Antibiotic use at weaning can reduce acute illness in pigs

The transition into the nursery phase for just-weaned pigs presents many challenges as they adapt to a new diet, a new environment and increased competition. Combine these stressors with exposure to bacterial pathogens such as Streptococcus suis and Haemophilus parasuis, and young pigs often need some extra help.

“Industry practice is to control respiratory disease in young, growing pigs with an antibiotic treatment at weaning,” said Joel Steckelberg, Iowa State University veterinary student. “I wanted to compare the effectiveness of two antibiotics, ceftiofur and enrofloxacin, on early wean-finish pig health.”

His study involved a 3,100-head sow farm that weaned pigs negative for porcine reproductive and respiratory syndrome virus (PRRSV) but with a high incidence of S. suis-related pneumonia and post-weaning septicemia.¹

Pigs from 325 litters were weaned, on average, at 24.5 days of age, weighing 13.4 pounds, and were placed into pens of 54 pigs. The pens were randomly assigned to one of three treatment groups: ceftiofur (Ce), 1,275 pigs; enrofloxacin (En), 1,289 pigs; and negative control (NC), 1,280 pigs.

Steckelberg collected oral-fluid samples when pigs were enrolled in the study and again at its conclusion (5 weeks after the last pigs were enrolled). Two mortality spikes occurred and were investigated diagnostically.

A contract grower, blinded to the treatment groups, recorded mortalities, treatments and pulls into hospital pens. Individual pig care (IPC) scores were applied on days 2, 7, 11, 21 and 35 post-weaning. This was done to determine the percentage of acute (A), subacute (B) and chronic (C) pigs for each treatment group (Table 1).

To provide perspective of the pigs’ health profile, Steckelberg noted the following:

• Oral fluids collected at placement were negative for PRRS and influenza-A virus of swine (IAV-S).
• Tissue results from the first mortality spike showed all treatment groups had suis septicemia and were negative for PRRS and IAV-S.
• Oral fluids tested for the second mortality spike were positive for IAV-S.
• Oral fluids collected at the study’s conclusion were negative for IAV-S, and eight out of 12 samples were PRRSV-positive after vaccination (Fostera PRRS) 1 week prior.

The mortality percentage, as well as pigs in the hospital pens, were not statistically different among the three treatment groups, as shown in Table 1, Steckelberg noted.

In this flow, antibiotic treatments at weaning had no significant effect on early wean-finish mortality and recorded mixed results on morbidity when previously healthy pigs faced S. suis challenges.

“Groups that received antibiotics at weaning did have a significant reduction in acutely sick pigs,” he added, “thereby showing some health improvement during the early wean-finish phase.”

¹ Steckelberg J, et al. Evaluation of antibiotics at weaning on swine respiratory disease in early wean-finish phase. Student Seminar, 49^th American Association of Swine Veterinarians’ Annual Meeting. 2018;73-74.