Antibiotic usage on pig farms - an explanation
15th Oct 2016 / By Dr Georgina Crayford
There is currently a great deal of attention on how pig farmers use antibiotics, with some calling for an end to the ‘unacceptable’ routine preventative mass-medication of animals.
While the pig industry is making progress on reducing its antibiotic use and fully accepts more needs to be done, we feel the need to point out that some of the statements being made are based on misconceptions of what happens on farms.
Pigs are usually penned in groups and as such it is often necessary to treat pigs at the group level to successfully manage infections. Some may refer to this as ‘mass medication’, which sounds more alarming than it is. Group treatment is achieved through administration of antibiotics in feed or water. However, where appropriate, pigs can also be treated individually using injectable antibiotics.
Group treatment is used by vets for either ‘prophylaxis’ or ‘metaphylaxis’. Metaphylaxis is when a group of animals is treated following identification of clinical signs of infection in one or a few animals within the group. The whole group is treated because all of the animals are at risk of infection, indeed some may already be infected but not yet showing symptoms.
This approach is also used in human medicine, for example if a school child is diagnosed with bacterial meningitis, the other children in the class will be treated with antibiotics even if they are not showing symptoms in case they have already been infected.
Prophylaxis, also known as preventative treatment, is when animals are given antibiotics in the absence of disease, to prevent them becoming ill. Sometimes this is necessary for example when there is a known history of a certain bacteria affecting pigs on a unit.
Routine preventative treatment should be avoided by farmers and their vets by addressing the underlying disease problem through control measures such as improved biosecurity. However, some bacteria are particularly tenacious and difficult to eliminate.
Penicillins and tetracyclines constitute the bulk of antibiotic sales for use in livestock in the UK. Sales of fluoroquinolones and 3rd/4th generation cephalosporins (both classed as critically important antibiotics for humans) are very low in the UK, representing just 0.9 per cent of total sales combined.
There are some fluoroquinolones antibiotics available for administration through drinking water, however none of these are authorised for use in pigs and none are authorised for administration in-feed either.
Similarly, no 3rd/4th generation cephalosporin antibiotics are available as an in-feed or in-water formulation, meaning these last-resort antibiotics are only ever administered to individual animals.
In the UK, all antibiotics licensed for use in animals are classified POM-V medicines. This means they can only be prescribed by, and used as directed by a veterinarian.
As we never tire from saying, we are fully committed to addressing the antibiotic challenge. But we must balance this with protecting the health of our pigs.