I always think than one of the weakest areas when considering biosecurity are loading bays. If we think in sow farms, weaners or finishers as well as culled sows must be move out routinely, but also in many farms, replacements have to be moved in. “The biggest the farm is, the more transfer of animals are necessary weekly and the higher the biosecurity risk is” ... read more test →
In the post-weaning period we observe PRRS seroconversion with a mortality of up to 35%. The piglets present symptoms consistent with circovirosis, although the histological and serological results only indicate the presence of PRRSv. The sows are PRRS stable and the piglets are negative at birth. What could be happening? Post-weaning PRRS seroconversion is not always a consequence of producing viremic piglets but rather it is often an infection that... read more test →
Length of the quarantine: When we want to introduce negative replacements to a PRRS positive farm, the quarantine, or acclimation rather, must be long. "Long" meaning a period of not less than 2 months, because during this period our intention is to infect the new arrivals, giving them time to recover from the infection and lose their status as virus shedders before introducing them into the farm and starting to... read more test →
Monitoring programs will differ depending on whether they are to be applied to a farm, an area, or a country, but I understand that in this case we are referring to a farm. The program will vary depending on the type of farm and its disease status. In the case of the PRRS, five possible statuses have been described: What sample and technique should we use to check... read more test →
On a farrow to finish farm where sows are vaccinated every 3 months against PRRS virus and the piglets are not vaccinated, the piglet's ELISA results are these ones: 3-week-old piglets: PRRSV ELISA negative 8-week-old piglets: PRRSV ELISA positive. What could be causing the fact that 3-week-old piglets do not have PRRS virus maternal immunity? First of all we need to clarify how the passive immunity though PRRSV live vaccines... read more test →
Attenuated PRRS vaccines (Modified Live Vaccines) are not designed to pass immunity to the piglets, although they will. How do naïve animals response to PRRS vaccines? PRRS live attenuated vaccines do not produce high levels of circulating antibodies (IgG), which we want to find present in the colostrum (humoral immunity). In PRRS-negative animals the PRRS vaccines produce a weak serological reaction, although it allows cellular immunity development sufficient to... read more test →
The inoculation of PRRS live virus from the farm as a method to acclimatise the gilts has been used extensively with positive results provided that: It can be done on isolation as not to disturb the stability of the farm. It can be done early enough to have at least some 6 weeks so the PRRS infection produced has the time to cool down. But keep in mind that it... read more test →
Unfortunately, the PRRS intranasal immunisation route does not provide advantages, but disadvantages, with respect to the intramuscular route. PRRS intranasal vaccination: Disadvantages Long ago, based on the experiences with the vaccination against Aujeszky's disease and the good results obtained with the intranasal vaccination when the maternal immunity interference was to be overcome, the use of the same route to protect the animals against the PRRS virus was pondered over.... read more test →
When talking about PRRS vaccination, it's always better to do a blanket vaccination 3 times a year. The reason of this is directly related to the goals we want to achieve when vaccinating against PRRS. What's the aim of PRRS vaccination? The objectives of every PRRS vaccination protocol are the following: to avoid PRRS virus circulation among sows. to prevent reproductive failure in sows to avoid, as a... read more test →
As many other infectious agents, PRRS virus will benefit when stressors are affecting the pigs as their immune capacity will be reduced, thus helping the virus to infect. PRRS virus and environmental factors Some published work describes the most severe increase in nursery mortality rate occurs in winter months confirming also the interaction between PRRS virus and environmental factors (Stevenson et al., 1993). Low room temperature Increased thermal... read more test →