Control of Infection

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If EVA infection is suspected in any horse, stop all breeding activities immediately, notify the APHA as set out on page 20, isolate the horse(s) concerned and seek veterinary advice about the next steps.

If EVA is confirmed in any mare, stallion or teaser:

1. Stop mating, teasing and collection/insemination of semen, and stop movement of horses on and off the premises immediately;

2. Notify the APHA immediately as set out on page 20 and seek veterinary advice. Any directions given by the APHA must be followed;

3. Isolate and treat clinical cases as advised by the attending veterinary surgeon and/or officers;

4. Group the in-contacts away from other horses on the premises and ask the attending veterinary surgeon to take samples for virus detection. When the results are available, separate any healthy horses which have tested negative away from those which have tested positive. Horses which have tested positive should be treated as advised by the attending veterinary surgeon and local APHA officers, and kept in isolation until freedom from active infection is confirmed;

5. Ask the attending veterinary surgeon to screen all other horses at the premises by blood testing. If any of these return positive results, they should be separated from those with negative results, and be treated as advised by the veterinary surgeon and the local APHA officers. They should be kept in isolation until freedom from active infection is confirmed;

6. Arrange for one straw from each ejaculate of stored semen from infected stallions and their in-contacts to be tested by a laboratory. If any straw is infected, all straws from that ejaculate should be destroyed;

7. Inform:

  • owners (or persons authorised to act on their behalf) of horses at, and due to arrive at, the premises;
  • owners (or persons authorised to act on their behalf) of horses which have left the premises;
  • recipients of semen from the premises;
  • the national breeders’ association;

8. Clean and disinfect stables, equipment, including that used for semen collection and processing, and vehicles used for horse transport. Defra publishes a list of approved disinfectants here (select only ‘General’ for products suitable for EVA).

9. Good hygiene must be exercised. If possible, separate staff should be used for each different group of horses to prevent indirect transmission of infection between the groups;

10. Arrange for the attending veterinary surgeon to repeat the blood testing after 14 days and again every 14 days until freedom from active infection is confirmed. Use the same laboratory for repeat samples as for the first samples. If any of the previously healthy or seronegative horses become ill or seropositive, they should be moved into the appropriate group and treated as advised by the veterinary surgeon and the local APHA officers. Testing of these horses should continue until freedom from active infection is confirmed. Seropositive stallions and teasers must be investigated to determine whether they are shedders (see Appendix 5). Those which prove to be shedders must be kept in strict isolation until their future is decided and must not be used for breeding activities during this time;

11. Do not resume any breeding activities or movement on and off the premises until freedom from active infection is confirmed in all infected and in-contact horses. Breeding and movement should only be resumed with the approval of the attending veterinary surgeon and the local APHA Field Service office;

12. Pregnant mares must be isolated for at least 28 days after leaving the premises. Those remaining on the premises should be kept in isolation for at least 28 days after active infection has stopped;

13. Any mares who became infected after their pregnancy began should be foaled in isolation. If in any doubt, consult a veterinary surgeon.