2. DEFINITIONS: PDF version
a.)

Maedi visna is a viral disease of sheep and is caused by infection with MV-v. For purposes of this program, this disease is identical to the disease called ovine progressive pneumonia in the United States.

  • Common clinical signs include chronic wasting, decreased exercise tolerance, respiratory distress and hard udder at lambing.
  • Production losses in serologically positive sheep occur through decreased reproductive performance; higher lamb mortality rates through poor mothering; early culling; and lower weight gains by lambs because of poor milk production.
  • Once a sheep is infected with the virus, it remains infected for its lifetime.
  • It also sheds the virus through respiratory secretions, colostrum and milk, and blood. Infected sheep produce antibodies to the virus which are detected by serological tests.
b.)
 Must means that the owner of the flock, or their designated agent is required to carry out the stated activity (e.g. test, remove).
c.)
 A sheep is a ram, ewe or wether. Usually, a sheep is 365 days of age or greater, but for parts of this program, this term may be used for animals 180 days of age or greater.
d.)
 All goats residing in the flock are required to be subjected to the same testing and removal protocols as sheep. This is because goats can become infected with MV-v and may be able to transmit the virus to sheep. Therefore when the protocol says "sheep", it is implicit that all goats in the flock or housed on the flock premises, are counted as sheep and all testing and biosecurity protocols apply to goats as well as sheep.
e.)
 A lamb is a ram, ewe or wether less than 180 days of age and is the offspring of both the birth dam (natural mother or embryo recipient) and of the foster dam (if the lamb was fostered). When determining disease status, the following is considered:
i.
Serological status of birth mother (natural or recipient).
ii.
Serological status of foster dam.
iii.
Not the serological status of the sire unless fathered by fresh semen by artificial insemination.
iv.
The serological status of the genetic dam (donor) in cases of embryo collection and transfer, unless if the embryos have been handled in accordance with the protocol set out by the International Embryo Transfer Society for the sanitary handling of embryos. (Manual of the International Embryo Transfer Society. Third Edition. 1998. Ed. DA Stringfellow and SM Seidel. International Embryo Transfer Society. Champaign Illinois.)
f.)
A flock, for purposes of this program, is a population of sheep and goats which at any time during the year are managed within the same facility, i.e. if sheep share pastures, housing, feeders, waterers or other equipment that has not been disinfected between groups, then they are considered part of the same flock even if they reside at different farms for part or all of the year.
g.)
A flock premise are all buildings, dry lots, paddocks and pastures or fields occupied at any time by the flock.
h.)
To remove from the flock suggests that the sheep or lambs are to be sold directly to slaughter for meat and not as breeding stock. This is a guideline and the actual disposal fate of the animals is not enforced by this program.
i.)
The test date - is the date that the samples were taken from the sheep, not the date that the results were received.