Queensland worms, flies and lice update - September 2018

Brisbane: Maxine Murphy, Veterinary Parasitologist (maxine@paraboss.com.au)

All classes of stock now need to be worm tested (WormTest) in the run up to summer to ensure that barber’s pole infections do not overwhelm drought affected stock. Dry times do reduce egg and larval survival in the environment, but nutritionally stressed animals are less able to cope with even low to moderate worm burdens.

Conditions for barber’s pole worm are becoming increasingly favourable and the problem will only escalate once rain falls. This worm is a prolific egg layer and well able to take advantage of any moisture on the ground. A few days of showery and overcast weather will prompt worm eggs to hatch and the resultant larvae to mature through to the infective stage ready to be ingested by lambs when grazing. Grazing close to the ground on short green pick puts sheep at further risk of greater intake of infective larvae.

Drench resistance is making it increasingly difficult to find an effective drench. If your sheep do need to be drenched, try doing a “DrenchCheck” by taking dung samples from about 20 sheep when the mob is drenched, and then 14 days later. The post drench worm egg counts need to be 100 eggs per gram or less for the drench to be considered fully effective. If your drench was less effective, back it up with a WormTest in 2 weeks.

In the next few months worm test representative mobs, say 1 in every 3 of the same class, every 4–6 weeks and check the tail groups of all mobs for the first signs of anaemia i.e. lagging behind the others. While testing representative mobs saves the cost of testing all mobs it also carries the risk that the results may not be representative. If in doubt, test additional mobs.