Sows and gilts with active or recent infections are more likely to shed a virus or bacteria to offspring. The goal of sow herd stabilization is to reduce that exposure.

Three key considerations for evaluating sow herd stability are: biosecurity and parity distribution, isolation and acclimation protocols and vaccination programs.

1. Biosecurity refers to ways to reduce disease introduction. Minimizing disease risk helps stabilize the immune status of swine units. Know what diseases are present on your farm, isolate new breeding stock after arrival, purchase breeding stock from one source, and use different boots and coveralls after sending cull animals or going to markets.

Also, minimize farm visitors, shower before entering the unit and establish traffic patterns to reduce exposure to disease-causing agents.

A written and well-defined biosecurity plan helps reinforce the importance of curbing disease entry.

2. Incoming animals are isolated to minimize disease introduction; 60 days is recommended. Acclimation ensures new introductions will be exposed to existing disease problems. Expose replacement gilts and boars to cull breeding stock to expose them to farm pathogens. Manure feedback and vaccination also are common practices.

Vaccination programs are important tools to help boost immunity in replacement animals. Each farm will have different needs based on location, disease loads, weaning age, immunity of the source farm and the perspective of the owner/manager.

First, assess what diseases are present. Serology or blood testing can help establish this information. Routine sow herd monitoring and the isolation/acclimation (I/A) area can ensure gilts have proper immunity.

Case Study No. 1

I was called to a 1,500-sow gilt multiplier. The farm had some respiratory disease and a chronic finisher cough. The breeding and gestation areas seemed to perform well. But sow herd stability was questioned. There were no isolation protocols. Blood samples were drawn in the sow herd and finishing herd from which replacements were selected. PRRS (porcine reproductive and respiratory syndrome) and Mycoplasmal pneumonia titers were identified in late finishing. The sow herd had very low titers.

I recommended finding an isolation area for the finishing gilts. Because the PRRS titers were high, there was increased risk to the sow herd to take them directly into the gestation barn. We planned to remove the gilts at 180 lb. and move them offsite to allow time to build up natural immunity. Cull sows were taken to expose gilts to any other farm diseases. Gilts were vaccinated for parvovirus and leptospirosis, mycoplasma and PRRS in the isolation area.

In larger herds or where multiple gestation barns are available, we recommend housing gilts and first-parity females together and second parity and older sows in other gestation barns. In isolation areas, vaccination protocols and housing similar-aged animals together all help to lower the challenge or disease exposure to other herd mates. By decreasing this exposure you help minimize disease risk to other sows and offspring.

Case Study No. 2

I was called to a 1,200-sow, farrow-to-wean farm to evaluate some off-feed gestating sows. They were coughing and had fevers of 105F. The number of abortions increased from the previous week, and many lactating sows were also feverish. Many sows had a nasal discharge and a very characteristic barky cough.

I took blood samples and nasal swabs from sows with temperatures more than 105F. Blood samples showed very high antibody titers for the H3N2 strain of swine influenza virus (SIV).

We isolated SIV from nasal swabs. The entire breeding herd was placed on aspirin in the drinking water to help combat the fevers and get the sows eating. An autogenous SIV vaccine was made from the H3N2 farm isolate and used on the entire breeding herd. It was given twice in I/A for incoming gilts to increase the level of protection for SIV.

By blanket vaccinating the herd and ensuring that gilts are previously exposed and vaccinated for SIV, the sow herd becomes less active for SIV and more stabilized.

Sow herd stabilization is an important part of a herd health plan. Routine monitoring of the isolation area helps to ensure that gilts have been exposed to important pathogens on the farm.

Monitoring the sow herd through blood testing and observing for clinical signs of disease will help determine the success of the stabilization strategy. The goal of disease stabilization is to prevent clinical disease in the swine unit to minimize negative effects on production.

Contact your veterinarian to discuss sow herd stabilization and how to implement your herd health plan.