Eradication of Mycoplasma hyopneumoniae by partial depopulation and strategic medication with Vetmulin® / Rodotium® (Tiamulin)

The cash-flow disruption of a partial depopulation is less pronounced in comparison to a total depopulation and repopulation. The success rate of eradication by partial depopulation together with medication, namely Vetmulin® / Rodotium® (tiamulin) in combination with stringent biosecurity measures is high (approximately 90 - 95%). This is because: 

• M. hyopneumoniae is very sensitive to tiamulin
• High and consistent tiamulin concentrations are achieved in lung tissue and bronchial fluid

Field case

• Farrow to weaning herd of 700 sows
• The weaners (27 days old) were moved weekly to a compartmentalised nursery site and finally, at 11 weeks of age, transfered to all-in-all-out finishing barns
• The nursery and the different fattening units were located at different sites
• The pigs were suffering from chronic coughing and poor technical performance
• Enzootic Pneumonia was diagnosed

Stabilisation before the start of the medication program to reduce active shedding and transmission

• All pigs younger than 10 months of age were removed from the sow herd. Only animals older than 10 months and suckling piglets remained on site
• All diseased pigs were removed
• There was a temporary cessation of new pig introduction for 5 weeks
• Strict hygiene and disinfection protocols were implemented

Medication program

Sows

• Vetmulin® / Rodotium® microgranulated premix at 8-10 mg tiamulin hydrogen fumarate / kg bodyweight per day for 2 weeks
• Sick sows refusing to eat during the treatment period were removed from the herd or injected with Vetmulin® / Rodotium® 162 mg tiamulin base / ml (1.5 ml / 20 kg bodyweight)

Suckling piglets: intramuscular injection with tulathromycin

• 2.5 mg/kg bodyweight every 5 days
• from 1 week before until the end of the treatment period of the sows

The eradication took place in summertime to reduce pathogen transmission and facilitate the hygiene program.

M. hyopneumoniae - free pigs

• Pigs born of sows that were treated for the full 14 days prior to giving birth were: 
  • considered to be free from M. hyopneumoniae
  • no longer vaccinated against M. hyopneumoniae
  • transferred to completely depopulated facilities for weaners and fatteners that were thoroughly cleaned and disinfected at least one week before transfer
• Only gilts originating from negative herds were introduced to the breeding herd afterwards

M. hyopneumoniae monitoring after treatment cessation

• At 14, 23 and 30 weeks after the end of the medication program, weaners (11 weeks), fatteners (16-17 and 23-24 weeks), sows and gilts were sampled: 
  • Serology - ELISA tests: 155 negative results
  • Oral fluids and nasal swabs - PCR: 30 negative results
• Slaughterhouse check: absence of typical lung lesions
• Clinical signs: absent, resulting in a decreased use of antimicrobials

Boost in technical performance

• Suckling piglets

Table 1. Technical data of the suckling piglets comparing the 16 weeks immediately before and the 16 weeks immediately after treatment

• Nursery pigs

Table 2. Technical data of the pigs in the nursery comparing the 16 weeks immediately before and the 16 weeks immediately after treatment (total of 9589 and 8171 nursery pigs, respectively)

• Fattening pigs

Table 3. Technical data of fatteners comparing the last fattening batch before and the first batch after treatment (n=650)

Conclusion

M. hyopneumoniae was eradicated successfully by using a strategic medication program of Vetmulin® / Rodotium® in combination with biosecurity measures. An enormous performance boost was noted without a total depopulation of the sow herd or a stop in farrowing. 

References are available on request