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PIC International Animal Health IPVS Symposium 2010

Mycoplasma hyopneumoniae Elimination in a 3800 Sow, Multi-Site System

Jerome 0. Geiger1, Doug Groth2
1PIC, 100 Bluegrass Commons, Hendersonville, TN, 37075 2Carthage Veterinary Service


Introduction

Mycoplasma hyopneumoniae (Mh) was successfully eliminated from a 3800 sow multi-site system. Several elements were considered important to the successful elimination: stabilization of the sow herd’s immunity, segregation of all nursery/finishing animals, strategic use of antibiotics in the sow herd and neonates, complete depopulation of the nursery/finisher facilities, one-directional pig flow, and strict control of people traffic.

Materials and Methods

A 3800 sow multi-site production system was stocked and operating >5 years as Mh negative based on monthly serology, clinical signs and post-mortem examinations. The system was also negative for Porcine Reproductive and Respiratory Syndrome (PRRS). Breeding, gestation and farrowing occurred on Site 1. A gilt development unit (GDU) was also contained in Site 1. Except for the internal replacement gilts in the GDU, the weaned pig flow rotated around three facilities, 18-60 miles from the sow herd.
In Jan.08, clinical signs indicated a change of health status in the sow herd. Mh was diagnosed by Dako ELISA serology and histopathology in the sow herd and followed normal flows through the nursery/finisher system. All animals in the internal GDU and sow herd were infected by natural exposure. The breeding herd and GDU were vaccinated against Mh (M+PAC, Intervet) in late Jan.08 and again in Feb.08.
In Oct.08, efforts began to eliminate Mh, starting with depopulation of the GDU. The entire reproductive herd was vaccinated against Mh in Dec.08 (M+PAC, Intervet) and again Jan.09 (RespiSure, Pfizer). During Jan.09, the breeding herd received Lincomycin (Lincocin, Pfizer) through the water system and piglets received a weight-appropriate dose of injectable tulathromycin (Draxxin, Pfizer, 2mg/kg) at birth and 11 days later. During Jan.09, weaning occurred at >18 days of age (average weaning age was 20.6 days). By Feb.09, all females in Site 1 breeding herd were >11 months of age.
Starting in Feb.09, naïve replacement gilts entered the GDU and weaned pigs flowed into depopulated facilities. Each site of the post-weaning facilities was empty >2 weeks, though individual rooms were empty much longer.
Starting one month after the first negative replacement gilts (sentinels) entered Site 1, random sentinels were serologically tested monthly. Random pigs were tested monthly in the downstream flow as well, allowing for maternal antibody degradation. Mh IDEXX ELISA was used as the screening test. Mh Dako ELISA was used as the differential/confirmatory test on any positive IDEXX samples.

Results

Although sows infected naturally still exist in the breeding herd, shedding of Mh has apparently not occurred, based on continued monthly serologic sampling of sentinel animals and pig flow after the nursery depopulations. The absence of clinical signs and lack of Mh lesions on slaughter checks and routine necropsies (including Mh cultures, PCRs and histopathology) support this position. At the time of writing, serologic testing of sow herd sentinels at Site 1 has been Mh negative 12 months (>350 samples) and the off-site finishers have provided Mh negative slaughter-aged pigs six months (>100 samples). Tissues from >25 animals have been submitted for complete Mh analysis. Three slaughter checks from two finisher sites (n=90 pigs total) have shown no Mh lesions.

Discussion

In this case, Mh was eliminated with the following key factors:
  • Mh vaccination of the entire sow herd shortly after initial exposure and at end of elimination.
  • Continuous matings and farrowings throughout elimination process.
  • Youngest Mh positive animals were >11 months of age and in their second parity before introduction of Mh naïve replacements and weaning of Mh (suspected) negative piglet flow.
  • Lincomycin in water medication to breeding herd at end of elimination at Site 1.
  • ulathromycin injection of piglets at birth and 11 days later.
  • Depopulation of nursery and finisher facilities before receiving Mh negative pigs.



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