Skin-related ailments

Issues with sheep scratching come to the fore each year during the winter. Discussions often centre on treatments perceived to be unsuccessful. The reality is a significant number of these treatments are unsuccessful but not because the product has not worked, rather the cause was misdiagnosed. With a lot of labour and expense going into these cases, the starting point must always be an accurate diagnosis. While sheep scab and lice remain the most common culprits, external parasites are not always to blame, with bacterial and fungal infections also present.

Lice are relatively easy to see by the naked eye and move through the wool when parted. The lice parasite is long, shaped similar to a wasp and with a yellow or pale brown colour. If in doubt, your vet will be quickly able to diagnose by examining using magnification or taking a sample for examination under a microscope. There is generally no wool loss or secondary infections with lice apart from if sheep are aggressively scratching and have damaged their skin.

Identifying sheep scab is more difficult as the sheep scab mites are tiny and barely visible to the naked eye. They are brown in colour and round. They feed on flesh and are generally found on the skin where scabby lesions and wool loss are characteristic signs. It is also important to note that while the sheep scab mite is the most common, there are other mites that cause significant problems. A skin scraping taken by your vet for diagnosis can usually confirm the cause quite quickly.

Plunge dipping is the complete solution to addressing external parasites, with no other alternative available that targets all of them. Lice can be addressed by the use of pour-on products while sheep scab can be targeted by injectables but this treatment route is now only recommended where plunge dipping is not an option due to the increase in anthelmintic resistance.

These skin scrapings are also useful where there is doubt about the cause of issues and can be especially beneficial where treatment has taken place for external parasites and sheep are still displaying discomfort. For example, fungal problems such as ringworm are rare and difficult to treat but knowing the cause of the problem is the first step in allowing a treatment programme to be put in place.

CLP concerns

Significant issues continue to be reported with lambs complying with the clean livestock policy. Some questions have been raised again about shearing lambs (entirely or crutching) and the level of wool regrowth required to allow repeat action to be taken at factory level if required. Teagasc research shows that in general four weeks’ wool regrowth is required to allow lambs to be re-shorn pre-slaughter if required.

Research has also shown the benefits of shearing are purely management-based, with no performance benefit in terms of increasing daily liveweight gain. Where shearing is taking place along cut lines then it is important to note that this must take place the whole way up to the animal’s neck and on the opposite end to the tail head. Shearing just the belly region will in many cases be insufficient. In long wool breeds, the entire animal may need to be shorn due to wool falling down over cut lines.