Tapeworms have a head (known as the scolex) and a segmented body. There are three known species of tapeworm, with Anoplocephala perfoliata being the most common. Other species reported are rare and rarely cause disease.

Tapeworms do not have separate sexes, the segments (proglotids) contain eggs which develop and mature. These mature segments detach and are passed out in the horse's faeces where they disintegrate, releasing the eggs.

The tapeworm life cycle is about 6 months long and has an intermediate host called the oribatid (forage) mite found on the pasture, as well as in food and bedding. The mite consumes the egg passed in the faeces, and the immature tapeworm (cysticercoid) then develops inside the mite before it itself is ingested by the horse.

Tapeworm infection is increasing with as many as
2 out of 3 horses in the UK infected (Lyons S et al, 2000) (Owen R et al, 1998).

Size/Appearance: Tapeworm can be up to 20cm in length, although normally average around
4-5cm; rarer species can be up to 80cm long. They are white in colour.

Location in Horse: Found at the narrow junction between the small and large intestine, tapeworm use the four suckers on their head to attach to the lining of the digestive tract to avoid being swept away from the intestine by peristalsis.

Symptoms: Symptoms of tapeworm include hair loss and enteritis, along with spasmodic colic and ileocaecal colic and can even cause fatal perforation of the intestine.