Vet offers advice on sheep ectoparasite control

Novartis Animal Health vet Thomas Tiley was at the National Sheep Association Winter Fair 2011 at Bakewell Agricultural Centre on 27th January to hold a seminar and offer advice on sheep ectoparasite control.

His seminar at the event covered the problems posed to farmers of ticks, mites, lice and especially blowfly with the message that prevention was better than cure.

"There was a general feeling that the blowfly season had got worse and is happening earlier, and I had one or two questions about whether I favoured early treatment," he said.

"At Novartis Animal Health we have CLiKZiN® which was launched in January as an effective preventative that lasts eight weeks and has only a seven day meat withhold. This means you can readily get lambs to market at this period. It’s a line extension of CLiK®, which has a longer period of protection at 16 weeks.

"What happens in some cases is that farmers have been waiting for strike and treating with Crovect®, and then following up with CLiK afterwards. The difficulty with this method is that you have to check the sheep on a daily basis, so it uses up a lot of manpower and time.


During the seminar he explained the lifecycle of blowfly, where the adults live and breed on the animal, lay their eggs and the eggs hatch and develop into larvae that feed on the animal’s tissue. The feeding process is where the damage is done and is known as "Fly Strike" or "Myiasis".

The most popular method of blowfly prevention among UK farmers, he said, was the use of pour on insect growth regulators (IGRs) such as CLiKZiN and CLiK; because they act at the first larval stage and provide the longest protection.

Ticks are mainly a problem in spring and autumn, and more commonly acquired on rough grazing such as hill land and moors. The clinical signs come from the diseases transmitted by the ticks, such as tick-borne fever, louping ill and tick pyaemia. They all can be treated with a synthetic pyrethroid (SP) pour on such as Crovect.

Lice are mainly a winter and autumn problem, and with direct transmission, they particularly affect housed sheep. Diagnosis is by sight or skin scrape, and treatment can be with SP pour ons, or organophosphate (OP) dips.

Scab is found mainly in autumn and winter, with the symptoms easily confused with lice. They can be controlled with OP dips or 3-ML injections.