Specimen: Serum, or heart blood from a dead fetus
Container: Red top or gel tube
Collection protocol: Venepuncture; To identify carriers, take serum and request pooling (5 samples per pool).
Special handling/shipping requirements: Samples are to be transported and stored chilled. Do not freeze samples.
General information about the disease:
Hairy shaker disease (HSD) is caused by a Pestivirus. Border disease viruses (BDV) survive for only a short time in the environment. Spread is usually by the oral/nasal route thus the rate of virus transmission is increased under conditions of intensive husbandry. As with BVD the persistently infected (PI) sheep is a major component of disease transmission. Healthy non-pregnant sheep exposed to the virus may have mild symptoms with a slight fever, a short lived viraemia and develop a long-lived immunity. The virus appears to be able to cross the placenta with ease.
When previously naïve ewes are first exposed during pregnancy effects similar to those in BVD infection are seen and vary depending on the age of the fetus at the time of infection. It appears that prior to 16 days gestation the zygote is refractory to infection, and after 90 days gestation the ovine fetal immune system is capable of eliminating the infecting virus. However infection between 16-90 days of gestation causes: early embryonic death, abortions and stillbirths, birth of lambs with malformations, dead or alive (often dying soon after if alive), birth of small, weak lambs, some often ‘hairy’ and occasionally ‘shaking’. Combinations of all of the above can be seen on one property. The ‘hairy’ fleece on lambs is the most obvious clinical sign but if lambs survive past a few months of age this may disappear. It can be useful to identify ‘hairy’ lambs at tailing/docking. As not all persistently infected lambs (PI’s) are ‘hairy’ it is important to check flock members byblood testing. Surviving lambs are persistently infected and excrete virus in their urine, faeces, saliva and blood. They have poor growth rates and are often susceptible to many other diseases. Infected ewe lambs that survive to sexual maturity and breed will always produce a PI lamb. Infected males that reach sexual maturity will have poor quality, highly infective semen and reduced fertility. These PI lambs should be culled or identified as a non-replacement at the time of tailing/docking. As with cattle, PI animals can develop ‘mucosal disease’ type infections and often die within a few weeks.
General information about when this test is indicated:
Looking to confirm clinical cases and identify it as a cause of abortion and to identify carriers.
Comparison with other related tests: There is an antibody ELISA is available