Monitoring for swine dysentery: six years' experience with a control scheme

A control scheme for swine dysentery was initiated in Britain by the Pig Health Control Association in January 1978. To qualify, herds must not show clinical signs suggestive of swine dysentery or, if any suspicious signs arise, laboratory tests must be negative for Treponema hyodysenteriae. In addition, a range of pharmaceutical compounds that might mask the disease or its laboratory diagnosis may not be used routinely after weaning, either for treatment or as food additives. Qualifying herds can import pigs only from other qualifying herds or via hysterectomy/hysterotomy or embryo transfer methods; artificial insemination is also permitted. During the first six years, 91 herds qualified at some stage, and at the end of 1983, 56 herds (average size 200 sows) were still listed. By this date, 72 herds had imported stock from 36 other qualifying herds; despite this degree of inter-herd connection, no evidence of swine dysentery has occurred within the scheme since its inception, nor has this disease appeared in herds established entirely from listed herds. It seems, therefore, that freedom from swine dysentery (unlike enzootic pneumonia) can be readily maintained in a controlled group of pig herds identified by these monitoring methods.