Haemonchus contortus (Barber’s Pole) is a red and white striped parasite which sucks blood from the stomach lining of sheep. The red stripe is the blood sucked from the host animal, and as a result, it can cause debilitating effects and even death in animals with heavy infestation.
Significant burdens will affect production or remove enough blood to kill lambs and even adult sheep.
It is a seasonal parasite, usually appearing in summer and autumn, however, we do see occasional cases before the Christmas period.
Outbreaks occur when we have rain or a heavy dew after a hot and dry period. With the right environmental conditions, larval numbers on pasture can rise rapidly, and their ingestion by grazing sheep results in the sudden appearance of ill-thrift, lethargy, and death.
As it is a blood sucking parasite, host animals suffer from anaemia (lack of healthy red blood cells). These blood cells usually carry oxygen to all organs and tissues within the body. When an animal suffers from anaemia, they have a lack of energy and inability to keep up with the mob, often sitting down when the animals are moved.
Other signs in affected animals may be ill-thrift (this can be seen as a large tail-end), rapid shallow breathing, and collapsed or dead animals in the paddock.
If you are handling animals, you can assess the colour of their eye membranes which are usually a salmon pink colour. With a high Barbers Pole burden and lack of circulating blood cells, these can become ghostly white.
Firstly, it is not typical for Barber’s Pole to cause a scour unlike other gut parasites.
Secondly, these worms can produce THOUSANDS of eggs per day compared to other gut parasites who usually produce about 200 daily. Furthermore, given ideal sub-tropical conditions, Barbers Pole can grow from egg to infective larval stage in just one week. Other species of gut parasites tend to take 21 days before they develop to this stage.
Finally, Barbers Pole eggs and larvae tend to survive longer than other worm species on pasture during hot dry periods. The problem with this is that they can then emerge all at once when a little moisture arrives, posing a huge risk to your flock.
Keep drench intervals at 28 days for lambs grazing contaminated pasture – do not stretch them out.
Consider using a drench with residual protection against Barbers Pole in conjunction with your usual double or triple drench. Please talk to us about which combination may suit your flock best. Specific drench options in our clinic this season are as follows.
Marathon® or Cydectin® – both offer 35 days of protection with a 10-day meat withhold.
Abclo® or Clomax® – both offer 42 days of protection with a 56-day meat withhold (better for replacements)
Monitor ewes, two-tooths and lambs separately. It may be necessary to treat two-tooths for Barbers Pole without all mixed age ewes requiring a treatment.
Faecal egg counts (FECs) of lambs just prior to when they require their next drench can be enlightening. If high counts are developing quickly, it could be due to Barbers Pole infestation.
Early FEC’s of lambs, even while still on mum, can be a guide; the egg counts of unweaned lambs can vary enormously, and remarkably high FECs could point to Barbers Pole being present.
Consider investing in a larval culture – we send a mixed faecal sample to the laboratory to hatch and grow out the eggs. The larvae are examined under a microscope, and we get a breakdown of the species present.
If you are handling lambs, look for paleness of the eye membranes. Normal eye membranes (the pink tissue under the lower lid is easiest to look at) are a salmon pink colour. Gums are hard to assess – they often look pale, even in healthy lambs.
A new PCR test for larval differentiation will soon be available from Awanui Laboratories (late Feb/early March)
This test will be ideal for determining if there is a considerable proportion of Barbers Pole present in sheep faecal samples.
Results for each species will be graded as ‘not detected, very low, low, medium, high and very high’
It will be the same price as larval culture, but with only a 3-day turnaround.
Now is the time to be monitoring for Barber’s Pole.
An assessment of weather conditions, history of the pasture being grazed, monitoring FECs and observation of animals are all important.
If you suspect you have a Barber’s Pole problem developing, or have experienced one in previous years, please call us or pop in to discuss the current level of risk and the best options for prevention and treatment.
