PARASITES IN FOALS

Many owners erroneously believe that foals do not require regular worming, and that worming may even be harmful. In fact, foals under six months old are particularly sensitive to worm infestation as they have little resistance, few body reserves and are inclined to eat the manure of other horses. Parasites may even be acquired via milk.

Worms known as Strongyloides westeri are acquired via milk. Peak patency (maximum egg production by mature worms within the foal) occurs at 3-6 weeks of age. These worms live in the small intestine and horses develop a good resistance with age. These worms are responsible for diarrhoea in some foals.

Ascarids (round worms) also live in the small intestine, but are acquired by ingesting eggs with pasture or manure. Ascarid infection can cause intestinal blockage and rupture, intussusception, ill thrift, diarrhoea and can even cause respiratory problems (as part of the larval migration takes place through the foal’s lungs).
Tape worms and cyathastomes can also be of great significance in the foal and young horse.

At Riverdene, routine worming begins with the mare around the time of foaling in order to minimise transfer to her new foal. Foals commence a worming program at around three weeks of age and this continues approximately every three weeks until weaning age when a normal six to eight weeks interval is considered adequate.

Many commercial wormers are considered suitable for use in foals, however, moxidectin based wormers should only be used in older foals and with great caution as deaths have occurred from overdose with this product.

Management practices such as strategic cleaning and rotating of paddocks, use of feeders rather than feeding on the ground and not over crowding enhances the effectiveness and decreases reliance on chemical wormers and should be used as an adjunct whenever possible.

Please feel free to contact us at Riverdene for more information on parasite control in the young (or older) horse.