Prevention of atrophic rhinitis in piglets by means of intranasal administration of a live non-AR-pathogenic Bordetella bronchiseptica vaccine.

The effect of intranasal vaccination of piglets with live non-AR-pathogenic Bordetella bronchiseptica (BB-) against Atrophic Rhinitis (AR) was investigated in a preliminary investigation and in a field trial. In the preliminary investigation 2-day-old SPF piglets (n = 13) were vaccinated. Three weeks after vaccination, challenges were carried out by means of a spray with an AR-pathogenic B (BB+) or an AR-pathogenic Pasteurella multocida (PM+) broth-culture. Four weeks later the piglets were necropsied and examined for atrophy of the ventral conchae (AVC). In contrast with the non-vaccinated SPF piglets, the vaccinated piglets showed a strong and significant reduction of AVC, after both BB+ and PM+ challenge. In the field trial three groups were formed by drawing lots: ten litters (82 piglets) were vaccinated; ten litters (92 piglets) formed the control group and 11 litters (104 piglets) were treated with a placebo. The litters were spread over two units. In unit 1 AR and PM+ were demonstrated incidentally, in unit 2, however, persistently. BB+ was isolated equally frequently in both units. Clinical and bacteriological examinations were done in piglets of 3, 6 and 8 weeks of age. Necropsy examinations was carried out in 41 piglets of 8 weeks of age, chosen randomly by drawing lots. In spite of a second vaccination at the age of 3 weeks, BB- was not well established; this was possibly caused by maternal BB antibodies. In the control and placebo groups PM+ was isolated earlier and more frequently than BB+. It appeared that AVC was correlated more strongly with PM+ than with BB+ infection in the field trial. The percentage of piglets with Brachygnathia superior (BS) at the age of 8 weeks indicated the AR situation in the herd. Although a significant reduction of AVC was determined in unit 2, it was not sufficient to indicate that this method of intranasal vaccination is useful in the prevention of AR in practice.