Take measures to control spread of orf

Orf Lamb.
Orf Lamb.

Orf is a common problem after lambing. It’s a continuous threat to UK flocks and outbreaks can have a drastic effect on health, welfare and productivity.

The disease is highly contagious and can affect sheep of all ages, most commonly young lambs or ewes’ udders at lambing.

A survey of 762 farms helped identify programmes that should be put in place to best control the disease. A key finding was that on farms where orf has been seen, both ewes and lambs should be vaccinated.

The survey found significant prevalence in lambs and though vaccination is the most important step to take, other strategies should also be implemented.

Increased numbers of orphan lambs were associated with the increase in cases of orf.

Controlling thistles, nettles and docks – thistles, in particular, which cause skin abrasions that allow the orf virus to enter the body and replicate – was also observed as being an important control measure.

The first sign of orf is usually scabby lesions around the nostrils and mouth, but it can soon spread to other parts of the body, such as teats, feet and tail. Orf-affected lambs are on average 2.2kg lighter. An orf outbreak can increase levels of ewe mastitis.

The virus can survive in cool, dry conditions so scabs may remain infectious in lambing sheds for years. Orf can spread to humans too so anyone handling infected sheep, wool or skins must ensure their hands are fully protected.

If orf has been seen on a farm, a simple vaccination programme with Scabivax Forte for all ewes and lambs can significantly reduce the impact. Pregnant ewes should be vaccinated not less than seven weeks before housing for lambing.

This will allow them to develop sufficient immunity in time for lambing and prevent contamination of the environment where lambs are born. Immunity develops within four to eight weeks after vaccination, but the vaccine does not offer long-term protection so ewes need to be boosted annually. Lambs are born naïve to the disease so can be vaccinated from one day old.

Scabivax Forte vaccination is straight forward to administer. The vaccine applicator ensures a precision dose is delivered every time via a single scratch between the animal’s foreleg and chest wall. Within seven to 10 days a row of scabs will form along the scratch, showing that the vaccine has ‘taken’. It is commonly done under the hind leg for convenience, but nuzzling by other lambs in this area increases the risk of spread so the forelimb is recommended.

If you would like a demonstration, we are happy to show how it’s done. Practising on a banana with some water is how we teach to make the scratch and get a feel for delivering the dose and getting the right depth of scratch.

Now is the time to think about vaccinating the ewes so if you’re having problems with orf on your farm, please contact the practice today to make a plan for your flock.