In the latest issue of Pig World, Lysan Eppink, Boehringer Ingelheim Animal Health UK and ROI’s swine veterinary adviser and president of the Pig Veterinary Society, offers advice on preventing flu in pigs.
Winter has arrived and as usual the (human) winter bugs, including influenza seem to be doing the rounds.
In pigs, influenza is not uncommon either and diagnosed all year round with a lift in winter and spring. The pig surveillance dashboard (results from SRUC and APHA lab submissions) not unexpectedly show that the most common sign of influenza infection is respiratory disease (about 63% of all cases since 2020), followed by animals wasting or found dead (both around 14%).
It can also cause reproductive problems (that can look a lot like PRRSv!), especially in herds where a strain is re-introduced.
Like PRRSv, influenza undermines the immune responses, sometimes resulting in secondary infections that can be more difficult to control than either infection on their own.
These secondary infections, combined with the fact that influenza is only shed for a three- day period, can make the diagnosis of influenza challenging. For that reason, it is important to call your vet as soon as the animals show signs of respiratory disease (lethargy, sneezing, coughing, reduced feed intakes and red eyes amongst others) so that samples are most likely to contain the virus.
A free testing service is available for nasal swabs (for samples submitted via SRUC and APHA) that includes further tests, if positive, to determine the specific strains. The information gathered is used for horizon scanning surveillance, so we know sooner rather than later if something has changed or something new has arrived, which, in turn, will help with the development of new control tools.
Another diagnostic test could be to look for antibodies, but that can take more time and be more difficult to interpret, especially when vaccinating.
Control of influenza depends on reducing the overall amount of the bug and circulation between different stages, preventing new strains coming in (including those from humans) and optimising the resilience of the animals, all part of a sound biosecurity protocol for any infectious pathogen.
To optimise the immunity and thus resilience, vaccines are a great help. But to get most out of the available vaccines, you need to make sure you are using the right one since not all strains are included in all vaccines.
Another reason to test as soon as you suspect your pigs might have influenza. It is also important to include all animals on site to make sure there is no safe space for the virus to hide. This includes ensuring incoming animals get enough time (in quarantine) to be tested, vaccinated and develop immunity for the relevant pathogens for your herd, before introduction into the herd.
Influenza does not need to be a big problem but, left to its own devices, it might very well cause a lot of trouble. As always, prevention is better than cure, so make use of the government-funded pathway visit and talk to your vet about preventative health plans.