Minimal disease pigs

Minimal disease (MD) pigs are pigs that have been separated from their sow as piglets and reared in total isolation from other non-MD pigs.

Piglets that are reared in total isolation from their sow and all other non-MD pigs will not become infected with certain disease-causing organisms (pathogens) that are normally present in pigs.

MD pigs are expected to be free of:

• enzootic pneumonia
• pleuropneumonia
• swine dysentery
• external parasites
• internal parasites.

Removal from litter

The term 'minimal disease' can only be applied to pigs that have been obtained by:

• surgical removal of the entire uterus or caesarean section
• snatch farrowing – removal of piglets as they are born
• medicated early weaning – suckling piglets that are removed 5 days after birth and subjected to a course of antibiotics before and after weaning.

Keeping diseases out

The most important factors for preventing introduction of new diseases in MD piggeries are:

• Location – MD piggeries must be at least 3km from other piggeries to prevent airborne diseases.
• Closed-herd approach – use artificial insemination, or isolate incoming replacement stock sourced from higher health-status herds with a quarantine period.
• On-farm conditions – good management of hygiene, pest control, load-out and building design, staff and visitor movement, medication and vaccination prevent diseases from being introduced.

Diseases not excluded

MD pigs are not guaranteed to be free of all diseases. Piglets derived by hysterectomy may contract and survive parvovirus or leptospirosis in the uterus.

Pigs derived by hysterectomy may also suffer common diseases including

• erysipelas
• baby piglet scours
• weaner scours
• oedema disease
• ileitis.

MD pigs have no background immunity, which makes them more likely to be severely affected if exposed to common diseases than conventional pigs.

Stocking a new piggery

When establishing a new piggery, it is strongly recommended to stock it with MD pigs.

Before purchasing stock, check prospective suppliers for:

• confirmed absence of diseases
• method of establishing disease-free status
• health monitoring routines.

Gnotobiotic pigs

Gnotobiotic pigs are pigs that are reared in a virtually sterile environment and are used for research work only. They have no application in commercial pig farming.