Worming Foals

For a quick and easy to view table showing which wormers can be used on Foals and at which age click here

Worming Foals and Youngstock

Worming Foals


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 use on lactating mares and foals here 

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 less high.

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 an 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 gramme 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 here