Impact of control options for Streptococcus suis and Haemophilus parasuis

Helping piglets make a smooth transition at weaning is always a priority, but bacterial pathogens such as Streptococcus suis (Strep. suis) and Haemophilus parasuis (H. parasuis) can make that goal particularly challenging. Not only do the pathogens negatively impact the piglets’ health and well-being but also the farm’s overall productivity and costs.

Working with Iowa Select Farms, Matt Finch, a second-year veterinary student at Iowa State University, carried out a study to compare the efficacy of a ceftiofur crystalline free acid (CCFA) treatment at weaning with an autogenous vaccination program and an untreated control group.1

The study’s first objective was to evaluate the treatments’ impact on piglet mortality and individual weights from piglet processing to 7 weeks post-weaning, Finch told Pig Health Today. A secondary objective was to evaluate the number of pigs needing antibiotic treatment post-weaning.

“This study is insightful not just because of production efficiencies and animal health but also because of the implications on responsible antibiotic use,” Finch said. “There has been increased consumer push-back on antibiotic use, and as swine veterinarians we need to be aware of antibiotic use.”

Two sow farms

Two sow farms from pig-dense central Iowa were selected for the study. Farm A was a 4,000-head, porcine reproductive and respiratory syndrome (PRRS) provisional-negative sow farm. Farm B was a PRRS-positive unstable, 4,300-head sow farm. Both had a confirmed history with Strep. suis and H. parasuis, including associated mortality. Finch further confirmed the pathogens’ presence through pig observations, necropsy evaluations and veterinary diagnostic laboratory testing.

Finch selected three of the most uniform gilts and three barrows from each litter farrowed at the farms for a designated week. The gilts and barrows were assigned to one of three treatment groups:

  • Autogenous vaccine, which included Strep suis Types 2, 1, 4, 27, and parasuis Type 4, given as 1-mL intramuscular (IM) injection in the neck at processing (day 2 to 4) and at weaning (day 18).
  • CCFA given as a 0.3-mL IM neck injection at weaning.
  • Control which received no treatment.

“I administered the treatments and new syringes were used for each treatment,” Finch noted. “Needles were changed every 10 pigs.”

Piglet enrollment

At weaning, the two pig flows (farms) were placed into separate but similarly designed wean-to-finish barns and received the same feed rations.

In the end, the pigs involved in each treatment group by farm broke out as follows:

 

Autogenous vaccine

CCFA

Control

Farm A

230 pigs

230 pigs

229 pigs

Farm B

322 pigs

322 pigs

320 pigs

 

Notably, Farm A had fewer pigs in the final enrollment because some piglets received an antibiotic treatment and had to be removed from the study. “This taught me a good lesson about communication,” Finch acknowledged, “especially when you need to rely on others in the field.”

The data collected included individual pig weights at processing, weaning and 7 days post-weaning. Mortality and any individual pig treatment, in accordance with the system’s standard of care, were recorded daily.

Final outcome

Once the data was collected and analyzed, the results showed no significant difference in mortality or final weights between treatment groups for pigs from either Farm A or Farm B, Finch noted.

There was a significant difference in the post-weaning antibiotic treatments for Farm A with the CCFA pigs receiving fewer treatments. This difference was not observed in pigs from Farm B.

 

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“Both were high-health farms, which may have contributed to the limited response of CCFA and the autogenous vaccination program,” Finch said.

Still, the data did show that by giving CCFA at weaning, the farm was able to reduce post-weaning treatments. “This response correlates to improved pig health, decrease labor associated with individual pig treatments and, ultimately, supports responsible use of antibiotics,” he concluded.


1 Finch M, et al. Evaluation of the efficacy of ceftiofur crystalline free acid versus autogenous vaccination for control of Streptococcus suis and Haemophilus parasuis in a commercial swine production system. Student Research, 50th American Association of Swine Veterinarians’ Annual Meeting. 2019;109.