CLINICAL, SEROLOGICAL AND VIROLOGICAL CHARACTERISTICS OF AN OUTBREAK OF PARESIS AND NEONATAL FOAL DISEASE DUE TO EQUINE HERPESVIRUS-1 ON A STUD FARM

An outbreak of equine herpesvirus-l (EHV-1) occurred on a large stud f arm with 133 mares, 54 foals and four stallions, and at least 85 mares , 22 foals and three stallions were infected, Clinical disease was obs erved in 16 mares, two stallions and 13 foals and the predominant clin ical signs were scrotal oedema, ataxia and loss of libido in the stall ions, ataxia and recumbency in the mares and uveitis and nasal dischar ge in the foals, although pneumonia and colic with intussusception wer e also recorded at autopsy, Neurological disease was more common in th e mares nursing foals (12 of 38 infected) than in barren mares (one of 46 infected), Three mares died during the outbreak and no mares that had been recumbent bred again, Control procedures were based on virolo gical and serological testing and stringent management practices to li mit the spread of infection between groups of mares and foals and away from the stud farm, There were marked antibody responses in the adult horses, but they were generally poor in the feats; three of the nine viraemic foals did not develop significant increases in the levels of circulating antibody, Recommendations are made for the management of f uture outbreaks.