Symptoms of BTV-3

How can you officially detect BTV-3 on-farm?

Detection of evidence of disease/exposure to a virus usually falls into two categories:

  1.    Looking for the virus itself (antigen testing).
  2.    Looking for an animal’s response to the virus (antibody testing). Both natural infection and vaccination should result in a positive test for antibodies.

There are different samples that can be collected for these tests. Most commonly a blood test, but other samples such as swabs, urine or bulk milk samples from a dairy herd, can also be used to detect both virus and antibody with varying degrees of success. The best sample to take to be certain of infection, and the timing of sample collection, is dependent on the virus we are working with.

Adult animals may show little or no clinical signs, so farmers and their vets need to be vigilant.

View Clinical signs of bluetongue | AHDB to find photos of clinicals signs and symptoms

In sheep: 

  • Lethargy, reluctance to move 
  • Crusty erosions around the nostrils and on the muzzle 
  • Ulcers or sores in the mouth and nose
  • Discharge from the eyes or nose and drooling from mouth
  • Swelling of the muzzle, face and above the hoof 
  • Reddening of the skin above the hoof 
  • Redness of the mouth, eyes, nose 
  • Breathing problems 
  • Abortion, foetal deformities and stillbirths
  • Death

In cattle:

  • Crusty erosions around the nostrils and muzzle 
  • Redness of the mouth, eyes, nose 
  • Redding of the skin above the hoof 
  • Nasal discharge 
  • Reddening and erosions on the teats 
  • Lethargy
  • Milk drop
  • Abortion, foetal deformities and stillbirths

Cattle do not often show clear signs of disease so owners should also look out for signs of fatigue and lower productivity including reduced milk yield. 

In calves:

Calves can become infected with bluetongue (BTV-3) before birth if the mother is infected while pregnant. Signs of infection include: 

  • Calves born small, weak, deformed or blind 
  • Death of calves within a few days of birth 
  • Stillbirths

Livestock keepers and vets should consider bluetongue as a possible cause for calves showing these signs.