MAEDI VISNA (MV)
WHAT IS MAEDI VISNA?
Maedi Visna (MV) is a viral disease which was introduced into the UK by imported sheep. It has since spread, especially in commercial flocks. MV is a chronic disease of sheep caused by a retrovirus. The disease has a long incubation period which means the disease can spread widely within a flock before it is diagnosed. The name ‘Maedi Visna’ derives from two Icelandic words which describe two of the main clinical signs: – pneumonia and wasting. The condition is highly contagious, difficult to diagnose and is fatal. There is no vaccine available and no treatment.Outbreaks have been witnessed throughout the country and it is estimated that there are at least 100,000 sheep infected in the national flock.
Clinical signs are only seen in adult sheep and include: – progressive paralysis, wasting, arthritis and chronic mastitis
Infection in a flock can be devastating with a 10-20% adult mortality. Ewes are more likely to develop mastitis and in addition chronic debility reduces milk production thereby affecting lamb survival and performance. Arthritis and poor fertility can also increase culling rates within the flock.
The virus is present in milk, colostrum, faeces and respiratory secretions. Lambs can be infected by drinking their mother’s colostrum or milk. A lamb stealing milk from another dam is also at risk of infection. Other sources are contaminated water or feed when uninfected sheep are housed or at pasture with infected sheep.
What is the MV accreditation scheme?
The scheme is run by SRUC and open nationally to all flock keepers who intend to conform to the rules and regulations of the membership. MV accredited sheep must be kept separate from non-accredited sheep at all times. Membership is at the discretion of SRUC Veterinary Services. There are many benefits of joining the scheme:
- It reduces the risk of your flock getting the virus
- Allows you to attend MV accredited shows and sales with your flock
- Allows you to export to Maedi Visna free countries
- Allows you to advertise your flock as MV accredited
- Adds value to your flock and enables you to sell to purchasers who have MV accredited flocks
To become MV/CAE accredited, the flock/herd must undergo the following qualifying tests
At the first qualifying test, all animals in the flock/herd aged 12 months or older must be tested UNLESS:
- The flock/herd has been established for a minimum of 3 years
- At least 90% of female replacements are home bred
- Any purchased animals in the past 3 years have come from MV/CAE accredited flocks/herds
- There is no other animal on the holding(s) that is to remain non-MV/CAE accredited
The second qualifying test is to be carried out 6 to 12 months after the first qualifying test. All animals over 12 months of age must be tested.
A flock can become MV accredited when it:
- Passes two qualifying blood tests between 6 and 12 months apart
- Has certification from a vet that the holding can comply with scheme rules and conditions
Once MV accredited, a proportion of the flock is blood tested every 2 or 3 years and the member is issued with certificates of status for selling or moving scheme sheep. Shows and sales are licensed to provide space for MV accredited sheep.
The full rules of the scheme are available here