Vaccines should be administered several weeks before mating of gilts, with the aim of providing immunity before and during the susceptible gestation period. However, vaccination has to be performed after the disappearance of colostral immunity in these nulliparous animals (Paul and Mengelin 1986). These limits define a short space of time for effective vaccination of gilts to be inseminated at an early age (before 7 months of age). Although inactivated vaccines are safe by definition, there is evidence that sufficiently attenuated live vaccines are unlikely to cause reproductive failure, although administered during pregnancy. The duration of immunity after vaccination is difficult to predict, although different studies show efficacy up to 4 months after administration of an inactivated vaccine ( Joo and Johnson 1977b). Vaccination is recommended for sows and boars. If a farm were negative to PPV, vaccination with an inactivated vaccine would be the choice, although it is unusual to find farms free of the virus when they are infected and the result can be disastrous (Donaldson-Wood et al. 1977). For its part, the vaccination of boars reduces their role in the spread of the disease. Vaccination is the most used preventive and control measure in the swine industry worldwide. The most common vaccination procedures in sows include a primary vaccination with two doses 3-4 weeks apart and revaccination at each lactation, 7-10 days post-partum. In boars the recommendation is a two-dose primary vaccination as with females, and revaccination every 4-6 months.
References •
Pig Diseases, 8 th edition 2006 D.J. Taylor.
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Diseases of Swine 9 th edition 2006 Straw, Zimmerman, D’Allaire, Taylor.
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Maldonado J, Segalés J, Martínez-Puig D, Calsamiglia M, Riera P, Domingo M, Artigas C. 2005. Identification of viral pathogens in aborted fetuses and stillborn piglets from cases of swine reproductive failure in Spain. Vet J.169:454456.
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Martínez-Guinó L, Kekarainen T, Maldonado J, Aramouni M, Llorens A, Segalés J. 2010. Torque teno sus virus (TTV) detection in aborted and slaughterhouse collected foetuses. Theriogenology 74:277281.
THE VISION ON THE FARM As we know, PPV is a ubiquitous virus and sometimes - because a farm’s routine or work does not permit - it is not given the importance we give to other more current diseases. We can see by observing field samples that sometimes replacement sows are not prepared to face a future pregnancy with guarantees. Therefore, good adaptation to the farm where replacements are sent is of great importance by means of effective vaccination programmes to prevent maternal immunity and generate an appropriate response.