Worms in Depth Series: Tapeworm

What is a Tapeworm?

Tapeworms are an internal parasite that can affect horses. They have a flattened, segmented body which may grow many centimeters in length. There are 3 species of tapeworm that can affect horses in the UK:

 A. perfoliata

 A. magna

 P. mamillana

A. perfoliata is the most common species of tapeworm in the UK. The head of A. perfoliata is equipped with four suckers with which the parasite can secure itself to the gut of its host. Nutrients are then absorbed from the host to the parasite.

Tapeworm Life Cycle

The tapeworm is different from many other parasites because it has an indirect life cycle. This means it requires an intermediate host in order to develop. The intermediate host of A. perfoliata is the forage mite, which ingests tapeworm eggs in the environment. This mite is found in very large numbers on pastures and often even in hay and straw.

Inside the mite, the tapeworm egg undergoes cellular division and development to become a larva.

This process takes 12-15 weeks. Inadvertent ingestion of mites containing infective larvae occurs as horse’s graze, and it can result in tapeworm infection. Larvae then develop within the primary host – the horse – to mature tapeworms. They can begin shedding segments full of eggs in 6-10 weeks. The entire lifecycle of the tapeworm is approximately 6 months.

Tapeworm Lifecycle

The Effects of Tapeworm

The equine tapeworm usually congregates around the ileocecal valve in the intestinal tract, at the junction between the large and small intestines. It is in this small area of the horse’s intestinal tract that changes attributable to tapeworms are found.

Unfortunately, most tapeworm infestations have few symptoms, but cause subclinical damage that may be present for some time before causing visible disease. Signs to look out for include:

– Digestive upset

– Poor Growth

– Unthriftiness

– Recurrent spasmodic colic

How to test for Tapeworm

Testing for tapeworms cannot be done through the standard faecal worm egg count (FWEC). Either a blood test or the relatively new saliva test can be used to identify whether your horse has a tapeworm burden in its gut.

A blood sample can be taken by your vet to test for infection, a method known as the ELISA or tapeworm antibody test. A horse with a high level of tapeworm infection will produce a large number of antibodies, which can be detected in the blood.

The test indicates a broad level of intensity, rather than tapeworm numbers. The amount of antibodies will indicate whether the burden is low, medium or high.

While the blood test is useful for assessing whether your horse has been infected with tapeworms in the past, it is not a reliable indicator of response to treatment. This is because it takes around four to five months for the antibody levels to return to normal after the worms have been killed. Therefore, the test only needs to be carried out once a year.

The saliva test — EquiSal Tapeworm — has been developed by scientists at Austin Davis Biologics at the company’s laboratory in Northamptonshire. A horse’s saliva is taken by its owner using a specially developed swab, and then sent off to the laboratory for analysis.

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