Scottish Government

Executive Summary

1. Background

Sheep scab is a major welfare concern to the sheep industry. If left untreated, it can lead to much reduced performance, poor welfare and significant financial losses for producers. Since 2004, the Scottish Government has been working with industry through the Scottish Sheep Scab Initiative to encourage more responsible control of the disease. Although this has raised awareness of sheep scab, concerns remain that it is widespread in Scotland. Sheep scab has been identified as a priority for improved control by the Scottish Animal Health and Welfare Advisory Group.

2. Aims

This project was commissioned by the Scottish Government in June 2007. The aims of the study were: to review the evidence base for effective sheep scab control; to investigate and define the control options; and to investigate attitudes among producers and stakeholders. The purpose of the project was to provide evidence to support the development of legislation and to provide the necessary guidance to ensure that it can be implemented efficiently and effectively.

The project was delivered by ADAS with the VLA, the University of Strathclyde and independent consultants, Harriet Fuller and Ray Keatinge.

3. Approach

An iterative approach was followed. A review of the available evidence base was conducted. Informed by the outcome of the literature review, a qualitative risk assessment for the introduction and spread of sheep scab into and between flocks in Scotland was undertaken. Potential disease control options within the defined risk pathways were identified and evaluated. To support the development of control options, an indicative cost:benefit analysis was completed. Two-part telephone interviews with 150 producers across Scotland took place to investigate attitudes towards sheep scab, its control and selected control options. This work was supplemented by dialogue with stakeholders and local authority representatives.

4. Findings

4.1 Evidence base

Sheep scab is not being adequately controlled in Great Britain and it is feared that the situation will continue to deteriorate in the absence of a more strategic and co-ordinated approach. There is a groundswell of opinion from within the sheep industry and from disease control professionals for more concerted effort. There are good examples in regions of Scotland where sheep scab has been controlled through local initiatives and where a cordon sanitaire is robust, eradication can be achieved and sustained.

4.2 Risk assessment

The question, 'starting with a sheep flock in Scotland which is free of sheep scab, what is the probability per year that the flock will become infested and subsequently spread the disease to another flock?' was addressed. It was assessed that the annual risk of infestation was medium for all flocks. The risk was assessed to be highest for hill flocks and this reflected less opportunity for control in these more extensively managed areas. Once initial infestation occurs however, the risk of spread within the flock was assessed as higher in lowland and upland flocks and this reflected the more intensive management associated with these systems.

4.3 Control options

Control options were envisaged as follows:

• Option 1: no change on the current situation, this represents the baseline;
• Option 2: voluntary control over a sustained period of time. Producers advised of the initiative, reminded of the need to treat sheep scab effectively and encouraged to co-operate with neighbours. Cost to farmers seeking diagnosis subsidised and support made available to farm practice vets to assist in diagnosis and recommendation of appropriate treatment. Veterinary surgeons charged with task of co-ordinating treatment among clients and subsidised to do so. Cost:benefit analysis and case studies used to promote the benefits of biosecurity, quarantine and effective prevention and treatment of sheep scab.
• Option 3: compulsory control that requires all producers to treat their animals within a defined time period. To opt-out would require a rigorous risk assessment to decide whether or not treatment is required. All producers that share common grazing would be required to treat as they would be deemed high risk. Unnecessary use of macrocyclic lactones avoided due to concerns of resistance to anthelmintics. Producers required to pass a test on the treatment of animals for sheep scab before treating. Authorities to be informed when treatment takes place with a random checking system in place. Robust certification system to be in place in order to address risk of livestock standstill.

4.4 Cost:benefit analysis

A notable conclusion of the cost:benefit analysis was that in the current situation the control costs (£5.1m) may be about eight times as large as the disease cost (£0.6m) - this is not irrational since the cost of the disease might increase greatly if the current effort to control scab were to be reduced. The current control costs may be considerable as a reflection of uncoordinated activity that does not achieve control most efficiently. Scope to generate benefits from more active control of sheep scab is limited since full disease control would only reduce the disease cost by an estimated £0.6m. Estimates show that the cost of improved voluntary and compulsory control incurred higher costs than benefits although this is sensitive to the assumptions made. The analysis cannot take into account the longer term benefits of much reduced treatment needs if the incidence of scab is brought down to more acceptable levels.

4.5 Attitudinal survey

The groundswell of opinion among producers of the need for more concerted action was reflected in the finding that 92% of respondents felt that farmers must work together to reduce the number of incidents of sheep scab. At 90%, a similar proportion agreed that sheep scab poses a major threat to the health and welfare of sheep. High levels of agreement (80%) were seen in response to a perceived need for the government and local authorities to co-ordinate efforts and a recognition that a small minority of farms are failing to control sheep scab. At 58%, just over half of all respondents had heard of the SSSI.

On a scale from 1 (very difficult) to 4 (very easy), the selected control options were perceived as somewhere between 2 and 3 in terms of ease of implementation. Using a similar scale from 1 (not at all effective) to 4 (very effective), the selected control options were perceived between 2.5 and 3.5. On both parameters, a compulsory control programme was most highly rated e.g. the easiest to implement and the most effective of the given options.

Among stakeholders, there was broad consensus that sheep scab could be eliminated, at least in theory, from Scotland although the scale of this undertaking was emphasised by several respondents.

There was agreement among stakeholders that the majority of producers were well-intentioned although this did not always translate into the most efficient or effective behaviour. The efforts of the majority were undermined by a minority that failed to engage in effective treatment and control of sheep scab.

Stakeholders were broadly in agreement with regard to the perceived merits of the proposed treatment options with the exception of their reactions to the proposal for a compulsory treatment period. On the latter, at one end of the spectrum were those respondents that argued for compulsory dipping with few exemptions. At the other end of the spectrum were those that rejected the concept of compulsory treatment and emphasised instead the need for an industry driven, risk-based approach.

5. Key conclusions

• It is estimated that the total cost to the Scottish economy of sheep scab and its control is approximately £6 million per year. On the assumption that there are some 16k flocks and almost 8m sheep in Scotland, this equates to an annual cost of £375 per flock or 75 pence per head.
• Sheep scab is costing the Scottish sheep industry an estimated £0.6m per year due to lost production. Control costs, at an estimated £5.1m are considerable. Much of this control cost is attributed to repeated treatments that may not be used most appropriately. Failure to make a correct diagnosis, incorrect selection of treatment and poor administration of the treatment are also associated with heightened control costs;
• The consensus of respondents, stakeholders and local authority representatives was that it is a small minority of producers that harbour disease in their flocks, undermining the efforts of the wider industry;
• Despite several good examples of where farmers and vets have worked together to achieve much improved control, there is a general lack of a co-ordinated approach;
• The current situation is not sustainable given the hidden costs of selecting for resistance in both scab mites and macrocyclic lactone resistant nematodes from over use of any of the available treatments. Additional treatments are not anticipated in the near future;
• Compulsory control programmes have been shown to work in Great Britain in the past. However, fundamental changes in the economics and management structure of the sheep industry have increased the challenge of effective control. An increase in average flock size, reduced labour on farms, increased number of hobby farmers, movements of sheep within and outside Scotland (to slaughter / for breeding), a reduced statutory veterinary service and the increasing concerns about medicine residues in food ( e.g. in organic systems) make the arguments for compulsory control far more difficult than in the past;
• Although most producers that responded to this survey perceived compulsory treatment as the most effective and easiest of the given control options to implement, blanket treatment that encourages widespread use of chemicals is contrary to SCOPS philosophy to ensure sustainable parasite control.