Streptococcus suis will be experienced by virtually every production system.

It can be referred to as an old problem, but it continues to cause significant losses in today's swine industry.

Whether it's joint infections in young pigs or sudden death loss in the finisher, Strep suis has the ability to steal significant profits from an operation.

Case Study No. 1

This farm is a 2,500-sow, farrow-to-wean operation that was recently remodeled to sell weaned pigs exclusively.

Originally, this was a feeder pig operation with on-site nurseries, but the owners decided to expand the sow herd. They converted nurseries into farrowing and added a few gestation stalls. They contracted with four producers to purchase their weaned pigs for a fixed price. Extra gilts were purchased as part of the expansion.

As production ramped up and the number of gilt litters increased, the number of pigs rejected by the growers increased. The rejection rate started at 1 to 1-Ω% and increased to nearly 4%. This represented almost 40 pigs each week the producer was not being paid for.

In investigating the cause of the problem, I reviewed the past four weeks of delivery grade sheets with the producer. The reports indicated that 75% of the pigs were rejected due to swollen joints and lameness.

As we observed the pigs in the farrowing crates, it was evident that there were an unusually large number of swollen joints. I reviewed piglet-processing techniques with the staff, and found that they were using the same clipping tool for the teeth and the tails without disinfecting between pigs. I recommended that they use different tools for each and disinfect the clipping tool in a diluted chlorihexidine solution.

We also discussed the possibility of not clipping needle teeth at all. Many farms have successfully used this approach to reduce joint and navel infections.

I submitted three joint swabs from affected pigs to the laboratory for culture, and a Strep suis and a Strep equulii were isolated.

The farm followed the recommendations to discontinue clipping needle teeth and also instituted an antibiotic injection at processing. The rejection rate due to swollen joints quickly returned to normal.

Case Study No. 2

The second farm's experiences were similar to those of the first farm. Except in this case, when we tried reviewing processing techniques, injectable antibiotics, changing disinfectants and anything else we could think of, nothing seemed to work.

We then formulated an autogenous Strep suis vaccine that was isolated from the joints of the infected pigs. This vaccine was administered to the sows at three and five weeks prefarrowing. As these vaccinated sows and gilts began to farrow, there was a marked improvement, and now, over a period of six months, the farm has returned to a normal rejection rate.

Case Study No. 3

This case deals with a 2,400-head finishing barn that receives pigs every 18 weeks from a contract-farrowing unit. Pigs are about 45 lb. on arrival and are marketed at an average of 260 lb. The barn is managed all-in, all-out. Death loss is typically 2-3%.

This particular group of pigs started well and was averaging 60 lb. when the barn manager called our veterinary clinic because three pigs died suddenly the previous day and four died suddenly overnight.

Postmortem examinations of the pigs did not show anything significant, so tissues were collected and submitted to the laboratory for culture. The next day the lab reported that a pure culture of what appeared to be Strep suis was isolated. In the meantime, the barn manager called and said that six more pigs died overnight.

We recommended that the producer inject all pigs in the room with procaine penicillin G. The individual pigs were not showing signs before dying, so our only choice was to treat the entire group. Death loss immediately stopped and that flow of pigs never experienced that type of outbreak again. The laboratory later confirmed the isolation of Strep suis.


Strep suis is an ever-present organism that waits for an opportunity to cause problems. Control can sometimes be as simple as basic sanitation and adjusting procedures.

However, sometimes control can be a challenge, and more aggressive methods are warranted.

Either way, a thorough investigation and proper laboratory workup are helpful to sort out specific causes and intervention methods.

Nurseries are probably the stage of production where Strep suis causes the most losses. But each farm and case is different. Your local veterinarian is the most qualified person to help sort out the causative factors and formulation of preventative protocols.