The resumption of breeding and store sheep sales means farmers need to consider their quarantine strategies and, in particular, pay closeattention to ensuring scab does not enter their flocks through bought-in replacements or finishers.

Key to controlling scab is correct diagnosis, warns EBLEX sheep scientist Liz Genever. “Scab awareness has increased markedly among sheep producers in recent years, but, unfortunately, many are still failing to seek a diagnosis from their vet before treating. This means a significant proportion of flocks thought to have the disease don’t.”

Coupled with that, 9-10% of farmers have been treating scab with inappropriate products. “The rise in scab and lice in autumn

    SCAB STRATEGY
    • Confirm diagnosis before treating
    • Quarantine bought-in stock
    • Dose for heaviest animal
    • Co-operate with neighbours
    and winter and the similar irritation, itching, rubbing and wool loss caused by both conditions can mean they arehard to tell apart,” warns Ms Genever.

    But scab tends to be more severe and, unlike lice, which are generally found on sheep with a body condition score of three or less, can be present in sheep in any condition.

    She says accurate diagnosis was less critical when dipping was the primary treatment due to the range of activity of OPs against many external parasites. “But the move from dipping towards more injectable anthelmintic treatments makes good diagnosis more important.”

    Using these products inappropriately increases the danger of resistance developing in both intestinal worms and scab mites and, more importantly, risks leaving the real cause of the problem and its associated health and performance consequences untreated.

    SAC vet Brian Hosie says with many sales crammed into a short time there is a temptation to let quarantine treatments lapse and hope infection does not arrive with bought-in stock. “But there is no excuse for this. Implementing quarantine treamtents should be no more difficult this year than any other.”

    As a starting point Mr Hosie says all sheep should be quarantined for four weeks and treated with a levamisole and a macrocyclic lactone wormer to reduce the chances of anthelmintic resistance being bought in.

    “Secondary to this should be the scab treatment. This can either be an injectable product or dip, but where it is an OP dip, at least two weeks should be left between worming with a levamisole product and dipping with an OP.”

    With injectables the data sheet should be followed carefully, as treated and untreated sheep should not be mixed.

    “Injectable products don’t kill scab mites immediately, so its possible treated sheep could still be carrying infection and hence reinfect previously treated sheep.”