• All horses are different.
Younger horses (less than 5 years) do not have as much immunity to worm infestations, making them more predisposed to developing heavy parasitic burdens. The same applies to older horses (greater than 15 years) especially those with concurrent illness.

• No universal worming chemical.
There is no single horse wormer that will meet all worming requirements. Different types of worms need different chemicals to kill them. This is further complicated more by the small red worm (cyathastome). It is killed by most wormers when in adult form, living within the gut. However when the larvae burrows into the gut wall only two wormers are licensed to treat these, ‘Equest’ and a 5 day course of ‘Panacur Equine Guard’. However, more recently it has become apparent that there is increasing resistance to ‘Panacur Equine Guard’

• Environmental issues.
Wormers may lead to insect and earthworm deaths in the pasture. The full environmental issues are unclear. Therefore wormers should be used only when needed.

• Continuous Use.
Continuous use of the same wormer or under dosing of individual horses can lead to resistance to that wormer. A weight tape should always be used to get a good idea of a horse’s weight.

*See Worming Continued at the top of the page for more information.

Reading various guides to the worming of your horse can be confusing and often appear to give conflicting advice. This is because there is not one single simple solution to the worming problem. At the Old Pound we frequently treat horses with colic, weight loss and diarrhoea caused by worms. This is due to the fact that worms are very good at evading control measures. One can take various approaches to worming a horse so that you will be able to see which strategy best suits your situation.