Watch Out for Sheep Scab (Lesley Stubbings)
Lesley Stubbings, Sheep Specialist
The sheep scab mite is highly contagious, and causes intense irritation to the sheep, which will rub itself causing crusty yellow sores and loss of wool. Scab is highly contagious so should be treated as a flock problem, not just an individual one.
Sheep scab used to be thought of as a disease of Autumn and Winter, but it is now common throughout the year, though the majority of outbreaks still occur between September and March.
Some farmers are all too aware they are at risk because they have sheep on common grazing, or have neighbouring farms with a history of scab. Others will be largely unaware of the risk until it hits them, apparently out of the blue. In these cases the resulting outbreak can be quite dramatic and swift action is essential.
How can the risks be minimised?
Firstly, it is vital to remember that ALL in-coming sheep are a potential risk. While the buying season is more or less over, there are still a lot of sheep movements, for example to and from tack, and store lambs brought onto the farm. Quarantine for a minimum of 21 days and, where possible, treatment is essential (store lambs can be an issue due to withdrawal periods, so check labels carefully). Contractors, such as scanners and transporters may also pose a risk.
Secondly, the threat from neighbours can be reduced by checking and repairing fences and considering double fencing along high-risk boundaries. Unfortunately, those neighbours with persistent scab also tend to be the ones with dodgy fences and gates. A lot of scab outbreaks are simply caused by stray sheep being put into well-maintained fields by well meaning people to get them off the road. Investing in some good padlocks will prevent this happening!
How should we deal with an outbreak?
Where an outbreak of sheep scab is suspected, it is essential that the farmer gets an accurate diagnosis from his Vet before rushing into treatment, particularly if he's planning to use an endectocide. For example, scab and lice often present similar symptoms, but are controlled using different treatments. If scab is confirmed then the options are either an endectocide (pour-on or injectable) or – perhaps less practical for smaller flocks – plunge dipping in an OP – but NOT jetting or showering.
Failure to control scab is usually due to ineffective or incomplete application of treatments. This includes dipping in a dirty bath that has not been properly replenished, dipping for too short a time and/or without full immersion, and not injecting all sheep in a group or putting them back with untreated sheep in an infested area. The manufacturer's instructions must be followed to the letter to avoid the re-emergence of scab and the inevitable cost and hassle of re-treating the whole lot again.
For further sheep welfare information, see 'Managing Your Flock for Peak Health', programme 2 in the series 'Sheep on Your Smallholding'.