Barbers Pole worm (Haemonchus) can have a devasting effect on a sheep flock especially under ideal climatic conditions. Typically, barbers pole shows itself in late summer when there are ideal warm and wet conditions. With the wetter than usual summer so far, we are starting to see Barbers Pole earlier than usual.
Of the sheep parasites, Barbers Pole can have a very rapid life cycle (14 days). Another feature is that Barbers pole worms are high egg producers laying up to 10,000 eggs per day. With warm weather and adequate moisture an explosion of infective larvae on pasture can occur. Incoming larvae cause disease as well as the adults by directly sucking blood from the sheep. Acute Barbers Pole infection does not usually cause scouring and as larvae are non-egg producing a faecal egg count may give a false negative. Animals are sluggish, lag behind mobs and have pale gums.
With a proper parasite management plan, targeted drenches and rotational grazing the output of eggs on to pasture can be reduced to help avoid a Barbers Pole outbreak.
For lambs, regular 28-day drench intervals are necessary to avoid a large autumn build-up of eggs on pasture. Drenching with a triple active anthelmintic such as Matrix Hi-Min is the good option due to its known effectiveness (efficacy) with luckily no known resistance in Barbers Pole. However, with emerging triple resistance a FECRT will tell you which drenches are working well on your farm.
In the face of an outbreak or over the Barbers pole risk period, using a drench with persistent activity is an option. There are two commonly used action families with persistent activity against Barbers Pole; Moxidectin and Closantel.
Excessive use of single active persistent activity drenches is not without risk and can have high selection pressure for drench resistance. Trimox Hi-Min contains moxidectin and two other actives and is a great option when Barbers Pole is present. Best practice is to use an exit drench such as Zolvix Plus or Startect (limited availability) after using single active persistent activity drenches. It is also good practice to do an egg count 7 -10 days after drenching for Barbers pole to see if any leakage is occurring.
To discuss your options and local conditions, please don’t hesitate to get in touch with us.
Alex Meban (BVSc)