Camilla Strang and Richard Newton of the AHT’s Epidemiology and Disease Surveillance Group describe the management of a recent outbreak of equine herpesvirus type 1 neurological disease On 31 May 2017 the Animal Health Trust (AHT) was informed of a case of equine herpesvirus type 1 (EHV-1) neurological disease on a thoroughbred racing yard in northern England. The affected animal, a non-vaccinated four-year-old gelding, had presented with hindlimb oedema, pyrexia and loss of vision. It had been euthanased on 29 May and sent for postmortem examination. The diagnosis was confirmed based on a premortem nasopharyngeal swab, and upper respiratory muscosa, lymph node, brain and spinal tissues sampled postmortem being positive for EHV-1 by qPCR. The British Horseracing Authority (BHA) was notified and voluntary movement restrictions were immediately initiated to avoid potential viral transmission to other groups of horses. Further advice on outbreak management was provided by the AHT Epidemiology and Disease Surveillance Group. The group advised further diagnostic testing of the remaining horses on the yard to initially gauge the existing infectious and exposure status of the population and subsequently to provide firm laboratory-based evidence with which to declare disease clearance and safely resume racing activities. The affected premises contained 122 animals, including the index case and none was vaccinated against EHV-1 and EHV-4. Recommendations made for initial laboratory testing were to blood sample all animals on the premises and measure antibody levels against EHV-1 and EHV-4 using the complement fixation (CF) test. This would gauge the extent of immune response …