Beware - Barber's pole is lurking

“How does barber’s pole infection kill so many sheep?”

Having some knowledge of barber's pole worm (Haemonchus contortus), and its debilitating effect on sheep mobs is vital to combatting the disease. Barber’s pole is a seasonal worm which tends to overwinter as low numbers of adults in sheep, only to feature as disease outbreaks in the warm moist late summer period.

A barber’s pole outbreak can be prevented by having a parasite management plan incorporating the provision of low parasite larvae pasture and a structured drenching programme over the summer period.

  • Firstly, the long uterus of the female worm may produce thousands of eggs per day - up to 10,000. Also, given ideal sub- tropical conditions, they can grow to infective larvae in just one week.
  • Secondly, unlike most intestinal worm species, large intakes of worm larvae can literally bleed a sheep to death before they even lay a single egg.

You cannot rely on faecal egg counting.

Sheep, particularly lambs, but all ages of sheep, may succumb if faced with a large larval intake, and need to be observed for classical blood loss signs like lethargy and paleness of the eyes and gums. Barber's pole outbreak is literally an infection of blood sucking worms.

Barber’s pole worm is an easy worm to kill, but given the short reproductive cycle of this species, sheep can become reinfected in a short space of time (within a normal three-week drench interval). It is for this reason that certain long-acting products including closantel and/or moxidectin as single actives or combinations are marketed for combatting this parasite. These can give up to 49 days protection. There are however a few caveats when drenching for barber’s pole, such as long withholding times and the possibility of outbreaks of other worm species during the payout period.

Please contact your vet if this is an issue for you.


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