Last week I found some ruminants with clinical symptoms of Bluetongue at a farm abroad. The owner did not notice this Bluetongue.
He thought the blue tongue is the typical appearance of the disease. The blue tongue is rather an exception in this disease!
"Knutten", (tiny biting flies) that suck blood are responsible for spreading the virus. They are mainly active during warm days.
The incubation period of Bluetongue varies from 5 to 20 days. We distinguish two forms of Bluetongue: the acute and the subclinical form.
Animals infected with the subclinical form often show little or no signs of disease.
The acute form can strike hard in sensitive small ruminants. In addition, the mortality in infected sheep can be as high as 10%.
We do not see this in cattle.
The virus attacks the blood vessels in infected animals.
The symptoms are:
• High fever for a few days to more than one week
• fast and difficult breathing
• inflamed mucous membrane in the mouth resulting in salivation
• nasal discharge and crusting on the nose
• swollen head and inflammation around the eyes
• swollen underfeet and crown edges resulting in lameness
• pregnant animals can abort. We also sometimes see premature births
• In sheep, breakage of the wool fibers can occur, which can cause baldness
• affected animals lose weight due to sharp decrease in appetite
• infected animals are often slow and lethargic.
The clinical picture is very similar to the symptoms of foot and mouth disease.
The virus can survive for a long time in red blood cells of infected animals. In addition, the survival time of the virus is longer in cattle than in sheep. The survival time of the virus can be up to 60 days after infection.
PREVENTION AND TREATMENT
Well-organized fly control at animal level limits the risk of contamination by "Knutten", (tiny biting flies).
A timely double vaccination against Bluetongue offers the best protection.
There are efficient (inactivated) vaccines for cattle, sheep and goats.
The basic vaccination consists of two vaccinations 21 days apart. One month after the 2nd vaccination, the vaccinated animal is adequately protected for one year.
Vaccinated animals should receive one booster vaccination every year to maintain immunity.
The vaccine is serotype specific.
This means that it protects against one of the 24 known types of Bluetongue virus.
Treatment is mainly aimed at the reduction of swelling, pain and fever. Depending on the situation, the vet can use diuretics, anti-inflammatories and / or corticosteroids, (whether or not in combination).
This with the aim of increasing the well-being of the infected animal.