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Contagious Equine Metritis (CEM)
In Great Britain (England, Scotland and Wales), isolation of an organism known or suspected to be T. equigenitalis (CEMO) must be notified under the Infectious Diseases of Horses Order 1987 to the Animal & Plant Health Agency (APHA). Please see Appendix 1 for APHA contact details.

Laboratories that have notified a suspect isolation are required to send the swab sample and/or the swab extract for PCR testing to the APHA Veterinary Investigation Centre Penrith (Merrythought, Calthwaite, Penrith, Cumbria CA11 9RR; tel: 01768 885314; email: for official confirmation or negation of a suspected positive diagnosis of CEM.

Following an extended consultation between Government and the equine industry a new industry-led Contagious Equine Metritis (CEM) control protocol came into effect on 1 February 2018 as an initial pilot scheme in England, Scotland and Wales; there was no change in the arrangements for control of CEM in Northern Ireland (for more details please see Appendix 11). CEM remains notifiable throughout the UK and as such the disease will continue to be confirmed by the APHA Veterinary Exotic and Notifiable Diseases Unit (VENDU) on the instructions of the Chief Veterinary Officer (CVO) in the country in GB where the disease is suspected. In 2021 the status of the industry-led CEM control protocol was changed from a pilot to an established protocol.

The basis of this industry-led scheme in GB is that when APHA is notified by a laboratory of a suspect T. equigenitalis isolation, APHA will inform the owner/ agent of the horse of the suspicious result and ask the owner/agent whether, if CEM is confirmed and they are compliant with the Code of Practice, they wish to take part in the protocol.

If they elect to take part in the protocol further investigation will be carried out by an approved veterinary surgeon (AVS) appointed by a specialist advisor to the equine industry. A list is held by the British Equine Veterinary Association (BEVA). The owner or agent has 24 hours to inform that advisor of their agreement and to provide them with the required information about the infected horse(s), the premises and the attending veterinary surgeon involved. The specialist advisor will appoint an appropriate specialist in agreement with the owner/keeper, who, if CEM is confirmed, will visit the positive horse and premises and will advise the advisor whether the situation is compliant with the Code of Practice or not. The specialist may be the attending veterinary surgeon if he/she is on the BEVA Approved Veterinary Surgeon (AVS) list and if he/she consents to this responsibility.

If the owner does not wish to take part in the protocol or the premises are not compliant with the Code of Practice, the advisor will advise Defra of this and APHA will take over the investigation and may make charges. Defra may serve Statutory Notices on the affected premises, declaring them an infected place and impose mandatory requirements, including:

  • taking samples or obtaining information to establish the source and extent of disease;
  • prohibiting or controlling movement of any horse, carcase or other item;
  • prohibiting the breeding activities of any implicated horses;
  • disinfection or destruction of infected articles or materials;
  • cleansing and disinfection of premises and vehicles.

In the event of statutory powers being invoked, Defra would nominate the laboratories to undertake the testing of all samples required by the subsequent investigation.

Failure to comply with Statutory Notices is an offence under the Animal Health Act 1981 and may lead to prosecution.

If T. equigenitalis is isolated, it is advisable for owners, or a person authorised to act on their behalf, to inform the appropriate national breeders’ association.

Thereafter, the outbreak and any contacts will be investigated, infected horses treated and re-tested as recommended by this Code of Practice until all infected horses are shown to have been repeatedly tested negative. If the specialist advisor is involved, they will then notify Defra that this is the case and VENDU will, if the appropriate person is satisfied, declare the outbreak over.

Klebsiella pneumoniae and Pseudomonas aeruginosa

In the UK, isolation of K. pneumoniae or P. aeruginosa is not notifiable by law. However, if infection occurs in stallions, it is advisable for the owner, or a person authorised to act on their behalf, to inform the national breeders’ association.