Contagious equine metritis: how to spot and report the disease

How to spot contagious equine metritis, what to do if you suspect it and measures to prevent its spread.

Contagious equine metritis (CEM) affects horses, donkeys, mules, zebras and other members of the equid family.

It doesn’t affect humans.

The last outbreak of CEM in Great Britain was in 2012.

How to spot CEM

Stallions do not show clinical signs of the disease, but they can carry it.

In mares you should look out for discharge from swollen genitals, especially 1-6 days after mating.

Infected mares may also be temporarily infertile, so if your animal is failing to get into foal, get it examined by a vet.

Laboratories and CEM

CEM is a notifiable disease for laboratories. If a laboratory suspects the disease is present in a sample from your animal, they must contact their nearest Animal and Plant Health Agency office immediately. Failure to do so is an offence.

How CEM spreads

CEM spreads from horse to horse during mating. It can also spread when horses are artificially inseminated.

Preventing and controlling CEM

Preventing CEM

You can use the HBLB Code Of Practice to help prevent infection and to stop the disease spreading.

You can also prevent CEM by practising strict biosecurity on your premises.

If you suspect CEM

You should:

  • tell your vet immediately - they may take samples from your horse for lab testing
  • isolate any horses you think are affected
  • stop the suspect horses mating
  • avoid using semen from stallions with suspected or confirmed infection

If CEM is confirmed

If CEM is confirmed, the outbreak will be controlled in line with the contingency plan for exotic notifiable diseases.

Further information on prevention and control

Controls to prevent disease

What happens when a notifiable disease is suspected or confirmed

Legislation relating to CEM

The main domestic legislation on CEM is the Infectious Diseases of Horses Order 1987.

Published 26 August 2014
Last updated 1 October 2014 + show all updates
  1. AHVLA documents have been re-assigned to the new Animal and Plant Health Agency (APHA).

  2. First published.