Author: Farm Vets South West

“The blood sucking worm that causes disease even in adult ewes.
Do not underestimate it”

For more information, news and offers please visit our website:
http://www.thefarmvets.co.uk/
FarmVets SouthWest is a farm animal only veterinary practice covering Somerset and East Devon. The practice prides itself on traditional service values, but with a modern approach, to compliment the needs of
today’s farmers. We have an experienced team of farm vets.

FVSW Bridgwater
Unit 8, Sedgemoor Auction Centre, Market Way
North Petherton, Somerset TA6 6DF T: 01278-663399 F: 01278-661135

FVSW Ilminster
5 Larchfield Industrial Estate
Dowlish Ford
Ilminster, Somerset, TA19 0PF T: 01460-55004 F: 01460-55007

Stopgate Cross
Yarcombe, Honiton Devon
EX14 9NB
T: 01404-861214 F: 01404-861363

Information on:

Haemonchosis

Your local partner in farm animal health

Information leaflet: Haemonchosis

Haemonchus contortus is a parasitic roundworm of sheep. In terms of epidemiology it is similar to the worms causing PGE but it causes disease in a different manner and so is considered separately here.
H. contortus lives within the abomasum (4th stomach) and feeds on the blood of the sheep. As such, it doesn’t cause diarrhoea and the signs seen in affected sheep are related to blood loss. If large numbers of worms establish quickly affected sheep can die suddenly from acute blood loss. Smaller numbers lead to chronic disease.

Signs of haemonchosis:
Epidemiology
The epidemiology of H.contortus is similar to the worms which cause PGE. H. contortus requires higher temperatures than some worms for the larvae to develop on pasture so disease is often seen later in the year than PGE. The female H.contortus can produce tens of thousands of eggs per day and so worm numbers can build up very rapidly when conditions are suitable. Unlike with PGE, adult ewes remain susceptible to H. contortus infection but there is individual variation in how susceptible they are.

Pallor (pale mucous membranes)	Poor growth rates
Sub-mandibular oedema (bottle jaw)	Weight loss
Poor fleece production	Brittle Wool
Dark faeces	Sudden death

Control of haemonchosis
Control of haemonchosis is similar to control of PGE in many aspects (e.g. grazing management, use of bio-active forages, breeding for less susceptible sheep). FWECs and growth rates can be used to indicate the need for treatment as in PGE, however the fact that pallor is one of the signs of haemonchosis allows the colour of the inside of the eyelids to be used to determine whether or not individual animals need treatment (the FAMACHA scoring system). As H. contortus sucks blood it is susceptible to certain drugs e.g. closantel, which are not effective against other worms. This allows targeted treatment of H. contortus, reducing the risk of development of wormer resistance in other worm species.
Please contact the practice for more advice about the control of haemonchosis or to order FAMACHA scoresheets etc.

Information leaflet: Haemonchosis