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BEF is an example of an arbovirus because it is spread by biting insects. The most likely insects to transmit the virus in NSW are mosquitoes.
Affected animals will have a sudden onset of fever on the first day, milking cows will have a sudden drop in milk production. Animals will stop eating and drinking, they may develop nasal discharge and begin salivating. They will also develop a shifting lameness with reluctance to move. Some animals may lie down and refuse to get up. The joints may appear swollen and there can be swelling around the jaw.

The nerves that control swallowing can also be affected and these animals are at risk of getting food and water or saliva into their lungs which can cause pneumonia.  Cows may abort their pregnancies up to several weeks later.

Milk production can reduce by around 50% however yield should return to normal after about three weeks, but cows affected late in lactation often dry off. Bulls and fat cows tend to show more severe signs than other cattle and such animals lose condition rapidly and are slow to regain their body weight. A number of bulls will suffer temporary infertility which can last for up to six months.

In the majority of cases the disease runs a short course followed by a full recovery. However, the disease can vary in severity. Some animals can remain unwell for several weeks.

A small proportion of animals may suffer permanent paralysis.

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Vaccination is available to prevent BEF. To achieve long acting effective cover two doses are needed. Animals can be vaccinated from 6 months of age and should be revaccinated annually. Some producers may decide to only vaccinate bulls and stud cows. Due to the severe drop in milk production, vaccination is often worthwhile in dairy herds. Local knowledge of the frequency of outbreaks will assist decisions on the age of stock to be vaccinated. Feel free to call us to discuss your decision to vaccinate.

We have vaccines available to order so call us today to order on (02) 66843818.