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Serotherapy in Pigs: UK UseThis document is a letter from Richard Potter, President of the UK Pig Veterinary Society responding to the letter from Steve Dean, Director of Licensing at the UK's Veterinary Medicines Directorate, highlighting a number of concerns regards the regulatory requirements for the use of serotherapy in the UK.
7 Mansfield Street
London W1M 0AT
11 February 2002
SEROTHERAPY IN PIGS
Post-weaning Multisystemic Wasting Syndrome (PMWS) of pigs has been present in England since 1999 and is causing very high levels of mortality in many herds. The disease is remarkably unresponsive to conventional treatments and, as a result, a number of novel therapeutic approaches have been proposed. Reports from elsewhere in Europe that the serum from convalescent pigs may confer passive immunity on piglets, if it is given to them by intraperitoneal injection, has led to growing interest in the use of this technique in this country. This treatment is known as serotherapy and the legal framework that controls the use of this technique is outlined in the letter from the Veterinary Medicines Directorate (VMD) [reproduced here].
The technique involves sacrificing a full-grown, apparently healthy pig that has been exposed to the syndrome during the growing phase and harvesting its blood. The serum is separated and then administered to piglets at around weaning age by intraperitoneal injection. The objective is to confer some passive immunity to the agent that causes PMWS at the pig's most susceptible age. Anecdotal evidence suggests that this technique may reduce mortality in treated pigs, but as yet there is no properly controlled published data available to assess its efficacy.
The private veterinary surgeon is allowed to carry out this procedure, as outlined by the VMD. However, although this process may be legal, as advisors to the pig industry there is a need to consider any potential risks of administering "raw" serum to young piglets. Very careful thought should be given to the possibility of inadvertently transferring infectious agents and thus causing other disease problems. The fact that the law allows a vet to collect blood from his client's pig at an abattoir and take it back to the farm of origin, must raise serious worries, especially as the country has only just achieved freedom from Foot and Mouth Disease. It would seem particularly irresponsible to do this, even though it may be legal.
PMWS is a devastating disease and it is understandable that farmers with herds that are severely affected will want to try anything that appears to offer hope. Serotherapy may work, but whether this is the case or not is currently unclear. It is the responsibility of the attending veterinary surgeon to point this out and also that there are risks attached to the use of serotherapy. There is an urgent need for good evidence to support this practice and for guidance on serum processing in order to minimise any risks that may be involved, before its use becomes widespread.
Veterinary surgeons who undertake serotherapy must take full responsibility for any adverse reactions that occur and it would be prudent to check that professional liability insurance would still apply.
RICHARD POTTER, MA.VetMB.CertPM.MRCVS
President, Pig Veterinary Society
(Issued on behalf of The Pig Veterinary Society, Southview, East Tytherton, Chippenham, Wiltshire, SN15 4LX Richard Potter President, Pig Veterinary Society, Larkmead Veterinary Group, Ilges Lane, Cholsey, Wallingford, Oxon OX10 9PA)