Keeping Pigs

CHAPTER 3

BIOSECURITY

The Code of Practice describes biosecurity as 'a set of management actions and physical measures designed to reduce the risk of introduction, establishment and spread of disease to, from and within the pig herd'.1

Many smallholders aim for a natural level of immunity and don't like to obsess over biosecurity practices. However, it is important to note that the introduction of disease on to a holding, for example by buying a pig carrying an infectious disease, is actually quite unnatural and can have very severe consequences. As an example, many keepers who have inadvertently brought lice on to the holding, thought of as a fairly mild disease in the plethora of available options, will never be able to eradicate it fully, leading to whole herd injections every few months. This is far from natural! Therefore we encourage smallholders to take biosecurity seriously. We agree: your own pigs' dirt is good, but sudden exposure to high levels of disease from other holdings should be avoided.

MOVING PIGS ON TO A HOLDING

To prevent the introduction of disease on to a holding, most commercial pig-breeding farms operate a closed herd. This means that no new pigs come on site, and new bloodlines enter in the form of tubes of boar semen (which is tested for infectious disease). Many will have operated this system for seventy years or more, and an élite few will genuinely be free from our most worrisome pig diseases. The rest will just be stable in their own diseases and no longer suffer badly from them.

Sue and Stephen's isolation area, on a hard standing away from other pigs.

Most smallholders, however, will require pigs to enter the holding, and therefore an isolation (quarantine) area for new pigs becomes really important. For those showing pigs, this is crucial. Correct utilisation of an APHA-approved isolation area means that your entire holding does not need to go into standstill every time you return pigs from a show. Remember that without this, when a pig enters a holding, no pigs must move off the holding for the next twenty days.

New pigs entering a holding, or pigs being reintroduced on to a holding, should spend at least two weeks in an isolation area before mixing with the rest of the herd. This is so that the pigs can be closely monitored for signs of disease before being introduced to your pigs.

An isolation area should be on a hard standing, so that it can be thoroughly cleaned and disinfected between uses, and at least three metres away from other pigs. Isolation areas should have dedicated personal protective equipment in the form of a boiler suit, wellies and gloves. At the very least, attend to the area last in the day, and thoroughly clean and disinfect boots and clothing afterwards.

Monitor isolated pigs closely for signs of disease such as coughing, diarrhoea, lameness, itching and difficulty breathing. If you see any of these symptoms, consult your veterinary surgeon before you admit these pigs into the main herd. This is one occasion where in-depth diagnostics, or return of the pigs, is warranted to avoid putting your own pigs at risk. If you see signs in one pig in the group, do not introduce any of the pigs until you have got to the bottom of the problem. There are several diseases for which pigs remain a carrier even after they have been successfully treated for the disease, therefore think very carefully before introducing a pig to your herd that has shown signs of disease, even after it has recovered.

The commonest complicating factor to the good practice of isolating pigs is the requirement for pigs to have the company of other pigs. This should only be relevant for breeding boars being loaned or returned. In an ideal world, all loan boars would pair with a castrated friend. If this isn't possible, keep hired boars in the next paddock from some other pigs. Choose a suitable group carefully, and ensure that the boar is secure so he can't pick a fight or breed with any of them. Don't allow nose-to-nose contact, but allow them to have a chat.

Before buying, verify the vaccination status of any incoming pigs. During the isolation period, make sure that the vaccines that incoming pigs have received are the same as those yours have received, and that incoming pigs will be covered from the diseases that you have on the holding. Vaccination courses often take more than two weeks, so it may be preferable to ask the previous holding to vaccinate the pigs for you. You should worm incoming pigs twice with an ivermectin wormer, two weeks apart. This will kill external and internal parasites, especially lice, which are a real nuisance when brought on to a holding. We discuss this more in Chapter 12, 'Parasite Control'.

Where isolation is not possible, you must be able to trust the source of incoming stock. This includes the holdings to which you loan your boar. Gain a thorough disease history from the holding, especially for parasites (internal and external), diarrhoea and reproductive problems. Be sure to ask for courses of vaccines and wormers to be completed before pigs arrive.

For those simply rearing weaners to go to slaughter, best practice may be more easily replicated. Commercial pig farms rearing pigs (often taking weaners through to finishing) operate what we call an all-in-all-out (AIAO) system in which the unit is emptied of pigs, fully cleaned, disinfected and dried before it is filled with pigs again. In this way, those buying yearly weaners can clean and disinfect housing and leave a paddock free from pigs for the next few months. Most pig pathogens will die in the soil after a few months so this should do a similar job to an AIAO system, especially over a cold winter. If the last group of piglets experienced diarrhoea, be sure to use a disinfectant that will kill coccidia.

HUMAN CONTACT

Remember to maintain as much human contact with isolated pigs as possible, especially brought in gilts, so that they remain, or become, easy to handle.

SWINE DYSENTERY

The disease swine dysentery is important to mention for smallholdings in this context. This bacterial disease causes diarrhoea (often bloody, but not always) and weight loss (or lack of weight gain). Pigs can die from dysentery, but they can also carry the disease with few clinical signs, infecting other pigs that they come across. The disease is devastating for holdings because it is so difficult to eradicate once it has taken hold. Therefore, preventing swine dysentery warrants particular attention when moving pigs on and off holdings. Show pigs have been highlighted as a specific risk for the spread of swine dysentery. The disease is so serious that holdings with it are encouraged to log this on AHDB's 'significant diseases charter'2 so that we can understand where it is in the country.

MOVEMENT OF PEOPLE AND OBJECTS ON AND OFF THE HOLDING

Whilst most diseases enter through incoming pigs, it is also important to consider incoming people and objects. Pathogens can sit in the tread of a wellington boot or in the tyre of a vehicle, and it may mean that you bring home more than you think. A line of separation between off farm and on farm allows you only to allow visitors and vehicles that you trust past this point. AHDB provides signage to make this clear to visitors.3 Collection of carcasses should take place, where possible, at the perimeter so that external vehicles do not enter the holding. A boot dip filled with clean disinfectant costs very little, gives an extra line of defence, and also lets incoming visitors know that you are serious about preventing disease on your holding.

Some of Pete's smallholders proudly displaying their AHDB biosecurity signs.

Sue and Stephen's diligently completed visitors' book.

Ask that visitors wear clean clothes and wellies after being with other pigs, and where possible, ask that visitors haven't been near their pigs that day. Any visitors to the holding should sign a visitors' book. This is so that notifiable disease can be traced if it occurred. Red Tractor states that this should display:4

the date of the visit

the name of the visitor and the organisation if relevant

the purpose of the visit

the date of the last contact with pigs

confirmation that the person hasn't experienced vomiting, diarrhoea or flu-like symptoms in the last twenty-four hours

OTHER PRECAUTIONS

Movement Within the Holding

On the holding, different aged pigs should be kept separate where possible. It is best practice to move from the youngest piglets to the oldest pigs through the day, as piglets are less resilient to disease. Pay particular attention when moving from a sick pig that might have an infectious disease back to the main holding, and clean and disinfect where appropriate.

Human Safety

As covered in Chapter 9, 'Diseases of Pigs', pigs can transmit diseases to humans, and vice versa. Wash your hands thoroughly after tending to pigs, especially before eating, and wear gloves if they are showing any signs of disease. Pigs and humans can catch the same type of flu virus, so if you have flu, don't go near pigs as you may infect them.

Notifiable...