable for  Lactating Mares 





Suitable for Foals

From two weeks of age

From eight weeks of age 

From two weeks of age 




As a general recommendation mares should be wormed throughout the gestation period with a final treatment being given 2-4 weeks prior to foaling. Take extra caution particularly with dosages when worming young stock for the first time if you are not certain about any previous treatments given or if the treatment you are considering is the first one administered to the horse. As a general guide foals should be wormed as soon as they start to graze pastures or pick at the mares droppings with reference being made to the suitability for foals with regard to each product used. Again the worming intervals for foal worming depend on which product is selected but with foals the manufacture recommended interval will act as good guide. As a guide to dosages a 4 month old thoroughbred will weigh about 180kg whereas a new born will be about 50kg. At 6 months the weight will be between 200 and 230kg. Tapeworm infestation is unlikely in foals under two months of age.

Youngsters and foals are prone to Ascarids (Large Redworm) for the early part of their life usually developing immunity at 18 months but recently this Large Redworm burden has been seen in horses over 5 years old. This is a very dangerous parasite in youngsters with adult worms being up to 40cm long.One type of roundworms that can affect foals from an earlier age is Intestinal Threadworms (Strongyloides westeri).  In foals this can cause diarrhoea, weakness, weight loss and poor growth. Infected mares pass the worm in their milk on to their young foals. If this infection is suspected there are wormers that can be used from 2 weeks of age. 

If possible try to graze young horses separately from older horses as the young horses are likely to have the highest worm burden and therefore will cause the majority of pasture contamination. Younger horses need to be wormed more regularly than their older stable mates. Tapeworm burden is generally worse in young horses between the ages of 6 months to 2 years with the years of 3 to 15 having much lower infestations and levels rising again in veteran horses. This situation is very much the same with regard to roundworms, and recent studies have shown that where there is a roundworm infestation there is a strong likelihood of a tapeworm infestation too. If possible it is a good idea to avoid putting young stock on the pastures that have been grazed by last year’s foals.


Worming Foals

For a quick and easy to view table showing which wormers can be used on Foals look above

Worming Foals and Youngstock

The majority of wormers available for horses in the UK are suitable for using on foals and young stock. However there are certain exceptions and so it is vital that you read the small print on the box and also on the instruction leaflet inside the packet. This is also the case when using any animal medicine even when you are familiar with the product concerned. 

We have the full list of product names and their individual restrictions with regard to

Naturally foals are very sensitive to possible overdosing so you must accurately ascertain the weight of the foals and dose accordingly.
With regard to when to start a worming treatment first off try to identify the level of risk by looking at the circumstances of the stock holding and the management of the pastures etc.

Circumstances which could put youngstock at high risk are:

Repeated use each year of the same pasture for each year’s new foals.

Sharing the grazing with other youngsters or foals.

General overstocking of the available grazing.

A previously poor worming regime or testing on the mares.

Circumstances which may mean the foals are at a lower risk are:

Dung removal carried out on regular basis.

Resting pastures for lengthy periods ideally 12 months or as much as possible during the months when demands on pastures are lower.

Using pastures that did not have foals on in the previous year.

Not grazing foals with other youngsters.

Youngsters and foals are prone to Ascarids (Large Redworm) for the early part of their life usually developing immunity at 18 months but recently this Large Redworm burden has been seen in horses over 5 years old. This is a very dangerous parasite in youngsters with adult worms being up to 40cm long.

One of the roundworms that can affect foals from an earlier age are Intestinal Threadworms (Strongyloides westeri)  In foals this can cause  diarrhoea, weakness, weight loss and poor growth. Infected mares pass the worm in their milk onto their young foals so treatment of the mare in the last month of pregnancy may be an option.. If this infection is suspected there are wormers that can be used from 2 weeks of age. 

Once the risk factors and conditions has been taken into consideration you can then decide when to start a worming regime for foals with 4-8 weeks been used as a general guide. With regard to the general treatment of foals and young stock and as to how often wormers are given, the management and circumstances must be again taken into account and most importantly the recommended dosing interval relevant to the product chosen. The results of faecal worm egg counts on foals should be regarded as a positive or negative as the eggs per gram reading is not relevant to the burden a foal may carry.

We have the full list of product names and their individual restrictions with regard to use on lactating mares and foals


Worming Donkeys

Wormers suitable for donkeys shown below

For more information on the different brands of equine wormers available click here

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 donkey treatment and available from us.


Panacur Equine Guard

Horses and other Equines

Panacur Equine Granules

Donkeys and Horses

Panacur Equine Paste

Horses and Other Equines


Donkeys and Horses

Strongid P Paste

Donkeys and Horses

Pyratape Paste

Donkeys and Horses

 A Quick Guide

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 pertaining circumstances. Although the range of licensed products for donkeys is more limited than for horses, there is still a range which will enable you to plan over a longer period without over reliance on any one chemical group, whilst remembering that there are products in the above list that have different brand names but are in fact the same active ingredients and certain products will treat for a broader spectrum of parasites when used at higher doses. We are here to help fine tuning or organising any such plan.

LUNGWORMS (Dictyocaulus arnfieldi)

Lungworms are white in colour and are between 6 and 10 cm in length.

The lifecycle of lungworms is different to other nematodes as adults settle in the lungs rather than the intestine. Eggs are laid then travel up the trachea, are swallowed and passed out in the faeces. Further development then takes place on the pasture, infective larvae are swallowed by horses or donkeys to further develop into egg laying adults.

It has been remarked that a large percentage of donkeys carry lungworms,
with some research claiming levels as low as 4% and some almost 100%. These are obviously dependent on circumstances where the data was gathered, but general thinking seems to be that the actual figure is closer to 50%. Donkeys often show no clinical signs of infestation and it is in donkeys where the parasite reaches full maturity.  Donkeys do not always develop the symptomatic cough that is seen in horses but if horses are grazed alongside donkeys then particular care must be taken to treat for lungworms accordingly with particular attention to foals as they can sustain permanent lung damage if infected. 


Annual horse worming programme for effective parasite control

Annual Horse Wormer and Testing Programme


View a worming calendar with tactical worming guidelines
View which brands fall in to which chemical group

Nothing is set in stone about what to use and when as you plan your worm control, as in all walks of life opinions vary and of course commercial issues are present too. The entire supply chain of equine wormers is very vigorously regulated and all those in that supply chain are duty bound to provide the best possible advice and guidance to you the end user. Here at we have tried to gather all such opinions and research and use that information to provide guidance on your worming planning. Hard evidence shows that continuing use of the same active worming ingredient can lead to resistance so it seems logical to adopt a rotational approach to product choice. 

We have all noticed a climate change in the UK in the last few years with wet summers and warm winters being
perfect conditions for the parasites to breed and multiply. This means it is even more important nowadays to take that expert advice when choosing your wormers as the traditional natural enemy of those pesky blighters are red hot dry summers and very cold winters.
If you have selected to rotate your worming products make sure you are choosing a different ingredient not just a different brand. Develop an effective worming programme on an annual basis using tactical worming for specific parasites, using faecal worm egg counts and tapeworm
tests when conditions are suitable and rotating active ingredients during the grazing season (not each time you worm your horse).  Select one of the distinct chemical groups, which are:  


lvermectin and Moxidectin




Fenbendazole, Mebendazole, Oxibendazole

Products based solely on Praziquantel only are effective for tapeworm control and must be used in conjunction with products based on the three main chemical groups.

Combination wormers are also available containing lvermectin and Praziquantel and a combination of Moxidectin and Praziquantel. These products offer great convenience at times when tapeworm treatment is required along with routine worming.

If there are reasons for routine worming on a continual basis use your selected group during a 12-18 month period with particular emphasis to rotation during the grazing season. The grazing season is basically the summer months and although your selection of products may well be based on an annual selection, it is the grazing season when particular attention should be paid to rotation of the active ingredients. Outside of the grazing season are the occasions when specific worming products should be used for tactical equine worming. Change your selected group annually to a different chemical group so that your stock does not build up a resistance to wormer use. Also you must consider the use of faecal worm egg counts and tapeworm tests to help with deciding when, if and what to treat with.

There has been evidence of a resistance building to products in the Benzimidazole group in certain areas so it is best to take expert advice before relying on products within that group to control worm burden.

- View which brands fall in to which chemical group?

Although most of the leading brands of horse wormers are effective against adult redworms (take expert advice before relying on Benzimidazoles, ascertain that your horse is infected with worms that are susceptible to it by taking a dung sample and having an egg count done) there are times when you will need to worm tactically to treat for specific worm types at certain times of the year. Whichever chemical group you choose to use on an annual basis you will still need to dose tactically to control encysted small redworm, tapeworm and bots.

- View a worming calendar with tactical worming guidelines

Herbal worming products are now available using a specific combination of plants to repel parasites. As data is limited with regard to how effective these herbal preparations are in combating worm burden, it is best to take expert advice before relying on herbal products.

Different chemicals work in different ways within the body of the dosed horse so extra thought needs to be given to such circumstances of age, general health condition, administration to mares, foals and stallions and also pasture management. There are many ways in which pasture management such as poo picking, faecal worm egg counts and tapeworm tests and field use can help in reducing the use of chemical wormers, so why not tell the experts about your particular circumstances and let them tailor a plan specifically for you?

A critical time for parasite control is the early months so take special care when treating foals. Ensure you select an ingredient that is suitable for use on foals and use that at the correct times.

A common mistake when treating horses is under dosing, ensure that you ascertain the weight of your horse as accurately as you can either by using a weight tape or even better a weigh bridge. Correct dosing is important, if you under dose your horse the product will not work efficiently and could lead to resistance.

If you administer a sub therapeutic level of the drug, you will expose 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 those generations will become more adept at surviving chemical treatments with the potential to develop a resistance to the chemicals.

There are brands on the market that now that treat up to 700kg in a single syringe and now Equimax is available in tablet form with each pack treating up to 800kg. These larger syringes and tubes give that little bit extra to play with when dosing. When you estimate the weight of your horse remember we all lie about our weight so if in doubt, when estimating the weight err on the generous side. Although a slight overdose of wormer is unlikely to have harmful effects, as with all drugs, it is important to dose accurately and in accordance with the manufacturer’s recommendations.

Don’t forget the environment when selecting your products, be particularly concerned about aquatic life in and around your pastures. Make sure that NO product enters the water courses and protect the flora and fauna from spillage and waste. Above all
else, be careful when you have your dogs about as some products are very dangerous and can be fatal if ingested by dogs, particularly collies. You must read the instructions on the packing and keep yourself up to date with the latest thinking.

The above guidelines to an effective worming programme are the opinions of the author and are not the definitive answer.  They are however a base for an effective procedure that can be modified with the assistance of your vet or other professionals authorised to advise on animal health.  The author hopes that this article will help you to care for your horse but cannot be held responsible for any errors, omissions or changes in acceptable procedure.

We are more than happy to help out with any queries that you may have with regard to worming your horses, please feel free to contact us by email or telephone 01423332134