Britain's Levy Board has extensively changed its codes of practice regarding the infectious diseases CEM, EHV and EVA, which can severely disrupt horse breeding. John Parker, chairman of the committee responsible for drawing up the codes, revealed on December 10: "Changes to horse breeding, including the increasing use of walking in, artificial insemination and international travel of breeding stock, led to a full review of the codes. There are significant changes to some recommendations and a new style designed to make the codes easier for breeders and veterinary surgeons to use." Richard Greenwood, chief veterinary adviser to the British Thoroughbred Breeders' Association, added: "A recent outbreak of CEM in UK non-Thoroughbreds and of EVA in Irish Thoroughbreds underlines the need for all horse breeders to implement the recommendations in the codes. The increased number of paralytic EHV cases in 2003 emphasizes the need for stud managers to inform owners of horses in contact with the stud when cases occur so that those owners have the chance to stop the further spread of disease." The main changes to the codes include:- a) Following the CEM outbreak in 2002, the code now advises that, prior to mating or AI, mare owners or their veterinary surgeons should satisfy themselves about the disease status of the stallion and stallion owners should require current negative swab certificates for all visiting mares. b) Following several atypical cases in 2003, the 2004 code for EHV recommends that, where this disease is the suspected cause of abortion, the placenta should be submitted for laboratory diagnosis as well as the fetus. c) The period of isolation and movement restriction on EHV affected premises has been 28 days for many years. The 2004 Code now recommends that it may be possible to move non-pregnant mares off the premises before 28 days after the last case if: 1) they have been isolated from pregnant mares and handled by separate staff; 2) testing of blood samples taken immediately and again after 14 days indicates that they are not infected; 3) there is no other evidence of spread of infection.d) The period within which horses for import should be blood tested for EVA prior to leaving their country of origin has been clarified as 28 days. Libby Archer, the scientific liaison executive of the Levy Board, emphasized that the codes of practice are minimum recommendations and all mare owners should contact the managers of stallion stud farms before sending mares, either to board or walk in for mating, to clarify any additional requirements. She pointed out that Fort Dodge's EVA vaccine Artervac has now returned to the British market, following an interruption in supply which left the breeding industry without the vaccine at the start of the 2003 breeding season. Supply resumed in the UK and Ireland in April, 2003, following the transfer of production to the U.S. The 46-page codes of practice is available in PDF format through the Levy Board's Internet site www.hblb.org.uk by clicking on "Veterinary Science And Education" and then "Codes Of Practice."