CESTODES
TAPEWORM (Anoplocephala perfoliata, Anoplocephala magna & Anoplocephaloides mamillana)
Tapeworms are an important and potentially very damaging parasite affecting the horse. They prefer to attach themselves to the junction of the small and large intestine- the ileocaecal junction. Here, they can cause bowel irritation, intussusception (where one part of the intestine telescopes into another), rupture, or twisting of the intestine.
It is thought that tapeworms may be responsible for up to 20% of surgical
colics. Tapeworms are present, to a
greater or lesser extent, in the majority of horses.
Parts of the country with acidic soils eg. Heath land which favour the survival
of the intermediate host of the tapeworm (the forage or oribatid mite), tend to
have the highest level of infection.
Appearance
Tapeworms in horses are generally much shorter than dog or cat tapeworms; they are flat, triangular and relatively short being approximately 8 cm long by about 1.5 cm wide. Segments of the body can detach and it is these segments that may on rare occasion be spotted by horse owners. The equine tapeworm can grow up to 20cm long and are white in colour; on occasion some rarer species can grow up to 80cm long. They live in huge numbers attached to the gut wall at a natural narrowing of the gut (the ileocaecal junction).
Treatment
Recent studies have shown that far from being a seasonal problem, tapeworm infection occurs all year round. The lifecycle of the tapeworm starts when the adult worm sheds fertilised eggs within the horses’ droppings. These are eaten by an intermediate host called the forage mite. This mite is then eaten by the horse, along with hay or grass, and over the next few months, adult tapeworms develop within the gut.
The forage mite not only lives on pasture, but also survives perfectly well in hay and on bedding which is why there is no real seasonality to tapeworm infestation. However, most infestations are picked up after horses have spent prolonged periods at grass. As a result of this, early autumn and spring are prime times for tapeworm infections to be managed. Tapeworm infestation cannot be diagnosed by faecal examination, so it is important to incorporate wormers that are effective against tapeworm in your overall worming and animal health planning schedule, alongside other tools such as saliva tests.Good pasture management is also essential to prevent tapeworm infection.
If treatment is required then Pyrantel based products should be used at twice the standard dose. Combination wormers containing Praziquantel are effective in treating tapeworm, or if only the tapeworm burden itself is to be tackled then products containing only Praziquantel are available.
Symptoms
Can cause colic, sometimes fatal, by blocking blood vessels.