The Smallholder's guide to Haemonchus Barber's Pole worm
If your pasture is even close to flooded right now, then you need to be worm aware.
This sudden change in weather from warm dry summer to cool wet autumn is precisely what those sneaky parasites have been waiting for!
The most worrying worm is Haemonchus contortus, aka Barber's Pole.
Who is at risk?
Sheep, goats & alpacas are this worm's target audience. It spends the dry summer laying in wait as larvae in the earth, then as the ground moistens with rain or heavy dew it migrates to the surface in its infective L3 stage - ready to be eaten by a grazing ruminant. It then burrows into the mucosa lining of the abomasum, completing two further changes in life-cycle until it releases eggs to re-infest the land. Horses & cattle are not affected.
The host animal builds up immunity - this usually prevents clinical signs in animals over 18-months old, however there is a very strong genetic difference in this immunity. Some adults become totally immune, whilst some remain susceptible for life.
What does it do?
It sucks blood. Its wiggly intestine filled with the host's blood gives it that 'Barber's Pole' effect. The host becomes anaemic and low in blood protein. The symptoms vary on level of infestation:
Poor growth rate in kids, lambs & cria
Decreased milk production in dairy goats
Lethargy & low energy levels
Fluid accumulation under the midline or lower jaw ('bottle jaw')
Collapse and death
Have we got Haemonchus?
The worm does release eggs into the faeces, these can be identified on a worm-egg count.
But - the number of eggs rarely correlates to the level of clinical disease. A few eggs found could mean a serious problem.
Also - the eggs looks the same under the microscope as less harmful trichostrongylus eggs.
Don't be put off doing a worm egg count though - an all clear result is fully reassuring, and a heavy burden needs treating.
How to interpret a positive test result?
It could be nothing to worry about, but you'll need to do a few things first:
Examine your flock: are they plump, fit & healthy? Is anyone lagging behind?
Check your milk records: are they producing the expected volume? Has anyone dropped production suddenly?
Do a FAMCHA test: is anyone anaemic?
Treat everyone who causes any concern
FAMCHA: what is it?
FAMCHA is a standardised method of gauging anaemia. It is named after the professor who invented it.
You can examine their mouths, but most of the available picture cards are based on their conjunctiva.
The most accurate comparison is to the individual's normal - so check your animals regularly and know their normal.
So I think they've got Haemonchus, what should I do?
Anyone ranking high up on the FAMCHA chart needs intensive care. You don't want to loose them. They need treating for the worm immediately, and again every 3 weeks until you get a clear worm-egg count. They'll also need some support: bring them indoors, keep them warm & dry, increase dietary protein. Dry them off if possible in your milking plan. An injection vitamin B12 may help rebuild the lost red blood cells. Watch for secondary infections such as pneumonia.
If you've got a small flock you could identify individuals that need worming, or treat everyone.
Which wormer you choose will depend on what you've used recently, species & pregnancy. Factor in milk & meat withdrawal periods too. There are comprehensive lists on wormadvice.com. But your vet or worm-egg-count provider should be able to help you choose.
Can I prevent my flock getting Haemonchus?
Yes! There's loads you can do:
1. Improve pasture drainage
2. Avoid flooded pastures
3. Minimise stocking density
4. Optimise nutrition
5. Scrupulous hygiene
6. Cross graze with horses
7. Feed high tannin forage & leaves
8. Copper oxide wire particles in goats
Watch out for my article on organic worming techniques that discusses the role of copper oxide, tannins, cross grazing, pasture management & diatomaceous earth.
All blog readers recieve 50% off worm-egg counts at wormadvice.com, just add 'BLOG' to the offer code box.
Good luck through Haemonchus season!
Best wishes, Emily
Dr Emily Boreham BVetMed MRCVS