Beware - barber's pole is prowling
I was asked at a discussion group meeting; how does barber's pole infection kill so many sheep? My answer was...
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.
Barber's pole outbreak is literally an infection of blood
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.
Drenching with a triple active anthelminic will minimise the selection of worm species present due to its excellent efficacy (>99.9%) against the resident population, and no selection for incoming resistant larvae in the days or weeks following drenching.
In the face of a barber's pole outbreak all stock need to be treated and preferably moved to a paddock of known nil or low infectivity. Often this "clean" paddock is purely fictional within the constraints of practical farm management, and using a product with persistent activity against barber's pole becomes the only realistic option. Check with your veterinarian for prevention options.