During their productive life, pigs are frequently exposed to infectious bacteria that cause respiratory and digestive diseases resulting in a significant economic impact for the swine industry.

Medication for the prevention of disease, including nervous, intestinal and respiratory infections is common in many countries, including Ireland. But antimicrobials in food animals have become a scientific, political and public concern.

The safe use of antimicrobials is part of Ireland’s National Action Plan on Antimicrobial Resistance 2017-2020 (INAP). The plan, and proposed legislation, means changes to the pig industry.

Vets and farmers are encouraged to reduce the amount of antibiotics given (especially in feed) and discouraged from using certain types of antibiotics (deemed critically important).

There is increased pressure to change the practice of treating large batches of animals (prophylaxis) and smaller groups of in-contact pigs (metaphylaxis). The ban on the therapeutic use of zinc oxide in farmed animals, including pigs, will come into effect under European legislation by June 2022.

Animal Health Ireland recommends the adoption of preventive measures. It is useful to generate herd health plans that include pest controls, vaccination, biosecurity and disinfection. In the presence of on-farm disease, specific vaccination programmes result in economic benefits as they prevent and/or control subclinical and clinical disease development.

Widely prevalent in Ireland

The most common grow-to-finish intestinal disease is enteropathy, also known as Ileitis, caused by Lawsonia intracellularis, a bacterium which is widely prevalent in Ireland. Infection is spread via the dung, with affected pigs continuing to shed the bacteria for up to 12 weeks.

The presence of Lawsonia in the gut prevents normal cell development and results in permanent thickening of the intestinal wall. Consequently, infected pigs suffer from poor growth rates and feed conversion efficiency reduction and, importantly, pig weight variability as a result of malabsorption of nutrients in feed.

Ileitis can be controlled to some extent with in-feed antibiotics and zinc products, but on farms where such products are no longer acceptable or become unavailable, Lawsonia vaccination can reduce the infection pressure.

The use of a new intramuscular vaccine for Lawsonia has been proven not only to reduce the duration of shedding of bacteria in the faeces, but also to reduce losses in average daily weight gain and mortality rates.

Following vaccination, the duration of immunity is at least 20 weeks, giving protection throughout the growing period. Studies in both Denmark and Australia have shown that vaccination reduced the use of antibiotics and antimicrobial products to control Lawsonia infection.

Vaccination will be necessary more than ever to overcome the expected increase in the incidence of Lawsonia caused by antimicrobial restriction in the coming years.

The proven benefits of vaccination include better feed conversion efficiency and increased growth rates but equally significant are reduced pig weight variability following reduced antimicrobial usage in many farm studies.

More information

Further information is available from your veterinary practitioner or MSD Animal Health, Red Oak North, South County Business Park, Leopardstown, Dublin 18, Ireland.

MSD Animal Health can be contacted at: 01-2970220; or emailed at: [email protected].