It is impossible to eradicate worms in the horse’s body altogether, so the main aim when worming is to control and reduce the number of worms.
Worm life cycle
Worm eggs can lie dormant in pasture for months until being eaten by the horse while grazing. The larvae then survive in the gut wall before hatching and living inside the body as parasites. Once they have matured, the worms lay eggs in the intestines, which are then passed out of the horse’s system in the dung. They remain in the pasture until being eaten by a horse, and the cycle starts again.
Reducing the worm burden
Effective worm control requires a program involving all horses living together, particularly where they are grazed together. It is a futile exercise to worm one animal sod then turn it back out to pasture with other untreated horses as re-infection will take place immediately. All horses should be given the same worming product and care should be taken that the correct dose is given for each horse’s weight, height and age. Over- or underdosing a horse encourages resistance in the worm population and lessens the impact of the drug, so administering the right quantity is important.
Good pasture management is also essential for controlling the worm burden. It is good practice to remove all droppings from the field on a regular basis to help break the worm life cycle. Grazing the pasture with cows or sheep can also be useful as they eat the eggs while grazing but are not suitable hosts for horse worms.
Signs of worm infestation Classic signs of worm infestation in horses ‘”elude a rough and dull coat, a “pot belly” where the horse’s ribs can be seen clearly while the stomach appears extremely tight and swollen, stunted growth and weight loss. Worms are not just restricted to the stomach of the horse but can live in many areas of the body, including the lungs, symptoms of which are coughing, nasal discharge and a raised temperature. Therefore, to be at their optimum peak health and performance, it is vital that all horses are regularly wormed.
