What type worms infest horses?
There are three species of worm of concern in horses: small redworms, large redworms and tapeworms. Small red worms (cyathostomes) currently cause the most concern. They may infest in huge numbers resulting in weight loss and colic. As part of their life cycle they “hibernate” in an encysted form within the intestine wall. In the spring these encysted worms can emerge together resulting in massive damage to the intestine wall. This emergence can result in diarrhoea and in extreme cases may be fatal. Large red worms are a traditional cause of colic in horses. They are now relatively rare in the horse population due to effective worming regimes. These worms migrate through blood vessels in the abdomen and the liver when they are immature larvae causing colic. Tapeworms are an emerging problem in horses. They are found in a specific site in the intestine next to the caecum. In large numbers they may cause the intestines to telescope into themselves (an intussusception) causing a blockage
