BDV
Border disease, also known as "hairy shaker" disease, is a viral infection in sheep caused by the Border Disease Virus (BDV), a type of pestivirus. This disease primarily affects pregnant ewes and their lambs, leading to significant production losses in affected flocks. It was first reported in 1959 from the border region of England and Wales and has since been recorded worldwide.
Symptoms and diagnosis of Border Disease in sheep 🩺
Symptoms
The symptoms of Border disease can vary depending on the age of the animal and the stage of pregnancy if the ewe is pregnant. Here are some common signs:
- High mortality rates in lambs
- Weak, small, or stillborn lambs
- Persistently infected (PI) lambs, often called "hairy shaker" lambs, which have a hairy fleece, smaller dome-shaped heads, and spindly legs
- Brain damage symptoms in lambs, such as tremors and poor coordination
- Higher barren rates in ewes
- Immunosuppression, making animals more susceptible to other diseases
"Hairy shaker" lambs are particularly distinctive due to their abnormal appearance and neurological symptoms.
Diagnosis
Diagnosing Border disease involves blood sampling older lambs and ewes to look for evidence of persistent infection or exposure to the virus. Laboratory tests such as antigen enzyme-linked immunosorbent assay (ELISA) or virus isolation in cell culture can confirm the presence of the virus. It's important to consult with your vet to decide on the most useful investigation plan.
How to treat Border Disease in sheep 💊
Unfortunately, there is no specific treatment for Border disease. Management focuses on supportive care for affected animals and preventing the spread of the virus within the flock. Persistently infected animals should be culled to prevent them from acting as a source of infection.
How to prevent Border Disease in sheep 🛡️
Preventing Infection
Preventing Border disease involves several strategies:
- Quarantine and test new stock before introducing them to the main flock
- Keep pregnant ewes away from cattle and other sheep that might be persistently infected
- Blood test animals to determine if they have been exposed to the virus or are persistently infected
- Do not retain or sell suspect "hairy shaker" lambs or weak lambs as breeding animals
It's crucial to discuss the Border disease status of any flock from which you are purchasing animals and involve your vet in these discussions as part of your flock protection plan.
Vaccination
There is currently only one commercial vaccine for Border disease, and it is not licensed in all countries. This killed adjuvanted vaccine contains representative strains of BDV and BVD-1 viruses and should be administered to young animals before they reach breeding age. Further vaccine development is needed to improve efficacy.