The barber pole worm, haemonchus contortus, is an extremely nasty parasite that does not cause scours. It sits in the abomasum, where it latches onto the wall and feeds on the blood of the sheep. As a result, haemonchus is often not spotted until ewes have developed severe anaemia and ill thrift, often becoming fatal. Unlike the other parasites mentioned, adults do not develop immunity, so haemonchus can develop in animals of any age. It is usually bought in by infected stock and may be resistant to yellow wormers, which is why we recommend treating all newly purchased animals with Zolvix™ on arrival and quarantining them (preferably indoors).
However, once grazing is contaminated with haemonchus, it is virtually impossible to eliminate without removing all stock from the infected field for a number of years. Of course, on many farms, this is not an option. Instead, ongoing and regular monitoring throughout the grazing season is essential to control levels before they creep up and cause losses through ill thrift or fatalities.
There is a chart, called the FAMACHA anaemia guide, to assess haemonchus levels in ewes. Alternatively, we can assess levels using a worm egg count, specifically looking for haemonchus. Please note, this test is not run by default, so when dropping samples off at the surgery, you must inform reception that you would like the sample run for haemonchus.
In extremely severe cases, a vaccine is available. Please speak to one of our Farm Vets if you would like to know more.
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