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PRRS: Reduce Risks

When a swine disease strikes, you want helpful information immediately. Fortunately, there’s SOURCE, a systematic approach to disease control, prevention and management using a step-by-step process developed by Boehringer Ingelheim.

The fourth step in the PRRS SOURCE process is “reduce risks.” Reducing the risks of PRRS transmission (both within the farm and from introduction of the virus from outside the farm) can be a challenge, but there are things you can do.

Once you’ve reviewed the risks that are associated with PRRS on the farm, work closely with your herd veterinarian to develop a customized plan to meet your PRRS goal. Biosecurity protocols are targeted at reducing transmission risks and typically fall into one of three categories:

  1. Hygiene/Sanitation
  2. Separation
  3. Exclusion

Internal risks

Understand internal risks in order to minimize transmission and maximize immunity to reduce persistent virus circulation within the farm.


  • Do not cross-foster pigs for these reasons:
    • Size
    • Saving sick, small or poor-doing pigs
    • Evening out piglet numbers
  • Cross-foster only for available teat space, ideally only in cases of sow mortality or sows that stop nursing
  • If possible, cross-foster only during the first 24 hours post-farrow
  • Keep as many piglets on the birth sow as possible
  • Manage farrowing rooms using an all-in/all-out protocol
    • Do not move pigs or sows between rooms
    • Do not hold pigs back at weaning
    • Follow strict all-in/all-out protocol and leave two to three days for cleaning, disinfection and drying out rooms
  • Piglet handling:
    • Evaluate all procedures for their effect on clinical disease and transmission, and minimize non-essential handling
    • Practice proper farrowing house hygiene – change/disinfect needles, gloves and processing equipment between litters
    • Immediately and humanely euthanize pigs that are unlikely to recover


  • Do not conduct feedback to gestating females
  • Enhanced sow farm sanitation
    • Wash and disinfect hallways post-weaning prior to loading farrowing rooms
    • Structure people movement so flow is from the youngest piglets to oldest piglets in farrowing

External risks

Understand external risks to minimize transmission and maximize immunity to reduce external virus introduction/re-introduction from outside the farm.

Status of replacement animals

+ Positive: If replacement animals have tested positive for PRRS, they should only be introduced to 1) herds where PRRS exists and are in a program to control the virus, or 2) vaccinated breeding herds that are in a PRRS control program and are actively vaccinating to develop uniform immunity.

- Negative: For farms trying to eliminate or prevent PRRS in their herds, any replacement pigs introduced to the herd must test negative for the virus.

? Unknown: If the status of replacement pigs is unknown, the current status can be obtained through diagnostics.

Quarantine period

  • Introducing animals to a new location can be a risk. It is important to know the current status of replacement animals or pigs moving from the nursery to the grow-finish phase.
  • It may be useful to quarantine animals for at least three weeks before they are introduced to the rest of the herd.
  • If any symptoms of PRRS appear, contact the farm’s veterinarian immediately.


Entry Protocols:

  • Downtime

Personnel should practice one night of down time before entering a farm.

Research has shown that extended periods of down time are not necessary for PRRS.

  • Shower in – shower out

Shower protocols have been proven to successfully decontaminate personnel contaminated with PRRS virus prior to entry. Showering upon entry to the system each day is recommended.

  • Danish entry system

This system utilizes the changing of coveralls and boots plus the washing of hands in designated areas prior to entering the animal air space. This has been demonstrated to be very effective for reducing the risk of PRRS virus spread by personnel between sites and buildings.


  • Gloves

The use of gloves can help prevent transfer of virus. Gloves should be changed regularly (i.e., between litters).

  • Sanitizers and hand washing

Frequent hand washing and use of sanitizers that contain iodine can successfully remove virus from hands.


  • Barn-specific coveralls should be available in all facilities and washed routinely.
  • Disposable coveralls are also an option.


  • Footbaths

Use of footbaths can greatly help reduce the risk of PRRS virus transfer between groups of pigs. Baths should be changed at least every day to maintain disinfectant efficacy. Chlorine bleach, as well as disinfectants like Synergize and Virkon are effective (Follow all label directions.)

  • Disposable or facility-specific books

Disposable or facility-specific boots should be used. Boots should never leave the farm, should be powerwashed to remove feces from the soles, and should be disinfected routinely.

  • Once on a farm, park away from both the pigs barn(s) and the waste control area. Avoid parking or driving in muddy areas. Keep windows up to prevent pests from entering the vehicle.
  • Know where the Line of Separation (“clean/dirty line”) is on the farm. If the farm visit requires being both inside and outside of the farm, perform all inside-the-farm duties prior to going outside of the farm.
  • Do not bring any food or drink onto the farm.
  • Following the farm visit, contain all garbage, clothing and used equipment in a garbage bag, and place away from clean supplies.
  • Remove dirty boots and coveralls, and clean hands with hand sanitizer.
  • Wash and disinfect the outside of the vehicle, and remove any mud or debris from inside of the vehicle.
  • Once at home, launder all clothing and footwear and shower.
  • Avoid ALL unnecessary human traffic.

Synergize is a trademark of Synergy Technologies, Inc. Virkon is a registered trademark of E.I. du Pont de Nemours and Company or its affiliates.


  • Any vehicles arriving at the farm from outside of the farm should not cross the Line of Separation (“clean/dirty line”). This includes any market or feed trucks, as well as personal vehicles, unless following a biosecurity protocol.
  • The load-out area should be at the Line of Separation, so that the pigs remain ‘inside the farm’ until loading onto the truck, which remains ‘outside the farm.’
  • Do not allow live-haul vehicles to enter farm without a thorough cleaning and disinfection.
  • Prepare the market truck by cleaning and disinfecting all areas of the truck between loads, including the cab of truck (pedals, floor mats, steering wheel, etc.).
  • Clean and disinfect all equipment, including sort-boards, rattle paddles, etc.
  • Clean boots and coveralls should be worn for each load, and once worn, should be stored in a separate area until they can be laundered.
  • No human foot traffic, including the truck driver, should ever cross the Line of Separation (from either direction).
  • Ensure adequate manpower is available to load the pigs.
  • Do not allow pigs to exit the truck during the load-out process.
  • All clothing and boots worn to load pigs should be laundered.
  • The load-out area should also be cleaned and disinfected immediately after the truck has pulled away.
  • All transportation-related risk reduction factors should be addressed in a farm biosecurity protocol that all employees are trained to understand and implement.


  • Proper sanitation is critical to limit the spread of the PRRS virus. Proper sanitation includes a hot-water wash, disinfection and adequate drying time.
  • Most virucidal disinfectants are very effective against PRRS virus. Commonly used disinfectants include Synergize and Virkon applied at a 0.8% and 1% concentration, respectively, for a minimum of two hours. (Follow all label directions.)

Synergize is a trademark of Synergy Technologies, Inc. Virkon is a registered trademark of E.I. du Pont de Nemours and Company or its affiliates.


  • If nearby farms (within 2 to 4 miles) have tested positive for PRRS, enlist stringent biosecurity measures for any persons or vehicles entering the farm.
  • Designate a clear Line of Separation – or a line that separates “inside the farm” from “outside the farm.” This should not be crossed by persons, animals, vehicles or equipment without them being cleaned and disinfected properly.


  • Ensure that any semen has tested negative for PRRS, and/or the boar stud/semen supplier is routinely testing boars to validate PRRS-negative status.

Environmental surfaces and fomites

  • Disinfect all incoming farm supplies

Allow a minimum of two hours for items to be in contact with disinfectant before introduction to facilities

  • Use a specific room for disinfection and drying (D&D room)


  • Install screens over all inlets, windows or areas that could be accessed by insects and/or rodents, and clean screens regularly
  • Consider using insecticides or rodenticides – pyrethrin-based products are highly effective against insects and commercially available as sprays or washes – and/or insect bait
  • Cut the grass, remove weeds and eliminate standing water surrounding the facilities to get rid of insect/rodent breeding areas

Manure handling

  • PRRS virus can survive in lagoon effluent for up to three days at 20 degrees C (68 F) and for seven days at 4 degrees C (39 F). Contact with PRRS virus-positive effluent can serve as a source of infection to naïve pigs. Therefore, producers who utilize recycled lagoon water may be at higher risk for external virus introduction than those who use deep pits.
  • When scheduling a manure hauler, share biosecurity protocols for the farm with them.
  • Explain where the Line of Separation is on the farm and that manure haulers should not cross that line.
  • Do not allow manure-hauling crew to enter the barns, office areas or come in direct contact with the pigs.
  • Farm personnel should avoid any direct contact with the crew and pumping equipment.
  • If farm personnel must cross the Line of Separation, clean boots, coveralls and gloves should be and then disposed of once used.
  • Clean and disinfect any reusable gear that came in contact with the pumping crew or equipment.
  • Consider providing a water source away from the farm for the manure hauler to use when cleaning their equipment before leaving the farm.


  • PRRS virus can be inactivated through the process of composting or incinerating carcasses. Therefore, only these methods should be applied. Rendering trucks should never be allowed to drive onto farm premises if possible.
  • The Animal Disposal Unit (ADU) should be located away from other livestock and should not allow access by wildfire.
  • Transporting dead animals (mortalities) to the ADU should be the last task of the day, and they should be brought to the Line of Separation so those outside of the farm do not have to cross the line to access the mortalities.
  • Wear designated coveralls and boots when handling mortalities.
  • Any tractor or truck equipment used to move mortalities should be washed, disinfected and dried before use.
  • Once mortalities are placed in the ADU (without crossing the Line of Separation), equipment must be washed and disinfected again, and clothing and boots should be removed, laundered and stored away from livestock areas.

Airborne spread

  • Install air filtration systems. (Consider budget, site location, level of acceptable risk and type of production system.)
  • Seal all potential air leaks; cracks in building or around windows, doors, shutters and idle fans
  • Install ‘double door’ entry/exit systems

Shared equipment

  • Any equipment shared with neighboring farms should be cleaned and disinfected each time it arrives at a different farm to limit the spread of the PRRS virus via manure, pests or debris.