Noyadd Farm, Rhayader

Focus Site Event: Control of ticks, scab and lice


One of the biggest challenges Welsh sheep farmers are facing is the control of ectoparasites as their resistance to chemical treatments is increasing and available effective chemical treatments are declining.

Control of ticks, scab and lice

Vet Liz Jones has noted that there was a specific tick problem in the Elan Valley area, due to farming common land and sheep mixing. Lice and Scab are also an issue.

Key messages

Tick numbers are increasing, due to mild winters and wet summers, ticks become active when temperature exceeds 7oC. They have a 3-year life cycle and take one blood meal per year and transmit diseases the following year.  Infection occurs when a tick takes on infected blood from a sheep, which survives in the salivary gland, this saliva is injected into the next host sheep the following year.

We are seeing less sheep grazing the common land, which has resulted in a change of vegetation on hill ground, ticks favour thick/dense vegetation especially bracken and heather which is also favoured by environmental stewardship schemes such as Glastir, ticks do not survive on improved grazing or well drained fields, because of low humidity.

Infections are also increasing as there has been a reduction in dipping sheep with Organophosphate. 

Louping ill – 5-10% mortality in infected areas. Death in sheep less than 2 years.  Once sheep are infected they develop lifelong immunity, which they pass onto their lambs in colostrum. The immunity lasts 4 months in the lambs, so it is best to not put them onto tick infected land, as mortality could be high. Louping III vaccine is available and should administered 1 month before they go onto the hill.

Control tick numbers through dipping – 6 week control – dip ewes post lambing to control spring ticks and again in the August/September to control Autumn ticks.

Pour On only protects the areas covered, ticks can still access legs and underbelly, but can be used on lambs over 1 week of age.

The only way to control Louping ill is through vaccination and tick control.

Tick diseases:

  • Louping Ill – vaccination – Dip – Pour on
  • Tickborne Fever – suppresses immune system = susceptible or other infections – joint ill / pasturella, pneumonia, abortion, infertility.  Confirmed via blood test. Do not expose sheep to tick habitats. OP dips and pour on to control.
  • Tick Pyaemia – joint ill / cripples – lambs between 2-12 weeks susceptible – treat with Betamox LA.

Lice infection, which can be seen by the human eye (red body and biting) in sheep has increased dramatically as the use of OP dips has declined.  Lice infestations increase in winter months and reduce in summer.  Shearing reduces lice by 60%. Sheep in poor condition will suffer more and can also be affected by breed, fleece length and sheep health. Lice spread sheep to sheep, so infection happens quickly on common land. OP dips are the best way to treat lice.

Prevention: Double fence neighbouring land, quarantine sheep off common land, disinfect shearing equipment, OP dip sheep post shearing.

Sheep catch scab through direct contact with other sheep and indirectly through market, bushes and shearing equipment. As infection takes hold the sheep will lose wool and scabs will form and the sheep will lose weight.

Scab diagnosis has to be done with skin scrapes by the vet. Vaccination and OP dips to treat.

Drenching – Sheep should be weighed BEFORE treatment so that the correct dose is administered, drench to the heaviest in the group. By guessing the weight of the sheep, the farmer is potentially losing money as the animal is not being treated properly.


With thanks to our keynote speaker – Liz Jones, Ddole Road Vets and Noyadd Farm host, Tony Morgan

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