Tapeworms unlike many other worms of the horse require an intermediate host to complete their lifecycle. The harvest mite ingests the tapeworm eggs from the horses dung and the horse ingests the harvest mite when eating forage.

There are two different species of tapeworm that we see in the UK, Anoplocephala perfolata and Anoplocephala magna.

Anoplocephala perfolata  is the main species to infect our horses, they are asexual and the segments contain eggs. Anoplocephala Perfolata are small segments that are cream in colour, they can be up to 20 cm long. You will find these tapeworms at the ileocaecal junction of the intestine, where the large and small intestine join. The segments attach around this junction and this can become very inflamed when a high burden is present. 

Anoplocephala magna is much rarer but present in the UK. These tapeworms are a similar colour but they are much longer, up to 80cm in length and look like the stereo typical tapeworm that most people picture. These tapeworms are found in the small intestine. 

Tapeworms have a six month lifecycle therefore it is generally unnecessary to treat more than once or twice per year. Horses at low risk of tapeworm infection may be treated annually but this will involve a risk assessment to determine whether 1 treatment will provide suitable cover. When a tapeworm treatment is given it treats any parasites present at the time of treatment it does not prevent tapeworm or provide lasting cover over the 6 months.

The idea of treating tapeworm in spring and autumn is a tradition from hunting yards, whereby the horses were turned out to grazing in the spring and stabled again from autumn, this method of treating removed any tapeworms present before going out to grass and then removed any picked up at the end of the grazing season. However as long as the gap is six months apart it does not matter in the year when the 2 treatments are given.

Monitoring tapeworm is difficult due to its lifecycle. To detect eggs in the dung there is a flotation test which will float any eggs present to give a positive or negative reading. This is relying on the tapeworm segment to have ruptured and distributed in the dung. Alternatively there is a blood test the measures the level of tapeworm antibody the immune system is producing to fight off any tapeworm infection. While this can be more accurate in initially at detecting a medium or high burden you have to allow for the immune systems memory. One the horse has been exposed to a tapeworm infection the immune system will keep a low level of the antibody in the system so if it were to come up against the tapeworm antigen again then it could quickly up the level of antibody to attack the infection. Thus if a low infection is picked up it could be a low tapeworm burden or the immune systems memory as once it has been positive it is unlikely to ever go back to clear. Keeping this in mind if a horse has a medium or high reading it will take some time for the level of antibody to drop down to low after the infection is treated.   

Symptoms of tapeworm infection include:

  • Digestive upset
  • Poor Growth
  • Unthriftiness
  • Ileal impaction and spasmodic colic
  • Intussusception – where the small intestine enters the large intestine
  • Fatal perforation of the intestine
  • Tapeworm Warning – we mentioned this in last month’s ENews and wanted to reiterate it.
    Due to the warm, mild winter we have experienced this year tapeworm may be more prevalent, therefore, we are advising you to be more vigilant.
    Outward symptoms do not always occur but when present these may include:
    • Unexplained lethargy
    • Poor condition
    • Spasmodic colic, often reoccurring bouts
    • Unexplained loose droppings
    Intelligent Worming programmes include an annual tapeworm treatment on the advice of Professor Chris Proudman where the horse is deemed to be at low risk of infection, but we cannot prevent your horse contracting tapeworm. Tapeworms have a six month life cycle.  The wormer will treat  any tapeworms present at the time of treatment it is not a preventative .  If your horse is having an annual tapeworm treatment but you would like to discuss including a second treatment this year please call us on 01267 223322 or email info@intelligentworming.co.uk